/drivers/sqlite-wp7/sqlite/pager_c.cs
C# | 7747 lines | 3789 code | 503 blank | 3455 comment | 1412 complexity | dc87b803f83c8f2d9d393c1a45ec3a23 MD5 | raw file
- using System;
- using System.Diagnostics;
- using System.IO;
- using i16 = System.Int16;
- using i64 = System.Int64;
- using u8 = System.Byte;
- using u16 = System.UInt16;
- using u32 = System.UInt32;
- using Pgno = System.UInt32;
- using sqlite3_int64 = System.Int64;
- namespace Community.CsharpSqlite
- {
- using System.Text;
- using DbPage = Sqlite3.PgHdr;
- public partial class Sqlite3
- {
- /*
- ** 2001 September 15
- **
- ** The author disclaims copyright to this source code. In place of
- ** a legal notice, here is a blessing:
- **
- ** May you do good and not evil.
- ** May you find forgiveness for yourself and forgive others.
- ** May you share freely, never taking more than you give.
- **
- *************************************************************************
- ** This is the implementation of the page cache subsystem or "pager".
- **
- ** The pager is used to access a database disk file. It implements
- ** atomic commit and rollback through the use of a journal file that
- ** is separate from the database file. The pager also implements file
- ** locking to prevent two processes from writing the same database
- ** file simultaneously, or one process from reading the database while
- ** another is writing.
- *************************************************************************
- ** Included in SQLite3 port to C#-SQLite; 2008 Noah B Hart
- ** C#-SQLite is an independent reimplementation of the SQLite software library
- **
- ** SQLITE_SOURCE_ID: 2011-01-28 17:03:50 ed759d5a9edb3bba5f48f243df47be29e3fe8cd7
- **
- *************************************************************************
- */
- #if !SQLITE_OMIT_DISKIO
- //#include "sqliteInt.h"
- //#include "wal.h"
- /******************* NOTES ON THE DESIGN OF THE PAGER ************************
- **
- ** This comment block describes invariants that hold when using a rollback
- ** journal. These invariants do not apply for journal_mode=WAL,
- ** journal_mode=MEMORY, or journal_mode=OFF.
- **
- ** Within this comment block, a page is deemed to have been synced
- ** automatically as soon as it is written when PRAGMA synchronous=OFF.
- ** Otherwise, the page is not synced until the xSync method of the VFS
- ** is called successfully on the file containing the page.
- **
- ** Definition: A page of the database file is said to be "overwriteable" if
- ** one or more of the following are true about the page:
- **
- ** (a) The original content of the page as it was at the beginning of
- ** the transaction has been written into the rollback journal and
- ** synced.
- **
- ** (b) The page was a freelist leaf page at the start of the transaction.
- **
- ** (c) The page number is greater than the largest page that existed in
- ** the database file at the start of the transaction.
- **
- ** (1) A page of the database file is never overwritten unless one of the
- ** following are true:
- **
- ** (a) The page and all other pages on the same sector are overwriteable.
- **
- ** (b) The atomic page write optimization is enabled, and the entire
- ** transaction other than the update of the transaction sequence
- ** number consists of a single page change.
- **
- ** (2) The content of a page written into the rollback journal exactly matches
- ** both the content in the database when the rollback journal was written
- ** and the content in the database at the beginning of the current
- ** transaction.
- **
- ** (3) Writes to the database file are an integer multiple of the page size
- ** in length and are aligned on a page boundary.
- **
- ** (4) Reads from the database file are either aligned on a page boundary and
- ** an integer multiple of the page size in length or are taken from the
- ** first 100 bytes of the database file.
- **
- ** (5) All writes to the database file are synced prior to the rollback journal
- ** being deleted, truncated, or zeroed.
- **
- ** (6) If a master journal file is used, then all writes to the database file
- ** are synced prior to the master journal being deleted.
- **
- ** Definition: Two databases (or the same database at two points it time)
- ** are said to be "logically equivalent" if they give the same answer to
- ** all queries. Note in particular the the content of freelist leaf
- ** pages can be changed arbitarily without effecting the logical equivalence
- ** of the database.
- **
- ** (7) At any time, if any subset, including the empty set and the total set,
- ** of the unsynced changes to a rollback journal are removed and the
- ** journal is rolled back, the resulting database file will be logical
- ** equivalent to the database file at the beginning of the transaction.
- **
- ** (8) When a transaction is rolled back, the xTruncate method of the VFS
- ** is called to restore the database file to the same size it was at
- ** the beginning of the transaction. (In some VFSes, the xTruncate
- ** method is a no-op, but that does not change the fact the SQLite will
- ** invoke it.)
- **
- ** (9) Whenever the database file is modified, at least one bit in the range
- ** of bytes from 24 through 39 inclusive will be changed prior to releasing
- ** the EXCLUSIVE lock, thus signaling other connections on the same
- ** database to flush their caches.
- **
- ** (10) The pattern of bits in bytes 24 through 39 shall not repeat in less
- ** than one billion transactions.
- **
- ** (11) A database file is well-formed at the beginning and at the conclusion
- ** of every transaction.
- **
- ** (12) An EXCLUSIVE lock is held on the database file when writing to
- ** the database file.
- **
- ** (13) A SHARED lock is held on the database file while reading any
- ** content out of the database file.
- **
- ******************************************************************************/
- /*
- ** Macros for troubleshooting. Normally turned off
- */
- #if TRACE
- static bool sqlite3PagerTrace = false; /* True to enable tracing */
- //#define sqlite3DebugPrintf printf
- //#define PAGERTRACE(X) if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
- static void PAGERTRACE( string T, params object[] ap ) { if ( sqlite3PagerTrace )sqlite3DebugPrintf( T, ap ); }
- #else
- //#define PAGERTRACE(X)
- static void PAGERTRACE( string T, params object[] ap )
- {
- }
- #endif
- /*
- ** The following two macros are used within the PAGERTRACE() macros above
- ** to print out file-descriptors.
- **
- ** PAGERID() takes a pointer to a Pager struct as its argument. The
- ** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
- ** struct as its argument.
- */
- //#define PAGERID(p) ((int)(p.fd))
- static int PAGERID( Pager p )
- {
- return p.GetHashCode();
- }
- //#define FILEHANDLEID(fd) ((int)fd)
- static int FILEHANDLEID( sqlite3_file fd )
- {
- return fd.GetHashCode();
- }
- /*
- ** The Pager.eState variable stores the current 'state' of a pager. A
- ** pager may be in any one of the seven states shown in the following
- ** state diagram.
- **
- ** OPEN <------+------+
- ** | | |
- ** V | |
- ** +---------> READER-------+ |
- ** | | |
- ** | V |
- ** |<-------WRITER_LOCKED------> ERROR
- ** | | ^
- ** | V |
- ** |<------WRITER_CACHEMOD-------->|
- ** | | |
- ** | V |
- ** |<-------WRITER_DBMOD---------->|
- ** | | |
- ** | V |
- ** +<------WRITER_FINISHED-------->+
- **
- **
- ** List of state transitions and the C [function] that performs each:
- **
- ** OPEN -> READER [sqlite3PagerSharedLock]
- ** READER -> OPEN [pager_unlock]
- **
- ** READER -> WRITER_LOCKED [sqlite3PagerBegin]
- ** WRITER_LOCKED -> WRITER_CACHEMOD [pager_open_journal]
- ** WRITER_CACHEMOD -> WRITER_DBMOD [syncJournal]
- ** WRITER_DBMOD -> WRITER_FINISHED [sqlite3PagerCommitPhaseOne]
- ** WRITER_*** -> READER [pager_end_transaction]
- **
- ** WRITER_*** -> ERROR [pager_error]
- ** ERROR -> OPEN [pager_unlock]
- **
- **
- ** OPEN:
- **
- ** The pager starts up in this state. Nothing is guaranteed in this
- ** state - the file may or may not be locked and the database size is
- ** unknown. The database may not be read or written.
- **
- ** * No read or write transaction is active.
- ** * Any lock, or no lock at all, may be held on the database file.
- ** * The dbSize, dbOrigSize and dbFileSize variables may not be trusted.
- **
- ** READER:
- **
- ** In this state all the requirements for reading the database in
- ** rollback (non-WAL) mode are met. Unless the pager is (or recently
- ** was) in exclusive-locking mode, a user-level read transaction is
- ** open. The database size is known in this state.
- **
- ** A connection running with locking_mode=normal enters this state when
- ** it opens a read-transaction on the database and returns to state
- ** OPEN after the read-transaction is completed. However a connection
- ** running in locking_mode=exclusive (including temp databases) remains in
- ** this state even after the read-transaction is closed. The only way
- ** a locking_mode=exclusive connection can transition from READER to OPEN
- ** is via the ERROR state (see below).
- **
- ** * A read transaction may be active (but a write-transaction cannot).
- ** * A SHARED or greater lock is held on the database file.
- ** * The dbSize variable may be trusted (even if a user-level read
- ** transaction is not active). The dbOrigSize and dbFileSize variables
- ** may not be trusted at this point.
- ** * If the database is a WAL database, then the WAL connection is open.
- ** * Even if a read-transaction is not open, it is guaranteed that
- ** there is no hot-journal in the file-system.
- **
- ** WRITER_LOCKED:
- **
- ** The pager moves to this state from READER when a write-transaction
- ** is first opened on the database. In WRITER_LOCKED state, all locks
- ** required to start a write-transaction are held, but no actual
- ** modifications to the cache or database have taken place.
- **
- ** In rollback mode, a RESERVED or (if the transaction was opened with
- ** BEGIN EXCLUSIVE) EXCLUSIVE lock is obtained on the database file when
- ** moving to this state, but the journal file is not written to or opened
- ** to in this state. If the transaction is committed or rolled back while
- ** in WRITER_LOCKED state, all that is required is to unlock the database
- ** file.
- **
- ** IN WAL mode, WalBeginWriteTransaction() is called to lock the log file.
- ** If the connection is running with locking_mode=exclusive, an attempt
- ** is made to obtain an EXCLUSIVE lock on the database file.
- **
- ** * A write transaction is active.
- ** * If the connection is open in rollback-mode, a RESERVED or greater
- ** lock is held on the database file.
- ** * If the connection is open in WAL-mode, a WAL write transaction
- ** is open (i.e. sqlite3WalBeginWriteTransaction() has been successfully
- ** called).
- ** * The dbSize, dbOrigSize and dbFileSize variables are all valid.
- ** * The contents of the pager cache have not been modified.
- ** * The journal file may or may not be open.
- ** * Nothing (not even the first header) has been written to the journal.
- **
- ** WRITER_CACHEMOD:
- **
- ** A pager moves from WRITER_LOCKED state to this state when a page is
- ** first modified by the upper layer. In rollback mode the journal file
- ** is opened (if it is not already open) and a header written to the
- ** start of it. The database file on disk has not been modified.
- **
- ** * A write transaction is active.
- ** * A RESERVED or greater lock is held on the database file.
- ** * The journal file is open and the first header has been written
- ** to it, but the header has not been synced to disk.
- ** * The contents of the page cache have been modified.
- **
- ** WRITER_DBMOD:
- **
- ** The pager transitions from WRITER_CACHEMOD into WRITER_DBMOD state
- ** when it modifies the contents of the database file. WAL connections
- ** never enter this state (since they do not modify the database file,
- ** just the log file).
- **
- ** * A write transaction is active.
- ** * An EXCLUSIVE or greater lock is held on the database file.
- ** * The journal file is open and the first header has been written
- ** and synced to disk.
- ** * The contents of the page cache have been modified (and possibly
- ** written to disk).
- **
- ** WRITER_FINISHED:
- **
- ** It is not possible for a WAL connection to enter this state.
- **
- ** A rollback-mode pager changes to WRITER_FINISHED state from WRITER_DBMOD
- ** state after the entire transaction has been successfully written into the
- ** database file. In this state the transaction may be committed simply
- ** by finalizing the journal file. Once in WRITER_FINISHED state, it is
- ** not possible to modify the database further. At this point, the upper
- ** layer must either commit or rollback the transaction.
- **
- ** * A write transaction is active.
- ** * An EXCLUSIVE or greater lock is held on the database file.
- ** * All writing and syncing of journal and database data has finished.
- ** If no error occured, all that remains is to finalize the journal to
- ** commit the transaction. If an error did occur, the caller will need
- ** to rollback the transaction.
- **
- ** ERROR:
- **
- ** The ERROR state is entered when an IO or disk-full error (including
- ** SQLITE_IOERR_NOMEM) occurs at a point in the code that makes it
- ** difficult to be sure that the in-memory pager state (cache contents,
- ** db size etc.) are consistent with the contents of the file-system.
- **
- ** Temporary pager files may enter the ERROR state, but in-memory pagers
- ** cannot.
- **
- ** For example, if an IO error occurs while performing a rollback,
- ** the contents of the page-cache may be left in an inconsistent state.
- ** At this point it would be dangerous to change back to READER state
- ** (as usually happens after a rollback). Any subsequent readers might
- ** report database corruption (due to the inconsistent cache), and if
- ** they upgrade to writers, they may inadvertently corrupt the database
- ** file. To avoid this hazard, the pager switches into the ERROR state
- ** instead of READER following such an error.
- **
- ** Once it has entered the ERROR state, any attempt to use the pager
- ** to read or write data returns an error. Eventually, once all
- ** outstanding transactions have been abandoned, the pager is able to
- ** transition back to OPEN state, discarding the contents of the
- ** page-cache and any other in-memory state at the same time. Everything
- ** is reloaded from disk (and, if necessary, hot-journal rollback peformed)
- ** when a read-transaction is next opened on the pager (transitioning
- ** the pager into READER state). At that point the system has recovered
- ** from the error.
- **
- ** Specifically, the pager jumps into the ERROR state if:
- **
- ** 1. An error occurs while attempting a rollback. This happens in
- ** function sqlite3PagerRollback().
- **
- ** 2. An error occurs while attempting to finalize a journal file
- ** following a commit in function sqlite3PagerCommitPhaseTwo().
- **
- ** 3. An error occurs while attempting to write to the journal or
- ** database file in function pagerStress() in order to free up
- ** memory.
- **
- ** In other cases, the error is returned to the b-tree layer. The b-tree
- ** layer then attempts a rollback operation. If the error condition
- ** persists, the pager enters the ERROR state via condition (1) above.
- **
- ** Condition (3) is necessary because it can be triggered by a read-only
- ** statement executed within a transaction. In this case, if the error
- ** code were simply returned to the user, the b-tree layer would not
- ** automatically attempt a rollback, as it assumes that an error in a
- ** read-only statement cannot leave the pager in an internally inconsistent
- ** state.
- **
- ** * The Pager.errCode variable is set to something other than SQLITE_OK.
- ** * There are one or more outstanding references to pages (after the
- ** last reference is dropped the pager should move back to OPEN state).
- ** * The pager is not an in-memory pager.
- **
- **
- ** Notes:
- **
- ** * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
- ** connection is open in WAL mode. A WAL connection is always in one
- ** of the first four states.
- **
- ** * Normally, a connection open in exclusive mode is never in PAGER_OPEN
- ** state. There are two exceptions: immediately after exclusive-mode has
- ** been turned on (and before any read or write transactions are
- ** executed), and when the pager is leaving the "error state".
- **
- ** * See also: assert_pager_state().
- */
- //#define PAGER_OPEN 0
- //#define PAGER_READER 1
- //#define PAGER_WRITER_LOCKED 2
- //#define PAGER_WRITER_CACHEMOD 3
- //#define PAGER_WRITER_DBMOD 4
- //#define PAGER_WRITER_FINISHED 5
- //#define PAGER_ERROR 6
- const int PAGER_OPEN = 0;
- const int PAGER_READER = 1;
- const int PAGER_WRITER_LOCKED = 2;
- const int PAGER_WRITER_CACHEMOD = 3;
- const int PAGER_WRITER_DBMOD = 4;
- const int PAGER_WRITER_FINISHED = 5;
- const int PAGER_ERROR = 6;
- /*
- ** The Pager.eLock variable is almost always set to one of the
- ** following locking-states, according to the lock currently held on
- ** the database file: NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
- ** This variable is kept up to date as locks are taken and released by
- ** the pagerLockDb() and pagerUnlockDb() wrappers.
- **
- ** If the VFS xLock() or xUnlock() returns an error other than SQLITE_BUSY
- ** (i.e. one of the SQLITE_IOERR subtypes), it is not clear whether or not
- ** the operation was successful. In these circumstances pagerLockDb() and
- ** pagerUnlockDb() take a conservative approach - eLock is always updated
- ** when unlocking the file, and only updated when locking the file if the
- ** VFS call is successful. This way, the Pager.eLock variable may be set
- ** to a less exclusive (lower) value than the lock that is actually held
- ** at the system level, but it is never set to a more exclusive value.
- **
- ** This is usually safe. If an xUnlock fails or appears to fail, there may
- ** be a few redundant xLock() calls or a lock may be held for longer than
- ** required, but nothing really goes wrong.
- **
- ** The exception is when the database file is unlocked as the pager moves
- ** from ERROR to OPEN state. At this point there may be a hot-journal file
- ** in the file-system that needs to be rolled back (as part of a OPEN->SHARED
- ** transition, by the same pager or any other). If the call to xUnlock()
- ** fails at this point and the pager is left holding an EXCLUSIVE lock, this
- ** can confuse the call to xCheckReservedLock() call made later as part
- ** of hot-journal detection.
- **
- ** xCheckReservedLock() is defined as returning true "if there is a RESERVED
- ** lock held by this process or any others". So xCheckReservedLock may
- ** return true because the caller itself is holding an EXCLUSIVE lock (but
- ** doesn't know it because of a previous error in xUnlock). If this happens
- ** a hot-journal may be mistaken for a journal being created by an active
- ** transaction in another process, causing SQLite to read from the database
- ** without rolling it back.
- **
- ** To work around this, if a call to xUnlock() fails when unlocking the
- ** database in the ERROR state, Pager.eLock is set to UNKNOWN_LOCK. It
- ** is only changed back to a real locking state after a successful call
- ** to xLock(EXCLUSIVE). Also, the code to do the OPEN->SHARED state transition
- ** omits the check for a hot-journal if Pager.eLock is set to UNKNOWN_LOCK
- ** lock. Instead, it assumes a hot-journal exists and obtains an EXCLUSIVE
- ** lock on the database file before attempting to roll it back. See function
- ** PagerSharedLock() for more detail.
- **
- ** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in
- ** PAGER_OPEN state.
- */
- //#define UNKNOWN_LOCK (EXCLUSIVE_LOCK+1)
- const int UNKNOWN_LOCK = ( EXCLUSIVE_LOCK + 1 );
- /*
- ** A macro used for invoking the codec if there is one
- */
- // The E parameter is what executes when there is an error,
- // cannot implement here, since this is not really a macro
- // calling code must be modified to call E when truen
- #if SQLITE_HAS_CODEC
- //# define CODEC1(P,D,N,X,E) \
- //if( P.xCodec && P.xCodec(P.pCodec,D,N,X)==0 ){ E; }
- static bool CODEC1( Pager P, byte[] D, uint N /* page number */, int X /* E (moved to caller */)
- {
- return ( ( P.xCodec != null ) && ( P.xCodec( P.pCodec, D, N, X ) == null ) );
- }
- // The E parameter is what executes when there is an error,
- // cannot implement here, since this is not really a macro
- // calling code must be modified to call E when truen
- //# define CODEC2(P,D,N,X,E,O) \
- //if( P.xCodec==0 ){ O=(char*)D; }else \
- //if( (O=(char*)(P.xCodec(P.pCodec,D,N,X)))==0 ){ E; }
- static bool CODEC2( Pager P, byte[] D, uint N, int X, ref byte[] O )
- {
- if ( P.xCodec == null )
- {
- O = D; // do nothing
- return false;
- }
- else
- {
- return ( ( O = P.xCodec( P.pCodec, D, N, X ) ) == null );
- }
- }
- #else
- //# define CODEC1(P,D,N,X,E) /* NO-OP */
- static bool CODEC1 (Pager P, byte[] D, uint N /* page number */, int X /* E (moved to caller */) { return false; }
- //# define CODEC2(P,D,N,X,E,O) O=(char*)D
- static bool CODEC2( Pager P, byte[] D, uint N, int X, ref byte[] O ) { O = D; return false; }
- #endif
- /*
- ** The maximum allowed sector size. 64KiB. If the xSectorsize() method
- ** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
- ** This could conceivably cause corruption following a power failure on
- ** such a system. This is currently an undocumented limit.
- */
- //#define MAX_SECTOR_SIZE 0x10000
- const int MAX_SECTOR_SIZE = 0x10000;
- /*
- ** An instance of the following structure is allocated for each active
- ** savepoint and statement transaction in the system. All such structures
- ** are stored in the Pager.aSavepoint[] array, which is allocated and
- ** resized using sqlite3Realloc().
- **
- ** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
- ** set to 0. If a journal-header is written into the main journal while
- ** the savepoint is active, then iHdrOffset is set to the byte offset
- ** immediately following the last journal record written into the main
- ** journal before the journal-header. This is required during savepoint
- ** rollback (see pagerPlaybackSavepoint()).
- */
- //typedef struct PagerSavepoint PagerSavepoint;
- public class PagerSavepoint
- {
- public i64 iOffset; /* Starting offset in main journal */
- public i64 iHdrOffset; /* See above */
- public Bitvec pInSavepoint; /* Set of pages in this savepoint */
- public Pgno nOrig; /* Original number of pages in file */
- public Pgno iSubRec; /* Index of first record in sub-journal */
- #if !SQLITE_OMIT_WAL
- public u32 aWalData[WAL_SAVEPOINT_NDATA]; /* WAL savepoint context */
- #else
- public object aWalData = null; /* Used for C# convenience */
- #endif
- public static implicit operator bool( PagerSavepoint b )
- {
- return ( b != null );
- }
- };
- /*
- ** A open page cache is an instance of struct Pager. A description of
- ** some of the more important member variables follows:
- **
- ** eState
- **
- ** The current 'state' of the pager object. See the comment and state
- ** diagram above for a description of the pager state.
- **
- ** eLock
- **
- ** For a real on-disk database, the current lock held on the database file -
- ** NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
- **
- ** For a temporary or in-memory database (neither of which require any
- ** locks), this variable is always set to EXCLUSIVE_LOCK. Since such
- ** databases always have Pager.exclusiveMode==1, this tricks the pager
- ** logic into thinking that it already has all the locks it will ever
- ** need (and no reason to release them).
- **
- ** In some (obscure) circumstances, this variable may also be set to
- ** UNKNOWN_LOCK. See the comment above the #define of UNKNOWN_LOCK for
- ** details.
- **
- ** changeCountDone
- **
- ** This boolean variable is used to make sure that the change-counter
- ** (the 4-byte header field at byte offset 24 of the database file) is
- ** not updated more often than necessary.
- **
- ** It is set to true when the change-counter field is updated, which
- ** can only happen if an exclusive lock is held on the database file.
- ** It is cleared (set to false) whenever an exclusive lock is
- ** relinquished on the database file. Each time a transaction is committed,
- ** The changeCountDone flag is inspected. If it is true, the work of
- ** updating the change-counter is omitted for the current transaction.
- **
- ** This mechanism means that when running in exclusive mode, a connection
- ** need only update the change-counter once, for the first transaction
- ** committed.
- **
- ** setMaster
- **
- ** When PagerCommitPhaseOne() is called to commit a transaction, it may
- ** (or may not) specify a master-journal name to be written into the
- ** journal file before it is synced to disk.
- **
- ** Whether or not a journal file contains a master-journal pointer affects
- ** the way in which the journal file is finalized after the transaction is
- ** committed or rolled back when running in "journal_mode=PERSIST" mode.
- ** If a journal file does not contain a master-journal pointer, it is
- ** finalized by overwriting the first journal header with zeroes. If
- ** it does contain a master-journal pointer the journal file is finalized
- ** by truncating it to zero bytes, just as if the connection were
- ** running in "journal_mode=truncate" mode.
- **
- ** Journal files that contain master journal pointers cannot be finalized
- ** simply by overwriting the first journal-header with zeroes, as the
- ** master journal pointer could interfere with hot-journal rollback of any
- ** subsequently interrupted transaction that reuses the journal file.
- **
- ** The flag is cleared as soon as the journal file is finalized (either
- ** by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the
- ** journal file from being successfully finalized, the setMaster flag
- ** is cleared anyway (and the pager will move to ERROR state).
- **
- ** doNotSpill, doNotSyncSpill
- **
- ** These two boolean variables control the behaviour of cache-spills
- ** (calls made by the pcache module to the pagerStress() routine to
- ** write cached data to the file-system in order to free up memory).
- **
- ** When doNotSpill is non-zero, writing to the database from pagerStress()
- ** is disabled altogether. This is done in a very obscure case that
- ** comes up during savepoint rollback that requires the pcache module
- ** to allocate a new page to prevent the journal file from being written
- ** while it is being traversed by code in pager_playback().
- **
- ** If doNotSyncSpill is non-zero, writing to the database from pagerStress()
- ** is permitted, but syncing the journal file is not. This flag is set
- ** by sqlite3PagerWrite() when the file-system sector-size is larger than
- ** the database page-size in order to prevent a journal sync from happening
- ** in between the journalling of two pages on the same sector.
- **
- ** subjInMemory
- **
- ** This is a boolean variable. If true, then any required sub-journal
- ** is opened as an in-memory journal file. If false, then in-memory
- ** sub-journals are only used for in-memory pager files.
- **
- ** This variable is updated by the upper layer each time a new
- ** write-transaction is opened.
- **
- ** dbSize, dbOrigSize, dbFileSize
- **
- ** Variable dbSize is set to the number of pages in the database file.
- ** It is valid in PAGER_READER and higher states (all states except for
- ** OPEN and ERROR).
- **
- ** dbSize is set based on the size of the database file, which may be
- ** larger than the size of the database (the value stored at offset
- ** 28 of the database header by the btree). If the size of the file
- ** is not an integer multiple of the page-size, the value stored in
- ** dbSize is rounded down (i.e. a 5KB file with 2K page-size has dbSize==2).
- ** Except, any file that is greater than 0 bytes in size is considered
- ** to have at least one page. (i.e. a 1KB file with 2K page-size leads
- ** to dbSize==1).
- **
- ** During a write-transaction, if pages with page-numbers greater than
- ** dbSize are modified in the cache, dbSize is updated accordingly.
- ** Similarly, if the database is truncated using PagerTruncateImage(),
- ** dbSize is updated.
- **
- ** Variables dbOrigSize and dbFileSize are valid in states
- ** PAGER_WRITER_LOCKED and higher. dbOrigSize is a copy of the dbSize
- ** variable at the start of the transaction. It is used during rollback,
- ** and to determine whether or not pages need to be journalled before
- ** being modified.
- **
- ** Throughout a write-transaction, dbFileSize contains the size of
- ** the file on disk in pages. It is set to a copy of dbSize when the
- ** write-transaction is first opened, and updated when VFS calls are made
- ** to write or truncate the database file on disk.
- **
- ** The only reason the dbFileSize variable is required is to suppress
- ** unnecessary calls to xTruncate() after committing a transaction. If,
- ** when a transaction is committed, the dbFileSize variable indicates
- ** that the database file is larger than the database image (Pager.dbSize),
- ** pager_truncate() is called. The pager_truncate() call uses xFilesize()
- ** to measure the database file on disk, and then truncates it if required.
- ** dbFileSize is not used when rolling back a transaction. In this case
- ** pager_truncate() is called unconditionally (which means there may be
- ** a call to xFilesize() that is not strictly required). In either case,
- ** pager_truncate() may cause the file to become smaller or larger.
- **
- ** dbHintSize
- **
- ** The dbHintSize variable is used to limit the number of calls made to
- ** the VFS xFileControl(FCNTL_SIZE_HINT) method.
- **
- ** dbHintSize is set to a copy of the dbSize variable when a
- ** write-transaction is opened (at the same time as dbFileSize and
- ** dbOrigSize). If the xFileControl(FCNTL_SIZE_HINT) method is called,
- ** dbHintSize is increased to the number of pages that correspond to the
- ** size-hint passed to the method call. See pager_write_pagelist() for
- ** details.
- **
- ** errCode
- **
- ** The Pager.errCode variable is only ever used in PAGER_ERROR state. It
- ** is set to zero in all other states. In PAGER_ERROR state, Pager.errCode
- ** is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX
- ** sub-codes.
- */
- public class Pager
- {
- public sqlite3_vfs pVfs; /* OS functions to use for IO */
- public bool exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */
- public u8 journalMode; /* One of the PAGER_JOURNALMODE_* values */
- public u8 useJournal; /* Use a rollback journal on this file */
- public u8 noReadlock; /* Do not bother to obtain readlocks */
- public bool noSync; /* Do not sync the journal if true */
- public bool fullSync; /* Do extra syncs of the journal for robustness */
- public u8 ckptSyncFlags; /* SYNC_NORMAL or SYNC_FULL for checkpoint */
- public u8 syncFlags; /* SYNC_NORMAL or SYNC_FULL otherwise */
- public bool tempFile; /* zFilename is a temporary file */
- public bool readOnly; /* True for a read-only database */
- public bool alwaysRollback; /* Disable DontRollback() for all pages */
- public u8 memDb; /* True to inhibit all file I/O */
- /**************************************************************************
- ** The following block contains those class members that change during
- ** routine opertion. Class members not in this block are either fixed
- ** when the pager is first created or else only change when there is a
- ** significant mode change (such as changing the page_size, locking_mode,
- ** or the journal_mode). From another view, these class members describe
- ** the "state" of the pager, while other class members describe the
- ** "configuration" of the pager.
- */
- public u8 eState; /* Pager state (OPEN, READER, WRITER_LOCKED..) */
- public u8 eLock; /* Current lock held on database file */
- public bool changeCountDone; /* Set after incrementing the change-counter */
- public int setMaster; /* True if a m-j name has been written to jrnl */
- public u8 doNotSpill; /* Do not spill the cache when non-zero */
- public u8 doNotSyncSpill; /* Do not do a spill that requires jrnl sync */
- public u8 subjInMemory; /* True to use in-memory sub-journals */
- public Pgno dbSize; /* Number of pages in the database */
- public Pgno dbOrigSize; /* dbSize before the current transaction */
- public Pgno dbFileSize; /* Number of pages in the database file */
- public Pgno dbHintSize; /* Value passed to FCNTL_SIZE_HINT call */
- public int errCode; /* One of several kinds of errors */
- public int nRec; /* Pages journalled since last j-header written */
- public u32 cksumInit; /* Quasi-random value added to every checksum */
- public u32 nSubRec; /* Number of records written to sub-journal */
- public Bitvec pInJournal; /* One bit for each page in the database file */
- public sqlite3_file fd; /* File descriptor for database */
- public sqlite3_file jfd; /* File descriptor for main journal */
- public sqlite3_file sjfd; /* File descriptor for sub-journal */
- public i64 journalOff; /* Current write offset in the journal file */
- public i64 journalHdr; /* Byte offset to previous journal header */
- public sqlite3_backup pBackup; /* Pointer to list of ongoing backup processes */
- public PagerSavepoint[] aSavepoint;/* Array of active savepoints */
- public int nSavepoint; /* Number of elements in aSavepoint[] */
- public u8[] dbFileVers = new u8[16];/* Changes whenever database file changes */
- /*
- ** End of the routinely-changing class members
- ***************************************************************************/
- public u16 nExtra; /* Add this many bytes to each in-memory page */
- public i16 nReserve; /* Number of unused bytes at end of each page */
- public u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
- public u32 sectorSize; /* Assumed sector size during rollback */
- public int pageSize; /* Number of bytes in a page */
- public Pgno mxPgno; /* Maximum allowed size of the database */
- public i64 journalSizeLimit; /* Size limit for persistent journal files */
- public string zFilename; /* Name of the database file */
- public string zJournal; /* Name of the journal file */
- public dxBusyHandler xBusyHandler; /* Function to call when busy */
- public object pBusyHandlerArg; /* Context argument for xBusyHandler */
- #if SQLITE_TEST || DEBUG
- public int nHit, nMiss; /* Cache hits and missing */
- public int nRead, nWrite; /* Database pages read/written */
- #else
- public int nHit;
- #endif
- public dxReiniter xReiniter; //(DbPage*,int);/* Call this routine when reloading pages */
- #if SQLITE_HAS_CODEC
- //void *(*xCodec)(void*,void*,Pgno,int);
- public dxCodec xCodec; /* Routine for en/decoding data */
- //void (*xCodecSizeChng)(void*,int,int);
- public dxCodecSizeChng xCodecSizeChng; /* Notify of page size changes */
- //void (*xCodecFree)(void*);
- public dxCodecFree xCodecFree; /* Destructor for the codec */
- public codec_ctx pCodec; /* First argument to xCodec... methods */
- #endif
- public byte[] pTmpSpace; /* Pager.pageSize bytes of space for tmp use */
- public PCache pPCache; /* Pointer to page cache object */
- #if !SQLITE_OMIT_WAL
- public Wal pWal; /* Write-ahead log used by "journal_mode=wal" */
- public string zWal; /* File name for write-ahead log */
- #else
- public object pWal = null; /* Having this dummy here makes C# easier */
- #endif
- };
- /*
- ** The following global variables hold counters used for
- ** testing purposes only. These variables do not exist in
- ** a non-testing build. These variables are not thread-safe.
- */
- #if SQLITE_TEST
- //static int sqlite3_pager_readdb_count = 0; /* Number of full pages read from DB */
- //static int sqlite3_pager_writedb_count = 0; /* Number of full pages written to DB */
- //static int sqlite3_pager_writej_count = 0; /* Number of pages written to journal */
- static void PAGER_INCR( ref int v )
- {
- v++;
- }
- #else
- //# define PAGER_INCR(v)
- static void PAGER_INCR(ref int v) {}
- #endif
- /*
- ** Journal files begin with the following magic string. The data
- ** was obtained from /dev/random. It is used only as a sanity check.
- **
- ** Since version 2.8.0, the journal format contains additional sanity
- ** checking information. If the power fails while the journal is being
- ** written, semi-random garbage data might appear in the journal
- ** file after power is restored. If an attempt is then made
- ** to roll the journal back, the database could be corrupted. The additional
- ** sanity checking data is an attempt to discover the garbage in the
- ** journal and ignore it.
- **
- ** The sanity checking information for the new journal format consists
- ** of a 32-bit checksum on each page of data. The checksum covers both
- ** the page number and the pPager.pageSize bytes of data for the page.
- ** This cksum is initialized to a 32-bit random value that appears in the
- ** journal file right after the header. The random initializer is important,
- ** because garbage data that appears at the end of a journal is likely
- ** data that was once in other files that have now been deleted. If the
- ** garbage data came from an obsolete journal file, the checksums might
- ** be correct. But by initializing the checksum to random value which
- ** is different for every journal, we minimize that risk.
- */
- static byte[] aJournalMagic = new byte[] {
- 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
- };
- /*
- ** The size of the of each page record in the journal is given by
- ** the following macro.
- */
- //#define JOURNAL_PG_SZ(pPager) ((pPager.pageSize) + 8)
- static int JOURNAL_PG_SZ( Pager pPager )
- {
- return ( pPager.pageSize + 8 );
- }
- /*
- ** The journal header size for this pager. This is usually the same
- ** size as a single disk sector. See also setSectorSize().
- */
- //#define JOURNAL_HDR_SZ(pPager) (pPager.sectorSize)
- static u32 JOURNAL_HDR_SZ( Pager pPager )
- {
- return ( pPager.sectorSize );
- }
- /*
- ** The macro MEMDB is true if we are dealing with an in-memory database.
- ** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
- ** the value of MEMDB will be a constant and the compiler will optimize
- ** out code that would never execute.
- */
- #if SQLITE_OMIT_MEMORYDB
- //# define MEMDB 0
- const int MEMDB = 0;
- #else
- //# define MEMDB pPager.memDb
- #endif
- /*
- ** The maximum legal page number is (2^31 - 1).
- */
- //#define PAGER_MAX_PGNO 2147483647
- const int PAGER_MAX_PGNO = 2147483647;
- /*
- ** The argument to this macro is a file descriptor (type sqlite3_file*).
- ** Return 0 if it is not open, or non-zero (but not 1) if it is.
- **
- ** This is so that expressions can be written as:
- **
- ** if( isOpen(pPager->jfd) ){ ...
- **
- ** instead of
- **
- ** if( pPager->jfd->pMethods ){ ...
- */
- //#define isOpen(pFd) ((pFd)->pMethods)
- static bool isOpen( sqlite3_file pFd )
- {
- return pFd.pMethods != null;
- }
- /*
- ** Return true if this pager uses a write-ahead log instead of the usual
- ** rollback journal. Otherwise false.
- */
- #if !SQLITE_OMIT_WAL
- static int pagerUseWal(Pager *pPager){
- return (pPager->pWal!=0);
- }
- #else
- //# define pagerUseWal(x) 0
- static bool pagerUseWal( Pager x )
- {
- return false;
- }
- //# define pagerRollbackWal(x) 0
- static int pagerRollbackWal( Pager x )
- {
- return 0;
- }
- //# define pagerWalFrames(v,w,x,y,z) 0
- static int pagerWalFrames( Pager v, PgHdr w, Pgno x, int y, int z )
- {
- return 0;
- }
- //# define pagerOpenWalIfPresent(z) SQLITE_OK
- static int pagerOpenWalIfPresent( Pager z )
- {
- return SQLITE_OK;
- }
- //# define pagerBeginReadTransaction(z) SQLITE_OK
- static int pagerBeginReadTransaction( Pager z )
- {
- return SQLITE_OK;
- }
- #endif
- #if NDEBUG
- /*
- ** Usage:
- **
- ** Debug.Assert( assert_pager_state(pPager) );
- **
- ** This function runs many Debug.Asserts to try to find inconsistencies in
- ** the internal state of the Pager object.
- */
- static bool assert_pager_state( Pager p )
- {
- Pager pPager = p;
- /* State must be valid. */
- Debug.Assert( p.eState == PAGER_OPEN
- || p.eState == PAGER_READER
- || p.eState == PAGER_WRITER_LOCKED
- || p.eState == PAGER_WRITER_CACHEMOD
- || p.eState == PAGER_WRITER_DBMOD
- || p.eState == PAGER_WRITER_FINISHED
- || p.eState == PAGER_ERROR
- );
- /* Regardless of the current state, a temp-file connection always behaves
- ** as if it has an exclusive lock on the database file. It never updates
- ** the change-counter field, so the changeCountDone flag is always set.
- */
- Debug.Assert( p.tempFile == false || p.eLock == EXCLUSIVE_LOCK );
- Debug.Assert( p.tempFile == false || pPager.changeCountDone );
- /* If the useJournal flag is clear, the journal-mode must be "OFF".
- ** And if the journal-mode is "OFF", the journal file must not be open.
- */
- Debug.Assert( p.journalMode == PAGER_JOURNALMODE_OFF || p.useJournal != 0 );
- Debug.Assert( p.journalMode != PAGER_JOURNALMODE_OFF || !isOpen( p.jfd ) );
- /* Check that MEMDB implies noSync. And an in-memory journal. Since
- ** this means an in-memory pager performs no IO at all, it cannot encounter
- ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing
- ** a journal file. (although the in-memory journal implementation may
- ** return SQLITE_IOERR_NOMEM while the journal file is being written). It
- ** is therefore not possible for an in-memory pager to enter the ERROR
- ** state.
- */
- if (
- #if SQLITE_OMIT_MEMORYDB
- 0!=MEMDB
- #else
- 0 != pPager.memDb
- #endif
- )
- {
- Debug.Assert( p.noSync );
- Debug.Assert( p.journalMode == PAGER_JOURNALMODE_OFF
- || p.journalMode == PAGER_JOURNALMODE_MEMORY
- );
- Debug.Assert( p.eState != PAGER_ERROR && p.eState != PAGER_OPEN );
- Debug.Assert( pagerUseWal( p ) == false );
- }
- /* If changeCountDone is set, a RESERVED lock or greater must be held
- ** on the file.
- */
- Debug.Assert( pPager.changeCountDone == false || pPager.eLock >= RESERVED_LOCK );
- Debug.Assert( p.eLock != PENDING_LOCK );
- switch ( p.eState )
- {
- case PAGER_OPEN:
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- Debug.Assert( pPager.errCode == SQLITE_OK );
- Debug.Assert( sqlite3PcacheRefCount( pPager.pPCache ) == 0 || pPager.tempFile );
- break;
- case PAGER_READER:
- Debug.Assert( pPager.errCode == SQLITE_OK );
- Debug.Assert( p.eLock != UNKNOWN_LOCK );
- Debug.Assert( p.eLock >= SHARED_LOCK || p.noReadlock != 0 );
- break;
- case PAGER_WRITER_LOCKED:
- Debug.Assert( p.eLock != UNKNOWN_LOCK );
- Debug.Assert( pPager.errCode == SQLITE_OK );
- if ( !pagerUseWal( pPager ) )
- {
- Debug.Assert( p.eLock >= RESERVED_LOCK );
- }
- Debug.Assert( pPager.dbSize == pPager.dbOrigSize );
- Debug.Assert( pPager.dbOrigSize == pPager.dbFileSize );
- Debug.Assert( pPager.dbOrigSize == pPager.dbHintSize );
- Debug.Assert( pPager.setMaster == 0 );
- break;
- case PAGER_WRITER_CACHEMOD:
- Debug.Assert( p.eLock != UNKNOWN_LOCK );
- Debug.Assert( pPager.errCode == SQLITE_OK );
- if ( !pagerUseWal( pPager ) )
- {
- /* It is possible that if journal_mode=wal here that neither the
- ** journal file nor the WAL file are open. This happens during
- ** a rollback transaction that switches from journal_mode=off
- ** to journal_mode=wal.
- */
- Debug.Assert( p.eLock >= RESERVED_LOCK );
- Debug.Assert( isOpen( p.jfd )
- || p.journalMode == PAGER_JOURNALMODE_OFF
- || p.journalMode == PAGER_JOURNALMODE_WAL
- );
- }
- Debug.Assert( pPager.dbOrigSize == pPager.dbFileSize );
- Debug.Assert( pPager.dbOrigSize == pPager.dbHintSize );
- break;
- case PAGER_WRITER_DBMOD:
- Debug.Assert( p.eLock == EXCLUSIVE_LOCK );
- Debug.Assert( pPager.errCode == SQLITE_OK );
- Debug.Assert( !pagerUseWal( pPager ) );
- Debug.Assert( p.eLock >= EXCLUSIVE_LOCK );
- Debug.Assert( isOpen( p.jfd )
- || p.journalMode == PAGER_JOURNALMODE_OFF
- || p.journalMode == PAGER_JOURNALMODE_WAL
- );
- Debug.Assert( pPager.dbOrigSize <= pPager.dbHintSize );
- break;
- case PAGER_WRITER_FINISHED:
- Debug.Assert( p.eLock == EXCLUSIVE_LOCK );
- Debug.Assert( pPager.errCode == SQLITE_OK );
- Debug.Assert( !pagerUseWal( pPager ) );
- Debug.Assert( isOpen( p.jfd )
- || p.journalMode == PAGER_JOURNALMODE_OFF
- || p.journalMode == PAGER_JOURNALMODE_WAL
- );
- break;
- case PAGER_ERROR:
- /* There must be at least one outstanding reference to the pager if
- ** in ERROR state. Otherwise the pager should have already dropped
- ** back to OPEN state.
- */
- Debug.Assert( pPager.errCode != SQLITE_OK );
- Debug.Assert( sqlite3PcacheRefCount( pPager.pPCache ) > 0 );
- break;
- }
- return true;
- }
- #else
- static bool assert_pager_state( Pager pPager )
- {
- return true;
- }
- #endif //* ifndef NDEBUG */
- #if SQLITE_DEBUG
- /*
- ** Return a pointer to a human readable string in a static buffer
- ** containing the state of the Pager object passed as an argument. This
- ** is intended to be used within debuggers. For example, as an alternative
- ** to "print *pPager" in gdb:
- **
- ** (gdb) printf "%s", print_pager_state(pPager)
- */
- static string print_pager_state( Pager p )
- {
- StringBuilder zRet = new StringBuilder( 1024 );
- sqlite3_snprintf( 1024, zRet,
- "Filename: %s\n" +
- "State: %s errCode=%d\n" +
- "Lock: %s\n" +
- "Locking mode: locking_mode=%s\n" +
- "Journal mode: journal_mode=%s\n" +
- "Backing store: tempFile=%d memDb=%d useJournal=%d\n" +
- "Journal: journalOff=%lld journalHdr=%lld\n" +
- "Size: dbsize=%d dbOrigSize=%d dbFileSize=%d\n"
- , p.zFilename
- , p.eState == PAGER_OPEN ? "OPEN" :
- p.eState == PAGER_READER ? "READER" :
- p.eState == PAGER_WRITER_LOCKED ? "WRITER_LOCKED" :
- p.eState == PAGER_WRITER_CACHEMOD ? "WRITER_CACHEMOD" :
- p.eState == PAGER_WRITER_DBMOD ? "WRITER_DBMOD" :
- p.eState == PAGER_WRITER_FINISHED ? "WRITER_FINISHED" :
- p.eState == PAGER_ERROR ? "ERROR" : "?error?"
- , (int)p.errCode
- , p.eLock == NO_LOCK ? "NO_LOCK" :
- p.eLock == RESERVED_LOCK ? "RESERVED" :
- p.eLock == EXCLUSIVE_LOCK ? "EXCLUSIVE" :
- p.eLock == SHARED_LOCK ? "SHARED" :
- p.eLock == UNKNOWN_LOCK ? "UNKNOWN" : "?error?"
- , p.exclusiveMode ? "exclusive" : "normal"
- , p.journalMode == PAGER_JOURNALMODE_MEMORY ? "memory" :
- p.journalMode == PAGER_JOURNALMODE_OFF ? "off" :
- p.journalMode == PAGER_JOURNALMODE_DELETE ? "delete" :
- p.journalMode == PAGER_JOURNALMODE_PERSIST ? "persist" :
- p.journalMode == PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
- p.journalMode == PAGER_JOURNALMODE_WAL ? "wal" : "?error?"
- , p.tempFile ? 1 : 0, (int)p.memDb, (int)p.useJournal
- , p.journalOff, p.journalHdr
- , (int)p.dbSize, (int)p.dbOrigSize, (int)p.dbFileSize
- );
- return zRet.ToString();
- }
- #endif
- /*
- ** Return true if it is necessary to write page *pPg into the sub-journal.
- ** A page needs to be written into the sub-journal if there exists one
- ** or more open savepoints for which:
- **
- ** * The page-number is less than or equal to PagerSavepoint.nOrig, and
- ** * The bit corresponding to the page-number is not set in
- ** PagerSavepoint.pInSavepoint.
- */
- static bool subjRequiresPage( PgHdr pPg )
- {
- u32 pgno = pPg.pgno;
- Pager pPager = pPg.pPager;
- int i;
- for ( i = 0; i < pPager.nSavepoint; i++ )
- {
- PagerSavepoint p = pPager.aSavepoint[i];
- if ( p.nOrig >= pgno && 0 == sqlite3BitvecTest( p.pInSavepoint, pgno ) )
- {
- return true;
- }
- }
- return false;
- }
- /*
- ** Return true if the page is already in the journal file.
- */
- static bool pageInJournal( PgHdr pPg )
- {
- return sqlite3BitvecTest( pPg.pPager.pInJournal, pPg.pgno ) != 0;
- }
- /*
- ** Read a 32-bit integer from the given file descriptor. Store the integer
- ** that is read in pRes. Return SQLITE_OK if everything worked, or an
- ** error code is something goes wrong.
- **
- ** All values are stored on disk as big-endian.
- */
- static int read32bits( sqlite3_file fd, int offset, ref int pRes )
- {
- u32 u32_pRes = 0;
- int rc = read32bits( fd, offset, ref u32_pRes );
- pRes = (int)u32_pRes;
- return rc;
- }
- static int read32bits( sqlite3_file fd, i64 offset, ref u32 pRes )
- {
- int rc = read32bits( fd, (int)offset, ref pRes );
- return rc;
- }
- static int read32bits( sqlite3_file fd, int offset, ref u32 pRes )
- {
- byte[] ac = new byte[4];
- int rc = sqlite3OsRead( fd, ac, ac.Length, offset );
- if ( rc == SQLITE_OK )
- {
- pRes = sqlite3Get4byte( ac );
- }
- return rc;
- }
- /*
- ** Write a 32-bit integer into a string buffer in big-endian byte order.
- */
- //#define put32bits(A,B) sqlite3sqlite3Put4byte((u8*)A,B)
- static void put32bits( string ac, int offset, int val )
- {
- byte[] A = new byte[4];
- A[0] = (byte)ac[offset + 0];
- A[1] = (byte)ac[offset + 1];
- A[2] = (byte)ac[offset + 2];
- A[3] = (byte)ac[offset + 3];
- sqlite3Put4byte( A, 0, val );
- }
- static void put32bits( byte[] ac, int offset, int val )
- {
- sqlite3Put4byte( ac, offset, (u32)val );
- }
- static void put32bits( byte[] ac, u32 val )
- {
- sqlite3Put4byte( ac, 0U, val );
- }
- static void put32bits( byte[] ac, int offset, u32 val )
- {
- sqlite3Put4byte( ac, offset, val );
- }
- /*
- ** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK
- ** on success or an error code is something goes wrong.
- */
- static int write32bits( sqlite3_file fd, i64 offset, u32 val )
- {
- byte[] ac = new byte[4];
- put32bits( ac, val );
- return sqlite3OsWrite( fd, ac, 4, offset );
- }
- /*
- ** Unlock the database file to level eLock, which must be either NO_LOCK
- ** or SHARED_LOCK. Regardless of whether or not the call to xUnlock()
- ** succeeds, set the Pager.eLock variable to match the (attempted) new lock.
- **
- ** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
- ** called, do not modify it. See the comment above the #define of
- ** UNKNOWN_LOCK for an explanation of this.
- */
- static int pagerUnlockDb( Pager pPager, int eLock )
- {
- int rc = SQLITE_OK;
- Debug.Assert( !pPager.exclusiveMode || pPager.eLock == eLock );
- Debug.Assert( eLock == NO_LOCK || eLock == SHARED_LOCK );
- Debug.Assert( eLock != NO_LOCK || pagerUseWal( pPager ) == false );
- if ( isOpen( pPager.fd ) )
- {
- Debug.Assert( pPager.eLock >= eLock );
- rc = sqlite3OsUnlock( pPager.fd, eLock );
- if ( pPager.eLock != UNKNOWN_LOCK )
- {
- pPager.eLock = (u8)eLock;
- }
- IOTRACE( "UNLOCK %p %d\n", pPager, eLock );
- }
- return rc;
- }
- /*
- ** Lock the database file to level eLock, which must be either SHARED_LOCK,
- ** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
- ** Pager.eLock variable to the new locking state.
- **
- ** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
- ** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK.
- ** See the comment above the #define of UNKNOWN_LOCK for an explanation
- ** of this.
- */
- static int pagerLockDb( Pager pPager, int eLock )
- {
- int rc = SQLITE_OK;
- Debug.Assert( eLock == SHARED_LOCK || eLock == RESERVED_LOCK || eLock == EXCLUSIVE_LOCK );
- if ( pPager.eLock < eLock || pPager.eLock == UNKNOWN_LOCK )
- {
- rc = sqlite3OsLock( pPager.fd, eLock );
- if ( rc == SQLITE_OK && ( pPager.eLock != UNKNOWN_LOCK || eLock == EXCLUSIVE_LOCK ) )
- {
- pPager.eLock = (u8)eLock;
- IOTRACE( "LOCK %p %d\n", pPager, eLock );
- }
- }
- return rc;
- }
- /*
- ** This function determines whether or not the atomic-write optimization
- ** can be used with this pager. The optimization can be used if:
- **
- ** (a) the value returned by OsDeviceCharacteristics() indicates that
- ** a database page may be written atomically, and
- ** (b) the value returned by OsSectorSize() is less than or equal
- ** to the page size.
- **
- ** The optimization is also always enabled for temporary files. It is
- ** an error to call this function if pPager is opened on an in-memory
- ** database.
- **
- ** If the optimization cannot be used, 0 is returned. If it can be used,
- ** then the value returned is the size of the journal file when it
- ** contains rollback data for exactly one page.
- */
- #if SQLITE_ENABLE_ATOMIC_WRITE
- static int jrnlBufferSize(Pager *pPager){
- Debug.Assert( 0==MEMDB );
- if( !pPager.tempFile ){
- int dc; /* Device characteristics */
- int nSector; /* Sector size */
- int szPage; /* Page size */
- Debug.Assert( isOpen(pPager.fd) );
- dc = sqlite3OsDeviceCharacteristics(pPager.fd);
- nSector = pPager.sectorSize;
- szPage = pPager.pageSize;
- Debug.Assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
- Debug.Assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
- if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
- return 0;
- }
- }
- return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
- }
- #endif
- /*
- ** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
- ** on the cache using a hash function. This is used for testing
- ** and debugging only.
- */
- #if SQLITE_CHECK_PAGES
- /*
- ** Return a 32-bit hash of the page data for pPage.
- */
- static u32 pager_datahash(int nByte, unsigned char pData){
- u32 hash = 0;
- int i;
- for(i=0; i<nByte; i++){
- hash = (hash*1039) + pData[i];
- }
- return hash;
- }
- static void pager_pagehash(PgHdr pPage){
- return pager_datahash(pPage.pPager.pageSize, (unsigned char *)pPage.pData);
- }
- static u32 pager_set_pagehash(PgHdr pPage){
- pPage.pageHash = pager_pagehash(pPage);
- }
- /*
- ** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
- ** is defined, and NDEBUG is not defined, an Debug.Assert() statement checks
- ** that the page is either dirty or still matches the calculated page-hash.
- */
- //#define CHECK_PAGE(x) checkPage(x)
- static void checkPage(PgHdr pPg){
- Pager pPager = pPg.pPager;
- assert( pPager->eState!=PAGER_ERROR );
- assert( (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
- }
- #else
- //#define pager_datahash(X,Y) 0
- static int pager_datahash( int X, byte[] Y )
- {
- return 0;
- }
- //#define pager_pagehash(X) 0
- static int pager_pagehash( PgHdr X )
- {
- return 0;
- }
- //#define pager_set_pagehash(X)
- static void pager_set_pagehash( PgHdr X )
- {
- }
- //#define CHECK_PAGE(x)
- #endif //* SQLITE_CHECK_PAGES */
- /*
- ** When this is called the journal file for pager pPager must be open.
- ** This function attempts to read a master journal file name from the
- ** end of the file and, if successful, copies it into memory supplied
- ** by the caller. See comments above writeMasterJournal() for the format
- ** used to store a master journal file name at the end of a journal file.
- **
- ** zMaster must point to a buffer of at least nMaster bytes allocated by
- ** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
- ** enough space to write the master journal name). If the master journal
- ** name in the journal is longer than nMaster bytes (including a
- ** nul-terminator), then this is handled as if no master journal name
- ** were present in the journal.
- **
- ** If a master journal file name is present at the end of the journal
- ** file, then it is copied into the buffer pointed to by zMaster. A
- ** nul-terminator byte is appended to the buffer following the master
- ** journal file name.
- **
- ** If it is determined that no master journal file name is present
- ** zMaster[0] is set to 0 and SQLITE_OK returned.
- **
- ** If an error occurs while reading from the journal file, an SQLite
- ** error code is returned.
- */
- static int readMasterJournal( sqlite3_file pJrnl, byte[] zMaster, u32 nMaster )
- {
- int rc; /* Return code */
- int len = 0; /* Length in bytes of master journal name */
- i64 szJ = 0; /* Total size in bytes of journal file pJrnl */
- u32 cksum = 0; /* MJ checksum value read from journal */
- int u; /* Unsigned loop counter */
- byte[] aMagic = new byte[8]; /* A buffer to hold the magic header */
- zMaster[0] = 0;
- if ( SQLITE_OK != ( rc = sqlite3OsFileSize( pJrnl, ref szJ ) )
- || szJ < 16
- || SQLITE_OK != ( rc = read32bits( pJrnl, (int)( szJ - 16 ), ref len ) )
- || len >= nMaster
- || SQLITE_OK != ( rc = read32bits( pJrnl, szJ - 12, ref cksum ) )
- || SQLITE_OK != ( rc = sqlite3OsRead( pJrnl, aMagic, 8, szJ - 8 ) )
- || memcmp( aMagic, aJournalMagic, 8 ) != 0
- || SQLITE_OK != ( rc = sqlite3OsRead( pJrnl, zMaster, len, (long)( szJ - 16 - len ) ) )
- )
- {
- return rc;
- }
- /* See if the checksum matches the master journal name */
- for ( u = 0; u < len; u++ )
- {
- cksum -= zMaster[u];
- }
- if ( cksum != 0 )
- {
- /* If the checksum doesn't add up, then one or more of the disk sectors
- ** containing the master journal filename is corrupted. This means
- ** definitely roll back, so just return SQLITE_OK and report a (nul)
- ** master-journal filename.
- */
- len = 0;
- }
- if ( len == 0 )
- zMaster[0] = 0;
- return SQLITE_OK;
- }
- /*
- ** Return the offset of the sector boundary at or immediately
- ** following the value in pPager.journalOff, assuming a sector
- ** size of pPager.sectorSize bytes.
- **
- ** i.e for a sector size of 512:
- **
- ** Pager.journalOff Return value
- ** ---------------------------------------
- ** 0 0
- ** 512 512
- ** 100 512
- ** 2000 2048
- **
- */
- static i64 journalHdrOffset( Pager pPager )
- {
- i64 offset = 0;
- i64 c = pPager.journalOff;
- if ( c != 0 )
- {
- offset = (int)( ( ( c - 1 ) / pPager.sectorSize + 1 ) * pPager.sectorSize );//offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
- }
- Debug.Assert( offset % pPager.sectorSize == 0 ); //Debug.Assert(offset % JOURNAL_HDR_SZ(pPager) == 0);
- Debug.Assert( offset >= c );
- Debug.Assert( ( offset - c ) < pPager.sectorSize );//Debug.Assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
- return offset;
- }
- static void seekJournalHdr( Pager pPager )
- {
- pPager.journalOff = journalHdrOffset( pPager );
- }
- /*
- ** The journal file must be open when this function is called.
- **
- ** This function is a no-op if the journal file has not been written to
- ** within the current transaction (i.e. if Pager.journalOff==0).
- **
- ** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
- ** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
- ** zero the 28-byte header at the start of the journal file. In either case,
- ** if the pager is not in no-sync mode, sync the journal file immediately
- ** after writing or truncating it.
- **
- ** If Pager.journalSizeLimit is set to a positive, non-zero value, and
- ** following the truncation or zeroing described above the size of the
- ** journal file in bytes is larger than this value, then truncate the
- ** journal file to Pager.journalSizeLimit bytes. The journal file does
- ** not need to be synced following this operation.
- **
- ** If an IO error occurs, abandon processing and return the IO error code.
- ** Otherwise, return SQLITE_OK.
- */
- static int zeroJournalHdr( Pager pPager, int doTruncate )
- {
- int rc = SQLITE_OK; /* Return code */
- Debug.Assert( isOpen( pPager.jfd ) );
- if ( pPager.journalOff != 0 )
- {
- i64 iLimit = pPager.journalSizeLimit; /* Local cache of jsl */
- IOTRACE( "JZEROHDR %p\n", pPager );
- if ( doTruncate != 0 || iLimit == 0 )
- {
- rc = sqlite3OsTruncate( pPager.jfd, 0 );
- }
- else
- {
- byte[] zeroHdr = new byte[28];// = {0};
- rc = sqlite3OsWrite( pPager.jfd, zeroHdr, zeroHdr.Length, 0 );
- }
- if ( rc == SQLITE_OK && !pPager.noSync )
- {
- rc = sqlite3OsSync( pPager.jfd, SQLITE_SYNC_DATAONLY | pPager.syncFlags );
- }
- /* At this point the transaction is committed but the write lock
- ** is still held on the file. If there is a size limit configured for
- ** the persistent journal and the journal file currently consumes more
- ** space than that limit allows for, truncate it now. There is no need
- ** to sync the file following this operation.
- */
- if ( rc == SQLITE_OK && iLimit > 0 )
- {
- i64 sz = 0;
- rc = sqlite3OsFileSize( pPager.jfd, ref sz );
- if ( rc == SQLITE_OK && sz > iLimit )
- {
- rc = sqlite3OsTruncate( pPager.jfd, iLimit );
- }
- }
- }
- return rc;
- }
- /*
- ** The journal file must be open when this routine is called. A journal
- ** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
- ** current location.
- **
- ** The format for the journal header is as follows:
- ** - 8 bytes: Magic identifying journal format.
- ** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
- ** - 4 bytes: Random number used for page hash.
- ** - 4 bytes: Initial database page count.
- ** - 4 bytes: Sector size used by the process that wrote this journal.
- ** - 4 bytes: Database page size.
- **
- ** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
- */
- static int writeJournalHdr( Pager pPager )
- {
- int rc = SQLITE_OK; /* Return code */
- byte[] zHeader = pPager.pTmpSpace; /* Temporary space used to build header */
- u32 nHeader = (u32)pPager.pageSize; /* Size of buffer pointed to by zHeader */
- u32 nWrite; /* Bytes of header sector written */
- int ii; /* Loop counter */
- Debug.Assert( isOpen( pPager.jfd ) ); /* Journal file must be open. */
- if ( nHeader > JOURNAL_HDR_SZ( pPager ) )
- {
- nHeader = JOURNAL_HDR_SZ( pPager );
- }
- /* If there are active savepoints and any of them were created
- ** since the most recent journal header was written, update the
- ** PagerSavepoint.iHdrOffset fields now.
- */
- for ( ii = 0; ii < pPager.nSavepoint; ii++ )
- {
- if ( pPager.aSavepoint[ii].iHdrOffset == 0 )
- {
- pPager.aSavepoint[ii].iHdrOffset = pPager.journalOff;
- }
- }
- pPager.journalHdr = pPager.journalOff = journalHdrOffset( pPager );
- /*
- ** Write the nRec Field - the number of page records that follow this
- ** journal header. Normally, zero is written to this value at this time.
- ** After the records are added to the journal (and the journal synced,
- ** if in full-sync mode), the zero is overwritten with the true number
- ** of records (see syncJournal()).
- **
- ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
- ** reading the journal this value tells SQLite to assume that the
- ** rest of the journal file contains valid page records. This assumption
- ** is dangerous, as if a failure occurred whilst writing to the journal
- ** file it may contain some garbage data. There are two scenarios
- ** where this risk can be ignored:
- **
- ** * When the pager is in no-sync mode. Corruption can follow a
- ** power failure in this case anyway.
- **
- ** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
- ** that garbage data is never appended to the journal file.
- */
- Debug.Assert( isOpen( pPager.fd ) || pPager.noSync );
- if ( pPager.noSync || ( pPager.journalMode == PAGER_JOURNALMODE_MEMORY )
- || ( sqlite3OsDeviceCharacteristics( pPager.fd ) & SQLITE_IOCAP_SAFE_APPEND ) != 0
- )
- {
- aJournalMagic.CopyTo( zHeader, 0 );// memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
- put32bits( zHeader, aJournalMagic.Length, 0xffffffff );
- }
- else
- {
- Array.Clear( zHeader, 0, aJournalMagic.Length + 4 );//memset(zHeader, 0, sizeof(aJournalMagic)+4);
- }
- /* The random check-hash initialiser */
- i64 i64Temp = 0;
- sqlite3_randomness( sizeof( i64 ), ref i64Temp );
- pPager.cksumInit = (u32)i64Temp;
- put32bits( zHeader, aJournalMagic.Length + 4, pPager.cksumInit );
- /* The initial database size */
- put32bits( zHeader, aJournalMagic.Length + 8, pPager.dbOrigSize );
- /* The assumed sector size for this process */
- put32bits( zHeader, aJournalMagic.Length + 12, pPager.sectorSize );
- /* The page size */
- put32bits( zHeader, aJournalMagic.Length + 16, (u32)pPager.pageSize );
- /* Initializing the tail of the buffer is not necessary. Everything
- ** works find if the following memset() is omitted. But initializing
- ** the memory prevents valgrind from complaining, so we are willing to
- ** take the performance hit.
- */
- // memset(&zHeader[sizeof(aJournalMagic)+20], 0,
- // nHeader-(sizeof(aJournalMagic)+20));
- Array.Clear( zHeader, aJournalMagic.Length + 20, (int)nHeader - ( aJournalMagic.Length + 20 ) );
- /* In theory, it is only necessary to write the 28 bytes that the
- ** journal header consumes to the journal file here. Then increment the
- ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next
- ** record is written to the following sector (leaving a gap in the file
- ** that will be implicitly filled in by the OS).
- **
- ** However it has been discovered that on some systems this pattern can
- ** be significantly slower than contiguously writing data to the file,
- ** even if that means explicitly writing data to the block of
- ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
- ** is done.
- **
- ** The loop is required here in case the sector-size is larger than the
- ** database page size. Since the zHeader buffer is only Pager.pageSize
- ** bytes in size, more than one call to sqlite3OsWrite() may be required
- ** to populate the entire journal header sector.
- */
- for ( nWrite = 0; rc == SQLITE_OK && nWrite < JOURNAL_HDR_SZ( pPager ); nWrite += nHeader )
- {
- IOTRACE( "JHDR %p %lld %d\n", pPager, pPager.journalHdr, nHeader );
- rc = sqlite3OsWrite( pPager.jfd, zHeader, (int)nHeader, pPager.journalOff );
- Debug.Assert( pPager.journalHdr <= pPager.journalOff );
- pPager.journalOff += (int)nHeader;
- }
- return rc;
- }
- /*
- ** The journal file must be open when this is called. A journal header file
- ** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
- ** file. The current location in the journal file is given by
- ** pPager.journalOff. See comments above function writeJournalHdr() for
- ** a description of the journal header format.
- **
- ** If the header is read successfully, *pNRec is set to the number of
- ** page records following this header and *pDbSize is set to the size of the
- ** database before the transaction began, in pages. Also, pPager.cksumInit
- ** is set to the value read from the journal header. SQLITE_OK is returned
- ** in this case.
- **
- ** If the journal header file appears to be corrupted, SQLITE_DONE is
- ** returned and *pNRec and *PDbSize are undefined. If JOURNAL_HDR_SZ bytes
- ** cannot be read from the journal file an error code is returned.
- */
- static int readJournalHdr(
- Pager pPager, /* Pager object */
- int isHot,
- i64 journalSize, /* Size of the open journal file in bytes */
- ref u32 pNRec, /* OUT: Value read from the nRec field */
- ref u32 pDbSize /* OUT: Value of original database size field */
- )
- {
- int rc; /* Return code */
- byte[] aMagic = new byte[8]; /* A buffer to hold the magic header */
- i64 iHdrOff; /* Offset of journal header being read */
- Debug.Assert( isOpen( pPager.jfd ) ); /* Journal file must be open. */
- /* Advance Pager.journalOff to the start of the next sector. If the
- ** journal file is too small for there to be a header stored at this
- ** point, return SQLITE_DONE.
- */
- pPager.journalOff = journalHdrOffset( pPager );
- if ( pPager.journalOff + JOURNAL_HDR_SZ( pPager ) > journalSize )
- {
- return SQLITE_DONE;
- }
- iHdrOff = pPager.journalOff;
- /* Read in the first 8 bytes of the journal header. If they do not match
- ** the magic string found at the start of each journal header, return
- ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
- ** proceed.
- */
- if ( isHot != 0 || iHdrOff != pPager.journalHdr )
- {
- rc = sqlite3OsRead( pPager.jfd, aMagic, aMagic.Length, iHdrOff );
- if ( rc != 0 )
- {
- return rc;
- }
- if ( memcmp( aMagic, aJournalMagic, aMagic.Length ) != 0 )
- {
- return SQLITE_DONE;
- }
- }
- /* Read the first three 32-bit fields of the journal header: The nRec
- ** field, the checksum-initializer and the database size at the start
- ** of the transaction. Return an error code if anything goes wrong.
- */
- if ( SQLITE_OK != ( rc = read32bits( pPager.jfd, iHdrOff + 8, ref pNRec ) )
- || SQLITE_OK != ( rc = read32bits( pPager.jfd, iHdrOff + 12, ref pPager.cksumInit ) )
- || SQLITE_OK != ( rc = read32bits( pPager.jfd, iHdrOff + 16, ref pDbSize ) )
- )
- {
- return rc;
- }
- if ( pPager.journalOff == 0 )
- {
- u32 iPageSize = 0; /* Page-size field of journal header */
- u32 iSectorSize = 0; /* Sector-size field of journal header */
- /* Read the page-size and sector-size journal header fields. */
- if ( SQLITE_OK != ( rc = read32bits( pPager.jfd, iHdrOff + 20, ref iSectorSize ) )
- || SQLITE_OK != ( rc = read32bits( pPager.jfd, iHdrOff + 24, ref iPageSize ) )
- )
- {
- return rc;
- }
- /* Versions of SQLite prior to 3.5.8 set the page-size field of the
- ** journal header to zero. In this case, assume that the Pager.pageSize
- ** variable is already set to the correct page size.
- */
- if ( iPageSize == 0 )
- {
- iPageSize = (u32)pPager.pageSize;
- }
- /* Check that the values read from the page-size and sector-size fields
- ** are within range. To be 'in range', both values need to be a power
- ** of two greater than or equal to 512 or 32, and not greater than their
- ** respective compile time maximum limits.
- */
- if ( iPageSize < 512 || iSectorSize < 32
- || iPageSize > SQLITE_MAX_PAGE_SIZE || iSectorSize > MAX_SECTOR_SIZE
- || ( ( iPageSize - 1 ) & iPageSize ) != 0 || ( ( iSectorSize - 1 ) & iSectorSize ) != 0
- )
- {
- /* If the either the page-size or sector-size in the journal-header is
- ** invalid, then the process that wrote the journal-header must have
- ** crashed before the header was synced. In this case stop reading
- ** the journal file here.
- */
- return SQLITE_DONE;
- }
- /* Update the page-size to match the value read from the journal.
- ** Use a testcase() macro to make sure that malloc failure within
- ** PagerSetPagesize() is tested.
- */
- rc = sqlite3PagerSetPagesize( pPager, ref iPageSize, -1 );
- testcase( rc != SQLITE_OK );
- /* Update the assumed sector-size to match the value used by
- ** the process that created this journal. If this journal was
- ** created by a process other than this one, then this routine
- ** is being called from within pager_playback(). The local value
- ** of Pager.sectorSize is restored at the end of that routine.
- */
- pPager.sectorSize = iSectorSize;
- }
- pPager.journalOff += (int)JOURNAL_HDR_SZ( pPager );
- return rc;
- }
- /*
- ** Write the supplied master journal name into the journal file for pager
- ** pPager at the current location. The master journal name must be the last
- ** thing written to a journal file. If the pager is in full-sync mode, the
- ** journal file descriptor is advanced to the next sector boundary before
- ** anything is written. The format is:
- **
- ** + 4 bytes: PAGER_MJ_PGNO.
- ** + N bytes: Master journal filename in utf-8.
- ** + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
- ** + 4 bytes: Master journal name checksum.
- ** + 8 bytes: aJournalMagic[].
- **
- ** The master journal page checksum is the sum of the bytes in the master
- ** journal name, where each byte is interpreted as a signed 8-bit integer.
- **
- ** If zMaster is a NULL pointer (occurs for a single database transaction),
- ** this call is a no-op.
- */
- static int writeMasterJournal( Pager pPager, string zMaster )
- {
- int rc; /* Return code */
- int nMaster; /* Length of string zMaster */
- i64 iHdrOff; /* Offset of header in journal file */
- i64 jrnlSize = 0; /* Size of journal file on disk */
- u32 cksum = 0; /* Checksum of string zMaster */
- Debug.Assert( pPager.setMaster == 0 );
- Debug.Assert( !pagerUseWal( pPager ) );
- if ( null == zMaster
- || pPager.journalMode == PAGER_JOURNALMODE_MEMORY
- || pPager.journalMode == PAGER_JOURNALMODE_OFF
- )
- {
- return SQLITE_OK;
- }
- pPager.setMaster = 1;
- Debug.Assert( isOpen( pPager.jfd ) );
- Debug.Assert( pPager.journalHdr <= pPager.journalOff );
- /* Calculate the length in bytes and the checksum of zMaster */
- for ( nMaster = 0; nMaster < zMaster.Length && zMaster[nMaster] != 0; nMaster++ )
- {
- cksum += zMaster[nMaster];
- }
- /* If in full-sync mode, advance to the next disk sector before writing
- ** the master journal name. This is in case the previous page written to
- ** the journal has already been synced.
- */
- if ( pPager.fullSync )
- {
- pPager.journalOff = journalHdrOffset( pPager );
- }
- iHdrOff = pPager.journalOff;
- /* Write the master journal data to the end of the journal file. If
- ** an error occurs, return the error code to the caller.
- */
- if ( ( 0 != ( rc = write32bits( pPager.jfd, iHdrOff, (u32)PAGER_MJ_PGNO( pPager ) ) ) )
- || ( 0 != ( rc = sqlite3OsWrite( pPager.jfd, Encoding.UTF8.GetBytes( zMaster ), nMaster, iHdrOff + 4 ) ) )
- || ( 0 != ( rc = write32bits( pPager.jfd, iHdrOff + 4 + nMaster, (u32)nMaster ) ) )
- || ( 0 != ( rc = write32bits( pPager.jfd, iHdrOff + 4 + nMaster + 4, cksum ) ) )
- || ( 0 != ( rc = sqlite3OsWrite( pPager.jfd, aJournalMagic, 8, iHdrOff + 4 + nMaster + 8 ) ) )
- )
- {
- return rc;
- }
- pPager.journalOff += ( nMaster + 20 );
- /* If the pager is in peristent-journal mode, then the physical
- ** journal-file may extend past the end of the master-journal name
- ** and 8 bytes of magic data just written to the file. This is
- ** dangerous because the code to rollback a hot-journal file
- ** will not be able to find the master-journal name to determine
- ** whether or not the journal is hot.
- **
- ** Easiest thing to do in this scenario is to truncate the journal
- ** file to the required size.
- */
- if ( SQLITE_OK == ( rc = sqlite3OsFileSize( pPager.jfd, ref jrnlSize ) )
- && jrnlSize > pPager.journalOff
- )
- {
- rc = sqlite3OsTruncate( pPager.jfd, pPager.journalOff );
- }
- return rc;
- }
- /*
- ** Find a page in the hash table given its page number. Return
- ** a pointer to the page or NULL if the requested page is not
- ** already in memory.
- */
- static PgHdr pager_lookup( Pager pPager, u32 pgno )
- {
- PgHdr p = null; /* Return value */
- /* It is not possible for a call to PcacheFetch() with createFlag==0 to
- ** fail, since no attempt to allocate dynamic memory will be made.
- */
- sqlite3PcacheFetch( pPager.pPCache, pgno, 0, ref p );
- return p;
- }
- /*
- ** Discard the entire contents of the in-memory page-cache.
- */
- static void pager_reset( Pager pPager )
- {
- sqlite3BackupRestart( pPager.pBackup );
- sqlite3PcacheClear( pPager.pPCache );
- }
- /*
- ** Free all structures in the Pager.aSavepoint[] array and set both
- ** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
- ** if it is open and the pager is not in exclusive mode.
- */
- static void releaseAllSavepoints( Pager pPager )
- {
- int ii; /* Iterator for looping through Pager.aSavepoint */
- for ( ii = 0; ii < pPager.nSavepoint; ii++ )
- {
- sqlite3BitvecDestroy( ref pPager.aSavepoint[ii].pInSavepoint );
- }
- if ( !pPager.exclusiveMode || sqlite3IsMemJournal( pPager.sjfd ) )
- {
- sqlite3OsClose( pPager.sjfd );
- }
- //sqlite3_free( ref pPager.aSavepoint );
- pPager.aSavepoint = null;
- pPager.nSavepoint = 0;
- pPager.nSubRec = 0;
- }
- /*
- ** Set the bit number pgno in the PagerSavepoint.pInSavepoint
- ** bitvecs of all open savepoints. Return SQLITE_OK if successful
- ** or SQLITE_NOMEM if a malloc failure occurs.
- */
- static int addToSavepointBitvecs( Pager pPager, u32 pgno )
- {
- int ii; /* Loop counter */
- int rc = SQLITE_OK; /* Result code */
- for ( ii = 0; ii < pPager.nSavepoint; ii++ )
- {
- PagerSavepoint p = pPager.aSavepoint[ii];
- if ( pgno <= p.nOrig )
- {
- rc |= sqlite3BitvecSet( p.pInSavepoint, pgno );
- testcase( rc == SQLITE_NOMEM );
- Debug.Assert( rc == SQLITE_OK || rc == SQLITE_NOMEM );
- }
- }
- return rc;
- }
- /*
- ** This function is a no-op if the pager is in exclusive mode and not
- ** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
- ** state.
- **
- ** If the pager is not in exclusive-access mode, the database file is
- ** completely unlocked. If the file is unlocked and the file-system does
- ** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
- ** closed (if it is open).
- **
- ** If the pager is in ERROR state when this function is called, the
- ** contents of the pager cache are discarded before switching back to
- ** the OPEN state. Regardless of whether the pager is in exclusive-mode
- ** or not, any journal file left in the file-system will be treated
- ** as a hot-journal and rolled back the next time a read-transaction
- ** is opened (by this or by any other connection).
- */
- static void pager_unlock( Pager pPager )
- {
- Debug.Assert( pPager.eState == PAGER_READER
- || pPager.eState == PAGER_OPEN
- || pPager.eState == PAGER_ERROR
- );
- sqlite3BitvecDestroy( ref pPager.pInJournal );
- pPager.pInJournal = null;
- releaseAllSavepoints( pPager );
- if ( pagerUseWal( pPager ) )
- {
- Debug.Assert( !isOpen( pPager.jfd ) );
- sqlite3WalEndReadTransaction( pPager.pWal );
- pPager.eState = PAGER_OPEN;
- }
- else if ( !pPager.exclusiveMode )
- {
- int rc; /* Error code returned by pagerUnlockDb() */
- int iDc = isOpen( pPager.fd ) ? sqlite3OsDeviceCharacteristics( pPager.fd ) : 0;
- /* If the operating system support deletion of open files, then
- ** close the journal file when dropping the database lock. Otherwise
- ** another connection with journal_mode=delete might delete the file
- ** out from under us.
- */
- Debug.Assert( ( PAGER_JOURNALMODE_MEMORY & 5 ) != 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_OFF & 5 ) != 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_WAL & 5 ) != 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_DELETE & 5 ) != 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_TRUNCATE & 5 ) == 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_PERSIST & 5 ) == 1 );
- if ( 0 == ( iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN )
- || 1 != ( pPager.journalMode & 5 )
- )
- {
- sqlite3OsClose( pPager.jfd );
- }
- /* If the pager is in the ERROR state and the call to unlock the database
- ** file fails, set the current lock to UNKNOWN_LOCK. See the comment
- ** above the #define for UNKNOWN_LOCK for an explanation of why this
- ** is necessary.
- */
- rc = pagerUnlockDb( pPager, NO_LOCK );
- if ( rc != SQLITE_OK && pPager.eState == PAGER_ERROR )
- {
- pPager.eLock = UNKNOWN_LOCK;
- }
- /* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
- ** without clearing the error code. This is intentional - the error
- ** code is cleared and the cache reset in the block below.
- */
- Debug.Assert( pPager.errCode != 0 || pPager.eState != PAGER_ERROR );
- pPager.changeCountDone = false;
- pPager.eState = PAGER_OPEN;
- }
- /* If Pager.errCode is set, the contents of the pager cache cannot be
- ** trusted. Now that there are no outstanding references to the pager,
- ** it can safely move back to PAGER_OPEN state. This happens in both
- ** normal and exclusive-locking mode.
- */
- if ( pPager.errCode != 0 )
- {
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- pager_reset( pPager );
- pPager.changeCountDone = pPager.tempFile;
- pPager.eState = PAGER_OPEN;
- pPager.errCode = SQLITE_OK;
- }
- pPager.journalOff = 0;
- pPager.journalHdr = 0;
- pPager.setMaster = 0;
- }
- /*
- ** This function is called whenever an IOERR or FULL error that requires
- ** the pager to transition into the ERROR state may ahve occurred.
- ** The first argument is a pointer to the pager structure, the second
- ** the error-code about to be returned by a pager API function. The
- ** value returned is a copy of the second argument to this function.
- **
- ** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
- ** IOERR sub-codes, the pager enters the ERROR state and the error code
- ** is stored in Pager.errCode. While the pager remains in the ERROR state,
- ** all major API calls on the Pager will immediately return Pager.errCode.
- **
- ** The ERROR state indicates that the contents of the pager-cache
- ** cannot be trusted. This state can be cleared by completely discarding
- ** the contents of the pager-cache. If a transaction was active when
- ** the persistent error occurred, then the rollback journal may need
- ** to be replayed to restore the contents of the database file (as if
- ** it were a hot-journal).
- */
- static int pager_error( Pager pPager, int rc )
- {
- int rc2 = rc & 0xff;
- Debug.Assert( rc == SQLITE_OK ||
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- Debug.Assert(
- pPager.errCode == SQLITE_FULL ||
- pPager.errCode == SQLITE_OK ||
- ( pPager.errCode & 0xff ) == SQLITE_IOERR
- );
- if (
- rc2 == SQLITE_FULL || rc2 == SQLITE_IOERR )
- {
- pPager.errCode = rc;
- pPager.eState = PAGER_ERROR;
- }
- return rc;
- }
- /*
- ** This routine ends a transaction. A transaction is usually ended by
- ** either a COMMIT or a ROLLBACK operation. This routine may be called
- ** after rollback of a hot-journal, or if an error occurs while opening
- ** the journal file or writing the very first journal-header of a
- ** database transaction.
- **
- ** This routine is never called in PAGER_ERROR state. If it is called
- ** in PAGER_NONE or PAGER_SHARED state and the lock held is less
- ** exclusive than a RESERVED lock, it is a no-op.
- **
- ** Otherwise, any active savepoints are released.
- **
- ** If the journal file is open, then it is "finalized". Once a journal
- ** file has been finalized it is not possible to use it to roll back a
- ** transaction. Nor will it be considered to be a hot-journal by this
- ** or any other database connection. Exactly how a journal is finalized
- ** depends on whether or not the pager is running in exclusive mode and
- ** the current journal-mode (Pager.journalMode value), as follows:
- **
- ** journalMode==MEMORY
- ** Journal file descriptor is simply closed. This destroys an
- ** in-memory journal.
- **
- ** journalMode==TRUNCATE
- ** Journal file is truncated to zero bytes in size.
- **
- ** journalMode==PERSIST
- ** The first 28 bytes of the journal file are zeroed. This invalidates
- ** the first journal header in the file, and hence the entire journal
- ** file. An invalid journal file cannot be rolled back.
- **
- ** journalMode==DELETE
- ** The journal file is closed and deleted using sqlite3OsDelete().
- **
- ** If the pager is running in exclusive mode, this method of finalizing
- ** the journal file is never used. Instead, if the journalMode is
- ** DELETE and the pager is in exclusive mode, the method described under
- ** journalMode==PERSIST is used instead.
- **
- ** After the journal is finalized, the pager moves to PAGER_READER state.
- ** If running in non-exclusive rollback mode, the lock on the file is
- ** downgraded to a SHARED_LOCK.
- **
- ** SQLITE_OK is returned if no error occurs. If an error occurs during
- ** any of the IO operations to finalize the journal file or unlock the
- ** database then the IO error code is returned to the user. If the
- ** operation to finalize the journal file fails, then the code still
- ** tries to unlock the database file if not in exclusive mode. If the
- ** unlock operation fails as well, then the first error code related
- ** to the first error encountered (the journal finalization one) is
- ** returned.
- */
- static int pager_end_transaction( Pager pPager, int hasMaster )
- {
- int rc = SQLITE_OK; /* Error code from journal finalization operation */
- int rc2 = SQLITE_OK; /* Error code from db file unlock operation */
- /* Do nothing if the pager does not have an open write transaction
- ** or at least a RESERVED lock. This function may be called when there
- ** is no write-transaction active but a RESERVED or greater lock is
- ** held under two circumstances:
- **
- ** 1. After a successful hot-journal rollback, it is called with
- ** eState==PAGER_NONE and eLock==EXCLUSIVE_LOCK.
- **
- ** 2. If a connection with locking_mode=exclusive holding an EXCLUSIVE
- ** lock switches back to locking_mode=normal and then executes a
- ** read-transaction, this function is called with eState==PAGER_READER
- ** and eLock==EXCLUSIVE_LOCK when the read-transaction is closed.
- */
- Debug.Assert( assert_pager_state( pPager ) );
- Debug.Assert( pPager.eState != PAGER_ERROR );
- if ( pPager.eState < PAGER_WRITER_LOCKED && pPager.eLock < RESERVED_LOCK )
- {
- return SQLITE_OK;
- }
- releaseAllSavepoints( pPager );
- Debug.Assert( isOpen( pPager.jfd ) || pPager.pInJournal == null );
- if ( isOpen( pPager.jfd ) )
- {
- Debug.Assert( !pagerUseWal( pPager ) );
- /* Finalize the journal file. */
- if ( sqlite3IsMemJournal( pPager.jfd ) )
- {
- Debug.Assert( pPager.journalMode == PAGER_JOURNALMODE_MEMORY );
- sqlite3OsClose( pPager.jfd );
- }
- else if ( pPager.journalMode == PAGER_JOURNALMODE_TRUNCATE )
- {
- if ( pPager.journalOff == 0 )
- {
- rc = SQLITE_OK;
- }
- else
- {
- rc = sqlite3OsTruncate( pPager.jfd, 0 );
- }
- pPager.journalOff = 0;
- }
- else if ( pPager.journalMode == PAGER_JOURNALMODE_PERSIST
- || ( pPager.exclusiveMode && pPager.journalMode != PAGER_JOURNALMODE_WAL )
- )
- {
- rc = zeroJournalHdr( pPager, hasMaster );
- pPager.journalOff = 0;
- }
- else
- {
- /* This branch may be executed with Pager.journalMode==MEMORY if
- ** a hot-journal was just rolled back. In this case the journal
- ** file should be closed and deleted. If this connection writes to
- ** the database file, it will do so using an in-memory journal.
- */
- Debug.Assert( pPager.journalMode == PAGER_JOURNALMODE_DELETE
- || pPager.journalMode == PAGER_JOURNALMODE_MEMORY
- || pPager.journalMode == PAGER_JOURNALMODE_WAL
- );
- sqlite3OsClose( pPager.jfd );
- if ( !pPager.tempFile )
- {
- rc = sqlite3OsDelete( pPager.pVfs, pPager.zJournal, 0 );
- }
- }
- }
- #if SQLITE_CHECK_PAGES
- sqlite3PcacheIterateDirty(pPager.pPCache, pager_set_pagehash);
- if( pPager.dbSize==0 && sqlite3PcacheRefCount(pPager.pPCache)>0 ){
- PgHdr p = pager_lookup(pPager, 1);
- if( p != null ){
- p.pageHash = null;
- sqlite3PagerUnref(p);
- }
- }
- #endif
- sqlite3BitvecDestroy( ref pPager.pInJournal );
- pPager.pInJournal = null;
- pPager.nRec = 0;
- sqlite3PcacheCleanAll( pPager.pPCache );
- sqlite3PcacheTruncate( pPager.pPCache, pPager.dbSize );
- if ( pagerUseWal( pPager ) )
- {
- /* Drop the WAL write-lock, if any. Also, if the connection was in
- ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE
- ** lock held on the database file.
- */
- rc2 = sqlite3WalEndWriteTransaction( pPager.pWal );
- Debug.Assert( rc2 == SQLITE_OK );
- }
- if ( !pPager.exclusiveMode
- && ( !pagerUseWal( pPager ) || sqlite3WalExclusiveMode( pPager.pWal, 0 ) )
- )
- {
- rc2 = pagerUnlockDb( pPager, SHARED_LOCK );
- pPager.changeCountDone = false;
- }
- pPager.eState = PAGER_READER;
- pPager.setMaster = 0;
- return ( rc == SQLITE_OK ? rc2 : rc );
- }
- /*
- ** Execute a rollback if a transaction is active and unlock the
- ** database file.
- **
- ** If the pager has already entered the ERROR state, do not attempt
- ** the rollback at this time. Instead, pager_unlock() is called. The
- ** call to pager_unlock() will discard all in-memory pages, unlock
- ** the database file and move the pager back to OPEN state. If this
- ** means that there is a hot-journal left in the file-system, the next
- ** connection to obtain a shared lock on the pager (which may be this one)
- ** will roll it back.
- **
- ** If the pager has not already entered the ERROR state, but an IO or
- ** malloc error occurs during a rollback, then this will itself cause
- ** the pager to enter the ERROR state. Which will be cleared by the
- ** call to pager_unlock(), as described above.
- */
- static void pagerUnlockAndRollback( Pager pPager )
- {
- if ( pPager.eState != PAGER_ERROR && pPager.eState != PAGER_OPEN )
- {
- Debug.Assert( assert_pager_state( pPager ) );
- if ( pPager.eState >= PAGER_WRITER_LOCKED )
- {
- sqlite3BeginBenignMalloc();
- sqlite3PagerRollback( pPager );
- sqlite3EndBenignMalloc();
- }
- else if ( !pPager.exclusiveMode )
- {
- Debug.Assert( pPager.eState == PAGER_READER );
- pager_end_transaction( pPager, 0 );
- }
- }
- pager_unlock( pPager );
- }
- /*
- ** Parameter aData must point to a buffer of pPager.pageSize bytes
- ** of data. Compute and return a checksum based ont the contents of the
- ** page of data and the current value of pPager.cksumInit.
- **
- ** This is not a real checksum. It is really just the sum of the
- ** random initial value (pPager.cksumInit) and every 200th byte
- ** of the page data, starting with byte offset (pPager.pageSize%200).
- ** Each byte is interpreted as an 8-bit unsigned integer.
- **
- ** Changing the formula used to compute this checksum results in an
- ** incompatible journal file format.
- **
- ** If journal corruption occurs due to a power failure, the most likely
- ** scenario is that one end or the other of the record will be changed.
- ** It is much less likely that the two ends of the journal record will be
- ** correct and the middle be corrupt. Thus, this "checksum" scheme,
- ** though fast and simple, catches the mostly likely kind of corruption.
- */
- static u32 pager_cksum( Pager pPager, byte[] aData )
- {
- u32 cksum = pPager.cksumInit; /* Checksum value to return */
- int i = pPager.pageSize - 200; /* Loop counter */
- while ( i > 0 )
- {
- cksum += aData[i];
- i -= 200;
- }
- return cksum;
- }
- /*
- ** Report the current page size and number of reserved bytes back
- ** to the codec.
- */
- #if SQLITE_HAS_CODEC
- static void pagerReportSize( Pager pPager )
- {
- if ( pPager.xCodecSizeChng != null )
- {
- pPager.xCodecSizeChng( pPager.pCodec, pPager.pageSize,
- pPager.nReserve );
- }
- }
- #else
- //# define pagerReportSize(X) /* No-op if we do not support a codec */
- static void pagerReportSize(Pager X){}
- #endif
- /*
- ** Read a single page from either the journal file (if isMainJrnl==1) or
- ** from the sub-journal (if isMainJrnl==0) and playback that page.
- ** The page begins at offset *pOffset into the file. The *pOffset
- ** value is increased to the start of the next page in the journal.
- **
- ** The main rollback journal uses checksums - the statement journal does
- ** not.
- **
- ** If the page number of the page record read from the (sub-)journal file
- ** is greater than the current value of Pager.dbSize, then playback is
- ** skipped and SQLITE_OK is returned.
- **
- ** If pDone is not NULL, then it is a record of pages that have already
- ** been played back. If the page at *pOffset has already been played back
- ** (if the corresponding pDone bit is set) then skip the playback.
- ** Make sure the pDone bit corresponding to the *pOffset page is set
- ** prior to returning.
- **
- ** If the page record is successfully read from the (sub-)journal file
- ** and played back, then SQLITE_OK is returned. If an IO error occurs
- ** while reading the record from the (sub-)journal file or while writing
- ** to the database file, then the IO error code is returned. If data
- ** is successfully read from the (sub-)journal file but appears to be
- ** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
- ** two circumstances:
- **
- ** * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
- ** * If the record is being rolled back from the main journal file
- ** and the checksum field does not match the record content.
- **
- ** Neither of these two scenarios are possible during a savepoint rollback.
- **
- ** If this is a savepoint rollback, then memory may have to be dynamically
- ** allocated by this function. If this is the case and an allocation fails,
- ** SQLITE_NOMEM is returned.
- */
- static int pager_playback_one_page(
- Pager pPager, /* The pager being played back */
- ref i64 pOffset, /* Offset of record to playback */
- Bitvec pDone, /* Bitvec of pages already played back */
- int isMainJrnl, /* True for main rollback journal. False for Stmt jrnl */
- int isSavepnt /* True for a savepoint rollback */
- )
- {
- int rc;
- PgHdr pPg; /* An existing page in the cache */
- Pgno pgno = 0; /* The page number of a page in journal */
- u32 cksum = 0; /* Checksum used for sanity checking */
- byte[] aData; /* Temporary storage for the page */
- sqlite3_file jfd; /* The file descriptor for the journal file */
- bool isSynced; /* True if journal page is synced */
- Debug.Assert( ( isMainJrnl & ~1 ) == 0 ); /* isMainJrnl is 0 or 1 */
- Debug.Assert( ( isSavepnt & ~1 ) == 0 ); /* isSavepnt is 0 or 1 */
- Debug.Assert( isMainJrnl != 0 || pDone != null ); /* pDone always used on sub-journals */
- Debug.Assert( isSavepnt != 0 || pDone == null ); /* pDone never used on non-savepoint */
- aData = pPager.pTmpSpace;
- Debug.Assert( aData != null ); /* Temp storage must have already been allocated */
- Debug.Assert( pagerUseWal( pPager ) == false || ( 0 == isMainJrnl && isSavepnt != 0 ) );
- /* Either the state is greater than PAGER_WRITER_CACHEMOD (a transaction
- ** or savepoint rollback done at the request of the caller) or this is
- ** a hot-journal rollback. If it is a hot-journal rollback, the pager
- ** is in state OPEN and holds an EXCLUSIVE lock. Hot-journal rollback
- ** only reads from the main journal, not the sub-journal.
- */
- Debug.Assert( pPager.eState >= PAGER_WRITER_CACHEMOD
- || ( pPager.eState == PAGER_OPEN && pPager.eLock == EXCLUSIVE_LOCK )
- );
- Debug.Assert( pPager.eState >= PAGER_WRITER_CACHEMOD || isMainJrnl != 0 );
- /* Read the page number and page data from the journal or sub-journal
- ** file. Return an error code to the caller if an IO error occurs.
- */
- jfd = isMainJrnl != 0 ? pPager.jfd : pPager.sjfd;
- rc = read32bits( jfd, pOffset, ref pgno );
- if ( rc != SQLITE_OK )
- return rc;
- rc = sqlite3OsRead( jfd, aData, pPager.pageSize, ( pOffset ) + 4 );
- if ( rc != SQLITE_OK )
- return rc;
- pOffset += pPager.pageSize + 4 + isMainJrnl * 4;
- /* Sanity checking on the page. This is more important that I originally
- ** thought. If a power failure occurs while the journal is being written,
- ** it could cause invalid data to be written into the journal. We need to
- ** detect this invalid data (with high probability) and ignore it.
- */
- if ( pgno == 0 || pgno == PAGER_MJ_PGNO( pPager ) )
- {
- Debug.Assert( 0 == isSavepnt );
- return SQLITE_DONE;
- }
- if ( pgno > pPager.dbSize || sqlite3BitvecTest( pDone, pgno ) != 0 )
- {
- return SQLITE_OK;
- }
- if ( isMainJrnl != 0 )
- {
- rc = read32bits( jfd, ( pOffset ) - 4, ref cksum );
- if ( rc != 0 )
- return rc;
- if ( 0 == isSavepnt && pager_cksum( pPager, aData ) != cksum )
- {
- return SQLITE_DONE;
- }
- }
- /* If this page has already been played by before during the current
- ** rollback, then don't bother to play it back again.
- */
- if ( pDone != null && ( rc = sqlite3BitvecSet( pDone, pgno ) ) != SQLITE_OK )
- {
- return rc;
- }
- /* When playing back page 1, restore the nReserve setting
- */
- if ( pgno == 1 && pPager.nReserve != ( aData )[20] )
- {
- pPager.nReserve = ( aData )[20];
- pagerReportSize( pPager );
- }
- /* If the pager is in CACHEMOD state, then there must be a copy of this
- ** page in the pager cache. In this case just update the pager cache,
- ** not the database file. The page is left marked dirty in this case.
- **
- ** An exception to the above rule: If the database is in no-sync mode
- ** and a page is moved during an incremental vacuum then the page may
- ** not be in the pager cache. Later: if a malloc() or IO error occurs
- ** during a Movepage() call, then the page may not be in the cache
- ** either. So the condition described in the above paragraph is not
- ** assert()able.
- **
- ** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
- ** pager cache if it exists and the main file. The page is then marked
- ** not dirty. Since this code is only executed in PAGER_OPEN state for
- ** a hot-journal rollback, it is guaranteed that the page-cache is empty
- ** if the pager is in OPEN state.
- **
- ** Ticket #1171: The statement journal might contain page content that is
- ** different from the page content at the start of the transaction.
- ** This occurs when a page is changed prior to the start of a statement
- ** then changed again within the statement. When rolling back such a
- ** statement we must not write to the original database unless we know
- ** for certain that original page contents are synced into the main rollback
- ** journal. Otherwise, a power loss might leave modified data in the
- ** database file without an entry in the rollback journal that can
- ** restore the database to its original form. Two conditions must be
- ** met before writing to the database files. (1) the database must be
- ** locked. (2) we know that the original page content is fully synced
- ** in the main journal either because the page is not in cache or else
- ** the page is marked as needSync==0.
- **
- ** 2008-04-14: When attempting to vacuum a corrupt database file, it
- ** is possible to fail a statement on a database that does not yet exist.
- ** Do not attempt to write if database file has never been opened.
- */
- if ( pagerUseWal( pPager ) )
- {
- pPg = null;
- }
- else
- {
- pPg = pager_lookup( pPager, pgno );
- }
- Debug.Assert( pPg != null ||
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- pPager.memDb == 0
- #endif
- );
- Debug.Assert( pPager.eState != PAGER_OPEN || pPg == null );
- PAGERTRACE( "PLAYBACK %d page %d hash(%08x) %s\n",
- PAGERID( pPager ), pgno, pager_datahash( pPager.pageSize, aData ),
- ( isMainJrnl != 0 ? "main-journal" : "sub-journal" )
- );
- if ( isMainJrnl != 0 )
- {
- isSynced = pPager.noSync || ( pOffset <= pPager.journalHdr );
- }
- else
- {
- isSynced = ( pPg == null || 0 == ( pPg.flags & PGHDR_NEED_SYNC ) );
- }
- if ( isOpen( pPager.fd )
- && ( pPager.eState >= PAGER_WRITER_DBMOD || pPager.eState == PAGER_OPEN )
- && isSynced
- )
- {
- i64 ofst = ( pgno - 1 ) * pPager.pageSize;
- testcase( 0 == isSavepnt && pPg != null && ( pPg.flags & PGHDR_NEED_SYNC ) != 0 );
- Debug.Assert( !pagerUseWal( pPager ) );
- rc = sqlite3OsWrite( pPager.fd, aData, pPager.pageSize, ofst );
- if ( pgno > pPager.dbFileSize )
- {
- pPager.dbFileSize = pgno;
- }
- if ( pPager.pBackup != null )
- {
- if ( CODEC1( pPager, aData, pgno, SQLITE_DECRYPT ) )
- rc = SQLITE_NOMEM; // CODEC1( pPager, aData, pgno, 3, rc = SQLITE_NOMEM );
- sqlite3BackupUpdate( pPager.pBackup, pgno, (u8[])aData );
- if ( CODEC2( pPager, aData, pgno, SQLITE_ENCRYPT_READ_CTX, ref aData ) )
- rc = SQLITE_NOMEM;//CODEC2( pPager, aData, pgno, 7, rc = SQLITE_NOMEM, aData);
- }
- }
- else if ( 0 == isMainJrnl && pPg == null )
- {
- /* If this is a rollback of a savepoint and data was not written to
- ** the database and the page is not in-memory, there is a potential
- ** problem. When the page is next fetched by the b-tree layer, it
- ** will be read from the database file, which may or may not be
- ** current.
- **
- ** There are a couple of different ways this can happen. All are quite
- ** obscure. When running in synchronous mode, this can only happen
- ** if the page is on the free-list at the start of the transaction, then
- ** populated, then moved using sqlite3PagerMovepage().
- **
- ** The solution is to add an in-memory page to the cache containing
- ** the data just read from the sub-journal. Mark the page as dirty
- ** and if the pager requires a journal-sync, then mark the page as
- ** requiring a journal-sync before it is written.
- */
- Debug.Assert( isSavepnt != 0 );
- Debug.Assert( pPager.doNotSpill == 0 );
- pPager.doNotSpill++;
- rc = sqlite3PagerAcquire( pPager, pgno, ref pPg, 1 );
- Debug.Assert( pPager.doNotSpill == 1 );
- pPager.doNotSpill--;
- if ( rc != SQLITE_OK )
- return rc;
- pPg.flags &= ~PGHDR_NEED_READ;
- sqlite3PcacheMakeDirty( pPg );
- }
- if ( pPg != null )
- {
- /* No page should ever be explicitly rolled back that is in use, except
- ** for page 1 which is held in use in order to keep the lock on the
- ** database active. However such a page may be rolled back as a result
- ** of an internal error resulting in an automatic call to
- ** sqlite3PagerRollback().
- */
- byte[] pData = pPg.pData;
- Buffer.BlockCopy( aData, 0, pData, 0, pPager.pageSize );// memcpy(pData, (u8[])aData, pPager.pageSize);
- pPager.xReiniter( pPg );
- if ( isMainJrnl != 0 && ( 0 == isSavepnt || pOffset <= pPager.journalHdr ) )
- {
- /* If the contents of this page were just restored from the main
- ** journal file, then its content must be as they were when the
- ** transaction was first opened. In this case we can mark the page
- ** as clean, since there will be no need to write it out to the
- ** database.
- **
- ** There is one exception to this rule. If the page is being rolled
- ** back as part of a savepoint (or statement) rollback from an
- ** unsynced portion of the main journal file, then it is not safe
- ** to mark the page as clean. This is because marking the page as
- ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
- ** already in the journal file (recorded in Pager.pInJournal) and
- ** the PGHDR_NEED_SYNC flag is cleared, if the page is written to
- ** again within this transaction, it will be marked as dirty but
- ** the PGHDR_NEED_SYNC flag will not be set. It could then potentially
- ** be written out into the database file before its journal file
- ** segment is synced. If a crash occurs during or following this,
- ** database corruption may ensue.
- */
- Debug.Assert( !pagerUseWal( pPager ) );
- sqlite3PcacheMakeClean( pPg );
- }
- pager_set_pagehash( pPg );
- /* If this was page 1, then restore the value of Pager.dbFileVers.
- ** Do this before any decoding. */
- if ( pgno == 1 )
- {
- Buffer.BlockCopy( pData, 24, pPager.dbFileVers, 0, pPager.dbFileVers.Length ); //memcpy(pPager.dbFileVers, ((u8*)pData)[24], sizeof(pPager.dbFileVers));
- }
- /* Decode the page just read from disk */
- if ( CODEC1( pPager, pData, pPg.pgno, SQLITE_DECRYPT ) )
- rc = SQLITE_NOMEM; //CODEC1(pPager, pData, pPg.pgno, 3, rc=SQLITE_NOMEM);
- sqlite3PcacheRelease( pPg );
- }
- return rc;
- }
- /*
- ** Parameter zMaster is the name of a master journal file. A single journal
- ** file that referred to the master journal file has just been rolled back.
- ** This routine checks if it is possible to delete the master journal file,
- ** and does so if it is.
- **
- ** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not
- ** available for use within this function.
- **
- ** When a master journal file is created, it is populated with the names
- ** of all of its child journals, one after another, formatted as utf-8
- ** encoded text. The end of each child journal file is marked with a
- ** nul-terminator byte (0x00). i.e. the entire contents of a master journal
- ** file for a transaction involving two databases might be:
- **
- ** "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
- **
- ** A master journal file may only be deleted once all of its child
- ** journals have been rolled back.
- **
- ** This function reads the contents of the master-journal file into
- ** memory and loops through each of the child journal names. For
- ** each child journal, it checks if:
- **
- ** * if the child journal exists, and if so
- ** * if the child journal contains a reference to master journal
- ** file zMaster
- **
- ** If a child journal can be found that matches both of the criteria
- ** above, this function returns without doing anything. Otherwise, if
- ** no such child journal can be found, file zMaster is deleted from
- ** the file-system using sqlite3OsDelete().
- **
- ** If an IO error within this function, an error code is returned. This
- ** function allocates memory by calling sqlite3Malloc(). If an allocation
- ** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors
- ** occur, SQLITE_OK is returned.
- **
- ** TODO: This function allocates a single block of memory to load
- ** the entire contents of the master journal file. This could be
- ** a couple of kilobytes or so - potentially larger than the page
- ** size.
- */
- static int pager_delmaster( Pager pPager, string zMaster )
- {
- sqlite3_vfs pVfs = pPager.pVfs;
- int rc; /* Return code */
- sqlite3_file pMaster; /* Malloc'd master-journal file descriptor */
- sqlite3_file pJournal; /* Malloc'd child-journal file descriptor */
- //string zMasterJournal = null; /* Contents of master journal file */
- i64 nMasterJournal; /* Size of master journal file */
- string zJournal; /* Pointer to one journal within MJ file */
- string zMasterPtr; /* Space to hold MJ filename from a journal file */
- int nMasterPtr; /* Amount of space allocated to zMasterPtr[] */
- /* Allocate space for both the pJournal and pMaster file descriptors.
- ** If successful, open the master journal file for reading.
- */
- pMaster = new sqlite3_file();// (sqlite3_file*)sqlite3MallocZero( pVfs.szOsFile * 2 );
- pJournal = new sqlite3_file();// (sqlite3_file*)( ( (u8*)pMaster ) + pVfs.szOsFile );
- if ( null == pMaster )
- {
- rc = SQLITE_NOMEM;
- }
- else
- {
- const int flags = ( SQLITE_OPEN_READONLY | SQLITE_OPEN_MASTER_JOURNAL );
- int iDummy = 0;
- rc = sqlite3OsOpen( pVfs, zMaster, pMaster, flags, ref iDummy );
- }
- if ( rc != SQLITE_OK )
- goto delmaster_out;
- Debugger.Break(); //TODO --
- /* Load the entire master journal file into space obtained from
- ** sqlite3_malloc() and pointed to by zMasterJournal. Also obtain
- ** sufficient space (in zMasterPtr) to hold the names of master
- ** journal files extracted from regular rollback-journals.
- */
- //rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
- //if (rc != SQLITE_OK) goto delmaster_out;
- //nMasterPtr = pVfs.mxPathname + 1;
- // zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 1);
- // if ( !zMasterJournal )
- // {
- // rc = SQLITE_NOMEM;
- // goto delmaster_out;
- // }
- // zMasterPtr = &zMasterJournal[nMasterJournal+1];
- // rc = sqlite3OsRead( pMaster, zMasterJournal, (int)nMasterJournal, 0 );
- // if ( rc != SQLITE_OK ) goto delmaster_out;
- // zMasterJournal[nMasterJournal] = 0;
- // zJournal = zMasterJournal;
- // while ( ( zJournal - zMasterJournal ) < nMasterJournal )
- // {
- // int exists;
- // rc = sqlite3OsAccess( pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists );
- // if ( rc != SQLITE_OK )
- // {
- // goto delmaster_out;
- // }
- // if ( exists )
- // {
- // /* One of the journals pointed to by the master journal exists.
- // ** Open it and check if it points at the master journal. If
- // ** so, return without deleting the master journal file.
- // */
- // int c;
- // int flags = ( SQLITE_OPEN_READONLY | SQLITE_OPEN_MAIN_JOURNAL );
- // rc = sqlite3OsOpen( pVfs, zJournal, pJournal, flags, 0 );
- // if ( rc != SQLITE_OK )
- // {
- // goto delmaster_out;
- // }
- // rc = readMasterJournal( pJournal, zMasterPtr, nMasterPtr );
- // sqlite3OsClose( pJournal );
- // if ( rc != SQLITE_OK )
- // {
- // goto delmaster_out;
- // }
- // c = zMasterPtr[0] != 0 && strcmp( zMasterPtr, zMaster ) == 0;
- // if ( c )
- // {
- // /* We have a match. Do not delete the master journal file. */
- // goto delmaster_out;
- // }
- // }
- // zJournal += ( sqlite3Strlen30( zJournal ) + 1 );
- // }
- //
- //sqlite3OsClose(pMaster);
- //rc = sqlite3OsDelete( pVfs, zMaster, 0 );
- goto delmaster_out;
- delmaster_out:
- //sqlite3_free( ref zMasterJournal );
- if ( pMaster != null )
- {
- sqlite3OsClose( pMaster );
- Debug.Assert( !isOpen( pJournal ) );
- //sqlite3_free( ref pMaster );
- }
- return rc;
- }
- /*
- ** This function is used to change the actual size of the database
- ** file in the file-system. This only happens when committing a transaction,
- ** or rolling back a transaction (including rolling back a hot-journal).
- **
- ** If the main database file is not open, or the pager is not in either
- ** DBMOD or OPEN state, this function is a no-op. Otherwise, the size
- ** of the file is changed to nPage pages (nPage*pPager->pageSize bytes).
- ** If the file on disk is currently larger than nPage pages, then use the VFS
- ** xTruncate() method to truncate it.
- **
- ** Or, it might might be the case that the file on disk is smaller than
- ** nPage pages. Some operating system implementations can get confused if
- ** you try to truncate a file to some size that is larger than it
- ** currently is, so detect this case and write a single zero byte to
- ** the end of the new file instead.
- **
- ** If successful, return SQLITE_OK. If an IO error occurs while modifying
- ** the database file, return the error code to the caller.
- */
- static int pager_truncate( Pager pPager, u32 nPage )
- {
- int rc = SQLITE_OK;
- Debug.Assert( pPager.eState != PAGER_ERROR );
- Debug.Assert( pPager.eState != PAGER_READER );
- if ( isOpen( pPager.fd )
- && ( pPager.eState >= PAGER_WRITER_DBMOD || pPager.eState == PAGER_OPEN )
- )
- {
- i64 currentSize = 0, newSize;
- int szPage = pPager.pageSize;
- Debug.Assert( pPager.eLock == EXCLUSIVE_LOCK );
- /* TODO: Is it safe to use Pager.dbFileSize here? */
- rc = sqlite3OsFileSize( pPager.fd, ref currentSize );
- newSize = szPage * nPage;
- if ( rc == SQLITE_OK && currentSize != newSize )
- {
- if ( currentSize > newSize )
- {
- rc = sqlite3OsTruncate( pPager.fd, newSize );
- }
- else
- {
- byte[] pTmp = pPager.pTmpSpace;
- Array.Clear( pTmp, 0, szPage );//memset( pTmp, 0, szPage );
- testcase( ( newSize - szPage ) < currentSize );
- testcase( ( newSize - szPage ) == currentSize );
- testcase( ( newSize - szPage ) > currentSize );
- rc = sqlite3OsWrite( pPager.fd, pTmp, szPage, newSize - szPage );
- }
- if ( rc == SQLITE_OK )
- {
- pPager.dbSize = nPage;
- }
- }
- }
- return rc;
- }
- /*
- ** Set the value of the Pager.sectorSize variable for the given
- ** pager based on the value returned by the xSectorSize method
- ** of the open database file. The sector size will be used used
- ** to determine the size and alignment of journal header and
- ** master journal pointers within created journal files.
- **
- ** For temporary files the effective sector size is always 512 bytes.
- **
- ** Otherwise, for non-temporary files, the effective sector size is
- ** the value returned by the xSectorSize() method rounded up to 512 if
- ** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
- ** is greater than MAX_SECTOR_SIZE.
- */
- static void setSectorSize( Pager pPager )
- {
- Debug.Assert( isOpen( pPager.fd ) || pPager.tempFile );
- if ( !pPager.tempFile )
- {
- /* Sector size doesn't matter for temporary files. Also, the file
- ** may not have been opened yet, in which case the OsSectorSize()
- ** call will segfault.
- */
- pPager.sectorSize = (u32)sqlite3OsSectorSize( pPager.fd );
- }
- if ( pPager.sectorSize < 32 )
- {
- Debug.Assert( MAX_SECTOR_SIZE >= 512 );
- pPager.sectorSize = 512;
- }
- if ( pPager.sectorSize > MAX_SECTOR_SIZE )
- {
- pPager.sectorSize = MAX_SECTOR_SIZE;
- }
- }
- /*
- ** Playback the journal and thus restore the database file to
- ** the state it was in before we started making changes.
- **
- ** The journal file format is as follows:
- **
- ** (1) 8 byte prefix. A copy of aJournalMagic[].
- ** (2) 4 byte big-endian integer which is the number of valid page records
- ** in the journal. If this value is 0xffffffff, then compute the
- ** number of page records from the journal size.
- ** (3) 4 byte big-endian integer which is the initial value for the
- ** sanity checksum.
- ** (4) 4 byte integer which is the number of pages to truncate the
- ** database to during a rollback.
- ** (5) 4 byte big-endian integer which is the sector size. The header
- ** is this many bytes in size.
- ** (6) 4 byte big-endian integer which is the page size.
- ** (7) zero padding out to the next sector size.
- ** (8) Zero or more pages instances, each as follows:
- **
- ** When we speak of the journal header, we mean the first 7 items above.
- ** Each entry in the journal is an instance of the 8th item.
- **
- ** Call the value from the second bullet "nRec". nRec is the number of
- ** valid page entries in the journal. In most cases, you can compute the
- ** value of nRec from the size of the journal file. But if a power
- ** failure occurred while the journal was being written, it could be the
- ** case that the size of the journal file had already been increased but
- ** the extra entries had not yet made it safely to disk. In such a case,
- ** the value of nRec computed from the file size would be too large. For
- ** that reason, we always use the nRec value in the header.
- **
- ** If the nRec value is 0xffffffff it means that nRec should be computed
- ** from the file size. This value is used when the user selects the
- ** no-sync option for the journal. A power failure could lead to corruption
- ** in this case. But for things like temporary table (which will be
- ** deleted when the power is restored) we don't care.
- **
- ** If the file opened as the journal file is not a well-formed
- ** journal file then all pages up to the first corrupted page are rolled
- ** back (or no pages if the journal header is corrupted). The journal file
- ** is then deleted and SQLITE_OK returned, just as if no corruption had
- ** been encountered.
- **
- ** If an I/O or malloc() error occurs, the journal-file is not deleted
- ** and an error code is returned.
- **
- ** The isHot parameter indicates that we are trying to rollback a journal
- ** that might be a hot journal. Or, it could be that the journal is
- ** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
- ** If the journal really is hot, reset the pager cache prior rolling
- ** back any content. If the journal is merely persistent, no reset is
- ** needed.
- */
- static int pager_playback( Pager pPager, int isHot )
- {
- sqlite3_vfs pVfs = pPager.pVfs;
- i64 szJ = 0; /* Size of the journal file in bytes */
- u32 nRec = 0; /* Number of Records in the journal */
- u32 u; /* Unsigned loop counter */
- u32 mxPg = 0; /* Size of the original file in pages */
- int rc; /* Result code of a subroutine */
- int res = 1; /* Value returned by sqlite3OsAccess() */
- byte[] zMaster = null; /* Name of master journal file if any */
- int needPagerReset; /* True to reset page prior to first page rollback */
- /* Figure out how many records are in the journal. Abort early if
- ** the journal is empty.
- */
- Debug.Assert( isOpen( pPager.jfd ) );
- rc = sqlite3OsFileSize( pPager.jfd, ref szJ );
- if ( rc != SQLITE_OK )
- {
- goto end_playback;
- }
- /* Read the master journal name from the journal, if it is present.
- ** If a master journal file name is specified, but the file is not
- ** present on disk, then the journal is not hot and does not need to be
- ** played back.
- **
- ** TODO: Technically the following is an error because it assumes that
- ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
- ** (pPager.pageSize >= pPager.pVfs.mxPathname+1). Using os_unix.c,
- ** mxPathname is 512, which is the same as the minimum allowable value
- ** for pageSize.
- */
- zMaster = new byte[pPager.pVfs.mxPathname + 1];// pPager.pTmpSpace );
- rc = readMasterJournal( pPager.jfd, zMaster, (u32)pPager.pVfs.mxPathname + 1 );
- if ( rc == SQLITE_OK && zMaster[0] != 0 )
- {
- rc = sqlite3OsAccess( pVfs, Encoding.UTF8.GetString( zMaster, 0, zMaster.Length ), SQLITE_ACCESS_EXISTS, ref res );
- }
- zMaster = null;
- if ( rc != SQLITE_OK || res == 0 )
- {
- goto end_playback;
- }
- pPager.journalOff = 0;
- needPagerReset = isHot;
- /* This loop terminates either when a readJournalHdr() or
- ** pager_playback_one_page() call returns SQLITE_DONE or an IO error
- ** occurs.
- */
- while ( true )
- {
- /* Read the next journal header from the journal file. If there are
- ** not enough bytes left in the journal file for a complete header, or
- ** it is corrupted, then a process must have failed while writing it.
- ** This indicates nothing more needs to be rolled back.
- */
- rc = readJournalHdr( pPager, isHot, szJ, ref nRec, ref mxPg );
- if ( rc != SQLITE_OK )
- {
- if ( rc == SQLITE_DONE )
- {
- rc = SQLITE_OK;
- }
- goto end_playback;
- }
- /* If nRec is 0xffffffff, then this journal was created by a process
- ** working in no-sync mode. This means that the rest of the journal
- ** file consists of pages, there are no more journal headers. Compute
- ** the value of nRec based on this assumption.
- */
- if ( nRec == 0xffffffff )
- {
- Debug.Assert( pPager.journalOff == JOURNAL_HDR_SZ( pPager ) );
- nRec = (u32)( ( szJ - JOURNAL_HDR_SZ( pPager ) ) / JOURNAL_PG_SZ( pPager ) );
- }
- /* If nRec is 0 and this rollback is of a transaction created by this
- ** process and if this is the final header in the journal, then it means
- ** that this part of the journal was being filled but has not yet been
- ** synced to disk. Compute the number of pages based on the remaining
- ** size of the file.
- **
- ** The third term of the test was added to fix ticket #2565.
- ** When rolling back a hot journal, nRec==0 always means that the next
- ** chunk of the journal contains zero pages to be rolled back. But
- ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
- ** the journal, it means that the journal might contain additional
- ** pages that need to be rolled back and that the number of pages
- ** should be computed based on the journal file size.
- */
- if ( nRec == 0 && 0 == isHot &&
- pPager.journalHdr + JOURNAL_HDR_SZ( pPager ) == pPager.journalOff )
- {
- nRec = (u32)( ( szJ - pPager.journalOff ) / JOURNAL_PG_SZ( pPager ) );
- }
- /* If this is the first header read from the journal, truncate the
- ** database file back to its original size.
- */
- if ( pPager.journalOff == JOURNAL_HDR_SZ( pPager ) )
- {
- rc = pager_truncate( pPager, mxPg );
- if ( rc != SQLITE_OK )
- {
- goto end_playback;
- }
- pPager.dbSize = mxPg;
- }
- /* Copy original pages out of the journal and back into the
- ** database file and/or page cache.
- */
- for ( u = 0; u < nRec; u++ )
- {
- if ( needPagerReset != 0 )
- {
- pager_reset( pPager );
- needPagerReset = 0;
- }
- rc = pager_playback_one_page( pPager, ref pPager.journalOff, null, 1, 0 );
- if ( rc != SQLITE_OK )
- {
- if ( rc == SQLITE_DONE )
- {
- rc = SQLITE_OK;
- pPager.journalOff = szJ;
- break;
- }
- else if ( rc == SQLITE_IOERR_SHORT_READ )
- {
- /* If the journal has been truncated, simply stop reading and
- ** processing the journal. This might happen if the journal was
- ** not completely written and synced prior to a crash. In that
- ** case, the database should have never been written in the
- ** first place so it is OK to simply abandon the rollback. */
- rc = SQLITE_OK;
- goto end_playback;
- }
- else
- {
- /* If we are unable to rollback, quit and return the error
- ** code. This will cause the pager to enter the error state
- ** so that no further harm will be done. Perhaps the next
- ** process to come along will be able to rollback the database.
- */
- goto end_playback;
- }
- }
- }
- }
- /*NOTREACHED*/
- end_playback:
- /* Following a rollback, the database file should be back in its original
- ** state prior to the start of the transaction, so invoke the
- ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
- ** assertion that the transaction counter was modified.
- */
- sqlite3_int64 iDummy = 0;
- Debug.Assert(
- pPager.fd.pMethods == null ||
- sqlite3OsFileControl( pPager.fd, SQLITE_FCNTL_DB_UNCHANGED, ref iDummy ) >= SQLITE_OK
- );
- /* If this playback is happening automatically as a result of an IO or
- ** malloc error that occurred after the change-counter was updated but
- ** before the transaction was committed, then the change-counter
- ** modification may just have been reverted. If this happens in exclusive
- ** mode, then subsequent transactions performed by the connection will not
- ** update the change-counter at all. This may lead to cache inconsistency
- ** problems for other processes at some point in the future. So, just
- ** in case this has happened, clear the changeCountDone flag now.
- */
- pPager.changeCountDone = pPager.tempFile;
- if ( rc == SQLITE_OK )
- {
- zMaster = new byte[pPager.pVfs.mxPathname + 1];//pPager.pTmpSpace );
- rc = readMasterJournal( pPager.jfd, zMaster, (u32)pPager.pVfs.mxPathname + 1 );
- testcase( rc != SQLITE_OK );
- }
- if ( rc == SQLITE_OK
- && ( pPager.eState >= PAGER_WRITER_DBMOD || pPager.eState == PAGER_OPEN )
- )
- {
- rc = sqlite3PagerSync( pPager );
- }
- if ( rc == SQLITE_OK )
- {
- rc = pager_end_transaction( pPager, zMaster[0] != '\0' ? 1 : 0 );
- testcase( rc != SQLITE_OK );
- }
- if ( rc == SQLITE_OK && zMaster[0] != '\0' && res != 0 )
- {
- /* If there was a master journal and this routine will return success,
- ** see if it is possible to delete the master journal.
- */
- rc = pager_delmaster( pPager, Encoding.UTF8.GetString( zMaster, 0, zMaster.Length ) );
- testcase( rc != SQLITE_OK );
- }
- /* The Pager.sectorSize variable may have been updated while rolling
- ** back a journal created by a process with a different sector size
- ** value. Reset it to the correct value for this process.
- */
- setSectorSize( pPager );
- return rc;
- }
- /*
- ** Read the content for page pPg out of the database file and into
- ** pPg.pData. A shared lock or greater must be held on the database
- ** file before this function is called.
- **
- ** If page 1 is read, then the value of Pager.dbFileVers[] is set to
- ** the value read from the database file.
- **
- ** If an IO error occurs, then the IO error is returned to the caller.
- ** Otherwise, SQLITE_OK is returned.
- */
- static int readDbPage( PgHdr pPg )
- {
- Pager pPager = pPg.pPager; /* Pager object associated with page pPg */
- Pgno pgno = pPg.pgno; /* Page number to read */
- int rc = SQLITE_OK; /* Return code */
- int isInWal = 0; /* True if page is in log file */
- int pgsz = pPager.pageSize; /* Number of bytes to read */
- Debug.Assert( pPager.eState >= PAGER_READER &&
- #if SQLITE_OMIT_MEMORYDB
- 0 == MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- Debug.Assert( isOpen( pPager.fd ) );
- if ( NEVER( !isOpen( pPager.fd ) ) )
- {
- Debug.Assert( pPager.tempFile );
- Array.Clear( pPg.pData, 0, pPager.pageSize );// memset(pPg.pData, 0, pPager.pageSize);
- return SQLITE_OK;
- }
- if ( pagerUseWal( pPager ) )
- {
- /* Try to pull the page from the write-ahead log. */
- rc = sqlite3WalRead( pPager.pWal, pgno, ref isInWal, pgsz, pPg.pData );
- }
- if ( rc == SQLITE_OK && 0 == isInWal )
- {
- i64 iOffset = ( pgno - 1 ) * (i64)pPager.pageSize;
- rc = sqlite3OsRead( pPager.fd, pPg.pData, pgsz, iOffset );
- if ( rc == SQLITE_IOERR_SHORT_READ )
- {
- rc = SQLITE_OK;
- }
- }
- if ( pgno == 1 )
- {
- if ( rc != 0 )
- {
- /* If the read is unsuccessful, set the dbFileVers[] to something
- ** that will never be a valid file version. dbFileVers[] is a copy
- ** of bytes 24..39 of the database. Bytes 28..31 should always be
- ** zero or the size of the database in page. Bytes 32..35 and 35..39
- ** should be page numbers which are never 0xffffffff. So filling
- ** pPager.dbFileVers[] with all 0xff bytes should suffice.
- **
- ** For an encrypted database, the situation is more complex: bytes
- ** 24..39 of the database are white noise. But the probability of
- ** white noising equaling 16 bytes of 0xff is vanishingly small so
- ** we should still be ok.
- */
- for ( int i = 0; i < pPager.dbFileVers.Length; pPager.dbFileVers[i++] = 0xff )
- ; // memset(pPager.dbFileVers, 0xff, sizeof(pPager.dbFileVers));
- }
- else
- {
- //u8[] dbFileVers = pPg.pData[24];
- Buffer.BlockCopy( pPg.pData, 24, pPager.dbFileVers, 0, pPager.dbFileVers.Length ); //memcpy(&pPager.dbFileVers, dbFileVers, sizeof(pPager.dbFileVers));
- }
- }
- if ( CODEC1( pPager, pPg.pData, pgno, SQLITE_DECRYPT ) )
- rc = SQLITE_NOMEM;//CODEC1(pPager, pPg.pData, pgno, 3, rc = SQLITE_NOMEM);
- #if SQLITE_TEST
- // PAGER_INCR(ref sqlite3_pager_readdb_count);
- int iValue;
- iValue = sqlite3_pager_readdb_count.iValue;
- PAGER_INCR( ref iValue );
- sqlite3_pager_readdb_count.iValue = iValue;
- PAGER_INCR( ref pPager.nRead );
- #endif
- IOTRACE( "PGIN %p %d\n", pPager, pgno );
- PAGERTRACE( "FETCH %d page %d hash(%08x)\n",
- PAGERID( pPager ), pgno, pager_pagehash( pPg ) );
- return rc;
- }
- #if !SQLITE_OMIT_WAL
- /*
- ** This function is invoked once for each page that has already been
- ** written into the log file when a WAL transaction is rolled back.
- ** Parameter iPg is the page number of said page. The pCtx argument
- ** is actually a pointer to the Pager structure.
- **
- ** If page iPg is present in the cache, and has no outstanding references,
- ** it is discarded. Otherwise, if there are one or more outstanding
- ** references, the page content is reloaded from the database. If the
- ** attempt to reload content from the database is required and fails,
- ** return an SQLite error code. Otherwise, SQLITE_OK.
- */
- static int pagerUndoCallback(void *pCtx, Pgno iPg){
- int rc = SQLITE_OK;
- Pager *pPager = (Pager *)pCtx;
- PgHdr *pPg;
- pPg = sqlite3PagerLookup(pPager, iPg);
- if( pPg ){
- if( sqlite3PcachePageRefcount(pPg)==1 ){
- sqlite3PcacheDrop(pPg);
- }else{
- rc = readDbPage(pPg);
- if( rc==SQLITE_OK ){
- pPager->xReiniter(pPg);
- }
- sqlite3PagerUnref(pPg);
- }
- }
- /* Normally, if a transaction is rolled back, any backup processes are
- ** updated as data is copied out of the rollback journal and into the
- ** database. This is not generally possible with a WAL database, as
- ** rollback involves simply truncating the log file. Therefore, if one
- ** or more frames have already been written to the log (and therefore
- ** also copied into the backup databases) as part of this transaction,
- ** the backups must be restarted.
- */
- sqlite3BackupRestart(pPager->pBackup);
- return rc;
- }
- /*
- ** This function is called to rollback a transaction on a WAL database.
- */
- static int pagerRollbackWal(Pager *pPager){
- int rc; /* Return Code */
- PgHdr *pList; /* List of dirty pages to revert */
- /* For all pages in the cache that are currently dirty or have already
- ** been written (but not committed) to the log file, do one of the
- ** following:
- **
- ** + Discard the cached page (if refcount==0), or
- ** + Reload page content from the database (if refcount>0).
- */
- pPager->dbSize = pPager->dbOrigSize;
- rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
- pList = sqlite3PcacheDirtyList(pPager->pPCache);
- while( pList && rc==SQLITE_OK ){
- PgHdr *pNext = pList->pDirty;
- rc = pagerUndoCallback((void *)pPager, pList->pgno);
- pList = pNext;
- }
- return rc;
- }
- /*
- ** This function is a wrapper around sqlite3WalFrames(). As well as logging
- ** the contents of the list of pages headed by pList (connected by pDirty),
- ** this function notifies any active backup processes that the pages have
- ** changed.
- **
- ** The list of pages passed into this routine is always sorted by page number.
- ** Hence, if page 1 appears anywhere on the list, it will be the first page.
- */
- static int pagerWalFrames(
- Pager *pPager, /* Pager object */
- PgHdr *pList, /* List of frames to log */
- Pgno nTruncate, /* Database size after this commit */
- int isCommit, /* True if this is a commit */
- int syncFlags /* Flags to pass to OsSync() (or 0) */
- ){
- int rc; /* Return code */
- #if (SQLITE_DEBUG) || (SQLITE_CHECK_PAGES)
- PgHdr *p; /* For looping over pages */
- #endif
- assert( pPager->pWal );
- #if SQLITE_DEBUG
- /* Verify that the page list is in accending order */
- for(p=pList; p && p->pDirty; p=p->pDirty){
- assert( p->pgno < p->pDirty->pgno );
- }
- #endif
- if( pList->pgno==1 ) pager_write_changecounter(pList);
- rc = sqlite3WalFrames(pPager->pWal,
- pPager->pageSize, pList, nTruncate, isCommit, syncFlags
- );
- if( rc==SQLITE_OK && pPager->pBackup ){
- PgHdr *p;
- for(p=pList; p; p=p->pDirty){
- sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
- }
- }
- #if SQLITE_CHECK_PAGES
- for(p=pList; p; p=p->pDirty){
- pager_set_pagehash(p);
- }
- #endif
- return rc;
- }
- /*
- ** Begin a read transaction on the WAL.
- **
- ** This routine used to be called "pagerOpenSnapshot()" because it essentially
- ** makes a snapshot of the database at the current point in time and preserves
- ** that snapshot for use by the reader in spite of concurrently changes by
- ** other writers or checkpointers.
- */
- static int pagerBeginReadTransaction(Pager *pPager){
- int rc; /* Return code */
- int changed = 0; /* True if cache must be reset */
- assert( pagerUseWal(pPager) );
- assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
- /* sqlite3WalEndReadTransaction() was not called for the previous
- ** transaction in locking_mode=EXCLUSIVE. So call it now. If we
- ** are in locking_mode=NORMAL and EndRead() was previously called,
- ** the duplicate call is harmless.
- */
- sqlite3WalEndReadTransaction(pPager->pWal);
- rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
- if( rc!=SQLITE_OK || changed ){
- pager_reset(pPager);
- }
- return rc;
- }
- #endif
- /*
- ** Update the value of the change-counter at offsets 24 and 92 in
- ** the header and the sqlite version number at offset 96.
- **
- ** This is an unconditional update. See also the pager_incr_changecounter()
- ** routine which only updates the change-counter if the update is actually
- ** needed, as determined by the pPager->changeCountDone state variable.
- */
- static void pager_write_changecounter( PgHdr pPg )
- {
- u32 change_counter;
- /* Increment the value just read and write it back to byte 24. */
- change_counter = sqlite3Get4byte( pPg.pPager.dbFileVers ) + 1;
- put32bits( pPg.pData, 24, change_counter );
- /* Also store the SQLite version number in bytes 96..99 and in
- ** bytes 92..95 store the change counter for which the version number
- ** is valid. */
- put32bits( pPg.pData, 92, change_counter );
- put32bits( pPg.pData, 96, SQLITE_VERSION_NUMBER );
- }
- /*
- ** This function is called as part of the transition from PAGER_OPEN
- ** to PAGER_READER state to determine the size of the database file
- ** in pages (assuming the page size currently stored in Pager.pageSize).
- **
- ** If no error occurs, SQLITE_OK is returned and the size of the database
- ** in pages is stored in *pnPage. Otherwise, an error code (perhaps
- ** SQLITE_IOERR_FSTAT) is returned and *pnPage is left unmodified.
- */
- static int pagerPagecount( Pager pPager, ref Pgno pnPage )
- {
- Pgno nPage; /* Value to return via *pnPage */
- /* Query the WAL sub-system for the database size. The WalDbsize()
- ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
- ** if the database size is not available. The database size is not
- ** available from the WAL sub-system if the log file is empty or
- ** contains no valid committed transactions.
- */
- Debug.Assert( pPager.eState == PAGER_OPEN );
- Debug.Assert( pPager.eLock >= SHARED_LOCK || pPager.noReadlock != 0 );
- nPage = sqlite3WalDbsize( pPager.pWal );
- /* If the database size was not available from the WAL sub-system,
- ** determine it based on the size of the database file. If the size
- ** of the database file is not an integer multiple of the page-size,
- ** round down to the nearest page. Except, any file larger than 0
- ** bytes in size is considered to contain at least one page.
- */
- if ( nPage == 0 )
- {
- i64 n = 0; /* Size of db file in bytes */
- Debug.Assert( isOpen( pPager.fd ) || pPager.tempFile );
- if ( isOpen( pPager.fd ) )
- {
- int rc = sqlite3OsFileSize( pPager.fd, ref n );
- if ( rc != SQLITE_OK )
- {
- return rc;
- }
- }
- nPage = (Pgno)( n / pPager.pageSize );
- if ( nPage == 0 && n > 0 )
- {
- nPage = 1;
- }
- }
- /* If the current number of pages in the file is greater than the
- ** configured maximum pager number, increase the allowed limit so
- ** that the file can be read.
- */
- if ( nPage > pPager.mxPgno )
- {
- pPager.mxPgno = (Pgno)nPage;
- }
- pnPage = nPage;
- return SQLITE_OK;
- }
- #if !SQLITE_OMIT_WAL
- /*
- ** Check if the *-wal file that corresponds to the database opened by pPager
- ** exists if the database is not empy, or verify that the *-wal file does
- ** not exist (by deleting it) if the database file is empty.
- **
- ** If the database is not empty and the *-wal file exists, open the pager
- ** in WAL mode. If the database is empty or if no *-wal file exists and
- ** if no error occurs, make sure Pager.journalMode is not set to
- ** PAGER_JOURNALMODE_WAL.
- **
- ** Return SQLITE_OK or an error code.
- **
- ** The caller must hold a SHARED lock on the database file to call this
- ** function. Because an EXCLUSIVE lock on the db file is required to delete
- ** a WAL on a none-empty database, this ensures there is no race condition
- ** between the xAccess() below and an xDelete() being executed by some
- ** other connection.
- */
- static int pagerOpenWalIfPresent(Pager *pPager){
- int rc = SQLITE_OK;
- Debug.Assert( pPager.eState==PAGER_OPEN );
- Debug.Assert( pPager.eLock>=SHARED_LOCK || pPager.noReadlock );
- if( !pPager.tempFile ){
- int isWal; /* True if WAL file exists */
- Pgno nPage; /* Size of the database file */
- rc = pagerPagecount(pPager, &nPage);
- if( rc ) return rc;
- if( nPage==0 ){
- rc = sqlite3OsDelete(pPager.pVfs, pPager.zWal, 0);
- isWal = 0;
- }else{
- rc = sqlite3OsAccess(
- pPager.pVfs, pPager.zWal, SQLITE_ACCESS_EXISTS, &isWal
- );
- }
- if( rc==SQLITE_OK ){
- if( isWal ){
- testcase( sqlite3PcachePagecount(pPager.pPCache)==0 );
- rc = sqlite3PagerOpenWal(pPager, 0);
- }else if( pPager.journalMode==PAGER_JOURNALMODE_WAL ){
- pPager.journalMode = PAGER_JOURNALMODE_DELETE;
- }
- }
- }
- return rc;
- }
- #endif
- /*
- ** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
- ** the entire master journal file. The case pSavepoint==NULL occurs when
- ** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
- ** savepoint.
- **
- ** When pSavepoint is not NULL (meaning a non-transaction savepoint is
- ** being rolled back), then the rollback consists of up to three stages,
- ** performed in the order specified:
- **
- ** * Pages are played back from the main journal starting at byte
- ** offset PagerSavepoint.iOffset and continuing to
- ** PagerSavepoint.iHdrOffset, or to the end of the main journal
- ** file if PagerSavepoint.iHdrOffset is zero.
- **
- ** * If PagerSavepoint.iHdrOffset is not zero, then pages are played
- ** back starting from the journal header immediately following
- ** PagerSavepoint.iHdrOffset to the end of the main journal file.
- **
- ** * Pages are then played back from the sub-journal file, starting
- ** with the PagerSavepoint.iSubRec and continuing to the end of
- ** the journal file.
- **
- ** Throughout the rollback process, each time a page is rolled back, the
- ** corresponding bit is set in a bitvec structure (variable pDone in the
- ** implementation below). This is used to ensure that a page is only
- ** rolled back the first time it is encountered in either journal.
- **
- ** If pSavepoint is NULL, then pages are only played back from the main
- ** journal file. There is no need for a bitvec in this case.
- **
- ** In either case, before playback commences the Pager.dbSize variable
- ** is reset to the value that it held at the start of the savepoint
- ** (or transaction). No page with a page-number greater than this value
- ** is played back. If one is encountered it is simply skipped.
- */
- static int pagerPlaybackSavepoint( Pager pPager, PagerSavepoint pSavepoint )
- {
- i64 szJ; /* Effective size of the main journal */
- i64 iHdrOff; /* End of first segment of main-journal records */
- int rc = SQLITE_OK; /* Return code */
- Bitvec pDone = null; /* Bitvec to ensure pages played back only once */
- Debug.Assert( pPager.eState != PAGER_ERROR );
- Debug.Assert( pPager.eState >= PAGER_WRITER_LOCKED );
- /* Allocate a bitvec to use to store the set of pages rolled back */
- if ( pSavepoint != null )
- {
- pDone = sqlite3BitvecCreate( pSavepoint.nOrig );
- if ( null == pDone )
- {
- return SQLITE_NOMEM;
- }
- }
- /* Set the database size back to the value it was before the savepoint
- ** being reverted was opened.
- */
- pPager.dbSize = pSavepoint != null ? pSavepoint.nOrig : pPager.dbOrigSize;
- pPager.changeCountDone = pPager.tempFile;
- if ( !pSavepoint && pagerUseWal( pPager ) )
- {
- return pagerRollbackWal( pPager );
- }
- /* Use pPager.journalOff as the effective size of the main rollback
- ** journal. The actual file might be larger than this in
- ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST. But anything
- ** past pPager.journalOff is off-limits to us.
- */
- szJ = pPager.journalOff;
- Debug.Assert( pagerUseWal( pPager ) == false || szJ == 0 );
- /* Begin by rolling back records from the main journal starting at
- ** PagerSavepoint.iOffset and continuing to the next journal header.
- ** There might be records in the main journal that have a page number
- ** greater than the current database size (pPager.dbSize) but those
- ** will be skipped automatically. Pages are added to pDone as they
- ** are played back.
- */
- if ( pSavepoint != null && !pagerUseWal( pPager ) )
- {
- iHdrOff = pSavepoint.iHdrOffset != 0 ? pSavepoint.iHdrOffset : szJ;
- pPager.journalOff = pSavepoint.iOffset;
- while ( rc == SQLITE_OK && pPager.journalOff < iHdrOff )
- {
- rc = pager_playback_one_page( pPager, ref pPager.journalOff, pDone, 1, 1 );
- }
- Debug.Assert( rc != SQLITE_DONE );
- }
- else
- {
- pPager.journalOff = 0;
- }
- /* Continue rolling back records out of the main journal starting at
- ** the first journal header seen and continuing until the effective end
- ** of the main journal file. Continue to skip out-of-range pages and
- ** continue adding pages rolled back to pDone.
- */
- while ( rc == SQLITE_OK && pPager.journalOff < szJ )
- {
- u32 ii; /* Loop counter */
- u32 nJRec = 0; /* Number of Journal Records */
- u32 dummy = 0;
- rc = readJournalHdr( pPager, 0, (int)szJ, ref nJRec, ref dummy );
- Debug.Assert( rc != SQLITE_DONE );
- /*
- ** The "pPager.journalHdr+JOURNAL_HDR_SZ(pPager)==pPager.journalOff"
- ** test is related to ticket #2565. See the discussion in the
- ** pager_playback() function for additional information.
- */
- if ( nJRec == 0
- && pPager.journalHdr + JOURNAL_HDR_SZ( pPager ) >= pPager.journalOff
- )
- {
- nJRec = (u32)( ( szJ - pPager.journalOff ) / JOURNAL_PG_SZ( pPager ) );
- }
- for ( ii = 0; rc == SQLITE_OK && ii < nJRec && pPager.journalOff < szJ; ii++ )
- {
- rc = pager_playback_one_page( pPager, ref pPager.journalOff, pDone, 1, 1 );
- }
- Debug.Assert( rc != SQLITE_DONE );
- }
- Debug.Assert( rc != SQLITE_OK || pPager.journalOff >= szJ );
- /* Finally, rollback pages from the sub-journal. Page that were
- ** previously rolled back out of the main journal (and are hence in pDone)
- ** will be skipped. Out-of-range pages are also skipped.
- */
- if ( pSavepoint != null )
- {
- u32 ii; /* Loop counter */
- i64 offset = pSavepoint.iSubRec * ( 4 + pPager.pageSize );
- if ( pagerUseWal( pPager ) )
- {
- rc = sqlite3WalSavepointUndo( pPager.pWal, pSavepoint.aWalData );
- }
- for ( ii = pSavepoint.iSubRec; rc == SQLITE_OK && ii < pPager.nSubRec; ii++ )
- {
- Debug.Assert( offset == ii * ( 4 + pPager.pageSize ) );
- rc = pager_playback_one_page( pPager, ref offset, pDone, 0, 1 );
- }
- Debug.Assert( rc != SQLITE_DONE );
- }
- sqlite3BitvecDestroy( ref pDone );
- if ( rc == SQLITE_OK )
- {
- pPager.journalOff = (int)szJ;
- }
- return rc;
- }
- /*
- ** Change the maximum number of in-memory pages that are allowed.
- */
- static void sqlite3PagerSetCachesize( Pager pPager, int mxPage )
- {
- sqlite3PcacheSetCachesize( pPager.pPCache, mxPage );
- }
- /*
- ** Adjust the robustness of the database to damage due to OS crashes
- ** or power failures by changing the number of syncs()s when writing
- ** the rollback journal. There are three levels:
- **
- ** OFF sqlite3OsSync() is never called. This is the default
- ** for temporary and transient files.
- **
- ** NORMAL The journal is synced once before writes begin on the
- ** database. This is normally adequate protection, but
- ** it is theoretically possible, though very unlikely,
- ** that an inopertune power failure could leave the journal
- ** in a state which would cause damage to the database
- ** when it is rolled back.
- **
- ** FULL The journal is synced twice before writes begin on the
- ** database (with some additional information - the nRec field
- ** of the journal header - being written in between the two
- ** syncs). If we assume that writing a
- ** single disk sector is atomic, then this mode provides
- ** assurance that the journal will not be corrupted to the
- ** point of causing damage to the database during rollback.
- **
- ** The above is for a rollback-journal mode. For WAL mode, OFF continues
- ** to mean that no syncs ever occur. NORMAL means that the WAL is synced
- ** prior to the start of checkpoint and that the database file is synced
- ** at the conclusion of the checkpoint if the entire content of the WAL
- ** was written back into the database. But no sync operations occur for
- ** an ordinary commit in NORMAL mode with WAL. FULL means that the WAL
- ** file is synced following each commit operation, in addition to the
- ** syncs associated with NORMAL.
- **
- ** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL. The
- ** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
- ** using fcntl(F_FULLFSYNC). SQLITE_SYNC_NORMAL means to do an
- ** ordinary fsync() call. There is no difference between SQLITE_SYNC_FULL
- ** and SQLITE_SYNC_NORMAL on platforms other than MacOSX. But the
- ** synchronous=FULL versus synchronous=NORMAL setting determines when
- ** the xSync primitive is called and is relevant to all platforms.
- **
- ** Numeric values associated with these states are OFF==1, NORMAL=2,
- ** and FULL=3.
- */
- #if !SQLITE_OMIT_PAGER_PRAGMAS
- static void sqlite3PagerSetSafetyLevel(
- Pager pPager, /* The pager to set safety level for */
- int level, /* PRAGMA synchronous. 1=OFF, 2=NORMAL, 3=FULL */
- int bFullFsync, /* PRAGMA fullfsync */
- int bCkptFullFsync /* PRAGMA checkpoint_fullfsync */
- )
- {
- Debug.Assert( level >= 1 && level <= 3 );
- pPager.noSync = ( level == 1 || pPager.tempFile );
- pPager.fullSync = ( level == 3 && !pPager.tempFile );
- if ( pPager.noSync )
- {
- pPager.syncFlags = 0;
- pPager.ckptSyncFlags = 0;
- }
- else if ( bFullFsync != 0 )
- {
- pPager.syncFlags = SQLITE_SYNC_FULL;
- pPager.ckptSyncFlags = SQLITE_SYNC_FULL;
- }
- else if ( bCkptFullFsync != 0 )
- {
- pPager.syncFlags = SQLITE_SYNC_NORMAL;
- pPager.ckptSyncFlags = SQLITE_SYNC_FULL;
- }
- else
- {
- pPager.syncFlags = SQLITE_SYNC_NORMAL;
- pPager.ckptSyncFlags = SQLITE_SYNC_NORMAL;
- }
- }
- #endif
- /*
- ** The following global variable is incremented whenever the library
- ** attempts to open a temporary file. This information is used for
- ** testing and analysis only.
- */
- #if SQLITE_TEST
- //static int sqlite3_opentemp_count = 0;
- #endif
- /*
- ** Open a temporary file.
- **
- ** Write the file descriptor into *pFile. Return SQLITE_OK on success
- ** or some other error code if we fail. The OS will automatically
- ** delete the temporary file when it is closed.
- **
- ** The flags passed to the VFS layer xOpen() call are those specified
- ** by parameter vfsFlags ORed with the following:
- **
- ** SQLITE_OPEN_READWRITE
- ** SQLITE_OPEN_CREATE
- ** SQLITE_OPEN_EXCLUSIVE
- ** SQLITE_OPEN_DELETEONCLOSE
- */
- static int pagerOpentemp(
- Pager pPager, /* The pager object */
- ref sqlite3_file pFile, /* Write the file descriptor here */
- int vfsFlags /* Flags passed through to the VFS */
- )
- {
- int rc; /* Return code */
- #if SQLITE_TEST
- sqlite3_opentemp_count.iValue++; /* Used for testing and analysis only */
- #endif
- vfsFlags |= SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
- SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
- int dummy = 0;
- rc = sqlite3OsOpen( pPager.pVfs, null, pFile, vfsFlags, ref dummy );
- Debug.Assert( rc != SQLITE_OK || isOpen( pFile ) );
- return rc;
- }
- /*
- ** Set the busy handler function.
- **
- ** The pager invokes the busy-handler if sqlite3OsLock() returns
- ** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
- ** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE
- ** lock. It does *not* invoke the busy handler when upgrading from
- ** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
- ** (which occurs during hot-journal rollback). Summary:
- **
- ** Transition | Invokes xBusyHandler
- ** --------------------------------------------------------
- ** NO_LOCK . SHARED_LOCK | Yes
- ** SHARED_LOCK . RESERVED_LOCK | No
- ** SHARED_LOCK . EXCLUSIVE_LOCK | No
- ** RESERVED_LOCK . EXCLUSIVE_LOCK | Yes
- **
- ** If the busy-handler callback returns non-zero, the lock is
- ** retried. If it returns zero, then the SQLITE_BUSY error is
- ** returned to the caller of the pager API function.
- */
- static void sqlite3PagerSetBusyhandler(
- Pager pPager, /* Pager object */
- dxBusyHandler xBusyHandler, /* Pointer to busy-handler function */
- //int (*xBusyHandler)(void *),
- object pBusyHandlerArg /* Argument to pass to xBusyHandler */
- )
- {
- pPager.xBusyHandler = xBusyHandler;
- pPager.pBusyHandlerArg = pBusyHandlerArg;
- }
- /*
- ** Change the page size used by the Pager object. The new page size
- ** is passed in *pPageSize.
- **
- ** If the pager is in the error state when this function is called, it
- ** is a no-op. The value returned is the error state error code (i.e.
- ** one of SQLITE_IOERR, an SQLITE_IOERR_xxx sub-code or SQLITE_FULL).
- **
- ** Otherwise, if all of the following are true:
- **
- ** * the new page size (value of *pPageSize) is valid (a power
- ** of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
- **
- ** * there are no outstanding page references, and
- **
- ** * the database is either not an in-memory database or it is
- ** an in-memory database that currently consists of zero pages.
- **
- ** then the pager object page size is set to *pPageSize.
- **
- ** If the page size is changed, then this function uses sqlite3PagerMalloc()
- ** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt
- ** fails, SQLITE_NOMEM is returned and the page size remains unchanged.
- ** In all other cases, SQLITE_OK is returned.
- **
- ** If the page size is not changed, either because one of the enumerated
- ** conditions above is not true, the pager was in error state when this
- ** function was called, or because the memory allocation attempt failed,
- ** then *pPageSize is set to the old, retained page size before returning.
- */
- static int sqlite3PagerSetPagesize( Pager pPager, ref u32 pPageSize, int nReserve )
- {
- int rc = SQLITE_OK;
- /* It is not possible to do a full assert_pager_state() here, as this
- ** function may be called from within PagerOpen(), before the state
- ** of the Pager object is internally consistent.
- **
- ** At one point this function returned an error if the pager was in
- ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
- ** there is at least one outstanding page reference, this function
- ** is a no-op for that case anyhow.
- */
- u32 pageSize = pPageSize;
- Debug.Assert( pageSize == 0 || ( pageSize >= 512 && pageSize <= SQLITE_MAX_PAGE_SIZE ) );
- if ( ( pPager.memDb == 0 || pPager.dbSize == 0 )
- && sqlite3PcacheRefCount( pPager.pPCache ) == 0
- && pageSize != 0 && pageSize != (u32)pPager.pageSize
- )
- {
- //char *pNew = NULL; /* New temp space */
- i64 nByte = 0;
- if ( pPager.eState > PAGER_OPEN && isOpen( pPager.fd ) )
- {
- rc = sqlite3OsFileSize( pPager.fd, ref nByte );
- }
- //if ( rc == SQLITE_OK )
- //{
- //pNew = (char *)sqlite3PageMalloc(pageSize);
- //if( !pNew ) rc = SQLITE_NOMEM;
- //}
- if ( rc == SQLITE_OK )
- {
- pager_reset( pPager );
- pPager.dbSize = (Pgno)( nByte / pageSize );
- pPager.pageSize = (int)pageSize;
- sqlite3PageFree( ref pPager.pTmpSpace );
- pPager.pTmpSpace = sqlite3Malloc( pageSize );// pNew;
- sqlite3PcacheSetPageSize( pPager.pPCache, (int)pageSize );
- }
- }
- pPageSize = (u32)pPager.pageSize;
- if ( rc == SQLITE_OK )
- {
- if ( nReserve < 0 )
- nReserve = pPager.nReserve;
- Debug.Assert( nReserve >= 0 && nReserve < 1000 );
- pPager.nReserve = (i16)nReserve;
- pagerReportSize( pPager );
- }
- return rc;
- }
- /*
- ** Return a pointer to the "temporary page" buffer held internally
- ** by the pager. This is a buffer that is big enough to hold the
- ** entire content of a database page. This buffer is used internally
- ** during rollback and will be overwritten whenever a rollback
- ** occurs. But other modules are free to use it too, as long as
- ** no rollbacks are happening.
- */
- static byte[] sqlite3PagerTempSpace( Pager pPager )
- {
- return pPager.pTmpSpace;
- }
- /*
- ** Attempt to set the maximum database page count if mxPage is positive.
- ** Make no changes if mxPage is zero or negative. And never reduce the
- ** maximum page count below the current size of the database.
- **
- ** Regardless of mxPage, return the current maximum page count.
- */
- static Pgno sqlite3PagerMaxPageCount( Pager pPager, int mxPage )
- {
- if ( mxPage > 0 )
- {
- pPager.mxPgno = (Pgno)mxPage;
- }
- Debug.Assert( pPager.eState != PAGER_OPEN ); /* Called only by OP_MaxPgcnt */
- Debug.Assert( pPager.mxPgno >= pPager.dbSize ); /* OP_MaxPgcnt enforces this */
- return pPager.mxPgno;
- }
- /*
- ** The following set of routines are used to disable the simulated
- ** I/O error mechanism. These routines are used to avoid simulated
- ** errors in places where we do not care about errors.
- **
- ** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
- ** and generate no code.
- */
- #if SQLITE_TEST
- //extern int sqlite3_io_error_pending;
- //extern int sqlite3_io_error_hit;
- static int saved_cnt;
- static void disable_simulated_io_errors()
- {
- saved_cnt = sqlite3_io_error_pending.iValue;
- sqlite3_io_error_pending.iValue = -1;
- }
- static void enable_simulated_io_errors()
- {
- sqlite3_io_error_pending.iValue = saved_cnt;
- }
- #else
- //# define disable_simulated_io_errors()
- //# define enable_simulated_io_errors()
- #endif
- /*
- ** Read the first N bytes from the beginning of the file into memory
- ** that pDest points to.
- **
- ** If the pager was opened on a transient file (zFilename==""), or
- ** opened on a file less than N bytes in size, the output buffer is
- ** zeroed and SQLITE_OK returned. The rationale for this is that this
- ** function is used to read database headers, and a new transient or
- ** zero sized database has a header than consists entirely of zeroes.
- **
- ** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
- ** the error code is returned to the caller and the contents of the
- ** output buffer undefined.
- */
- static int sqlite3PagerReadFileheader( Pager pPager, int N, byte[] pDest )
- {
- int rc = SQLITE_OK;
- Array.Clear( pDest, 0, N ); //memset(pDest, 0, N);
- Debug.Assert( isOpen( pPager.fd ) || pPager.tempFile );
- /* This routine is only called by btree immediately after creating
- ** the Pager object. There has not been an opportunity to transition
- ** to WAL mode yet.
- */
- Debug.Assert( !pagerUseWal( pPager ) );
- if ( isOpen( pPager.fd ) )
- {
- IOTRACE( "DBHDR %p 0 %d\n", pPager, N );
- rc = sqlite3OsRead( pPager.fd, pDest, N, 0 );
- if ( rc == SQLITE_IOERR_SHORT_READ )
- {
- rc = SQLITE_OK;
- }
- }
- return rc;
- }
- /*
- ** This function may only be called when a read-transaction is open on
- ** the pager. It returns the total number of pages in the database.
- **
- ** However, if the file is between 1 and <page-size> bytes in size, then
- ** this is considered a 1 page file.
- */
- static void sqlite3PagerPagecount( Pager pPager, ref Pgno pnPage )
- {
- Debug.Assert( pPager.eState >= PAGER_READER );
- Debug.Assert( pPager.eState != PAGER_WRITER_FINISHED );
- pnPage = pPager.dbSize;
- }
- /*
- ** Try to obtain a lock of type locktype on the database file. If
- ** a similar or greater lock is already held, this function is a no-op
- ** (returning SQLITE_OK immediately).
- **
- ** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
- ** the busy callback if the lock is currently not available. Repeat
- ** until the busy callback returns false or until the attempt to
- ** obtain the lock succeeds.
- **
- ** Return SQLITE_OK on success and an error code if we cannot obtain
- ** the lock. If the lock is obtained successfully, set the Pager.state
- ** variable to locktype before returning.
- */
- static int pager_wait_on_lock( Pager pPager, int locktype )
- {
- int rc; /* Return code */
- /* Check that this is either a no-op (because the requested lock is
- ** already held, or one of the transistions that the busy-handler
- ** may be invoked during, according to the comment above
- ** sqlite3PagerSetBusyhandler().
- */
- Debug.Assert( ( pPager.eLock >= locktype )
- || ( pPager.eLock == NO_LOCK && locktype == SHARED_LOCK )
- || ( pPager.eLock == RESERVED_LOCK && locktype == EXCLUSIVE_LOCK )
- );
- do
- {
- rc = pagerLockDb( pPager, locktype );
- } while ( rc == SQLITE_BUSY && pPager.xBusyHandler( pPager.pBusyHandlerArg ) != 0 );
- return rc;
- }
- /*
- ** Function assertTruncateConstraint(pPager) checks that one of the
- ** following is true for all dirty pages currently in the page-cache:
- **
- ** a) The page number is less than or equal to the size of the
- ** current database image, in pages, OR
- **
- ** b) if the page content were written at this time, it would not
- ** be necessary to write the current content out to the sub-journal
- ** (as determined by function subjRequiresPage()).
- **
- ** If the condition asserted by this function were not true, and the
- ** dirty page were to be discarded from the cache via the pagerStress()
- ** routine, pagerStress() would not write the current page content to
- ** the database file. If a savepoint transaction were rolled back after
- ** this happened, the correct behaviour would be to restore the current
- ** content of the page. However, since this content is not present in either
- ** the database file or the portion of the rollback journal and
- ** sub-journal rolled back the content could not be restored and the
- ** database image would become corrupt. It is therefore fortunate that
- ** this circumstance cannot arise.
- */
- #if SQLITE_DEBUG
- static void assertTruncateConstraintCb( PgHdr pPg )
- {
- Debug.Assert( ( pPg.flags & PGHDR_DIRTY ) != 0 );
- Debug.Assert( !subjRequiresPage( pPg ) || pPg.pgno <= pPg.pPager.dbSize );
- }
- static void assertTruncateConstraint( Pager pPager )
- {
- sqlite3PcacheIterateDirty( pPager.pPCache, assertTruncateConstraintCb );
- }
- #else
- //# define assertTruncateConstraint(pPager)
- static void assertTruncateConstraintCb(PgHdr pPg) { }
- static void assertTruncateConstraint(Pager pPager) { }
- #endif
- /*
- ** Truncate the in-memory database file image to nPage pages. This
- ** function does not actually modify the database file on disk. It
- ** just sets the internal state of the pager object so that the
- ** truncation will be done when the current transaction is committed.
- */
- static void sqlite3PagerTruncateImage( Pager pPager, u32 nPage )
- {
- Debug.Assert( pPager.dbSize >= nPage );
- Debug.Assert( pPager.eState >= PAGER_WRITER_CACHEMOD );
- pPager.dbSize = nPage;
- assertTruncateConstraint( pPager );
- }
- /*
- ** This function is called before attempting a hot-journal rollback. It
- ** syncs the journal file to disk, then sets pPager.journalHdr to the
- ** size of the journal file so that the pager_playback() routine knows
- ** that the entire journal file has been synced.
- **
- ** Syncing a hot-journal to disk before attempting to roll it back ensures
- ** that if a power-failure occurs during the rollback, the process that
- ** attempts rollback following system recovery sees the same journal
- ** content as this process.
- **
- ** If everything goes as planned, SQLITE_OK is returned. Otherwise,
- ** an SQLite error code.
- */
- static int pagerSyncHotJournal( Pager pPager )
- {
- int rc = SQLITE_OK;
- if ( !pPager.noSync )
- {
- rc = sqlite3OsSync( pPager.jfd, SQLITE_SYNC_NORMAL );
- }
- if ( rc == SQLITE_OK )
- {
- rc = sqlite3OsFileSize( pPager.jfd, ref pPager.journalHdr );
- }
- return rc;
- }
- /*
- ** Shutdown the page cache. Free all memory and close all files.
- **
- ** If a transaction was in progress when this routine is called, that
- ** transaction is rolled back. All outstanding pages are invalidated
- ** and their memory is freed. Any attempt to use a page associated
- ** with this page cache after this function returns will likely
- ** result in a coredump.
- **
- ** This function always succeeds. If a transaction is active an attempt
- ** is made to roll it back. If an error occurs during the rollback
- ** a hot journal may be left in the filesystem but no error is returned
- ** to the caller.
- */
- static int sqlite3PagerClose( Pager pPager )
- {
- u8[] pTmp = pPager.pTmpSpace;
- #if SQLITE_TEST
- disable_simulated_io_errors();
- #endif
- sqlite3BeginBenignMalloc();
- /* pPager->errCode = 0; */
- pPager.exclusiveMode = false;
- #if !SQLITE_OMIT_WAL
- sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
- pPager.pWal = 0;
- #endif
- pager_reset( pPager );
- if (
- #if SQLITE_OMIT_MEMORYDB
- 1==MEMDB
- #else
- 1 == pPager.memDb
- #endif
- )
- {
- pager_unlock( pPager );
- }
- else
- {
- /* If it is open, sync the journal file before calling UnlockAndRollback.
- ** If this is not done, then an unsynced portion of the open journal
- ** file may be played back into the database. If a power failure occurs
- ** while this is happening, the database could become corrupt.
- **
- ** If an error occurs while trying to sync the journal, shift the pager
- ** into the ERROR state. This causes UnlockAndRollback to unlock the
- ** database and close the journal file without attempting to roll it
- ** back or finalize it. The next database user will have to do hot-journal
- ** rollback before accessing the database file.
- */
- if ( isOpen( pPager.jfd ) )
- {
- pager_error( pPager, pagerSyncHotJournal( pPager ) );
- }
- pagerUnlockAndRollback( pPager );
- }
- sqlite3EndBenignMalloc();
- #if SQLITE_TEST
- enable_simulated_io_errors();
- #endif
- PAGERTRACE( "CLOSE %d\n", PAGERID( pPager ) );
- IOTRACE( "CLOSE %p\n", pPager );
- sqlite3OsClose( pPager.jfd );
- sqlite3OsClose( pPager.fd );
- //sqlite3_free( ref pTmp );
- sqlite3PcacheClose( pPager.pPCache );
- #if SQLITE_HAS_CODEC
- if ( pPager.xCodecFree != null )
- pPager.xCodecFree( ref pPager.pCodec );
- #endif
- Debug.Assert( null == pPager.aSavepoint && !pPager.pInJournal );
- Debug.Assert( !isOpen( pPager.jfd ) && !isOpen( pPager.sjfd ) );
- //sqlite3_free( ref pPager );
- return SQLITE_OK;
- }
- #if !NDEBUG || SQLITE_TEST
- /*
- ** Return the page number for page pPg.
- */
- static Pgno sqlite3PagerPagenumber( DbPage pPg )
- {
- return pPg.pgno;
- }
- #else
- static Pgno sqlite3PagerPagenumber( DbPage pPg ) { return pPg.pgno; }
- #endif
- /*
- ** Increment the reference count for page pPg.
- */
- static void sqlite3PagerRef( DbPage pPg )
- {
- sqlite3PcacheRef( pPg );
- }
- /*
- ** Sync the journal. In other words, make sure all the pages that have
- ** been written to the journal have actually reached the surface of the
- ** disk and can be restored in the event of a hot-journal rollback.
- **
- ** If the Pager.noSync flag is set, then this function is a no-op.
- ** Otherwise, the actions required depend on the journal-mode and the
- ** device characteristics of the the file-system, as follows:
- **
- ** * If the journal file is an in-memory journal file, no action need
- ** be taken.
- **
- ** * Otherwise, if the device does not support the SAFE_APPEND property,
- ** then the nRec field of the most recently written journal header
- ** is updated to contain the number of journal records that have
- ** been written following it. If the pager is operating in full-sync
- ** mode, then the journal file is synced before this field is updated.
- **
- ** * If the device does not support the SEQUENTIAL property, then
- ** journal file is synced.
- **
- ** Or, in pseudo-code:
- **
- ** if( NOT <in-memory journal> ){
- ** if( NOT SAFE_APPEND ){
- ** if( <full-sync mode> ) xSync(<journal file>);
- ** <update nRec field>
- ** }
- ** if( NOT SEQUENTIAL ) xSync(<journal file>);
- ** }
- **
- ** If successful, this routine clears the PGHDR_NEED_SYNC flag of every
- ** page currently held in memory before returning SQLITE_OK. If an IO
- ** error is encountered, then the IO error code is returned to the caller.
- */
- static int syncJournal( Pager pPager, int newHdr )
- {
- int rc = SQLITE_OK;
- Debug.Assert( pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- );
- Debug.Assert( assert_pager_state( pPager ) );
- Debug.Assert( !pagerUseWal( pPager ) );
- rc = sqlite3PagerExclusiveLock( pPager );
- if ( rc != SQLITE_OK )
- return rc;
- if ( !pPager.noSync )
- {
- Debug.Assert( !pPager.tempFile );
- if ( isOpen( pPager.jfd ) && pPager.journalMode != PAGER_JOURNALMODE_MEMORY )
- {
- int iDc = sqlite3OsDeviceCharacteristics( pPager.fd );
- Debug.Assert( isOpen( pPager.jfd ) );
- if ( 0 == ( iDc & SQLITE_IOCAP_SAFE_APPEND ) )
- {
- /* This block deals with an obscure problem. If the last connection
- ** that wrote to this database was operating in persistent-journal
- ** mode, then the journal file may at this point actually be larger
- ** than Pager.journalOff bytes. If the next thing in the journal
- ** file happens to be a journal-header (written as part of the
- ** previous connection's transaction), and a crash or power-failure
- ** occurs after nRec is updated but before this connection writes
- ** anything else to the journal file (or commits/rolls back its
- ** transaction), then SQLite may become confused when doing the
- ** hot-journal rollback following recovery. It may roll back all
- ** of this connections data, then proceed to rolling back the old,
- ** out-of-date data that follows it. Database corruption.
- **
- ** To work around this, if the journal file does appear to contain
- ** a valid header following Pager.journalOff, then write a 0x00
- ** byte to the start of it to prevent it from being recognized.
- **
- ** Variable iNextHdrOffset is set to the offset at which this
- ** problematic header will occur, if it exists. aMagic is used
- ** as a temporary buffer to inspect the first couple of bytes of
- ** the potential journal header.
- */
- i64 iNextHdrOffset;
- u8[] aMagic = new u8[8];
- u8[] zHeader = new u8[aJournalMagic.Length + 4];
- aJournalMagic.CopyTo( zHeader, 0 );// memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
- put32bits( zHeader, aJournalMagic.Length, pPager.nRec );
- iNextHdrOffset = journalHdrOffset( pPager );
- rc = sqlite3OsRead( pPager.jfd, aMagic, 8, iNextHdrOffset );
- if ( rc == SQLITE_OK && 0 == memcmp( aMagic, aJournalMagic, 8 ) )
- {
- u8[] zerobyte = new u8[1];
- rc = sqlite3OsWrite( pPager.jfd, zerobyte, 1, iNextHdrOffset );
- }
- if ( rc != SQLITE_OK && rc != SQLITE_IOERR_SHORT_READ )
- {
- return rc;
- }
- /* Write the nRec value into the journal file header. If in
- ** full-synchronous mode, sync the journal first. This ensures that
- ** all data has really hit the disk before nRec is updated to mark
- ** it as a candidate for rollback.
- **
- ** This is not required if the persistent media supports the
- ** SAFE_APPEND property. Because in this case it is not possible
- ** for garbage data to be appended to the file, the nRec field
- ** is populated with 0xFFFFFFFF when the journal header is written
- ** and never needs to be updated.
- */
- if ( pPager.fullSync && 0 == ( iDc & SQLITE_IOCAP_SEQUENTIAL ) )
- {
- PAGERTRACE( "SYNC journal of %d\n", PAGERID( pPager ) );
- IOTRACE( "JSYNC %p\n", pPager );
- rc = sqlite3OsSync( pPager.jfd, pPager.syncFlags );
- if ( rc != SQLITE_OK )
- return rc;
- }
- IOTRACE( "JHDR %p %lld\n", pPager, pPager.journalHdr );
- rc = sqlite3OsWrite(
- pPager.jfd, zHeader, zHeader.Length, pPager.journalHdr
- );
- if ( rc != SQLITE_OK )
- return rc;
- }
- if ( 0 == ( iDc & SQLITE_IOCAP_SEQUENTIAL ) )
- {
- PAGERTRACE( "SYNC journal of %d\n", PAGERID( pPager ) );
- IOTRACE( "JSYNC %p\n", pPager );
- rc = sqlite3OsSync( pPager.jfd, pPager.syncFlags |
- ( pPager.syncFlags == SQLITE_SYNC_FULL ? SQLITE_SYNC_DATAONLY : 0 )
- );
- if ( rc != SQLITE_OK )
- return rc;
- }
- pPager.journalHdr = pPager.journalOff;
- if ( newHdr != 0 && 0 == ( iDc & SQLITE_IOCAP_SAFE_APPEND ) )
- {
- pPager.nRec = 0;
- rc = writeJournalHdr( pPager );
- if ( rc != SQLITE_OK )
- return rc;
- }
- }
- else
- {
- pPager.journalHdr = pPager.journalOff;
- }
- }
- /* Unless the pager is in noSync mode, the journal file was just
- ** successfully synced. Either way, clear the PGHDR_NEED_SYNC flag on
- ** all pages.
- */
- sqlite3PcacheClearSyncFlags( pPager.pPCache );
- pPager.eState = PAGER_WRITER_DBMOD;
- Debug.Assert( assert_pager_state( pPager ) );
- return SQLITE_OK;
- }
- /*
- ** The argument is the first in a linked list of dirty pages connected
- ** by the PgHdr.pDirty pointer. This function writes each one of the
- ** in-memory pages in the list to the database file. The argument may
- ** be NULL, representing an empty list. In this case this function is
- ** a no-op.
- **
- ** The pager must hold at least a RESERVED lock when this function
- ** is called. Before writing anything to the database file, this lock
- ** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
- ** SQLITE_BUSY is returned and no data is written to the database file.
- **
- ** If the pager is a temp-file pager and the actual file-system file
- ** is not yet open, it is created and opened before any data is
- ** written out.
- **
- ** Once the lock has been upgraded and, if necessary, the file opened,
- ** the pages are written out to the database file in list order. Writing
- ** a page is skipped if it meets either of the following criteria:
- **
- ** * The page number is greater than Pager.dbSize, or
- ** * The PGHDR_DONT_WRITE flag is set on the page.
- **
- ** If writing out a page causes the database file to grow, Pager.dbFileSize
- ** is updated accordingly. If page 1 is written out, then the value cached
- ** in Pager.dbFileVers[] is updated to match the new value stored in
- ** the database file.
- **
- ** If everything is successful, SQLITE_OK is returned. If an IO error
- ** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
- ** be obtained, SQLITE_BUSY is returned.
- */
- static int pager_write_pagelist( Pager pPager, PgHdr pList )
- {
- int rc = SQLITE_OK; /* Return code */
- /* This function is only called for rollback pagers in WRITER_DBMOD state. */
- Debug.Assert( !pagerUseWal( pPager ) );
- Debug.Assert( pPager.eState == PAGER_WRITER_DBMOD );
- Debug.Assert( pPager.eLock == EXCLUSIVE_LOCK );
- /* If the file is a temp-file has not yet been opened, open it now. It
- ** is not possible for rc to be other than SQLITE_OK if this branch
- ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
- */
- if ( !isOpen( pPager.fd ) )
- {
- Debug.Assert( pPager.tempFile && rc == SQLITE_OK );
- rc = pagerOpentemp( pPager, ref pPager.fd, (int)pPager.vfsFlags );
- }
- /* Before the first write, give the VFS a hint of what the final
- ** file size will be.
- */
- Debug.Assert( rc != SQLITE_OK || isOpen( pPager.fd ) );
- if ( rc == SQLITE_OK && pPager.dbSize > pPager.dbHintSize )
- {
- sqlite3_int64 szFile = pPager.pageSize * (sqlite3_int64)pPager.dbSize;
- sqlite3OsFileControl( pPager.fd, SQLITE_FCNTL_SIZE_HINT, ref szFile );
- pPager.dbHintSize = pPager.dbSize;
- }
- while ( rc == SQLITE_OK && pList )
- {
- Pgno pgno = pList.pgno;
- /* If there are dirty pages in the page cache with page numbers greater
- ** than Pager.dbSize, this means sqlite3PagerTruncateImage() was called to
- ** make the file smaller (presumably by auto-vacuum code). Do not write
- ** any such pages to the file.
- **
- ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
- ** set (set by sqlite3PagerDontWrite()).
- */
- if ( pList.pgno <= pPager.dbSize && 0 == ( pList.flags & PGHDR_DONT_WRITE ) )
- {
- i64 offset = ( pList.pgno - 1 ) * (i64)pPager.pageSize; /* Offset to write */
- byte[] pData = null; /* Data to write */
- Debug.Assert( ( pList.flags & PGHDR_NEED_SYNC ) == 0 );
- if ( pList.pgno == 1 )
- pager_write_changecounter( pList );
- /* Encode the database */
- if ( CODEC2( pPager, pList.pData, pgno, SQLITE_ENCRYPT_WRITE_CTX, ref pData ) )
- return SQLITE_NOMEM;// CODEC2(pPager, pList.pData, pgno, 6, return SQLITE_NOMEM, pData);
- /* Write out the page data. */
- rc = sqlite3OsWrite( pPager.fd, pData, pPager.pageSize, offset );
- /* If page 1 was just written, update Pager.dbFileVers to match
- ** the value now stored in the database file. If writing this
- ** page caused the database file to grow, update dbFileSize.
- */
- if ( pgno == 1 )
- {
- Buffer.BlockCopy( pData, 24, pPager.dbFileVers, 0, pPager.dbFileVers.Length );// memcpy(pPager.dbFileVers, pData[24], pPager.dbFileVers).Length;
- }
- if ( pgno > pPager.dbFileSize )
- {
- pPager.dbFileSize = pgno;
- }
- /* Update any backup objects copying the contents of this pager. */
- sqlite3BackupUpdate( pPager.pBackup, pgno, pList.pData );
- PAGERTRACE( "STORE %d page %d hash(%08x)\n",
- PAGERID( pPager ), pgno, pager_pagehash( pList ) );
- IOTRACE( "PGOUT %p %d\n", pPager, pgno );
- #if SQLITE_TEST
- int iValue;
- iValue = sqlite3_pager_writedb_count.iValue;
- PAGER_INCR( ref iValue );
- sqlite3_pager_writedb_count.iValue = iValue;
- PAGER_INCR( ref pPager.nWrite );
- #endif
- }
- else
- {
- PAGERTRACE( "NOSTORE %d page %d\n", PAGERID( pPager ), pgno );
- }
- pager_set_pagehash( pList );
- pList = pList.pDirty;
- }
- return rc;
- }
- /*
- ** Ensure that the sub-journal file is open. If it is already open, this
- ** function is a no-op.
- **
- ** SQLITE_OK is returned if everything goes according to plan. An
- ** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen()
- ** fails.
- */
- static int openSubJournal( Pager pPager )
- {
- int rc = SQLITE_OK;
- if ( !isOpen( pPager.sjfd ) )
- {
- if ( pPager.journalMode == PAGER_JOURNALMODE_MEMORY || pPager.subjInMemory != 0 )
- {
- sqlite3MemJournalOpen( pPager.sjfd );
- }
- else
- {
- rc = pagerOpentemp( pPager, ref pPager.sjfd, SQLITE_OPEN_SUBJOURNAL );
- }
- }
- return rc;
- }
- /*
- ** Append a record of the current state of page pPg to the sub-journal.
- ** It is the callers responsibility to use subjRequiresPage() to check
- ** that it is really required before calling this function.
- **
- ** If successful, set the bit corresponding to pPg.pgno in the bitvecs
- ** for all open savepoints before returning.
- **
- ** This function returns SQLITE_OK if everything is successful, an IO
- ** error code if the attempt to write to the sub-journal fails, or
- ** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
- ** bitvec.
- */
- static int subjournalPage( PgHdr pPg )
- {
- int rc = SQLITE_OK;
- Pager pPager = pPg.pPager;
- if ( pPager.journalMode != PAGER_JOURNALMODE_OFF )
- {
- /* Open the sub-journal, if it has not already been opened */
- Debug.Assert( pPager.useJournal != 0 );
- Debug.Assert( isOpen( pPager.jfd ) || pagerUseWal( pPager ) );
- Debug.Assert( isOpen( pPager.sjfd ) || pPager.nSubRec == 0 );
- Debug.Assert( pagerUseWal( pPager )
- || pageInJournal( pPg )
- || pPg.pgno > pPager.dbOrigSize
- );
- rc = openSubJournal( pPager );
- /* If the sub-journal was opened successfully (or was already open),
- ** write the journal record into the file. */
- if ( rc == SQLITE_OK )
- {
- byte[] pData = pPg.pData;
- i64 offset = pPager.nSubRec * ( 4 + pPager.pageSize );
- byte[] pData2 = null;
- if ( CODEC2( pPager, pData, pPg.pgno, SQLITE_ENCRYPT_READ_CTX, ref pData2 ) )
- return SQLITE_NOMEM;//CODEC2(pPager, pData, pPg.pgno, 7, return SQLITE_NOMEM, pData2);
- PAGERTRACE( "STMT-JOURNAL %d page %d\n", PAGERID( pPager ), pPg.pgno );
- rc = write32bits( pPager.sjfd, offset, pPg.pgno );
- if ( rc == SQLITE_OK )
- {
- rc = sqlite3OsWrite( pPager.sjfd, pData2, pPager.pageSize, offset + 4 );
- }
- }
- }
- if ( rc == SQLITE_OK )
- {
- pPager.nSubRec++;
- Debug.Assert( pPager.nSavepoint > 0 );
- rc = addToSavepointBitvecs( pPager, pPg.pgno );
- }
- return rc;
- }
- /*
- ** This function is called by the pcache layer when it has reached some
- ** soft memory limit. The first argument is a pointer to a Pager object
- ** (cast as a void*). The pager is always 'purgeable' (not an in-memory
- ** database). The second argument is a reference to a page that is
- ** currently dirty but has no outstanding references. The page
- ** is always associated with the Pager object passed as the first
- ** argument.
- **
- ** The job of this function is to make pPg clean by writing its contents
- ** out to the database file, if possible. This may involve syncing the
- ** journal file.
- **
- ** If successful, sqlite3PcacheMakeClean() is called on the page and
- ** SQLITE_OK returned. If an IO error occurs while trying to make the
- ** page clean, the IO error code is returned. If the page cannot be
- ** made clean for some other reason, but no error occurs, then SQLITE_OK
- ** is returned by sqlite3PcacheMakeClean() is not called.
- */
- static int pagerStress( object p, PgHdr pPg )
- {
- Pager pPager = (Pager)p;
- int rc = SQLITE_OK;
- Debug.Assert( pPg.pPager == pPager );
- Debug.Assert( ( pPg.flags & PGHDR_DIRTY ) != 0 );
- /* The doNotSyncSpill flag is set during times when doing a sync of
- ** journal (and adding a new header) is not allowed. This occurs
- ** during calls to sqlite3PagerWrite() while trying to journal multiple
- ** pages belonging to the same sector.
- **
- ** The doNotSpill flag inhibits all cache spilling regardless of whether
- ** or not a sync is required. This is set during a rollback.
- **
- ** Spilling is also prohibited when in an error state since that could
- ** lead to database corruption. In the current implementaton it
- ** is impossible for sqlite3PCacheFetch() to be called with createFlag==1
- ** while in the error state, hence it is impossible for this routine to
- ** be called in the error state. Nevertheless, we include a NEVER()
- ** test for the error state as a safeguard against future changes.
- */
- if ( NEVER( pPager.errCode != 0 ) )
- return SQLITE_OK;
- if ( pPager.doNotSpill != 0 )
- return SQLITE_OK;
- if ( pPager.doNotSyncSpill != 0 && ( pPg.flags & PGHDR_NEED_SYNC ) != 0 )
- {
- return SQLITE_OK;
- }
- pPg.pDirty = null;
- if ( pagerUseWal( pPager ) )
- {
- /* Write a single frame for this page to the log. */
- if ( subjRequiresPage( pPg ) )
- {
- rc = subjournalPage( pPg );
- }
- if ( rc == SQLITE_OK )
- {
- rc = pagerWalFrames( pPager, pPg, 0, 0, 0 );
- }
- }
- else
- {
- /* Sync the journal file if required. */
- if ( ( pPg.flags & PGHDR_NEED_SYNC ) != 0
- || pPager.eState == PAGER_WRITER_CACHEMOD
- )
- {
- rc = syncJournal( pPager, 1 );
- }
- /* If the page number of this page is larger than the current size of
- ** the database image, it may need to be written to the sub-journal.
- ** This is because the call to pager_write_pagelist() below will not
- ** actually write data to the file in this case.
- **
- ** Consider the following sequence of events:
- **
- ** BEGIN;
- ** <journal page X>
- ** <modify page X>
- ** SAVEPOINT sp;
- ** <shrink database file to Y pages>
- ** pagerStress(page X)
- ** ROLLBACK TO sp;
- **
- ** If (X>Y), then when pagerStress is called page X will not be written
- ** out to the database file, but will be dropped from the cache. Then,
- ** following the "ROLLBACK TO sp" statement, reading page X will read
- ** data from the database file. This will be the copy of page X as it
- ** was when the transaction started, not as it was when "SAVEPOINT sp"
- ** was executed.
- **
- ** The solution is to write the current data for page X into the
- ** sub-journal file now (if it is not already there), so that it will
- ** be restored to its current value when the "ROLLBACK TO sp" is
- ** executed.
- */
- if ( NEVER(
- rc == SQLITE_OK && pPg.pgno > pPager.dbSize && subjRequiresPage( pPg )
- ) )
- {
- rc = subjournalPage( pPg );
- }
- /* Write the contents of the page out to the database file. */
- if ( rc == SQLITE_OK )
- {
- Debug.Assert( ( pPg.flags & PGHDR_NEED_SYNC ) == 0 );
- rc = pager_write_pagelist( pPager, pPg );
- }
- }
- /* Mark the page as clean. */
- if ( rc == SQLITE_OK )
- {
- PAGERTRACE( "STRESS %d page %d\n", PAGERID( pPager ), pPg.pgno );
- sqlite3PcacheMakeClean( pPg );
- }
- return pager_error( pPager, rc );
- }
- /*
- ** Allocate and initialize a new Pager object and put a pointer to it
- ** in *ppPager. The pager should eventually be freed by passing it
- ** to sqlite3PagerClose().
- **
- ** The zFilename argument is the path to the database file to open.
- ** If zFilename is NULL then a randomly-named temporary file is created
- ** and used as the file to be cached. Temporary files are be deleted
- ** automatically when they are closed. If zFilename is ":memory:" then
- ** all information is held in cache. It is never written to disk.
- ** This can be used to implement an in-memory database.
- **
- ** The nExtra parameter specifies the number of bytes of space allocated
- ** along with each page reference. This space is available to the user
- ** via the sqlite3PagerGetExtra() API.
- **
- ** The flags argument is used to specify properties that affect the
- ** operation of the pager. It should be passed some bitwise combination
- ** of the PAGER_OMIT_JOURNAL and PAGER_NO_READLOCK flags.
- **
- ** The vfsFlags parameter is a bitmask to pass to the flags parameter
- ** of the xOpen() method of the supplied VFS when opening files.
- **
- ** If the pager object is allocated and the specified file opened
- ** successfully, SQLITE_OK is returned and *ppPager set to point to
- ** the new pager object. If an error occurs, *ppPager is set to NULL
- ** and error code returned. This function may return SQLITE_NOMEM
- ** (sqlite3Malloc() is used to allocate memory), SQLITE_CANTOPEN or
- ** various SQLITE_IO_XXX errors.
- */
- static int sqlite3PagerOpen(
- sqlite3_vfs pVfs, /* The virtual file system to use */
- ref Pager ppPager, /* OUT: Return the Pager structure here */
- string zFilename, /* Name of the database file to open */
- int nExtra, /* Extra bytes append to each in-memory page */
- int flags, /* flags controlling this file */
- int vfsFlags, /* flags passed through to sqlite3_vfs.xOpen() */
- dxReiniter xReinit /* Function to reinitialize pages */
- )
- {
- u8 pPtr;
- Pager pPager = null; /* Pager object to allocate and return */
- int rc = SQLITE_OK; /* Return code */
- u8 tempFile = 0; /* True for temp files (incl. in-memory files) */ // Needs to be u8 for later tests
- u8 memDb = 0; /* True if this is an in-memory file */
- bool readOnly = false; /* True if this is a read-only file */
- int journalFileSize; /* Bytes to allocate for each journal fd */
- StringBuilder zPathname = null; /* Full path to database file */
- int nPathname = 0; /* Number of bytes in zPathname */
- bool useJournal = ( flags & PAGER_OMIT_JOURNAL ) == 0; /* False to omit journal */
- bool noReadlock = ( flags & PAGER_NO_READLOCK ) != 0; /* True to omit read-lock */
- int pcacheSize = sqlite3PcacheSize(); /* Bytes to allocate for PCache */
- u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE; /* Default page size */
- /* Figure out how much space is required for each journal file-handle
- ** (there are two of them, the main journal and the sub-journal). This
- ** is the maximum space required for an in-memory journal file handle
- ** and a regular journal file-handle. Note that a "regular journal-handle"
- ** may be a wrapper capable of caching the first portion of the journal
- ** file in memory to implement the atomic-write optimization (see
- ** source file journal.c).
- */
- if ( sqlite3JournalSize( pVfs ) > sqlite3MemJournalSize() )
- {
- journalFileSize = ROUND8( sqlite3JournalSize( pVfs ) );
- }
- else
- {
- journalFileSize = ROUND8( sqlite3MemJournalSize() );
- }
- /* Set the output variable to NULL in case an error occurs. */
- ppPager = null;
- #if !SQLITE_OMIT_MEMORYDB
- if ( ( flags & PAGER_MEMORY ) != 0 )
- {
- memDb = 1;
- zFilename = null;
- }
- #endif
- /* Compute and store the full pathname in an allocated buffer pointed
- ** to by zPathname, length nPathname. Or, if this is a temporary file,
- ** leave both nPathname and zPathname set to 0.
- */
- if ( !String.IsNullOrEmpty( zFilename ) )
- {
- nPathname = pVfs.mxPathname + 1;
- zPathname = new StringBuilder( nPathname * 2 );// sqlite3Malloc( nPathname * 2 );
- if ( zPathname == null )
- {
- return SQLITE_NOMEM;
- }
- //zPathname[0] = 0; /* Make sure initialized even if FullPathname() fails */
- rc = sqlite3OsFullPathname( pVfs, zFilename, nPathname, zPathname );
- nPathname = sqlite3Strlen30( zPathname );
- if ( rc == SQLITE_OK && nPathname + 8 > pVfs.mxPathname )
- {
- /* This branch is taken when the journal path required by
- ** the database being opened will be more than pVfs.mxPathname
- ** bytes in length. This means the database cannot be opened,
- ** as it will not be possible to open the journal file or even
- ** check for a hot-journal before reading.
- */
- rc = SQLITE_CANTOPEN_BKPT();
- }
- if ( rc != SQLITE_OK )
- {
- //sqlite3_free( ref zPathname );
- return rc;
- }
- }
- /* Allocate memory for the Pager structure, PCache object, the
- ** three file descriptors, the database file name and the journal
- ** file name. The layout in memory is as follows:
- **
- ** Pager object (sizeof(Pager) bytes)
- ** PCache object (sqlite3PcacheSize() bytes)
- ** Database file handle (pVfs.szOsFile bytes)
- ** Sub-journal file handle (journalFileSize bytes)
- ** Main journal file handle (journalFileSize bytes)
- ** Database file name (nPathname+1 bytes)
- ** Journal file name (nPathname+8+1 bytes)
- */
- //pPtr = (u8 *)sqlite3MallocZero(
- // ROUND8(sizeof(*pPager)) + /* Pager structure */
- // ROUND8(pcacheSize) + /* PCache object */
- // ROUND8(pVfs.szOsFile) + /* The main db file */
- // journalFileSize * 2 + /* The two journal files */
- // nPathname + 1 + /* zFilename */
- // nPathname + 8 + 1 /* zJournal */
- //#if !SQLITE_OMIT_WAL
- // + nPathname + 4 + 1 /* zWal */
- //#endif
- //);
- // Debug.Assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)));
- //if( !pPtr ){
- // //sqlite3_free(zPathname);
- // return SQLITE_NOMEM;
- //}
- pPager = new Pager();//(Pager*)(pPtr);
- pPager.pPCache = new PCache();//(PCache*)(pPtr += ROUND8(sizeof(*pPager)));
- pPager.fd = new sqlite3_file();//(sqlite3_file*)(pPtr += ROUND8(pcacheSize));
- pPager.sjfd = new sqlite3_file();//(sqlite3_file*)(pPtr += ROUND8(pVfs.szOsFile));
- pPager.jfd = new sqlite3_file();//(sqlite3_file*)(pPtr += journalFileSize);
- //pPager.zFilename = (char*)(pPtr += journalFileSize);
- //Debug.Assert( EIGHT_BYTE_ALIGNMENT(pPager.jfd) );
- /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
- if ( zPathname != null )
- {
- Debug.Assert( nPathname > 0 );
- //pPager.zJournal = (char*)(pPtr += nPathname + 1);
- //memcpy(pPager.zFilename, zPathname, nPathname);
- pPager.zFilename = zPathname.ToString();
- //memcpy(pPager.zJournal, zPathname, nPathname);
- //memcpy(&pPager.zJournal[nPathname], "-journal", 8);
- pPager.zJournal = pPager.zFilename + "-journal";
- #if !SQLITE_OMIT_WAL
- pPager.zWal = &pPager.zJournal[nPathname+8+1];
- memcpy(pPager.zWal, zPathname, nPathname);
- memcpy(&pPager.zWal[nPathname], "-wal", 4);
- #endif
- //sqlite3_free( ref zPathname );
- }
- else
- {
- pPager.zFilename = "";
- }
- pPager.pVfs = pVfs;
- pPager.vfsFlags = (u32)vfsFlags;
- /* Open the pager file.
- */
- if ( !String.IsNullOrEmpty( zFilename ) )
- {
- int fout = 0; /* VFS flags returned by xOpen() */
- rc = sqlite3OsOpen( pVfs, pPager.zFilename, pPager.fd, vfsFlags, ref fout );
- Debug.Assert( 0 == memDb );
- readOnly = ( fout & SQLITE_OPEN_READONLY ) != 0;
- /* If the file was successfully opened for read/write access,
- ** choose a default page size in case we have to create the
- ** database file. The default page size is the maximum of:
- **
- ** + SQLITE_DEFAULT_PAGE_SIZE,
- ** + The value returned by sqlite3OsSectorSize()
- ** + The largest page size that can be written atomically.
- */
- if ( rc == SQLITE_OK && !readOnly )
- {
- setSectorSize( pPager );
- Debug.Assert( SQLITE_DEFAULT_PAGE_SIZE <= SQLITE_MAX_DEFAULT_PAGE_SIZE );
- if ( szPageDflt < pPager.sectorSize )
- {
- if ( pPager.sectorSize > SQLITE_MAX_DEFAULT_PAGE_SIZE )
- {
- szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
- }
- else
- {
- szPageDflt = (u32)pPager.sectorSize;
- }
- }
- #if SQLITE_ENABLE_ATOMIC_WRITE
- {
- int iDc = sqlite3OsDeviceCharacteristics(pPager.fd);
- int ii;
- Debug.Assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
- Debug.Assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
- Debug.Assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536);
- for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){
- if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ){
- szPageDflt = ii;
- }
- }
- }
- #endif
- }
- }
- else
- {
- /* If a temporary file is requested, it is not opened immediately.
- ** In this case we accept the default page size and delay actually
- ** opening the file until the first call to OsWrite().
- **
- ** This branch is also run for an in-memory database. An in-memory
- ** database is the same as a temp-file that is never written out to
- ** disk and uses an in-memory rollback journal.
- */
- tempFile = 1;
- pPager.eState = PAGER_READER;
- pPager.eLock = EXCLUSIVE_LOCK;
- readOnly = ( vfsFlags & SQLITE_OPEN_READONLY ) != 0;
- }
- /* The following call to PagerSetPagesize() serves to set the value of
- ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
- */
- if ( rc == SQLITE_OK )
- {
- Debug.Assert( pPager.memDb == 0 );
- rc = sqlite3PagerSetPagesize( pPager, ref szPageDflt, -1 );
- testcase( rc != SQLITE_OK );
- }
- /* If an error occurred in either of the blocks above, free the
- ** Pager structure and close the file.
- */
- if ( rc != SQLITE_OK )
- {
- Debug.Assert( null == pPager.pTmpSpace );
- sqlite3OsClose( pPager.fd );
- //sqlite3_free( ref pPager );
- return rc;
- }
- /* Initialize the PCache object. */
- Debug.Assert( nExtra < 1000 );
- nExtra = ROUND8( nExtra );
- sqlite3PcacheOpen( (int)szPageDflt, nExtra, 0 == memDb,
- 0 == memDb ? (dxStress)pagerStress : null, pPager, pPager.pPCache );
- PAGERTRACE( "OPEN %d %s\n", FILEHANDLEID( pPager.fd ), pPager.zFilename );
- IOTRACE( "OPEN %p %s\n", pPager, pPager.zFilename );
- pPager.useJournal = (u8)( useJournal ? 1 : 0 );
- pPager.noReadlock = (u8)( noReadlock && readOnly ? 1 : 0 );
- /* pPager.stmtOpen = 0; */
- /* pPager.stmtInUse = 0; */
- /* pPager.nRef = 0; */
- /* pPager.stmtSize = 0; */
- /* pPager.stmtJSize = 0; */
- /* pPager.nPage = 0; */
- pPager.mxPgno = SQLITE_MAX_PAGE_COUNT;
- /* pPager.state = PAGER_UNLOCK; */
- #if FALSE
- Debug.Assert(pPager.state == (tempFile != 0 ? PAGER_EXCLUSIVE : PAGER_UNLOCK));
- #endif
- /* pPager.errMask = 0; */
- pPager.tempFile = tempFile != 0;
- Debug.Assert( tempFile == PAGER_LOCKINGMODE_NORMAL
- || tempFile == PAGER_LOCKINGMODE_EXCLUSIVE );
- Debug.Assert( PAGER_LOCKINGMODE_EXCLUSIVE == 1 );
- pPager.exclusiveMode = tempFile != 0;
- pPager.changeCountDone = pPager.tempFile;
- pPager.memDb = memDb;
- pPager.readOnly = readOnly;
- Debug.Assert( useJournal || pPager.tempFile );
- pPager.noSync = pPager.tempFile;
- pPager.fullSync = pPager.noSync;
- pPager.syncFlags = (byte)( pPager.noSync ? 0 : SQLITE_SYNC_NORMAL );
- pPager.ckptSyncFlags = pPager.syncFlags;
- /* pPager.pFirst = 0; */
- /* pPager.pFirstSynced = 0; */
- /* pPager.pLast = 0; */
- pPager.nExtra = (u16)nExtra;
- pPager.journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
- Debug.Assert( isOpen( pPager.fd ) || tempFile != 0 );
- setSectorSize( pPager );
- if ( !useJournal )
- {
- pPager.journalMode = PAGER_JOURNALMODE_OFF;
- }
- else if ( memDb != 0 )
- {
- pPager.journalMode = PAGER_JOURNALMODE_MEMORY;
- }
- /* pPager.xBusyHandler = 0; */
- /* pPager.pBusyHandlerArg = 0; */
- pPager.xReiniter = xReinit;
- /* memset(pPager.aHash, 0, sizeof(pPager.aHash)); */
- ppPager = pPager;
- return SQLITE_OK;
- }
- /*
- ** This function is called after transitioning from PAGER_UNLOCK to
- ** PAGER_SHARED state. It tests if there is a hot journal present in
- ** the file-system for the given pager. A hot journal is one that
- ** needs to be played back. According to this function, a hot-journal
- ** file exists if the following criteria are met:
- **
- ** * The journal file exists in the file system, and
- ** * No process holds a RESERVED or greater lock on the database file, and
- ** * The database file itself is greater than 0 bytes in size, and
- ** * The first byte of the journal file exists and is not 0x00.
- **
- ** If the current size of the database file is 0 but a journal file
- ** exists, that is probably an old journal left over from a prior
- ** database with the same name. In this case the journal file is
- ** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
- ** is returned.
- **
- ** This routine does not check if there is a master journal filename
- ** at the end of the file. If there is, and that master journal file
- ** does not exist, then the journal file is not really hot. In this
- ** case this routine will return a false-positive. The pager_playback()
- ** routine will discover that the journal file is not really hot and
- ** will not roll it back.
- **
- ** If a hot-journal file is found to exist, *pExists is set to 1 and
- ** SQLITE_OK returned. If no hot-journal file is present, *pExists is
- ** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
- ** to determine whether or not a hot-journal file exists, the IO error
- ** code is returned and the value of *pExists is undefined.
- */
- static int hasHotJournal( Pager pPager, ref int pExists )
- {
- sqlite3_vfs pVfs = pPager.pVfs;
- int rc = SQLITE_OK; /* Return code */
- int exists = 1; /* True if a journal file is present */
- int jrnlOpen = isOpen( pPager.jfd ) ? 1 : 0;
- Debug.Assert( pPager.useJournal != 0 );
- Debug.Assert( isOpen( pPager.fd ) );
- Debug.Assert( pPager.eState == PAGER_OPEN );
- Debug.Assert( jrnlOpen == 0 || ( sqlite3OsDeviceCharacteristics( pPager.jfd ) &
- SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
- ) != 0 );
- pExists = 0;
- if ( 0 == jrnlOpen )
- {
- rc = sqlite3OsAccess( pVfs, pPager.zJournal, SQLITE_ACCESS_EXISTS, ref exists );
- }
- if ( rc == SQLITE_OK && exists != 0 )
- {
- int locked = 0; /* True if some process holds a RESERVED lock */
- /* Race condition here: Another process might have been holding the
- ** the RESERVED lock and have a journal open at the sqlite3OsAccess()
- ** call above, but then delete the journal and drop the lock before
- ** we get to the following sqlite3OsCheckReservedLock() call. If that
- ** is the case, this routine might think there is a hot journal when
- ** in fact there is none. This results in a false-positive which will
- ** be dealt with by the playback routine. Ticket #3883.
- */
- rc = sqlite3OsCheckReservedLock( pPager.fd, ref locked );
- if ( rc == SQLITE_OK && locked == 0 )
- {
- Pgno nPage = 0; /* Number of pages in database file */
- /* Check the size of the database file. If it consists of 0 pages,
- ** then delete the journal file. See the header comment above for
- ** the reasoning here. Delete the obsolete journal file under
- ** a RESERVED lock to avoid race conditions and to avoid violating
- ** [H33020].
- */
- rc = pagerPagecount( pPager, ref nPage );
- if ( rc == SQLITE_OK )
- {
- if ( nPage == 0 )
- {
- sqlite3BeginBenignMalloc();
- if ( pagerLockDb( pPager, RESERVED_LOCK ) == SQLITE_OK )
- {
- sqlite3OsDelete( pVfs, pPager.zJournal, 0 );
- if ( !pPager.exclusiveMode )
- pagerUnlockDb( pPager, SHARED_LOCK );
- }
- sqlite3EndBenignMalloc();
- }
- else
- {
- /* The journal file exists and no other connection has a reserved
- ** or greater lock on the database file. Now check that there is
- ** at least one non-zero bytes at the start of the journal file.
- ** If there is, then we consider this journal to be hot. If not,
- ** it can be ignored.
- */
- if ( 0 == jrnlOpen )
- {
- int f = SQLITE_OPEN_READONLY | SQLITE_OPEN_MAIN_JOURNAL;
- rc = sqlite3OsOpen( pVfs, pPager.zJournal, pPager.jfd, f, ref f );
- }
- if ( rc == SQLITE_OK )
- {
- u8[] first = new u8[1];
- rc = sqlite3OsRead( pPager.jfd, first, 1, 0 );
- if ( rc == SQLITE_IOERR_SHORT_READ )
- {
- rc = SQLITE_OK;
- }
- if ( 0 == jrnlOpen )
- {
- sqlite3OsClose( pPager.jfd );
- }
- pExists = ( first[0] != 0 ) ? 1 : 0;
- }
- else if ( rc == SQLITE_CANTOPEN )
- {
- /* If we cannot open the rollback journal file in order to see if
- ** its has a zero header, that might be due to an I/O error, or
- ** it might be due to the race condition described above and in
- ** ticket #3883. Either way, assume that the journal is hot.
- ** This might be a false positive. But if it is, then the
- ** automatic journal playback and recovery mechanism will deal
- ** with it under an EXCLUSIVE lock where we do not need to
- ** worry so much with race conditions.
- */
- pExists = 1;
- rc = SQLITE_OK;
- }
- }
- }
- }
- }
- return rc;
- }
- /*
- ** This function is called to obtain a shared lock on the database file.
- ** It is illegal to call sqlite3PagerAcquire() until after this function
- ** has been successfully called. If a shared-lock is already held when
- ** this function is called, it is a no-op.
- **
- ** The following operations are also performed by this function.
- **
- ** 1) If the pager is currently in PAGER_OPEN state (no lock held
- ** on the database file), then an attempt is made to obtain a
- ** SHARED lock on the database file. Immediately after obtaining
- ** the SHARED lock, the file-system is checked for a hot-journal,
- ** which is played back if present. Following any hot-journal
- ** rollback, the contents of the cache are validated by checking
- ** the 'change-counter' field of the database file header and
- ** discarded if they are found to be invalid.
- **
- ** 2) If the pager is running in exclusive-mode, and there are currently
- ** no outstanding references to any pages, and is in the error state,
- ** then an attempt is made to clear the error state by discarding
- ** the contents of the page cache and rolling back any open journal
- ** file.
- **
- ** If everything is successful, SQLITE_OK is returned. If an IO error
- ** occurs while locking the database, checking for a hot-journal file or
- ** rolling back a journal file, the IO error code is returned.
- */
- static int sqlite3PagerSharedLock( Pager pPager )
- {
- int rc = SQLITE_OK; /* Return code */
- /* This routine is only called from b-tree and only when there are no
- ** outstanding pages. This implies that the pager state should either
- ** be OPEN or READER. READER is only possible if the pager is or was in
- ** exclusive access mode.
- */
- Debug.Assert( sqlite3PcacheRefCount( pPager.pPCache ) == 0 );
- Debug.Assert( assert_pager_state( pPager ) );
- Debug.Assert( pPager.eState == PAGER_OPEN || pPager.eState == PAGER_READER );
- if ( NEVER(
- #if SQLITE_OMIT_MEMORYDB
- 0!=MEMDB
- #else
- 0 != pPager.memDb
- #endif
- && pPager.errCode != 0 ) )
- {
- return pPager.errCode;
- }
- if ( !pagerUseWal( pPager ) && pPager.eState == PAGER_OPEN )
- {
- int bHotJournal = 1; /* True if there exists a hot journal-file */
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- Debug.Assert( pPager.noReadlock == 0 || pPager.readOnly );
- if ( pPager.noReadlock == 0 )
- {
- rc = pager_wait_on_lock( pPager, SHARED_LOCK );
- if ( rc != SQLITE_OK )
- {
- Debug.Assert( pPager.eLock == NO_LOCK || pPager.eLock == UNKNOWN_LOCK );
- goto failed;
- }
- }
- /* If a journal file exists, and there is no RESERVED lock on the
- ** database file, then it either needs to be played back or deleted.
- */
- if ( pPager.eLock <= SHARED_LOCK )
- {
- rc = hasHotJournal( pPager, ref bHotJournal );
- }
- if ( rc != SQLITE_OK )
- {
- goto failed;
- }
- if ( bHotJournal != 0 )
- {
- /* Get an EXCLUSIVE lock on the database file. At this point it is
- ** important that a RESERVED lock is not obtained on the way to the
- ** EXCLUSIVE lock. If it were, another process might open the
- ** database file, detect the RESERVED lock, and conclude that the
- ** database is safe to read while this process is still rolling the
- ** hot-journal back.
- **
- ** Because the intermediate RESERVED lock is not requested, any
- ** other process attempting to access the database file will get to
- ** this point in the code and fail to obtain its own EXCLUSIVE lock
- ** on the database file.
- **
- ** Unless the pager is in locking_mode=exclusive mode, the lock is
- ** downgraded to SHARED_LOCK before this function returns.
- */
- rc = pagerLockDb( pPager, EXCLUSIVE_LOCK );
- if ( rc != SQLITE_OK )
- {
- goto failed;
- }
- /* If it is not already open and the file exists on disk, open the
- ** journal for read/write access. Write access is required because
- ** in exclusive-access mode the file descriptor will be kept open
- ** and possibly used for a transaction later on. Also, write-access
- ** is usually required to finalize the journal in journal_mode=persist
- ** mode (and also for journal_mode=truncate on some systems).
- **
- ** If the journal does not exist, it usually means that some
- ** other connection managed to get in and roll it back before
- ** this connection obtained the exclusive lock above. Or, it
- ** may mean that the pager was in the error-state when this
- ** function was called and the journal file does not exist.
- */
- if ( !isOpen( pPager.jfd ) )
- {
- sqlite3_vfs pVfs = pPager.pVfs;
- int bExists = 0; /* True if journal file exists */
- rc = sqlite3OsAccess(
- pVfs, pPager.zJournal, SQLITE_ACCESS_EXISTS, ref bExists );
- if ( rc == SQLITE_OK && bExists != 0 )
- {
- int fout = 0;
- int f = SQLITE_OPEN_READWRITE | SQLITE_OPEN_MAIN_JOURNAL;
- Debug.Assert( !pPager.tempFile );
- rc = sqlite3OsOpen( pVfs, pPager.zJournal, pPager.jfd, f, ref fout );
- Debug.Assert( rc != SQLITE_OK || isOpen( pPager.jfd ) );
- if ( rc == SQLITE_OK && ( fout & SQLITE_OPEN_READONLY ) != 0 )
- {
- rc = SQLITE_CANTOPEN_BKPT();
- sqlite3OsClose( pPager.jfd );
- }
- }
- }
- /* Playback and delete the journal. Drop the database write
- ** lock and reacquire the read lock. Purge the cache before
- ** playing back the hot-journal so that we don't end up with
- ** an inconsistent cache. Sync the hot journal before playing
- ** it back since the process that crashed and left the hot journal
- ** probably did not sync it and we are required to always sync
- ** the journal before playing it back.
- */
- if ( isOpen( pPager.jfd ) )
- {
- Debug.Assert( rc == SQLITE_OK );
- rc = pagerSyncHotJournal( pPager );
- if ( rc == SQLITE_OK )
- {
- rc = pager_playback( pPager, 1 );
- pPager.eState = PAGER_OPEN;
- }
- }
- else if ( !pPager.exclusiveMode )
- {
- pagerUnlockDb( pPager, SHARED_LOCK );
- }
- if ( rc != SQLITE_OK )
- {
- /* This branch is taken if an error occurs while trying to open
- ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
- ** pager_unlock() routine will be called before returning to unlock
- ** the file. If the unlock attempt fails, then Pager.eLock must be
- ** set to UNKNOWN_LOCK (see the comment above the #define for
- ** UNKNOWN_LOCK above for an explanation).
- **
- ** In order to get pager_unlock() to do this, set Pager.eState to
- ** PAGER_ERROR now. This is not actually counted as a transition
- ** to ERROR state in the state diagram at the top of this file,
- ** since we know that the same call to pager_unlock() will very
- ** shortly transition the pager object to the OPEN state. Calling
- ** assert_pager_state() would fail now, as it should not be possible
- ** to be in ERROR state when there are zero outstanding page
- ** references.
- */
- pager_error( pPager, rc );
- goto failed;
- }
- Debug.Assert( pPager.eState == PAGER_OPEN );
- Debug.Assert( ( pPager.eLock == SHARED_LOCK )
- || ( pPager.exclusiveMode && pPager.eLock > SHARED_LOCK )
- );
- }
- if ( !pPager.tempFile
- && ( pPager.pBackup != null || sqlite3PcachePagecount( pPager.pPCache ) > 0 )
- )
- {
- /* The shared-lock has just been acquired on the database file
- ** and there are already pages in the cache (from a previous
- ** read or write transaction). Check to see if the database
- ** has been modified. If the database has changed, flush the
- ** cache.
- **
- ** Database changes is detected by looking at 15 bytes beginning
- ** at offset 24 into the file. The first 4 of these 16 bytes are
- ** a 32-bit counter that is incremented with each change. The
- ** other bytes change randomly with each file change when
- ** a codec is in use.
- **
- ** There is a vanishingly small chance that a change will not be
- ** detected. The chance of an undetected change is so small that
- ** it can be neglected.
- */
- Pgno nPage = 0;
- byte[] dbFileVers = new byte[pPager.dbFileVers.Length];
- rc = pagerPagecount( pPager, ref nPage );
- if ( rc != 0 )
- goto failed;
- if ( nPage > 0 )
- {
- IOTRACE( "CKVERS %p %d\n", pPager, dbFileVers.Length );
- rc = sqlite3OsRead( pPager.fd, dbFileVers, dbFileVers.Length, 24 );
- if ( rc != SQLITE_OK )
- {
- goto failed;
- }
- }
- else
- {
- Array.Clear( dbFileVers, 0, dbFileVers.Length );// memset( dbFileVers, 0, sizeof( dbFileVers ) );
- }
- if ( memcmp( pPager.dbFileVers, dbFileVers, dbFileVers.Length ) != 0 )
- {
- pager_reset( pPager );
- }
- }
- /* If there is a WAL file in the file-system, open this database in WAL
- ** mode. Otherwise, the following function call is a no-op.
- */
- rc = pagerOpenWalIfPresent( pPager );
- #if !SQLITE_OMIT_WAL
- Debug.Assert( pPager.pWal == null || rc == SQLITE_OK );
- #endif
- }
- if ( pagerUseWal( pPager ) )
- {
- Debug.Assert( rc == SQLITE_OK );
- rc = pagerBeginReadTransaction( pPager );
- }
- if ( pPager.eState == PAGER_OPEN && rc == SQLITE_OK )
- {
- rc = pagerPagecount( pPager, ref pPager.dbSize );
- }
- failed:
- if ( rc != SQLITE_OK )
- {
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- pager_unlock( pPager );
- Debug.Assert( pPager.eState == PAGER_OPEN );
- }
- else
- {
- pPager.eState = PAGER_READER;
- }
- return rc;
- }
- /*
- ** If the reference count has reached zero, rollback any active
- ** transaction and unlock the pager.
- **
- ** Except, in locking_mode=EXCLUSIVE when there is nothing to in
- ** the rollback journal, the unlock is not performed and there is
- ** nothing to rollback, so this routine is a no-op.
- */
- static void pagerUnlockIfUnused( Pager pPager )
- {
- if ( sqlite3PcacheRefCount( pPager.pPCache ) == 0 )
- {
- pagerUnlockAndRollback( pPager );
- }
- }
- /*
- ** Acquire a reference to page number pgno in pager pPager (a page
- ** reference has type DbPage*). If the requested reference is
- ** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
- **
- ** If the requested page is already in the cache, it is returned.
- ** Otherwise, a new page object is allocated and populated with data
- ** read from the database file. In some cases, the pcache module may
- ** choose not to allocate a new page object and may reuse an existing
- ** object with no outstanding references.
- **
- ** The extra data appended to a page is always initialized to zeros the
- ** first time a page is loaded into memory. If the page requested is
- ** already in the cache when this function is called, then the extra
- ** data is left as it was when the page object was last used.
- **
- ** If the database image is smaller than the requested page or if a
- ** non-zero value is passed as the noContent parameter and the
- ** requested page is not already stored in the cache, then no
- ** actual disk read occurs. In this case the memory image of the
- ** page is initialized to all zeros.
- **
- ** If noContent is true, it means that we do not care about the contents
- ** of the page. This occurs in two seperate scenarios:
- **
- ** a) When reading a free-list leaf page from the database, and
- **
- ** b) When a savepoint is being rolled back and we need to load
- ** a new page into the cache to be filled with the data read
- ** from the savepoint journal.
- **
- ** If noContent is true, then the data returned is zeroed instead of
- ** being read from the database. Additionally, the bits corresponding
- ** to pgno in Pager.pInJournal (bitvec of pages already written to the
- ** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
- ** savepoints are set. This means if the page is made writable at any
- ** point in the future, using a call to sqlite3PagerWrite(), its contents
- ** will not be journaled. This saves IO.
- **
- ** The acquisition might fail for several reasons. In all cases,
- ** an appropriate error code is returned and *ppPage is set to NULL.
- **
- ** See also sqlite3PagerLookup(). Both this routine and Lookup() attempt
- ** to find a page in the in-memory cache first. If the page is not already
- ** in memory, this routine goes to disk to read it in whereas Lookup()
- ** just returns 0. This routine acquires a read-lock the first time it
- ** has to go to disk, and could also playback an old journal if necessary.
- ** Since Lookup() never goes to disk, it never has to deal with locks
- ** or journal files.
- */
- // Under C# from the header file
- //#define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0)
- static int sqlite3PagerGet(
- Pager pPager, /* The pager open on the database file */
- u32 pgno, /* Page number to fetch */
- ref DbPage ppPage /* Write a pointer to the page here */
- )
- {
- return sqlite3PagerAcquire( pPager, pgno, ref ppPage, 0 );
- }
- static int sqlite3PagerAcquire(
- Pager pPager, /* The pager open on the database file */
- u32 pgno, /* Page number to fetch */
- ref DbPage ppPage, /* Write a pointer to the page here */
- u8 noContent /* Do not bother reading content from disk if true */
- )
- {
- int rc;
- PgHdr pPg = null;
- Debug.Assert( pPager.eState >= PAGER_READER );
- Debug.Assert( assert_pager_state( pPager ) );
- if ( pgno == 0 )
- {
- return SQLITE_CORRUPT_BKPT();
- }
- /* If the pager is in the error state, return an error immediately.
- ** Otherwise, request the page from the PCache layer. */
- if ( pPager.errCode != SQLITE_OK )
- {
- rc = pPager.errCode;
- }
- else
- {
- rc = sqlite3PcacheFetch( pPager.pPCache, pgno, 1, ref ppPage );
- }
- if ( rc != SQLITE_OK )
- {
- /* Either the call to sqlite3PcacheFetch() returned an error or the
- ** pager was already in the error-state when this function was called.
- ** Set pPg to 0 and jump to the exception handler. */
- pPg = null;
- goto pager_acquire_err;
- }
- Debug.Assert( ( ppPage ).pgno == pgno );
- Debug.Assert( ( ppPage ).pPager == pPager || ( ppPage ).pPager == null );
- if ( ( ppPage ).pPager != null && 0 == noContent )
- {
- /* In this case the pcache already contains an initialized copy of
- ** the page. Return without further ado. */
- Debug.Assert( pgno <= PAGER_MAX_PGNO && pgno != PAGER_MJ_PGNO( pPager ) );
- PAGER_INCR( ref pPager.nHit );
- return SQLITE_OK;
- }
- else
- {
- /* The pager cache has created a new page. Its content needs to
- ** be initialized. */
- #if SQLITE_TEST
- PAGER_INCR( ref pPager.nMiss );
- #endif
- pPg = ppPage;
- pPg.pPager = pPager;
- pPg.pExtra = new MemPage();//memset(pPg.pExtra, 0, pPager.nExtra);
- /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
- ** number greater than this, or the unused locking-page, is requested. */
- if ( pgno > PAGER_MAX_PGNO || pgno == PAGER_MJ_PGNO( pPager ) )
- {
- rc = SQLITE_CORRUPT_BKPT();
- goto pager_acquire_err;
- }
- if (
- #if SQLITE_OMIT_MEMORYDB
- 1==MEMDB
- #else
- pPager.memDb != 0
- #endif
- || pPager.dbSize < pgno || noContent != 0 || !isOpen( pPager.fd ) )
- {
- if ( pgno > pPager.mxPgno )
- {
- rc = SQLITE_FULL;
- goto pager_acquire_err;
- }
- if ( noContent != 0 )
- {
- /* Failure to set the bits in the InJournal bit-vectors is benign.
- ** It merely means that we might do some extra work to journal a
- ** page that does not need to be journaled. Nevertheless, be sure
- ** to test the case where a malloc error occurs while trying to set
- ** a bit in a bit vector.
- */
- sqlite3BeginBenignMalloc();
- if ( pgno <= pPager.dbOrigSize )
- {
- #if !NDEBUG || SQLITE_COVERAGE_TEST
- rc = sqlite3BitvecSet( pPager.pInJournal, pgno ); //TESTONLY( rc = ) sqlite3BitvecSet(pPager.pInJournal, pgno);
- #else
- sqlite3BitvecSet(pPager.pInJournal, pgno);
- #endif
- testcase( rc == SQLITE_NOMEM );
- }
- #if !NDEBUG || SQLITE_COVERAGE_TEST
- rc = addToSavepointBitvecs( pPager, pgno ); //TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
- #else
- addToSavepointBitvecs(pPager, pgno);
- #endif
- testcase( rc == SQLITE_NOMEM );
- sqlite3EndBenignMalloc();
- }
- //memset(pPg.pData, 0, pPager.pageSize);
- Array.Clear( pPg.pData, 0, pPager.pageSize );
- IOTRACE( "ZERO %p %d\n", pPager, pgno );
- }
- else
- {
- Debug.Assert( pPg.pPager == pPager );
- rc = readDbPage( pPg );
- if ( rc != SQLITE_OK )
- {
- goto pager_acquire_err;
- }
- }
- pager_set_pagehash( pPg );
- }
- return SQLITE_OK;
- pager_acquire_err:
- Debug.Assert( rc != SQLITE_OK );
- if ( pPg != null )
- {
- sqlite3PcacheDrop( pPg );
- }
- pagerUnlockIfUnused( pPager );
- ppPage = null;
- return rc;
- }
- /*
- ** Acquire a page if it is already in the in-memory cache. Do
- ** not read the page from disk. Return a pointer to the page,
- ** or 0 if the page is not in cache.
- **
- ** See also sqlite3PagerGet(). The difference between this routine
- ** and sqlite3PagerGet() is that _get() will go to the disk and read
- ** in the page if the page is not already in cache. This routine
- ** returns NULL if the page is not in cache or if a disk I/O error
- ** has ever happened.
- */
- static DbPage sqlite3PagerLookup( Pager pPager, u32 pgno )
- {
- PgHdr pPg = null;
- Debug.Assert( pPager != null );
- Debug.Assert( pgno != 0 );
- Debug.Assert( pPager.pPCache != null );
- Debug.Assert( pPager.eState >= PAGER_READER && pPager.eState != PAGER_ERROR );
- sqlite3PcacheFetch( pPager.pPCache, pgno, 0, ref pPg );
- return pPg;
- }
- /*
- ** Release a page reference.
- **
- ** If the number of references to the page drop to zero, then the
- ** page is added to the LRU list. When all references to all pages
- ** are released, a rollback occurs and the lock on the database is
- ** removed.
- */
- static void sqlite3PagerUnref( DbPage pPg )
- {
- if ( pPg != null )
- {
- Pager pPager = pPg.pPager;
- sqlite3PcacheRelease( pPg );
- pagerUnlockIfUnused( pPager );
- }
- }
- /*
- ** This function is called at the start of every write transaction.
- ** There must already be a RESERVED or EXCLUSIVE lock on the database
- ** file when this routine is called.
- **
- ** Open the journal file for pager pPager and write a journal header
- ** to the start of it. If there are active savepoints, open the sub-journal
- ** as well. This function is only used when the journal file is being
- ** opened to write a rollback log for a transaction. It is not used
- ** when opening a hot journal file to roll it back.
- **
- ** If the journal file is already open (as it may be in exclusive mode),
- ** then this function just writes a journal header to the start of the
- ** already open file.
- **
- ** Whether or not the journal file is opened by this function, the
- ** Pager.pInJournal bitvec structure is allocated.
- **
- ** Return SQLITE_OK if everything is successful. Otherwise, return
- ** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or
- ** an IO error code if opening or writing the journal file fails.
- */
- static int pager_open_journal( Pager pPager )
- {
- int rc = SQLITE_OK; /* Return code */
- sqlite3_vfs pVfs = pPager.pVfs; /* Local cache of vfs pointer */
- Debug.Assert( pPager.eState == PAGER_WRITER_LOCKED );
- Debug.Assert( assert_pager_state( pPager ) );
- Debug.Assert( pPager.pInJournal == null );
- /* If already in the error state, this function is a no-op. But on
- ** the other hand, this routine is never called if we are already in
- ** an error state. */
- if ( NEVER( pPager.errCode ) != 0 )
- return pPager.errCode;
- if ( !pagerUseWal( pPager ) && pPager.journalMode != PAGER_JOURNALMODE_OFF )
- {
- pPager.pInJournal = sqlite3BitvecCreate( pPager.dbSize );
- //if (pPager.pInJournal == null)
- //{
- // return SQLITE_NOMEM;
- //}
- /* Open the journal file if it is not already open. */
- if ( !isOpen( pPager.jfd ) )
- {
- if ( pPager.journalMode == PAGER_JOURNALMODE_MEMORY )
- {
- sqlite3MemJournalOpen( pPager.jfd );
- }
- else
- {
- int flags = /* VFS flags to open journal file */
- SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
- ( pPager.tempFile ?
- ( SQLITE_OPEN_DELETEONCLOSE | SQLITE_OPEN_TEMP_JOURNAL ) :
- ( SQLITE_OPEN_MAIN_JOURNAL )
- );
- #if SQLITE_ENABLE_ATOMIC_WRITE
- rc = sqlite3JournalOpen(
- pVfs, pPager.zJournal, pPager.jfd, flags, jrnlBufferSize(pPager)
- );
- #else
- int int0 = 0;
- rc = sqlite3OsOpen( pVfs, pPager.zJournal, pPager.jfd, flags, ref int0 );
- #endif
- }
- Debug.Assert( rc != SQLITE_OK || isOpen( pPager.jfd ) );
- }
- /* Write the first journal header to the journal file and open
- ** the sub-journal if necessary.
- */
- if ( rc == SQLITE_OK )
- {
- /* TODO: Check if all of these are really required. */
- pPager.nRec = 0;
- pPager.journalOff = 0;
- pPager.setMaster = 0;
- pPager.journalHdr = 0;
- rc = writeJournalHdr( pPager );
- }
- }
- if ( rc != SQLITE_OK )
- {
- sqlite3BitvecDestroy( ref pPager.pInJournal );
- pPager.pInJournal = null;
- }
- else
- {
- Debug.Assert( pPager.eState == PAGER_WRITER_LOCKED );
- pPager.eState = PAGER_WRITER_CACHEMOD;
- }
- return rc;
- }
- /*
- ** Begin a write-transaction on the specified pager object. If a
- ** write-transaction has already been opened, this function is a no-op.
- **
- ** If the exFlag argument is false, then acquire at least a RESERVED
- ** lock on the database file. If exFlag is true, then acquire at least
- ** an EXCLUSIVE lock. If such a lock is already held, no locking
- ** functions need be called.
- **
- ** If the subjInMemory argument is non-zero, then any sub-journal opened
- ** within this transaction will be opened as an in-memory file. This
- ** has no effect if the sub-journal is already opened (as it may be when
- ** running in exclusive mode) or if the transaction does not require a
- ** sub-journal. If the subjInMemory argument is zero, then any required
- ** sub-journal is implemented in-memory if pPager is an in-memory database,
- ** or using a temporary file otherwise.
- */
- static int sqlite3PagerBegin( Pager pPager, bool exFlag, int subjInMemory )
- {
- int rc = SQLITE_OK;
- if ( pPager.errCode != 0 )
- return pPager.errCode;
- Debug.Assert( pPager.eState >= PAGER_READER && pPager.eState < PAGER_ERROR );
- pPager.subjInMemory = (u8)subjInMemory;
- if ( ALWAYS( pPager.eState == PAGER_READER ) )
- {
- Debug.Assert( pPager.pInJournal == null );
- if ( pagerUseWal( pPager ) )
- {
- /* If the pager is configured to use locking_mode=exclusive, and an
- ** exclusive lock on the database is not already held, obtain it now.
- */
- if ( pPager.exclusiveMode && sqlite3WalExclusiveMode( pPager.pWal, -1 ) )
- {
- rc = pagerLockDb( pPager, EXCLUSIVE_LOCK );
- if ( rc != SQLITE_OK )
- {
- return rc;
- }
- sqlite3WalExclusiveMode( pPager.pWal, 1 );
- }
- /* Grab the write lock on the log file. If successful, upgrade to
- ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
- ** The busy-handler is not invoked if another connection already
- ** holds the write-lock. If possible, the upper layer will call it.
- */
- rc = sqlite3WalBeginWriteTransaction( pPager.pWal );
- }
- else
- {
- /* Obtain a RESERVED lock on the database file. If the exFlag parameter
- ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
- ** busy-handler callback can be used when upgrading to the EXCLUSIVE
- ** lock, but not when obtaining the RESERVED lock.
- */
- rc = pagerLockDb( pPager, RESERVED_LOCK );
- if ( rc == SQLITE_OK && exFlag )
- {
- rc = pager_wait_on_lock( pPager, EXCLUSIVE_LOCK );
- }
- }
- if ( rc == SQLITE_OK )
- {
- /* Change to WRITER_LOCKED state.
- **
- ** WAL mode sets Pager.eState to PAGER_WRITER_LOCKED or CACHEMOD
- ** when it has an open transaction, but never to DBMOD or FINISHED.
- ** This is because in those states the code to roll back savepoint
- ** transactions may copy data from the sub-journal into the database
- ** file as well as into the page cache. Which would be incorrect in
- ** WAL mode.
- */
- pPager.eState = PAGER_WRITER_LOCKED;
- pPager.dbHintSize = pPager.dbSize;
- pPager.dbFileSize = pPager.dbSize;
- pPager.dbOrigSize = pPager.dbSize;
- pPager.journalOff = 0;
- }
- Debug.Assert( rc == SQLITE_OK || pPager.eState == PAGER_READER );
- Debug.Assert( rc != SQLITE_OK || pPager.eState == PAGER_WRITER_LOCKED );
- Debug.Assert( assert_pager_state( pPager ) );
- }
- PAGERTRACE( "TRANSACTION %d\n", PAGERID( pPager ) );
- return rc;
- }
- /*
- ** Mark a single data page as writeable. The page is written into the
- ** main journal or sub-journal as required. If the page is written into
- ** one of the journals, the corresponding bit is set in the
- ** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
- ** of any open savepoints as appropriate.
- */
- static int pager_write( PgHdr pPg )
- {
- byte[] pData = pPg.pData;
- Pager pPager = pPg.pPager;
- int rc = SQLITE_OK;
- /* This routine is not called unless a write-transaction has already
- ** been started. The journal file may or may not be open at this point.
- ** It is never called in the ERROR state.
- */
- Debug.Assert( pPager.eState == PAGER_WRITER_LOCKED
- || pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- );
- Debug.Assert( assert_pager_state( pPager ) );
- /* If an error has been previously detected, report the same error
- ** again. This should not happen, but the check provides robustness. */
- if ( NEVER( pPager.errCode ) != 0 )
- return pPager.errCode;
- /* Higher-level routines never call this function if database is not
- ** writable. But check anyway, just for robustness. */
- if ( NEVER( pPager.readOnly ) )
- return SQLITE_PERM;
- #if SQLITE_CHECK_PAGES
- CHECK_PAGE(pPg);
- #endif
- /* The journal file needs to be opened. Higher level routines have already
- ** obtained the necessary locks to begin the write-transaction, but the
- ** rollback journal might not yet be open. Open it now if this is the case.
- **
- ** This is done before calling sqlite3PcacheMakeDirty() on the page.
- ** Otherwise, if it were done after calling sqlite3PcacheMakeDirty(), then
- ** an error might occur and the pager would end up in WRITER_LOCKED state
- ** with pages marked as dirty in the cache.
- */
- if ( pPager.eState == PAGER_WRITER_LOCKED )
- {
- rc = pager_open_journal( pPager );
- if ( rc != SQLITE_OK )
- return rc;
- }
- Debug.Assert( pPager.eState >= PAGER_WRITER_CACHEMOD );
- Debug.Assert( assert_pager_state( pPager ) );
- /* Mark the page as dirty. If the page has already been written
- ** to the journal then we can return right away.
- */
- sqlite3PcacheMakeDirty( pPg );
- if ( pageInJournal( pPg ) && !subjRequiresPage( pPg ) )
- {
- Debug.Assert( !pagerUseWal( pPager ) );
- }
- else
- {
- /* The transaction journal now exists and we have a RESERVED or an
- ** EXCLUSIVE lock on the main database file. Write the current page to
- ** the transaction journal if it is not there already.
- */
- if ( !pageInJournal( pPg ) && !pagerUseWal( pPager ) )
- {
- Debug.Assert( pagerUseWal( pPager ) == false );
- if ( pPg.pgno <= pPager.dbOrigSize && isOpen( pPager.jfd ) )
- {
- u32 cksum;
- byte[] pData2 = null;
- i64 iOff = pPager.journalOff;
- /* We should never write to the journal file the page that
- ** contains the database locks. The following Debug.Assert verifies
- ** that we do not. */
- Debug.Assert( pPg.pgno != ( ( PENDING_BYTE / ( pPager.pageSize ) ) + 1 ) );//PAGER_MJ_PGNO(pPager) );
- Debug.Assert( pPager.journalHdr <= pPager.journalOff );
- if ( CODEC2( pPager, pData, pPg.pgno, SQLITE_ENCRYPT_READ_CTX, ref pData2 ) )
- return SQLITE_NOMEM; // CODEC2(pPager, pData, pPg.pgno, 7, return SQLITE_NOMEM, pData2);
- cksum = pager_cksum( pPager, pData2 );
- /* Even if an IO or diskfull error occurred while journalling the
- ** page in the block above, set the need-sync flag for the page.
- ** Otherwise, when the transaction is rolled back, the logic in
- ** playback_one_page() will think that the page needs to be restored
- ** in the database file. And if an IO error occurs while doing so,
- ** then corruption may follow.
- */
- pPg.flags |= PGHDR_NEED_SYNC;
- rc = write32bits( pPager.jfd, iOff, pPg.pgno );
- if ( rc != SQLITE_OK )
- return rc;
- rc = sqlite3OsWrite( pPager.jfd, pData2, pPager.pageSize, iOff + 4 );
- if ( rc != SQLITE_OK )
- return rc;
- rc = write32bits( pPager.jfd, iOff + pPager.pageSize + 4, cksum );
- if ( rc != SQLITE_OK )
- return rc;
- IOTRACE( "JOUT %p %d %lld %d\n", pPager, pPg.pgno,
- pPager.journalOff, pPager.pageSize );
- #if SQLITE_TEST
- int iValue = sqlite3_pager_writej_count.iValue;
- PAGER_INCR( ref iValue );
- sqlite3_pager_writej_count.iValue = iValue;
- #endif
- PAGERTRACE( "JOURNAL %d page %d needSync=%d hash(%08x)\n",
- PAGERID( pPager ), pPg.pgno,
- ( ( pPg.flags & PGHDR_NEED_SYNC ) != 0 ? 1 : 0 ), pager_pagehash( pPg ) );
- pPager.journalOff += 8 + pPager.pageSize;
- pPager.nRec++;
- Debug.Assert( pPager.pInJournal != null );
- rc = sqlite3BitvecSet( pPager.pInJournal, pPg.pgno );
- testcase( rc == SQLITE_NOMEM );
- Debug.Assert( rc == SQLITE_OK || rc == SQLITE_NOMEM );
- rc |= addToSavepointBitvecs( pPager, pPg.pgno );
- if ( rc != SQLITE_OK )
- {
- Debug.Assert( rc == SQLITE_NOMEM );
- return rc;
- }
- }
- else
- {
- if ( pPager.eState != PAGER_WRITER_DBMOD )
- {
- pPg.flags |= PGHDR_NEED_SYNC;
- }
- PAGERTRACE( "APPEND %d page %d needSync=%d\n",
- PAGERID( pPager ), pPg.pgno,
- ( ( pPg.flags & PGHDR_NEED_SYNC ) != 0 ? 1 : 0 ) );
- }
- }
- /* If the statement journal is open and the page is not in it,
- ** then write the current page to the statement journal. Note that
- ** the statement journal format differs from the standard journal format
- ** in that it omits the checksums and the header.
- */
- if ( subjRequiresPage( pPg ) )
- {
- rc = subjournalPage( pPg );
- }
- }
- /* Update the database size and return.
- */
- if ( pPager.dbSize < pPg.pgno )
- {
- pPager.dbSize = pPg.pgno;
- }
- return rc;
- }
- /*
- ** Mark a data page as writeable. This routine must be called before
- ** making changes to a page. The caller must check the return value
- ** of this function and be careful not to change any page data unless
- ** this routine returns SQLITE_OK.
- **
- ** The difference between this function and pager_write() is that this
- ** function also deals with the special case where 2 or more pages
- ** fit on a single disk sector. In this case all co-resident pages
- ** must have been written to the journal file before returning.
- **
- ** If an error occurs, SQLITE_NOMEM or an IO error code is returned
- ** as appropriate. Otherwise, SQLITE_OK.
- */
- static int sqlite3PagerWrite( DbPage pDbPage )
- {
- int rc = SQLITE_OK;
- PgHdr pPg = pDbPage;
- Pager pPager = pPg.pPager;
- u32 nPagePerSector = (u32)( pPager.sectorSize / pPager.pageSize );
- Debug.Assert( pPager.eState >= PAGER_WRITER_LOCKED );
- Debug.Assert( pPager.eState != PAGER_ERROR );
- Debug.Assert( assert_pager_state( pPager ) );
- if ( nPagePerSector > 1 )
- {
- Pgno nPageCount = 0; /* Total number of pages in database file */
- Pgno pg1; /* First page of the sector pPg is located on. */
- Pgno nPage = 0; /* Number of pages starting at pg1 to journal */
- int ii; /* Loop counter */
- bool needSync = false; /* True if any page has PGHDR_NEED_SYNC */
- /* Set the doNotSyncSpill flag to 1. This is because we cannot allow
- ** a journal header to be written between the pages journaled by
- ** this function.
- */
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- Debug.Assert( pPager.doNotSyncSpill == 0 );
- pPager.doNotSyncSpill++;
- /* This trick assumes that both the page-size and sector-size are
- ** an integer power of 2. It sets variable pg1 to the identifier
- ** of the first page of the sector pPg is located on.
- */
- pg1 = (u32)( ( pPg.pgno - 1 ) & ~( nPagePerSector - 1 ) ) + 1;
- nPageCount = pPager.dbSize;
- if ( pPg.pgno > nPageCount )
- {
- nPage = ( pPg.pgno - pg1 ) + 1;
- }
- else if ( ( pg1 + nPagePerSector - 1 ) > nPageCount )
- {
- nPage = nPageCount + 1 - pg1;
- }
- else
- {
- nPage = nPagePerSector;
- }
- Debug.Assert( nPage > 0 );
- Debug.Assert( pg1 <= pPg.pgno );
- Debug.Assert( ( pg1 + nPage ) > pPg.pgno );
- for ( ii = 0; ii < nPage && rc == SQLITE_OK; ii++ )
- {
- u32 pg = (u32)( pg1 + ii );
- PgHdr pPage = new PgHdr();
- if ( pg == pPg.pgno || sqlite3BitvecTest( pPager.pInJournal, pg ) == 0 )
- {
- if ( pg != ( ( PENDING_BYTE / ( pPager.pageSize ) ) + 1 ) ) //PAGER_MJ_PGNO(pPager))
- {
- rc = sqlite3PagerGet( pPager, pg, ref pPage );
- if ( rc == SQLITE_OK )
- {
- rc = pager_write( pPage );
- if ( ( pPage.flags & PGHDR_NEED_SYNC ) != 0 )
- {
- needSync = true;
- }
- sqlite3PagerUnref( pPage );
- }
- }
- }
- else if ( ( pPage = pager_lookup( pPager, pg ) ) != null )
- {
- if ( ( pPage.flags & PGHDR_NEED_SYNC ) != 0 )
- {
- needSync = true;
- }
- sqlite3PagerUnref( pPage );
- }
- }
- /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages
- ** starting at pg1, then it needs to be set for all of them. Because
- ** writing to any of these nPage pages may damage the others, the
- ** journal file must contain sync()ed copies of all of them
- ** before any of them can be written out to the database file.
- */
- if ( rc == SQLITE_OK && needSync )
- {
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- for ( ii = 0; ii < nPage; ii++ )
- {
- PgHdr pPage = pager_lookup( pPager, (u32)( pg1 + ii ) );
- if ( pPage != null )
- {
- pPage.flags |= PGHDR_NEED_SYNC;
- sqlite3PagerUnref( pPage );
- }
- }
- }
- Debug.Assert( pPager.doNotSyncSpill == 1 );
- pPager.doNotSyncSpill--;
- }
- else
- {
- rc = pager_write( pDbPage );
- }
- return rc;
- }
- /*
- ** Return TRUE if the page given in the argument was previously passed
- ** to sqlite3PagerWrite(). In other words, return TRUE if it is ok
- ** to change the content of the page.
- */
- #if !NDEBUG
- static bool sqlite3PagerIswriteable( DbPage pPg )
- {
- return ( pPg.flags & PGHDR_DIRTY ) != 0;
- }
- #else
- static bool sqlite3PagerIswriteable( DbPage pPg ) { return true; }
- #endif
- /*
- ** A call to this routine tells the pager that it is not necessary to
- ** write the information on page pPg back to the disk, even though
- ** that page might be marked as dirty. This happens, for example, when
- ** the page has been added as a leaf of the freelist and so its
- ** content no longer matters.
- **
- ** The overlying software layer calls this routine when all of the data
- ** on the given page is unused. The pager marks the page as clean so
- ** that it does not get written to disk.
- **
- ** Tests show that this optimization can quadruple the speed of large
- ** DELETE operations.
- */
- static void sqlite3PagerDontWrite( PgHdr pPg )
- {
- Pager pPager = pPg.pPager;
- if ( ( pPg.flags & PGHDR_DIRTY ) != 0 && pPager.nSavepoint == 0 )
- {
- PAGERTRACE( "DONT_WRITE page %d of %d\n", pPg.pgno, PAGERID( pPager ) );
- IOTRACE( "CLEAN %p %d\n", pPager, pPg.pgno );
- pPg.flags |= PGHDR_DONT_WRITE;
- pager_set_pagehash( pPg );
- }
- }
- /*
- ** This routine is called to increment the value of the database file
- ** change-counter, stored as a 4-byte big-endian integer starting at
- ** byte offset 24 of the pager file. The secondary change counter at
- ** 92 is also updated, as is the SQLite version number at offset 96.
- **
- ** But this only happens if the pPager->changeCountDone flag is false.
- ** To avoid excess churning of page 1, the update only happens once.
- ** See also the pager_write_changecounter() routine that does an
- ** unconditional update of the change counters.
- **
- ** If the isDirectMode flag is zero, then this is done by calling
- ** sqlite3PagerWrite() on page 1, then modifying the contents of the
- ** page data. In this case the file will be updated when the current
- ** transaction is committed.
- **
- ** The isDirectMode flag may only be non-zero if the library was compiled
- ** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
- ** if isDirect is non-zero, then the database file is updated directly
- ** by writing an updated version of page 1 using a call to the
- ** sqlite3OsWrite() function.
- */
- static int pager_incr_changecounter( Pager pPager, bool isDirectMode )
- {
- int rc = SQLITE_OK;
- Debug.Assert( pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- );
- Debug.Assert( assert_pager_state( pPager ) );
- /* Declare and initialize constant integer 'isDirect'. If the
- ** atomic-write optimization is enabled in this build, then isDirect
- ** is initialized to the value passed as the isDirectMode parameter
- ** to this function. Otherwise, it is always set to zero.
- **
- ** The idea is that if the atomic-write optimization is not
- ** enabled at compile time, the compiler can omit the tests of
- ** 'isDirect' below, as well as the block enclosed in the
- ** "if( isDirect )" condition.
- */
- #if !SQLITE_ENABLE_ATOMIC_WRITE
- //# define DIRECT_MODE 0
- bool DIRECT_MODE = false;
- Debug.Assert( isDirectMode == false );
- UNUSED_PARAMETER( isDirectMode );
- #else
- //# define DIRECT_MODE isDirectMode
- int DIRECT_MODE = isDirectMode;
- #endif
- if ( !pPager.changeCountDone && pPager.dbSize > 0 )
- {
- PgHdr pPgHdr = null; /* Reference to page 1 */
- Debug.Assert( !pPager.tempFile && isOpen( pPager.fd ) );
- /* Open page 1 of the file for writing. */
- rc = sqlite3PagerGet( pPager, 1, ref pPgHdr );
- Debug.Assert( pPgHdr == null || rc == SQLITE_OK );
- /* If page one was fetched successfully, and this function is not
- ** operating in direct-mode, make page 1 writable. When not in
- ** direct mode, page 1 is always held in cache and hence the PagerGet()
- ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
- */
- if ( !DIRECT_MODE && ALWAYS( rc == SQLITE_OK ) )
- {
- rc = sqlite3PagerWrite( pPgHdr );
- }
- if ( rc == SQLITE_OK )
- {
- /* Actually do the update of the change counter */
- pager_write_changecounter( pPgHdr );
- /* If running in direct mode, write the contents of page 1 to the file. */
- if ( DIRECT_MODE )
- {
- u8[] zBuf = null;
- Debug.Assert( pPager.dbFileSize > 0 );
- if ( CODEC2( pPager, pPgHdr.pData, 1, SQLITE_ENCRYPT_WRITE_CTX, ref zBuf ) )
- return rc = SQLITE_NOMEM;//CODEC2(pPager, pPgHdr.pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
- if ( rc == SQLITE_OK )
- {
- rc = sqlite3OsWrite( pPager.fd, zBuf, pPager.pageSize, 0 );
- }
- if ( rc == SQLITE_OK )
- {
- pPager.changeCountDone = true;
- }
- }
- else
- {
- pPager.changeCountDone = true;
- }
- }
- /* Release the page reference. */
- sqlite3PagerUnref( pPgHdr );
- }
- return rc;
- }
- /*
- ** Sync the database file to disk. This is a no-op for in-memory databases
- ** or pages with the Pager.noSync flag set.
- **
- ** If successful, or if called on a pager for which it is a no-op, this
- ** function returns SQLITE_OK. Otherwise, an IO error code is returned.
- */
- static int sqlite3PagerSync( Pager pPager )
- {
- long rc = SQLITE_OK;
- if ( !pPager.noSync )
- {
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0 == MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- rc = sqlite3OsSync( pPager.fd, pPager.syncFlags );
- }
- else if ( isOpen( pPager.fd ) )
- {
- Debug.Assert(
- #if SQLITE_OMIT_MEMORYDB
- 0 == MEMDB
- #else
- 0 == pPager.memDb
- #endif
- );
- sqlite3OsFileControl( pPager.fd, SQLITE_FCNTL_SYNC_OMITTED, ref rc );
- }
- return (int)rc;
- }
- /*
- ** This function may only be called while a write-transaction is active in
- ** rollback. If the connection is in WAL mode, this call is a no-op.
- ** Otherwise, if the connection does not already have an EXCLUSIVE lock on
- ** the database file, an attempt is made to obtain one.
- **
- ** If the EXCLUSIVE lock is already held or the attempt to obtain it is
- ** successful, or the connection is in WAL mode, SQLITE_OK is returned.
- ** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is
- ** returned.
- */
- static int sqlite3PagerExclusiveLock( Pager pPager )
- {
- int rc = SQLITE_OK;
- Debug.Assert( pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- || pPager.eState == PAGER_WRITER_LOCKED
- );
- Debug.Assert( assert_pager_state( pPager ) );
- if ( false == pagerUseWal( pPager ) )
- {
- rc = pager_wait_on_lock( pPager, EXCLUSIVE_LOCK );
- }
- return rc;
- }
- /*
- ** Sync the database file for the pager pPager. zMaster points to the name
- ** of a master journal file that should be written into the individual
- ** journal file. zMaster may be NULL, which is interpreted as no master
- ** journal (a single database transaction).
- **
- ** This routine ensures that:
- **
- ** * The database file change-counter is updated,
- ** * the journal is synced (unless the atomic-write optimization is used),
- ** * all dirty pages are written to the database file,
- ** * the database file is truncated (if required), and
- ** * the database file synced.
- **
- ** The only thing that remains to commit the transaction is to finalize
- ** (delete, truncate or zero the first part of) the journal file (or
- ** delete the master journal file if specified).
- **
- ** Note that if zMaster==NULL, this does not overwrite a previous value
- ** passed to an sqlite3PagerCommitPhaseOne() call.
- **
- ** If the final parameter - noSync - is true, then the database file itself
- ** is not synced. The caller must call sqlite3PagerSync() directly to
- ** sync the database file before calling CommitPhaseTwo() to delete the
- ** journal file in this case.
- */
- static int sqlite3PagerCommitPhaseOne(
- Pager pPager, /* Pager object */
- string zMaster, /* If not NULL, the master journal name */
- bool noSync /* True to omit the xSync on the db file */
- )
- {
- int rc = SQLITE_OK; /* Return code */
- Debug.Assert( pPager.eState == PAGER_WRITER_LOCKED
- || pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- || pPager.eState == PAGER_ERROR
- );
- Debug.Assert( assert_pager_state( pPager ) );
- /* If a prior error occurred, report that error again. */
- if ( NEVER( pPager.errCode != 0 ) )
- return pPager.errCode;
- PAGERTRACE( "DATABASE SYNC: File=%s zMaster=%s nSize=%d\n",
- pPager.zFilename, zMaster, pPager.dbSize );
- /* If no database changes have been made, return early. */
- if ( pPager.eState < PAGER_WRITER_CACHEMOD )
- return SQLITE_OK;
- if (
- #if SQLITE_OMIT_MEMORYDB
- 0 != MEMDB
- #else
- 0 != pPager.memDb
- #endif
- )
- {
- /* If this is an in-memory db, or no pages have been written to, or this
- ** function has already been called, it is mostly a no-op. However, any
- ** backup in progress needs to be restarted.
- */
- sqlite3BackupRestart( pPager.pBackup );
- }
- else
- {
- if ( pagerUseWal( pPager ) )
- {
- PgHdr pList = sqlite3PcacheDirtyList( pPager.pPCache );
- if ( pList != null )
- {
- rc = pagerWalFrames( pPager, pList, pPager.dbSize, 1,
- ( pPager.fullSync ? pPager.syncFlags : (byte)0 )
- );
- }
- if ( rc == SQLITE_OK )
- {
- sqlite3PcacheCleanAll( pPager.pPCache );
- }
- }
- else
- {
- /* The following block updates the change-counter. Exactly how it
- ** does this depends on whether or not the atomic-update optimization
- ** was enabled at compile time, and if this transaction meets the
- ** runtime criteria to use the operation:
- **
- ** * The file-system supports the atomic-write property for
- ** blocks of size page-size, and
- ** * This commit is not part of a multi-file transaction, and
- ** * Exactly one page has been modified and store in the journal file.
- **
- ** If the optimization was not enabled at compile time, then the
- ** pager_incr_changecounter() function is called to update the change
- ** counter in 'indirect-mode'. If the optimization is compiled in but
- ** is not applicable to this transaction, call sqlite3JournalCreate()
- ** to make sure the journal file has actually been created, then call
- ** pager_incr_changecounter() to update the change-counter in indirect
- ** mode.
- **
- ** Otherwise, if the optimization is both enabled and applicable,
- ** then call pager_incr_changecounter() to update the change-counter
- ** in 'direct' mode. In this case the journal file will never be
- ** created for this transaction.
- */
- #if SQLITE_ENABLE_ATOMIC_WRITE
- PgHdr *pPg;
- Debug.Assert( isOpen(pPager.jfd)
- || pPager.journalMode==PAGER_JOURNALMODE_OFF
- || pPager.journalMode==PAGER_JOURNALMODE_WAL
- );
- if( !zMaster && isOpen(pPager.jfd)
- && pPager.journalOff==jrnlBufferSize(pPager)
- && pPager.dbSize>=pPager.dbOrigSize
- && (0==(pPg = sqlite3PcacheDirtyList(pPager.pPCache)) || 0==pPg.pDirty)
- ){
- /* Update the db file change counter via the direct-write method. The
- ** following call will modify the in-memory representation of page 1
- ** to include the updated change counter and then write page 1
- ** directly to the database file. Because of the atomic-write
- ** property of the host file-system, this is safe.
- */
- rc = pager_incr_changecounter(pPager, 1);
- }else{
- rc = sqlite3JournalCreate(pPager.jfd);
- if( rc==SQLITE_OK ){
- rc = pager_incr_changecounter(pPager, 0);
- }
- }
- #else
- rc = pager_incr_changecounter( pPager, false );
- #endif
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- /* If this transaction has made the database smaller, then all pages
- ** being discarded by the truncation must be written to the journal
- ** file. This can only happen in auto-vacuum mode.
- **
- ** Before reading the pages with page numbers larger than the
- ** current value of Pager.dbSize, set dbSize back to the value
- ** that it took at the start of the transaction. Otherwise, the
- ** calls to sqlite3PagerGet() return zeroed pages instead of
- ** reading data from the database file.
- */
- #if !SQLITE_OMIT_AUTOVACUUM
- if ( pPager.dbSize < pPager.dbOrigSize
- && pPager.journalMode != PAGER_JOURNALMODE_OFF
- )
- {
- Pgno i; /* Iterator variable */
- Pgno iSkip = PAGER_MJ_PGNO( pPager ); /* Pending lock page */
- Pgno dbSize = pPager.dbSize; /* Database image size */
- pPager.dbSize = pPager.dbOrigSize;
- for ( i = dbSize + 1; i <= pPager.dbOrigSize; i++ )
- {
- if ( 0 == sqlite3BitvecTest( pPager.pInJournal, i ) && i != iSkip )
- {
- PgHdr pPage = null; /* Page to journal */
- rc = sqlite3PagerGet( pPager, i, ref pPage );
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- rc = sqlite3PagerWrite( pPage );
- sqlite3PagerUnref( pPage );
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- }
- }
- pPager.dbSize = dbSize;
- }
- #endif
- /* Write the master journal name into the journal file. If a master
- ** journal file name has already been written to the journal file,
- ** or if zMaster is NULL (no master journal), then this call is a no-op.
- */
- rc = writeMasterJournal( pPager, zMaster );
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- /* Sync the journal file and write all dirty pages to the database.
- ** If the atomic-update optimization is being used, this sync will not
- ** create the journal file or perform any real IO.
- **
- ** Because the change-counter page was just modified, unless the
- ** atomic-update optimization is used it is almost certain that the
- ** journal requires a sync here. However, in locking_mode=exclusive
- ** on a system under memory pressure it is just possible that this is
- ** not the case. In this case it is likely enough that the redundant
- ** xSync() call will be changed to a no-op by the OS anyhow.
- */
- rc = syncJournal( pPager, 0 );
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- rc = pager_write_pagelist( pPager, sqlite3PcacheDirtyList( pPager.pPCache ) );
- if ( rc != SQLITE_OK )
- {
- Debug.Assert( rc != SQLITE_IOERR_BLOCKED );
- goto commit_phase_one_exit;
- }
- sqlite3PcacheCleanAll( pPager.pPCache );
- /* If the file on disk is not the same size as the database image,
- ** then use pager_truncate to grow or shrink the file here.
- */
- if ( pPager.dbSize != pPager.dbFileSize )
- {
- Pgno nNew = (Pgno)( pPager.dbSize - ( pPager.dbSize == PAGER_MJ_PGNO( pPager ) ? 1 : 0 ) );
- Debug.Assert( pPager.eState >= PAGER_WRITER_DBMOD );
- rc = pager_truncate( pPager, nNew );
- if ( rc != SQLITE_OK )
- goto commit_phase_one_exit;
- }
- /* Finally, sync the database file. */
- if ( !noSync )
- {
- rc = sqlite3PagerSync( pPager );
- }
- IOTRACE( "DBSYNC %p\n", pPager );
- }
- }
- commit_phase_one_exit:
- if ( rc == SQLITE_OK && !pagerUseWal( pPager ) )
- {
- pPager.eState = PAGER_WRITER_FINISHED;
- }
- return rc;
- }
- /*
- ** When this function is called, the database file has been completely
- ** updated to reflect the changes made by the current transaction and
- ** synced to disk. The journal file still exists in the file-system
- ** though, and if a failure occurs at this point it will eventually
- ** be used as a hot-journal and the current transaction rolled back.
- **
- ** This function finalizes the journal file, either by deleting,
- ** truncating or partially zeroing it, so that it cannot be used
- ** for hot-journal rollback. Once this is done the transaction is
- ** irrevocably committed.
- **
- ** If an error occurs, an IO error code is returned and the pager
- ** moves into the error state. Otherwise, SQLITE_OK is returned.
- */
- static int sqlite3PagerCommitPhaseTwo( Pager pPager )
- {
- int rc = SQLITE_OK; /* Return code */
- /* This routine should not be called if a prior error has occurred.
- ** But if (due to a coding error elsewhere in the system) it does get
- ** called, just return the same error code without doing anything. */
- if ( NEVER( pPager.errCode ) != 0 )
- return pPager.errCode;
- Debug.Assert( pPager.eState == PAGER_WRITER_LOCKED
- || pPager.eState == PAGER_WRITER_FINISHED
- || ( pagerUseWal( pPager ) && pPager.eState == PAGER_WRITER_CACHEMOD )
- );
- Debug.Assert( assert_pager_state( pPager ) );
- /* An optimization. If the database was not actually modified during
- ** this transaction, the pager is running in exclusive-mode and is
- ** using persistent journals, then this function is a no-op.
- **
- ** The start of the journal file currently contains a single journal
- ** header with the nRec field set to 0. If such a journal is used as
- ** a hot-journal during hot-journal rollback, 0 changes will be made
- ** to the database file. So there is no need to zero the journal
- ** header. Since the pager is in exclusive mode, there is no need
- ** to drop any locks either.
- */
- if ( pPager.eState == PAGER_WRITER_LOCKED
- && pPager.exclusiveMode
- && pPager.journalMode == PAGER_JOURNALMODE_PERSIST
- )
- {
- Debug.Assert( pPager.journalOff == JOURNAL_HDR_SZ( pPager ) || 0 == pPager.journalOff );
- pPager.eState = PAGER_READER;
- return SQLITE_OK;
- }
- PAGERTRACE( "COMMIT %d\n", PAGERID( pPager ) );
- rc = pager_end_transaction( pPager, pPager.setMaster );
- return pager_error( pPager, rc );
- }
- /*
- ** If a write transaction is open, then all changes made within the
- ** transaction are reverted and the current write-transaction is closed.
- ** The pager falls back to PAGER_READER state if successful, or PAGER_ERROR
- ** state if an error occurs.
- **
- ** If the pager is already in PAGER_ERROR state when this function is called,
- ** it returns Pager.errCode immediately. No work is performed in this case.
- **
- ** Otherwise, in rollback mode, this function performs two functions:
- **
- ** 1) It rolls back the journal file, restoring all database file and
- ** in-memory cache pages to the state they were in when the transaction
- ** was opened, and
- **
- ** 2) It finalizes the journal file, so that it is not used for hot
- ** rollback at any point in the future.
- **
- ** Finalization of the journal file (task 2) is only performed if the
- ** rollback is successful.
- **
- ** In WAL mode, all cache-entries containing data modified within the
- ** current transaction are either expelled from the cache or reverted to
- ** their pre-transaction state by re-reading data from the database or
- ** WAL files. The WAL transaction is then closed.
- */
- static int sqlite3PagerRollback( Pager pPager )
- {
- int rc = SQLITE_OK; /* Return code */
- PAGERTRACE( "ROLLBACK %d\n", PAGERID( pPager ) );
- /* PagerRollback() is a no-op if called in READER or OPEN state. If
- ** the pager is already in the ERROR state, the rollback is not
- ** attempted here. Instead, the error code is returned to the caller.
- */
- Debug.Assert( assert_pager_state( pPager ) );
- if ( pPager.eState == PAGER_ERROR )
- return pPager.errCode;
- if ( pPager.eState <= PAGER_READER )
- return SQLITE_OK;
- if ( pagerUseWal( pPager ) )
- {
- int rc2;
- rc = sqlite3PagerSavepoint( pPager, SAVEPOINT_ROLLBACK, -1 );
- rc2 = pager_end_transaction( pPager, pPager.setMaster );
- if ( rc == SQLITE_OK )
- rc = rc2;
- rc = pager_error( pPager, rc );
- }
- else if ( !isOpen( pPager.jfd ) || pPager.eState == PAGER_WRITER_LOCKED )
- {
- int eState = pPager.eState;
- rc = pager_end_transaction( pPager, 0 );
- if (
- #if SQLITE_OMIT_MEMORYDB
- 0==MEMDB
- #else
- 0 == pPager.memDb
- #endif
- && eState > PAGER_WRITER_LOCKED )
- {
- /* This can happen using journal_mode=off. Move the pager to the error
- ** state to indicate that the contents of the cache may not be trusted.
- ** Any active readers will get SQLITE_ABORT.
- */
- pPager.errCode = SQLITE_ABORT;
- pPager.eState = PAGER_ERROR;
- return rc;
- }
- }
- else
- {
- rc = pager_playback( pPager, 0 );
- }
- Debug.Assert( pPager.eState == PAGER_READER || rc != SQLITE_OK );
- Debug.Assert( rc == SQLITE_OK || rc == SQLITE_FULL || ( rc & 0xFF ) == SQLITE_IOERR );
- /* If an error occurs during a ROLLBACK, we can no longer trust the pager
- ** cache. So call pager_error() on the way out to make any error persistent.
- */
- return pager_error( pPager, rc );
- }
- /*
- ** Return TRUE if the database file is opened read-only. Return FALSE
- ** if the database is (in theory) writable.
- */
- static bool sqlite3PagerIsreadonly( Pager pPager )
- {
- return pPager.readOnly;
- }
- /*
- ** Return the number of references to the pager.
- */
- static int sqlite3PagerRefcount( Pager pPager )
- {
- return sqlite3PcacheRefCount( pPager.pPCache );
- }
- /*
- ** Return the approximate number of bytes of memory currently
- ** used by the pager and its associated cache.
- */
- static int sqlite3PagerMemUsed( Pager pPager )
- {
- int perPageSize = pPager.pageSize + pPager.nExtra + 20; //+ sizeof(PgHdr) + 5*sizeof(void*);
- return perPageSize * sqlite3PcachePagecount( pPager.pPCache )
- + 0// Not readily available under C#// sqlite3MallocSize(pPager);
- + pPager.pageSize;
- }
- /*
- ** Return the number of references to the specified page.
- */
- static int sqlite3PagerPageRefcount( DbPage pPage )
- {
- return sqlite3PcachePageRefcount( pPage );
- }
- #if SQLITE_TEST
- /*
- ** This routine is used for testing and analysis only.
- */
- static int[] sqlite3PagerStats( Pager pPager )
- {
- int[] a = new int[11];
- a[0] = sqlite3PcacheRefCount( pPager.pPCache );
- a[1] = sqlite3PcachePagecount( pPager.pPCache );
- a[2] = sqlite3PcacheGetCachesize( pPager.pPCache );
- a[3] = pPager.eState == PAGER_OPEN ? -1 : (int)pPager.dbSize;
- a[4] = pPager.eState;
- a[5] = pPager.errCode;
- a[6] = pPager.nHit;
- a[7] = pPager.nMiss;
- a[8] = 0; /* Used to be pPager.nOvfl */
- a[9] = pPager.nRead;
- a[10] = pPager.nWrite;
- return a;
- }
- #endif
- /*
- ** Return true if this is an in-memory pager.
- */
- static bool sqlite3PagerIsMemdb( Pager pPager )
- {
- #if SQLITE_OMIT_MEMORYDB
- return MEMDB != 0;
- #else
- return pPager.memDb != 0;
- #endif
- }
- /*
- ** Check that there are at least nSavepoint savepoints open. If there are
- ** currently less than nSavepoints open, then open one or more savepoints
- ** to make up the difference. If the number of savepoints is already
- ** equal to nSavepoint, then this function is a no-op.
- **
- ** If a memory allocation fails, SQLITE_NOMEM is returned. If an error
- ** occurs while opening the sub-journal file, then an IO error code is
- ** returned. Otherwise, SQLITE_OK.
- */
- static int sqlite3PagerOpenSavepoint( Pager pPager, int nSavepoint )
- {
- int rc = SQLITE_OK; /* Return code */
- int nCurrent = pPager.nSavepoint; /* Current number of savepoints */
- Debug.Assert( pPager.eState >= PAGER_WRITER_LOCKED );
- Debug.Assert( assert_pager_state( pPager ) );
- if ( nSavepoint > nCurrent && pPager.useJournal != 0 )
- {
- int ii; /* Iterator variable */
- PagerSavepoint[] aNew; /* New Pager.aSavepoint array */
- /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
- ** if the allocation fails. Otherwise, zero the new portion in case a
- ** malloc failure occurs while populating it in the for(...) loop below.
- */
- //aNew = (PagerSavepoint *)sqlite3Realloc(
- // pPager.aSavepoint, sizeof(PagerSavepoint)*nSavepoint
- //);
- Array.Resize( ref pPager.aSavepoint, nSavepoint );
- aNew = pPager.aSavepoint;
- //if( null==aNew ){
- // return SQLITE_NOMEM;
- //}
- // memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
- // pPager.aSavepoint = aNew;
- /* Populate the PagerSavepoint structures just allocated. */
- for ( ii = nCurrent; ii < nSavepoint; ii++ )
- {
- aNew[ii] = new PagerSavepoint();
- aNew[ii].nOrig = pPager.dbSize;
- if ( isOpen( pPager.jfd ) && pPager.journalOff > 0 )
- {
- aNew[ii].iOffset = pPager.journalOff;
- }
- else
- {
- aNew[ii].iOffset = (int)JOURNAL_HDR_SZ( pPager );
- }
- aNew[ii].iSubRec = pPager.nSubRec;
- aNew[ii].pInSavepoint = sqlite3BitvecCreate( pPager.dbSize );
- if ( null == aNew[ii].pInSavepoint )
- {
- return SQLITE_NOMEM;
- }
- if ( pagerUseWal( pPager ) )
- {
- sqlite3WalSavepoint( pPager.pWal, aNew[ii].aWalData );
- }
- pPager.nSavepoint = ii + 1;
- }
- Debug.Assert( pPager.nSavepoint == nSavepoint );
- assertTruncateConstraint( pPager );
- }
- return rc;
- }
- /*
- ** This function is called to rollback or release (commit) a savepoint.
- ** The savepoint to release or rollback need not be the most recently
- ** created savepoint.
- **
- ** Parameter op is always either SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE.
- ** If it is SAVEPOINT_RELEASE, then release and destroy the savepoint with
- ** index iSavepoint. If it is SAVEPOINT_ROLLBACK, then rollback all changes
- ** that have occurred since the specified savepoint was created.
- **
- ** The savepoint to rollback or release is identified by parameter
- ** iSavepoint. A value of 0 means to operate on the outermost savepoint
- ** (the first created). A value of (Pager.nSavepoint-1) means operate
- ** on the most recently created savepoint. If iSavepoint is greater than
- ** (Pager.nSavepoint-1), then this function is a no-op.
- **
- ** If a negative value is passed to this function, then the current
- ** transaction is rolled back. This is different to calling
- ** sqlite3PagerRollback() because this function does not terminate
- ** the transaction or unlock the database, it just restores the
- ** contents of the database to its original state.
- **
- ** In any case, all savepoints with an index greater than iSavepoint
- ** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
- ** then savepoint iSavepoint is also destroyed.
- **
- ** This function may return SQLITE_NOMEM if a memory allocation fails,
- ** or an IO error code if an IO error occurs while rolling back a
- ** savepoint. If no errors occur, SQLITE_OK is returned.
- */
- static int sqlite3PagerSavepoint( Pager pPager, int op, int iSavepoint )
- {
- int rc = pPager.errCode; /* Return code */
- Debug.Assert( op == SAVEPOINT_RELEASE || op == SAVEPOINT_ROLLBACK );
- Debug.Assert( iSavepoint >= 0 || op == SAVEPOINT_ROLLBACK );
- if ( rc == SQLITE_OK && iSavepoint < pPager.nSavepoint )
- {
- int ii; /* Iterator variable */
- int nNew; /* Number of remaining savepoints after this op. */
- /* Figure out how many savepoints will still be active after this
- ** operation. Store this value in nNew. Then free resources associated
- ** with any savepoints that are destroyed by this operation.
- */
- nNew = iSavepoint + ( ( op == SAVEPOINT_RELEASE ) ? 0 : 1 );
- for ( ii = nNew; ii < pPager.nSavepoint; ii++ )
- {
- sqlite3BitvecDestroy( ref pPager.aSavepoint[ii].pInSavepoint );
- }
- pPager.nSavepoint = nNew;
- /* If this is a release of the outermost savepoint, truncate
- ** the sub-journal to zero bytes in size. */
- if ( op == SAVEPOINT_RELEASE )
- {
- if ( nNew == 0 && isOpen( pPager.sjfd ) )
- {
- /* Only truncate if it is an in-memory sub-journal. */
- if ( sqlite3IsMemJournal( pPager.sjfd ) )
- {
- rc = sqlite3OsTruncate( pPager.sjfd, 0 );
- Debug.Assert( rc == SQLITE_OK );
- }
- pPager.nSubRec = 0;
- }
- }
- /* Else this is a rollback operation, playback the specified savepoint.
- ** If this is a temp-file, it is possible that the journal file has
- ** not yet been opened. In this case there have been no changes to
- ** the database file, so the playback operation can be skipped.
- */
- else if ( pagerUseWal( pPager ) || isOpen( pPager.jfd ) )
- {
- PagerSavepoint pSavepoint = ( nNew == 0 ) ? null : pPager.aSavepoint[nNew - 1];
- rc = pagerPlaybackSavepoint( pPager, pSavepoint );
- Debug.Assert( rc != SQLITE_DONE );
- }
- }
- return rc;
- }
- /*
- ** Return the full pathname of the database file.
- */
- static string sqlite3PagerFilename( Pager pPager )
- {
- return pPager.zFilename;
- }
- /*
- ** Return the VFS structure for the pager.
- */
- static sqlite3_vfs sqlite3PagerVfs( Pager pPager )
- {
- return pPager.pVfs;
- }
- /*
- ** Return the file handle for the database file associated
- ** with the pager. This might return NULL if the file has
- ** not yet been opened.
- */
- static sqlite3_file sqlite3PagerFile( Pager pPager )
- {
- return pPager.fd;
- }
- /*
- ** Return the full pathname of the journal file.
- */
- static string sqlite3PagerJournalname( Pager pPager )
- {
- return pPager.zJournal;
- }
- /*
- ** Return true if fsync() calls are disabled for this pager. Return FALSE
- ** if fsync()s are executed normally.
- */
- static bool sqlite3PagerNosync( Pager pPager )
- {
- return pPager.noSync;
- }
- #if SQLITE_HAS_CODEC
- /*
- ** Set or retrieve the codec for this pager
- */
- static void sqlite3PagerSetCodec(
- Pager pPager,
- dxCodec xCodec, //void *(*xCodec)(void*,void*,Pgno,int),
- dxCodecSizeChng xCodecSizeChng, //void (*xCodecSizeChng)(void*,int,int),
- dxCodecFree xCodecFree, //void (*xCodecFree)(void*),
- codec_ctx pCodec
- )
- {
- if ( pPager.xCodecFree != null )
- pPager.xCodecFree( ref pPager.pCodec );
- pPager.xCodec = ( pPager.memDb != 0 ) ? null : xCodec;
- pPager.xCodecSizeChng = xCodecSizeChng;
- pPager.xCodecFree = xCodecFree;
- pPager.pCodec = pCodec;
- pagerReportSize( pPager );
- }
- static object sqlite3PagerGetCodec( Pager pPager )
- {
- return pPager.pCodec;
- }
- #endif
- #if !SQLITE_OMIT_AUTOVACUUM
- /*
- ** Move the page pPg to location pgno in the file.
- **
- ** There must be no references to the page previously located at
- ** pgno (which we call pPgOld) though that page is allowed to be
- ** in cache. If the page previously located at pgno is not already
- ** in the rollback journal, it is not put there by by this routine.
- **
- ** References to the page pPg remain valid. Updating any
- ** meta-data associated with pPg (i.e. data stored in the nExtra bytes
- ** allocated along with the page) is the responsibility of the caller.
- **
- ** A transaction must be active when this routine is called. It used to be
- ** required that a statement transaction was not active, but this restriction
- ** has been removed (CREATE INDEX needs to move a page when a statement
- ** transaction is active).
- **
- ** If the fourth argument, isCommit, is non-zero, then this page is being
- ** moved as part of a database reorganization just before the transaction
- ** is being committed. In this case, it is guaranteed that the database page
- ** pPg refers to will not be written to again within this transaction.
- **
- ** This function may return SQLITE_NOMEM or an IO error code if an error
- ** occurs. Otherwise, it returns SQLITE_OK.
- */
- static int sqlite3PagerMovepage( Pager pPager, DbPage pPg, u32 pgno, int isCommit )
- {
- PgHdr pPgOld; /* The page being overwritten. */
- u32 needSyncPgno = 0; /* Old value of pPg.pgno, if sync is required */
- int rc; /* Return code */
- Pgno origPgno; /* The original page number */
- Debug.Assert( pPg.nRef > 0 );
- Debug.Assert( pPager.eState == PAGER_WRITER_CACHEMOD
- || pPager.eState == PAGER_WRITER_DBMOD
- );
- Debug.Assert( assert_pager_state( pPager ) );
- /* In order to be able to rollback, an in-memory database must journal
- ** the page we are moving from.
- */
- if (
- #if SQLITE_OMIT_MEMORYDB
- 1==MEMDB
- #else
- pPager.memDb != 0
- #endif
- )
- {
- rc = sqlite3PagerWrite( pPg );
- if ( rc != 0 )
- return rc;
- }
- /* If the page being moved is dirty and has not been saved by the latest
- ** savepoint, then save the current contents of the page into the
- ** sub-journal now. This is required to handle the following scenario:
- **
- ** BEGIN;
- ** <journal page X, then modify it in memory>
- ** SAVEPOINT one;
- ** <Move page X to location Y>
- ** ROLLBACK TO one;
- **
- ** If page X were not written to the sub-journal here, it would not
- ** be possible to restore its contents when the "ROLLBACK TO one"
- ** statement were is processed.
- **
- ** subjournalPage() may need to allocate space to store pPg.pgno into
- ** one or more savepoint bitvecs. This is the reason this function
- ** may return SQLITE_NOMEM.
- */
- if ( ( pPg.flags & PGHDR_DIRTY ) != 0
- && subjRequiresPage( pPg )
- && SQLITE_OK != ( rc = subjournalPage( pPg ) )
- )
- {
- return rc;
- }
- PAGERTRACE( "MOVE %d page %d (needSync=%d) moves to %d\n",
- PAGERID( pPager ), pPg.pgno, ( pPg.flags & PGHDR_NEED_SYNC ) != 0 ? 1 : 0, pgno );
- IOTRACE( "MOVE %p %d %d\n", pPager, pPg.pgno, pgno );
- /* If the journal needs to be sync()ed before page pPg.pgno can
- ** be written to, store pPg.pgno in local variable needSyncPgno.
- **
- ** If the isCommit flag is set, there is no need to remember that
- ** the journal needs to be sync()ed before database page pPg.pgno
- ** can be written to. The caller has already promised not to write to it.
- */
- if ( ( ( pPg.flags & PGHDR_NEED_SYNC ) != 0 ) && 0 == isCommit )
- {
- needSyncPgno = pPg.pgno;
- Debug.Assert( pageInJournal( pPg ) || pPg.pgno > pPager.dbOrigSize );
- Debug.Assert( ( pPg.flags & PGHDR_DIRTY ) != 0 );
- }
- /* If the cache contains a page with page-number pgno, remove it
- ** from its hash chain. Also, if the PGHDR_NEED_SYNC was set for
- ** page pgno before the 'move' operation, it needs to be retained
- ** for the page moved there.
- */
- pPg.flags &= ~PGHDR_NEED_SYNC;
- pPgOld = pager_lookup( pPager, pgno );
- Debug.Assert( null == pPgOld || pPgOld.nRef == 1 );
- if ( pPgOld != null )
- {
- pPg.flags |= ( pPgOld.flags & PGHDR_NEED_SYNC );
- if (
- #if SQLITE_OMIT_MEMORYDB
- 1==MEMDB
- #else
- pPager.memDb != 0
- #endif
- )
- {
- /* Do not discard pages from an in-memory database since we might
- ** need to rollback later. Just move the page out of the way. */
- sqlite3PcacheMove( pPgOld, pPager.dbSize + 1 );
- }
- else
- {
- sqlite3PcacheDrop( pPgOld );
- }
- }
- origPgno = pPg.pgno;
- sqlite3PcacheMove( pPg, pgno );
- sqlite3PcacheMakeDirty( pPg );
- /* For an in-memory database, make sure the original page continues
- ** to exist, in case the transaction needs to roll back. Use pPgOld
- ** as the original page since it has already been allocated.
- */
- if (
- #if SQLITE_OMIT_MEMORYDB
- 0!=MEMDB
- #else
- 0 != pPager.memDb
- #endif
- )
- {
- Debug.Assert( pPgOld );
- sqlite3PcacheMove( pPgOld, origPgno );
- sqlite3PagerUnref( pPgOld );
- }
- if ( needSyncPgno != 0 )
- {
- /* If needSyncPgno is non-zero, then the journal file needs to be
- ** sync()ed before any data is written to database file page needSyncPgno.
- ** Currently, no such page exists in the page-cache and the
- ** "is journaled" bitvec flag has been set. This needs to be remedied by
- ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
- ** flag.
- **
- ** If the attempt to load the page into the page-cache fails, (due
- ** to a malloc() or IO failure), clear the bit in the pInJournal[]
- ** array. Otherwise, if the page is loaded and written again in
- ** this transaction, it may be written to the database file before
- ** it is synced into the journal file. This way, it may end up in
- ** the journal file twice, but that is not a problem.
- */
- PgHdr pPgHdr = null;
- rc = sqlite3PagerGet( pPager, needSyncPgno, ref pPgHdr );
- if ( rc != SQLITE_OK )
- {
- if ( needSyncPgno <= pPager.dbOrigSize )
- {
- Debug.Assert( pPager.pTmpSpace != null );
- u32[] pTemp = new u32[pPager.pTmpSpace.Length];
- sqlite3BitvecClear( pPager.pInJournal, needSyncPgno, pTemp );//pPager.pTmpSpace );
- }
- return rc;
- }
- pPgHdr.flags |= PGHDR_NEED_SYNC;
- sqlite3PcacheMakeDirty( pPgHdr );
- sqlite3PagerUnref( pPgHdr );
- }
- return SQLITE_OK;
- }
- #endif
- /*
- ** Return a pointer to the data for the specified page.
- */
- static byte[] sqlite3PagerGetData( DbPage pPg )
- {
- Debug.Assert( pPg.nRef > 0 || pPg.pPager.memDb != 0 );
- return pPg.pData;
- }
- /*
- ** Return a pointer to the Pager.nExtra bytes of "extra" space
- ** allocated along with the specified page.
- */
- static MemPage sqlite3PagerGetExtra( DbPage pPg )
- {
- return pPg.pExtra;
- }
- /*
- ** Get/set the locking-mode for this pager. Parameter eMode must be one
- ** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or
- ** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
- ** the locking-mode is set to the value specified.
- **
- ** The returned value is either PAGER_LOCKINGMODE_NORMAL or
- ** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
- ** locking-mode.
- */
- static bool sqlite3PagerLockingMode( Pager pPager, int eMode )
- {
- Debug.Assert( eMode == PAGER_LOCKINGMODE_QUERY
- || eMode == PAGER_LOCKINGMODE_NORMAL
- || eMode == PAGER_LOCKINGMODE_EXCLUSIVE );
- Debug.Assert( PAGER_LOCKINGMODE_QUERY < 0 );
- Debug.Assert( PAGER_LOCKINGMODE_NORMAL >= 0 && PAGER_LOCKINGMODE_EXCLUSIVE >= 0 );
- Debug.Assert( pPager.exclusiveMode || false == sqlite3WalHeapMemory( pPager.pWal ) );
- if ( eMode >= 0 && !pPager.tempFile && !sqlite3WalHeapMemory( pPager.pWal ) )
- {
- pPager.exclusiveMode = eMode != 0;
- }
- return pPager.exclusiveMode;
- }
- /*
- ** Set the journal-mode for this pager. Parameter eMode must be one of:
- **
- ** PAGER_JOURNALMODE_DELETE
- ** PAGER_JOURNALMODE_TRUNCATE
- ** PAGER_JOURNALMODE_PERSIST
- ** PAGER_JOURNALMODE_OFF
- ** PAGER_JOURNALMODE_MEMORY
- ** PAGER_JOURNALMODE_WAL
- **
- ** The journalmode is set to the value specified if the change is allowed.
- ** The change may be disallowed for the following reasons:
- **
- ** * An in-memory database can only have its journal_mode set to _OFF
- ** or _MEMORY.
- **
- ** * Temporary databases cannot have _WAL journalmode.
- **
- ** The returned indicate the current (possibly updated) journal-mode.
- */
- static int sqlite3PagerSetJournalMode( Pager pPager, int eMode )
- {
- u8 eOld = pPager.journalMode; /* Prior journalmode */
- #if SQLITE_DEBUG
- /* The print_pager_state() routine is intended to be used by the debugger
- ** only. We invoke it once here to suppress a compiler warning. */
- print_pager_state( pPager );
- #endif
- /* The eMode parameter is always valid */
- Debug.Assert( eMode == PAGER_JOURNALMODE_DELETE
- || eMode == PAGER_JOURNALMODE_TRUNCATE
- || eMode == PAGER_JOURNALMODE_PERSIST
- || eMode == PAGER_JOURNALMODE_OFF
- || eMode == PAGER_JOURNALMODE_WAL
- || eMode == PAGER_JOURNALMODE_MEMORY );
- /* This routine is only called from the OP_JournalMode opcode, and
- ** the logic there will never allow a temporary file to be changed
- ** to WAL mode.
- */
- Debug.Assert( pPager.tempFile == false || eMode != PAGER_JOURNALMODE_WAL );
- /* Do allow the journalmode of an in-memory database to be set to
- ** anything other than MEMORY or OFF
- */
- if (
- #if SQLITE_OMIT_MEMORYDB
- 1==MEMDB
- #else
- 1 == pPager.memDb
- #endif
- )
- {
- Debug.Assert( eOld == PAGER_JOURNALMODE_MEMORY || eOld == PAGER_JOURNALMODE_OFF );
- if ( eMode != PAGER_JOURNALMODE_MEMORY && eMode != PAGER_JOURNALMODE_OFF )
- {
- eMode = eOld;
- }
- }
- if ( eMode != eOld )
- {
- /* Change the journal mode. */
- Debug.Assert( pPager.eState != PAGER_ERROR );
- pPager.journalMode = (u8)eMode;
- /* When transistioning from TRUNCATE or PERSIST to any other journal
- ** mode except WAL, unless the pager is in locking_mode=exclusive mode,
- ** delete the journal file.
- */
- Debug.Assert( ( PAGER_JOURNALMODE_TRUNCATE & 5 ) == 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_PERSIST & 5 ) == 1 );
- Debug.Assert( ( PAGER_JOURNALMODE_DELETE & 5 ) == 0 );
- Debug.Assert( ( PAGER_JOURNALMODE_MEMORY & 5 ) == 4 );
- Debug.Assert( ( PAGER_JOURNALMODE_OFF & 5 ) == 0 );
- Debug.Assert( ( PAGER_JOURNALMODE_WAL & 5 ) == 5 );
- Debug.Assert( isOpen( pPager.fd ) || pPager.exclusiveMode );
- if ( !pPager.exclusiveMode && ( eOld & 5 ) == 1 && ( eMode & 1 ) == 0 )
- {
- /* In this case we would like to delete the journal file. If it is
- ** not possible, then that is not a problem. Deleting the journal file
- ** here is an optimization only.
- **
- ** Before deleting the journal file, obtain a RESERVED lock on the
- ** database file. This ensures that the journal file is not deleted
- ** while it is in use by some other client.
- */
- sqlite3OsClose( pPager.jfd );
- if ( pPager.eLock >= RESERVED_LOCK )
- {
- sqlite3OsDelete( pPager.pVfs, pPager.zJournal, 0 );
- }
- else
- {
- int rc = SQLITE_OK;
- int state = pPager.eState;
- Debug.Assert( state == PAGER_OPEN || state == PAGER_READER );
- if ( state == PAGER_OPEN )
- {
- rc = sqlite3PagerSharedLock( pPager );
- }
- if ( pPager.eState == PAGER_READER )
- {
- Debug.Assert( rc == SQLITE_OK );
- rc = pagerLockDb( pPager, RESERVED_LOCK );
- }
- if ( rc == SQLITE_OK )
- {
- sqlite3OsDelete( pPager.pVfs, pPager.zJournal, 0 );
- }
- if ( rc == SQLITE_OK && state == PAGER_READER )
- {
- pagerUnlockDb( pPager, SHARED_LOCK );
- }
- else if ( state == PAGER_OPEN )
- {
- pager_unlock( pPager );
- }
- Debug.Assert( state == pPager.eState );
- }
- }
- }
- /* Return the new journal mode */
- return (int)pPager.journalMode;
- }
- /*
- ** Return the current journal mode.
- */
- static int sqlite3PagerGetJournalMode( Pager pPager )
- {
- return (int)pPager.journalMode;
- }
- /*
- ** Return TRUE if the pager is in a state where it is OK to change the
- ** journalmode. Journalmode changes can only happen when the database
- ** is unmodified.
- */
- static int sqlite3PagerOkToChangeJournalMode( Pager pPager )
- {
- Debug.Assert( assert_pager_state( pPager ) );
- if ( pPager.eState >= PAGER_WRITER_CACHEMOD )
- return 0;
- if ( NEVER( isOpen( pPager.jfd ) && pPager.journalOff > 0 ) )
- return 0;
- return 1;
- }
- /*
- ** Get/set the size-limit used for persistent journal files.
- **
- ** Setting the size limit to -1 means no limit is enforced.
- ** An attempt to set a limit smaller than -1 is a no-op.
- */
- static i64 sqlite3PagerJournalSizeLimit( Pager pPager, i64 iLimit )
- {
- if ( iLimit >= -1 )
- {
- pPager.journalSizeLimit = iLimit;
- }
- return pPager.journalSizeLimit;
- }
- /*
- ** Return a pointer to the pPager.pBackup variable. The backup module
- ** in backup.c maintains the content of this variable. This module
- ** uses it opaquely as an argument to sqlite3BackupRestart() and
- ** sqlite3BackupUpdate() only.
- */
- static sqlite3_backup sqlite3PagerBackupPtr( Pager pPager )
- {
- return pPager.pBackup;
- }
- #if !SQLITE_OMIT_WAL
- /*
- ** This function is called when the user invokes "PRAGMA checkpoint".
- */
- int sqlite3PagerCheckpoint(Pager *pPager){
- int rc = SQLITE_OK;
- if( pPager->pWal ){
- u8 *zBuf = (u8 *)pPager->pTmpSpace;
- rc = sqlite3WalCheckpoint(pPager->pWal, pPager->ckptSyncFlags,
- pPager->pageSize, zBuf);
- }
- return rc;
- }
- int sqlite3PagerWalCallback(Pager *pPager){
- return sqlite3WalCallback(pPager->pWal);
- }
- /*
- ** Return true if the underlying VFS for the given pager supports the
- ** primitives necessary for write-ahead logging.
- */
- int sqlite3PagerWalSupported(Pager *pPager){
- const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
- return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
- }
- /*
- ** Attempt to take an exclusive lock on the database file. If a PENDING lock
- ** is obtained instead, immediately release it.
- */
- static int pagerExclusiveLock(Pager *pPager){
- int rc; /* Return code */
- assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
- rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
- if( rc!=SQLITE_OK ){
- /* If the attempt to grab the exclusive lock failed, release the
- ** pending lock that may have been obtained instead. */
- pagerUnlockDb(pPager, SHARED_LOCK);
- }
- return rc;
- }
- /*
- ** Call sqlite3WalOpen() to open the WAL handle. If the pager is in
- ** exclusive-locking mode when this function is called, take an EXCLUSIVE
- ** lock on the database file and use heap-memory to store the wal-index
- ** in. Otherwise, use the normal shared-memory.
- */
- static int pagerOpenWal(Pager *pPager){
- int rc = SQLITE_OK;
- assert( pPager->pWal==0 && pPager->tempFile==0 );
- assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK || pPager->noReadlock);
- /* If the pager is already in exclusive-mode, the WAL module will use
- ** heap-memory for the wal-index instead of the VFS shared-memory
- ** implementation. Take the exclusive lock now, before opening the WAL
- ** file, to make sure this is safe.
- */
- if( pPager->exclusiveMode ){
- rc = pagerExclusiveLock(pPager);
- }
- /* Open the connection to the log file. If this operation fails,
- ** (e.g. due to malloc() failure), return an error code.
- */
- if( rc==SQLITE_OK ){
- rc = sqlite3WalOpen(pPager->pVfs,
- pPager->fd, pPager->zWal, pPager->exclusiveMode, &pPager->pWal
- );
- }
- return rc;
- }
- /*
- ** The caller must be holding a SHARED lock on the database file to call
- ** this function.
- **
- ** If the pager passed as the first argument is open on a real database
- ** file (not a temp file or an in-memory database), and the WAL file
- ** is not already open, make an attempt to open it now. If successful,
- ** return SQLITE_OK. If an error occurs or the VFS used by the pager does
- ** not support the xShmXXX() methods, return an error code. *pbOpen is
- ** not modified in either case.
- **
- ** If the pager is open on a temp-file (or in-memory database), or if
- ** the WAL file is already open, set *pbOpen to 1 and return SQLITE_OK
- ** without doing anything.
- */
- int sqlite3PagerOpenWal(
- Pager *pPager, /* Pager object */
- int *pbOpen /* OUT: Set to true if call is a no-op */
- ){
- int rc = SQLITE_OK; /* Return code */
- assert( assert_pager_state(pPager) );
- assert( pPager->eState==PAGER_OPEN || pbOpen );
- assert( pPager->eState==PAGER_READER || !pbOpen );
- assert( pbOpen==0 || *pbOpen==0 );
- assert( pbOpen!=0 || (!pPager->tempFile && !pPager->pWal) );
- if( !pPager->tempFile && !pPager->pWal ){
- if( !sqlite3PagerWalSupported(pPager) ) return SQLITE_CANTOPEN;
- /* Close any rollback journal previously open */
- sqlite3OsClose(pPager->jfd);
- rc = pagerOpenWal(pPager);
- if( rc==SQLITE_OK ){
- pPager->journalMode = PAGER_JOURNALMODE_WAL;
- pPager->eState = PAGER_OPEN;
- }
- }else{
- *pbOpen = 1;
- }
- return rc;
- }
- /*
- ** This function is called to close the connection to the log file prior
- ** to switching from WAL to rollback mode.
- **
- ** Before closing the log file, this function attempts to take an
- ** EXCLUSIVE lock on the database file. If this cannot be obtained, an
- ** error (SQLITE_BUSY) is returned and the log connection is not closed.
- ** If successful, the EXCLUSIVE lock is not released before returning.
- */
- int sqlite3PagerCloseWal(Pager *pPager){
- int rc = SQLITE_OK;
- assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
- /* If the log file is not already open, but does exist in the file-system,
- ** it may need to be checkpointed before the connection can switch to
- ** rollback mode. Open it now so this can happen.
- */
- if( !pPager->pWal ){
- int logexists = 0;
- rc = pagerLockDb(pPager, SHARED_LOCK);
- if( rc==SQLITE_OK ){
- rc = sqlite3OsAccess(
- pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
- );
- }
- if( rc==SQLITE_OK && logexists ){
- rc = pagerOpenWal(pPager);
- }
- }
- /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
- ** the database file, the log and log-summary files will be deleted.
- */
- if( rc==SQLITE_OK && pPager->pWal ){
- rc = pagerExclusiveLock(pPager);
- if( rc==SQLITE_OK ){
- rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
- pPager->pageSize, (u8*)pPager->pTmpSpace);
- pPager->pWal = 0;
- }
- }
- return rc;
- }
- #if SQLITE_HAS_CODEC
- /*
- ** This function is called by the wal module when writing page content
- ** into the log file.
- **
- ** This function returns a pointer to a buffer containing the encrypted
- ** page content. If a malloc fails, this function may return NULL.
- */
- void sqlite3PagerCodec(PgHdr *pPg){
- voidaData = 0;
- CODEC2(pPg->pPager, pPg->pData, pPg->pgno, 6, return 0, aData);
- return aData;
- }
- #endif //* SQLITE_HAS_CODEC */
- #endif //* !SQLITE_OMIT_WAL */
- #endif // * SQLITE_OMIT_DISKIO */
- }
- }