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/Include/pyarena.h

http://unladen-swallow.googlecode.com/
C++ Header | 62 lines | 14 code | 8 blank | 40 comment | 0 complexity | e3ed8eb8c70bf0f3dfebdc9c22e7a85d MD5 | raw file
 1/* An arena-like memory interface for the compiler.
 2 */
 3
 4#ifndef Py_PYARENA_H
 5#define Py_PYARENA_H
 6
 7#ifdef __cplusplus
 8extern "C" {
 9#endif
10
11  typedef struct _arena PyArena;
12
13  /* PyArena_New() and PyArena_Free() create a new arena and free it,
14     respectively.  Once an arena has been created, it can be used
15     to allocate memory via PyArena_Malloc().  Pointers to PyObject can
16     also be registered with the arena via PyArena_AddPyObject(), and the
17     arena will ensure that the PyObjects stay alive at least until
18     PyArena_Free() is called.  When an arena is freed, all the memory it
19     allocated is freed, the arena releases internal references to registered
20     PyObject*, and none of its pointers are valid.
21     XXX (tim) What does "none of its pointers are valid" mean?  Does it
22     XXX mean that pointers previously obtained via PyArena_Malloc() are
23     XXX no longer valid?  (That's clearly true, but not sure that's what
24     XXX the text is trying to say.)
25
26     PyArena_New() returns an arena pointer.  On error, it
27     returns a negative number and sets an exception.
28     XXX (tim):  Not true.  On error, PyArena_New() actually returns NULL,
29     XXX and looks like it may or may not set an exception (e.g., if the
30     XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on
31     XXX and an exception is set; OTOH, if the internal
32     XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
33     XXX an exception is not set in that case).
34  */
35  PyAPI_FUNC(PyArena *) PyArena_New(void);
36  PyAPI_FUNC(void) PyArena_Free(PyArena *);
37
38  /* Mostly like malloc(), return the address of a block of memory spanning
39   * `size` bytes, or return NULL (without setting an exception) if enough
40   * new memory can't be obtained.  Unlike malloc(0), PyArena_Malloc() with
41   * size=0 does not guarantee to return a unique pointer (the pointer
42   * returned may equal one or more other pointers obtained from
43   * PyArena_Malloc()).
44   * Note that pointers obtained via PyArena_Malloc() must never be passed to
45   * the system free() or realloc(), or to any of Python's similar memory-
46   * management functions.  PyArena_Malloc()-obtained pointers remain valid
47   * until PyArena_Free(ar) is called, at which point all pointers obtained
48   * from the arena `ar` become invalid simultaneously.
49   */
50  PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);
51
52  /* This routine isn't a proper arena allocation routine.  It takes
53   * a PyObject* and records it so that it can be DECREFed when the
54   * arena is freed.
55   */
56  PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);
57
58#ifdef __cplusplus
59}
60#endif
61
62#endif /* !Py_PYARENA_H */