/src/breakpad/src/third_party/protobuf/protobuf/src/google/protobuf/dynamic_message.cc
C++ | 558 lines | 352 code | 83 blank | 123 comment | 54 complexity | e6805a5a00b1c7fcceeb9979322782be MD5 | raw file
- // Protocol Buffers - Google's data interchange format
- // Copyright 2008 Google Inc. All rights reserved.
- // http://code.google.com/p/protobuf/
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- // Author: kenton@google.com (Kenton Varda)
- // Based on original Protocol Buffers design by
- // Sanjay Ghemawat, Jeff Dean, and others.
- //
- // DynamicMessage is implemented by constructing a data structure which
- // has roughly the same memory layout as a generated message would have.
- // Then, we use GeneratedMessageReflection to implement our reflection
- // interface. All the other operations we need to implement (e.g.
- // parsing, copying, etc.) are already implemented in terms of
- // Reflection, so the rest is easy.
- //
- // The up side of this strategy is that it's very efficient. We don't
- // need to use hash_maps or generic representations of fields. The
- // down side is that this is a low-level memory management hack which
- // can be tricky to get right.
- //
- // As mentioned in the header, we only expose a DynamicMessageFactory
- // publicly, not the DynamicMessage class itself. This is because
- // GenericMessageReflection wants to have a pointer to a "default"
- // copy of the class, with all fields initialized to their default
- // values. We only want to construct one of these per message type,
- // so DynamicMessageFactory stores a cache of default messages for
- // each type it sees (each unique Descriptor pointer). The code
- // refers to the "default" copy of the class as the "prototype".
- //
- // Note on memory allocation: This module often calls "operator new()"
- // to allocate untyped memory, rather than calling something like
- // "new uint8[]". This is because "operator new()" means "Give me some
- // space which I can use as I please." while "new uint8[]" means "Give
- // me an array of 8-bit integers.". In practice, the later may return
- // a pointer that is not aligned correctly for general use. I believe
- // Item 8 of "More Effective C++" discusses this in more detail, though
- // I don't have the book on me right now so I'm not sure.
- #include <algorithm>
- #include <google/protobuf/stubs/hash.h>
- #include <google/protobuf/stubs/common.h>
- #include <google/protobuf/dynamic_message.h>
- #include <google/protobuf/descriptor.h>
- #include <google/protobuf/descriptor.pb.h>
- #include <google/protobuf/generated_message_util.h>
- #include <google/protobuf/generated_message_reflection.h>
- #include <google/protobuf/reflection_ops.h>
- #include <google/protobuf/repeated_field.h>
- #include <google/protobuf/extension_set.h>
- #include <google/protobuf/wire_format.h>
- namespace google {
- namespace protobuf {
- using internal::WireFormat;
- using internal::ExtensionSet;
- using internal::GeneratedMessageReflection;
- // ===================================================================
- // Some helper tables and functions...
- namespace {
- // Compute the byte size of the in-memory representation of the field.
- int FieldSpaceUsed(const FieldDescriptor* field) {
- typedef FieldDescriptor FD; // avoid line wrapping
- if (field->label() == FD::LABEL_REPEATED) {
- switch (field->cpp_type()) {
- case FD::CPPTYPE_INT32 : return sizeof(RepeatedField<int32 >);
- case FD::CPPTYPE_INT64 : return sizeof(RepeatedField<int64 >);
- case FD::CPPTYPE_UINT32 : return sizeof(RepeatedField<uint32 >);
- case FD::CPPTYPE_UINT64 : return sizeof(RepeatedField<uint64 >);
- case FD::CPPTYPE_DOUBLE : return sizeof(RepeatedField<double >);
- case FD::CPPTYPE_FLOAT : return sizeof(RepeatedField<float >);
- case FD::CPPTYPE_BOOL : return sizeof(RepeatedField<bool >);
- case FD::CPPTYPE_ENUM : return sizeof(RepeatedField<int >);
- case FD::CPPTYPE_MESSAGE: return sizeof(RepeatedPtrField<Message>);
- case FD::CPPTYPE_STRING:
- switch (field->options().ctype()) {
- default: // TODO(kenton): Support other string reps.
- case FieldOptions::STRING:
- return sizeof(RepeatedPtrField<string>);
- }
- break;
- }
- } else {
- switch (field->cpp_type()) {
- case FD::CPPTYPE_INT32 : return sizeof(int32 );
- case FD::CPPTYPE_INT64 : return sizeof(int64 );
- case FD::CPPTYPE_UINT32 : return sizeof(uint32 );
- case FD::CPPTYPE_UINT64 : return sizeof(uint64 );
- case FD::CPPTYPE_DOUBLE : return sizeof(double );
- case FD::CPPTYPE_FLOAT : return sizeof(float );
- case FD::CPPTYPE_BOOL : return sizeof(bool );
- case FD::CPPTYPE_ENUM : return sizeof(int );
- case FD::CPPTYPE_MESSAGE: return sizeof(Message*);
- case FD::CPPTYPE_STRING:
- switch (field->options().ctype()) {
- default: // TODO(kenton): Support other string reps.
- case FieldOptions::STRING:
- return sizeof(string*);
- }
- break;
- }
- }
- GOOGLE_LOG(DFATAL) << "Can't get here.";
- return 0;
- }
- inline int DivideRoundingUp(int i, int j) {
- return (i + (j - 1)) / j;
- }
- static const int kSafeAlignment = sizeof(uint64);
- inline int AlignTo(int offset, int alignment) {
- return DivideRoundingUp(offset, alignment) * alignment;
- }
- // Rounds the given byte offset up to the next offset aligned such that any
- // type may be stored at it.
- inline int AlignOffset(int offset) {
- return AlignTo(offset, kSafeAlignment);
- }
- #define bitsizeof(T) (sizeof(T) * 8)
- } // namespace
- // ===================================================================
- class DynamicMessage : public Message {
- public:
- struct TypeInfo {
- int size;
- int has_bits_offset;
- int unknown_fields_offset;
- int extensions_offset;
- // Not owned by the TypeInfo.
- DynamicMessageFactory* factory; // The factory that created this object.
- const DescriptorPool* pool; // The factory's DescriptorPool.
- const Descriptor* type; // Type of this DynamicMessage.
- // Warning: The order in which the following pointers are defined is
- // important (the prototype must be deleted *before* the offsets).
- scoped_array<int> offsets;
- scoped_ptr<const GeneratedMessageReflection> reflection;
- scoped_ptr<const DynamicMessage> prototype;
- };
- DynamicMessage(const TypeInfo* type_info);
- ~DynamicMessage();
- // Called on the prototype after construction to initialize message fields.
- void CrossLinkPrototypes();
- // implements Message ----------------------------------------------
- Message* New() const;
- int GetCachedSize() const;
- void SetCachedSize(int size) const;
- Metadata GetMetadata() const;
- private:
- GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DynamicMessage);
- inline bool is_prototype() const {
- return type_info_->prototype == this ||
- // If type_info_->prototype is NULL, then we must be constructing
- // the prototype now, which means we must be the prototype.
- type_info_->prototype == NULL;
- }
- inline void* OffsetToPointer(int offset) {
- return reinterpret_cast<uint8*>(this) + offset;
- }
- inline const void* OffsetToPointer(int offset) const {
- return reinterpret_cast<const uint8*>(this) + offset;
- }
- const TypeInfo* type_info_;
- // TODO(kenton): Make this an atomic<int> when C++ supports it.
- mutable int cached_byte_size_;
- };
- DynamicMessage::DynamicMessage(const TypeInfo* type_info)
- : type_info_(type_info),
- cached_byte_size_(0) {
- // We need to call constructors for various fields manually and set
- // default values where appropriate. We use placement new to call
- // constructors. If you haven't heard of placement new, I suggest Googling
- // it now. We use placement new even for primitive types that don't have
- // constructors for consistency. (In theory, placement new should be used
- // any time you are trying to convert untyped memory to typed memory, though
- // in practice that's not strictly necessary for types that don't have a
- // constructor.)
- const Descriptor* descriptor = type_info_->type;
- new(OffsetToPointer(type_info_->unknown_fields_offset)) UnknownFieldSet;
- if (type_info_->extensions_offset != -1) {
- new(OffsetToPointer(type_info_->extensions_offset)) ExtensionSet;
- }
- for (int i = 0; i < descriptor->field_count(); i++) {
- const FieldDescriptor* field = descriptor->field(i);
- void* field_ptr = OffsetToPointer(type_info_->offsets[i]);
- switch (field->cpp_type()) {
- #define HANDLE_TYPE(CPPTYPE, TYPE) \
- case FieldDescriptor::CPPTYPE_##CPPTYPE: \
- if (!field->is_repeated()) { \
- new(field_ptr) TYPE(field->default_value_##TYPE()); \
- } else { \
- new(field_ptr) RepeatedField<TYPE>(); \
- } \
- break;
- HANDLE_TYPE(INT32 , int32 );
- HANDLE_TYPE(INT64 , int64 );
- HANDLE_TYPE(UINT32, uint32);
- HANDLE_TYPE(UINT64, uint64);
- HANDLE_TYPE(DOUBLE, double);
- HANDLE_TYPE(FLOAT , float );
- HANDLE_TYPE(BOOL , bool );
- #undef HANDLE_TYPE
- case FieldDescriptor::CPPTYPE_ENUM:
- if (!field->is_repeated()) {
- new(field_ptr) int(field->default_value_enum()->number());
- } else {
- new(field_ptr) RepeatedField<int>();
- }
- break;
- case FieldDescriptor::CPPTYPE_STRING:
- switch (field->options().ctype()) {
- default: // TODO(kenton): Support other string reps.
- case FieldOptions::STRING:
- if (!field->is_repeated()) {
- if (is_prototype()) {
- new(field_ptr) const string*(&field->default_value_string());
- } else {
- string* default_value =
- *reinterpret_cast<string* const*>(
- type_info_->prototype->OffsetToPointer(
- type_info_->offsets[i]));
- new(field_ptr) string*(default_value);
- }
- } else {
- new(field_ptr) RepeatedPtrField<string>();
- }
- break;
- }
- break;
- case FieldDescriptor::CPPTYPE_MESSAGE: {
- if (!field->is_repeated()) {
- new(field_ptr) Message*(NULL);
- } else {
- new(field_ptr) RepeatedPtrField<Message>();
- }
- break;
- }
- }
- }
- }
- DynamicMessage::~DynamicMessage() {
- const Descriptor* descriptor = type_info_->type;
- reinterpret_cast<UnknownFieldSet*>(
- OffsetToPointer(type_info_->unknown_fields_offset))->~UnknownFieldSet();
- if (type_info_->extensions_offset != -1) {
- reinterpret_cast<ExtensionSet*>(
- OffsetToPointer(type_info_->extensions_offset))->~ExtensionSet();
- }
- // We need to manually run the destructors for repeated fields and strings,
- // just as we ran their constructors in the the DynamicMessage constructor.
- // Additionally, if any singular embedded messages have been allocated, we
- // need to delete them, UNLESS we are the prototype message of this type,
- // in which case any embedded messages are other prototypes and shouldn't
- // be touched.
- for (int i = 0; i < descriptor->field_count(); i++) {
- const FieldDescriptor* field = descriptor->field(i);
- void* field_ptr = OffsetToPointer(type_info_->offsets[i]);
- if (field->is_repeated()) {
- switch (field->cpp_type()) {
- #define HANDLE_TYPE(UPPERCASE, LOWERCASE) \
- case FieldDescriptor::CPPTYPE_##UPPERCASE : \
- reinterpret_cast<RepeatedField<LOWERCASE>*>(field_ptr) \
- ->~RepeatedField<LOWERCASE>(); \
- break
- HANDLE_TYPE( INT32, int32);
- HANDLE_TYPE( INT64, int64);
- HANDLE_TYPE(UINT32, uint32);
- HANDLE_TYPE(UINT64, uint64);
- HANDLE_TYPE(DOUBLE, double);
- HANDLE_TYPE( FLOAT, float);
- HANDLE_TYPE( BOOL, bool);
- HANDLE_TYPE( ENUM, int);
- #undef HANDLE_TYPE
- case FieldDescriptor::CPPTYPE_STRING:
- switch (field->options().ctype()) {
- default: // TODO(kenton): Support other string reps.
- case FieldOptions::STRING:
- reinterpret_cast<RepeatedPtrField<string>*>(field_ptr)
- ->~RepeatedPtrField<string>();
- break;
- }
- break;
- case FieldDescriptor::CPPTYPE_MESSAGE:
- reinterpret_cast<RepeatedPtrField<Message>*>(field_ptr)
- ->~RepeatedPtrField<Message>();
- break;
- }
- } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_STRING) {
- switch (field->options().ctype()) {
- default: // TODO(kenton): Support other string reps.
- case FieldOptions::STRING: {
- string* ptr = *reinterpret_cast<string**>(field_ptr);
- if (ptr != &field->default_value_string()) {
- delete ptr;
- }
- break;
- }
- }
- } else if ((field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) &&
- !is_prototype()) {
- Message* message = *reinterpret_cast<Message**>(field_ptr);
- if (message != NULL) {
- delete message;
- }
- }
- }
- }
- void DynamicMessage::CrossLinkPrototypes() {
- // This should only be called on the prototype message.
- GOOGLE_CHECK(is_prototype());
- DynamicMessageFactory* factory = type_info_->factory;
- const Descriptor* descriptor = type_info_->type;
- // Cross-link default messages.
- for (int i = 0; i < descriptor->field_count(); i++) {
- const FieldDescriptor* field = descriptor->field(i);
- void* field_ptr = OffsetToPointer(type_info_->offsets[i]);
- if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE &&
- !field->is_repeated()) {
- // For fields with message types, we need to cross-link with the
- // prototype for the field's type.
- // For singular fields, the field is just a pointer which should
- // point to the prototype.
- *reinterpret_cast<const Message**>(field_ptr) =
- factory->GetPrototypeNoLock(field->message_type());
- }
- }
- }
- Message* DynamicMessage::New() const {
- void* new_base = reinterpret_cast<uint8*>(operator new(type_info_->size));
- memset(new_base, 0, type_info_->size);
- return new(new_base) DynamicMessage(type_info_);
- }
- int DynamicMessage::GetCachedSize() const {
- return cached_byte_size_;
- }
- void DynamicMessage::SetCachedSize(int size) const {
- // This is theoretically not thread-compatible, but in practice it works
- // because if multiple threads write this simultaneously, they will be
- // writing the exact same value.
- cached_byte_size_ = size;
- }
- Metadata DynamicMessage::GetMetadata() const {
- Metadata metadata;
- metadata.descriptor = type_info_->type;
- metadata.reflection = type_info_->reflection.get();
- return metadata;
- }
- // ===================================================================
- struct DynamicMessageFactory::PrototypeMap {
- typedef hash_map<const Descriptor*, const DynamicMessage::TypeInfo*> Map;
- Map map_;
- };
- DynamicMessageFactory::DynamicMessageFactory()
- : pool_(NULL), delegate_to_generated_factory_(false),
- prototypes_(new PrototypeMap) {
- }
- DynamicMessageFactory::DynamicMessageFactory(const DescriptorPool* pool)
- : pool_(pool), delegate_to_generated_factory_(false),
- prototypes_(new PrototypeMap) {
- }
- DynamicMessageFactory::~DynamicMessageFactory() {
- for (PrototypeMap::Map::iterator iter = prototypes_->map_.begin();
- iter != prototypes_->map_.end(); ++iter) {
- delete iter->second;
- }
- }
- const Message* DynamicMessageFactory::GetPrototype(const Descriptor* type) {
- MutexLock lock(&prototypes_mutex_);
- return GetPrototypeNoLock(type);
- }
- const Message* DynamicMessageFactory::GetPrototypeNoLock(
- const Descriptor* type) {
- if (delegate_to_generated_factory_ &&
- type->file()->pool() == DescriptorPool::generated_pool()) {
- return MessageFactory::generated_factory()->GetPrototype(type);
- }
- const DynamicMessage::TypeInfo** target = &prototypes_->map_[type];
- if (*target != NULL) {
- // Already exists.
- return (*target)->prototype.get();
- }
- DynamicMessage::TypeInfo* type_info = new DynamicMessage::TypeInfo;
- *target = type_info;
- type_info->type = type;
- type_info->pool = (pool_ == NULL) ? type->file()->pool() : pool_;
- type_info->factory = this;
- // We need to construct all the structures passed to
- // GeneratedMessageReflection's constructor. This includes:
- // - A block of memory that contains space for all the message's fields.
- // - An array of integers indicating the byte offset of each field within
- // this block.
- // - A big bitfield containing a bit for each field indicating whether
- // or not that field is set.
- // Compute size and offsets.
- int* offsets = new int[type->field_count()];
- type_info->offsets.reset(offsets);
- // Decide all field offsets by packing in order.
- // We place the DynamicMessage object itself at the beginning of the allocated
- // space.
- int size = sizeof(DynamicMessage);
- size = AlignOffset(size);
- // Next the has_bits, which is an array of uint32s.
- type_info->has_bits_offset = size;
- int has_bits_array_size =
- DivideRoundingUp(type->field_count(), bitsizeof(uint32));
- size += has_bits_array_size * sizeof(uint32);
- size = AlignOffset(size);
- // The ExtensionSet, if any.
- if (type->extension_range_count() > 0) {
- type_info->extensions_offset = size;
- size += sizeof(ExtensionSet);
- size = AlignOffset(size);
- } else {
- // No extensions.
- type_info->extensions_offset = -1;
- }
- // All the fields.
- for (int i = 0; i < type->field_count(); i++) {
- // Make sure field is aligned to avoid bus errors.
- int field_size = FieldSpaceUsed(type->field(i));
- size = AlignTo(size, min(kSafeAlignment, field_size));
- offsets[i] = size;
- size += field_size;
- }
- // Add the UnknownFieldSet to the end.
- size = AlignOffset(size);
- type_info->unknown_fields_offset = size;
- size += sizeof(UnknownFieldSet);
- // Align the final size to make sure no clever allocators think that
- // alignment is not necessary.
- size = AlignOffset(size);
- type_info->size = size;
- // Allocate the prototype.
- void* base = operator new(size);
- memset(base, 0, size);
- DynamicMessage* prototype = new(base) DynamicMessage(type_info);
- type_info->prototype.reset(prototype);
- // Construct the reflection object.
- type_info->reflection.reset(
- new GeneratedMessageReflection(
- type_info->type,
- type_info->prototype.get(),
- type_info->offsets.get(),
- type_info->has_bits_offset,
- type_info->unknown_fields_offset,
- type_info->extensions_offset,
- type_info->pool,
- this,
- type_info->size));
- // Cross link prototypes.
- prototype->CrossLinkPrototypes();
- return prototype;
- }
- } // namespace protobuf
- } // namespace google