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dfhack/depends/protobuf/google/protobuf/dynamic_message.cc

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// 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
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