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Diffstat (limited to 'toolkit/components/protobuf/src/google/protobuf/dynamic_message.cc')
| -rw-r--r-- | toolkit/components/protobuf/src/google/protobuf/dynamic_message.cc | 826 |
1 files changed, 826 insertions, 0 deletions
diff --git a/toolkit/components/protobuf/src/google/protobuf/dynamic_message.cc b/toolkit/components/protobuf/src/google/protobuf/dynamic_message.cc new file mode 100644 index 0000000000..1c96ca2080 --- /dev/null +++ b/toolkit/components/protobuf/src/google/protobuf/dynamic_message.cc @@ -0,0 +1,826 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// 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 Reflection 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_t[]". This is because "operator new()" means "Give me some +// space which I can use as I please." while "new uint8_t[]" 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 <google/protobuf/dynamic_message.h> + +#include <algorithm> +#include <cstddef> +#include <memory> +#include <new> +#include <unordered_map> + +#include <google/protobuf/descriptor.h> +#include <google/protobuf/descriptor.pb.h> +#include <google/protobuf/generated_message_reflection.h> +#include <google/protobuf/generated_message_util.h> +#include <google/protobuf/unknown_field_set.h> +#include <google/protobuf/stubs/hash.h> +#include <google/protobuf/arenastring.h> +#include <google/protobuf/extension_set.h> +#include <google/protobuf/map_field.h> +#include <google/protobuf/map_field_inl.h> +#include <google/protobuf/map_type_handler.h> +#include <google/protobuf/reflection_ops.h> +#include <google/protobuf/repeated_field.h> +#include <google/protobuf/wire_format.h> + +// Must be included last. +#include <google/protobuf/port_def.inc> + +namespace google { +namespace protobuf { + +using internal::DynamicMapField; +using internal::ExtensionSet; +using internal::MapField; + + +using internal::ArenaStringPtr; + +// =================================================================== +// Some helper tables and functions... + +namespace { + +bool IsMapFieldInApi(const FieldDescriptor* field) { return field->is_map(); } + +// Sync with helpers.h. +inline bool HasHasbit(const FieldDescriptor* field) { + // This predicate includes proto3 message fields only if they have "optional". + // Foo submsg1 = 1; // HasHasbit() == false + // optional Foo submsg2 = 2; // HasHasbit() == true + // This is slightly odd, as adding "optional" to a singular proto3 field does + // not change the semantics or API. However whenever any field in a message + // has a hasbit, it forces reflection to include hasbit offsets for *all* + // fields, even if almost all of them are set to -1 (no hasbit). So to avoid + // causing a sudden size regression for ~all proto3 messages, we give proto3 + // message fields a hasbit only if "optional" is present. If the user is + // explicitly writing "optional", it is likely they are writing it on + // primitive fields also. + return (field->has_optional_keyword() || field->is_required()) && + !field->options().weak(); +} + +inline bool InRealOneof(const FieldDescriptor* field) { + return field->containing_oneof() && + !field->containing_oneof()->is_synthetic(); +} + +// 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_t>); + case FD::CPPTYPE_INT64: + return sizeof(RepeatedField<int64_t>); + case FD::CPPTYPE_UINT32: + return sizeof(RepeatedField<uint32_t>); + case FD::CPPTYPE_UINT64: + return sizeof(RepeatedField<uint64_t>); + 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: + if (IsMapFieldInApi(field)) { + return sizeof(DynamicMapField); + } else { + 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<std::string>); + } + break; + } + } else { + switch (field->cpp_type()) { + case FD::CPPTYPE_INT32: + return sizeof(int32_t); + case FD::CPPTYPE_INT64: + return sizeof(int64_t); + case FD::CPPTYPE_UINT32: + return sizeof(uint32_t); + case FD::CPPTYPE_UINT64: + return sizeof(uint64_t); + 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(ArenaStringPtr); + } + 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_t); +static const int kMaxOneofUnionSize = sizeof(uint64_t); + +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: + explicit DynamicMessage(const DynamicMessageFactory::TypeInfo* type_info); + + // This should only be used by GetPrototypeNoLock() to avoid dead lock. + DynamicMessage(DynamicMessageFactory::TypeInfo* type_info, bool lock_factory); + + ~DynamicMessage() override; + + // Called on the prototype after construction to initialize message fields. + // Cross linking the default instances allows for fast reflection access of + // unset message fields. Without it we would have to go to the MessageFactory + // to get the prototype, which is a much more expensive operation. + // + // Generated messages do not cross-link to avoid dynamic initialization of the + // global instances. + // Instead, they keep the default instances in the FieldDescriptor objects. + void CrossLinkPrototypes(); + + // implements Message ---------------------------------------------- + + Message* New(Arena* arena) const override; + + int GetCachedSize() const override; + void SetCachedSize(int size) const override; + + Metadata GetMetadata() const override; + +#if defined(__cpp_lib_destroying_delete) && defined(__cpp_sized_deallocation) + static void operator delete(DynamicMessage* msg, std::destroying_delete_t); +#else + // We actually allocate more memory than sizeof(*this) when this + // class's memory is allocated via the global operator new. Thus, we need to + // manually call the global operator delete. Calling the destructor is taken + // care of for us. This makes DynamicMessage compatible with -fsized-delete. + // It doesn't work for MSVC though. +#ifndef _MSC_VER + static void operator delete(void* ptr) { ::operator delete(ptr); } +#endif // !_MSC_VER +#endif + + private: + DynamicMessage(const DynamicMessageFactory::TypeInfo* type_info, + Arena* arena); + + void SharedCtor(bool lock_factory); + + // Needed to get the offset of the internal metadata member. + friend class DynamicMessageFactory; + + bool is_prototype() const; + + inline void* OffsetToPointer(int offset) { + return reinterpret_cast<uint8_t*>(this) + offset; + } + inline const void* OffsetToPointer(int offset) const { + return reinterpret_cast<const uint8_t*>(this) + offset; + } + + void* MutableRaw(int i); + void* MutableExtensionsRaw(); + void* MutableWeakFieldMapRaw(); + void* MutableOneofCaseRaw(int i); + void* MutableOneofFieldRaw(const FieldDescriptor* f); + + const DynamicMessageFactory::TypeInfo* type_info_; + mutable std::atomic<int> cached_byte_size_; + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DynamicMessage); +}; + +struct DynamicMessageFactory::TypeInfo { + int size; + int has_bits_offset; + int oneof_case_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). + std::unique_ptr<uint32_t[]> offsets; + std::unique_ptr<uint32_t[]> has_bits_indices; + std::unique_ptr<const Reflection> reflection; + // Don't use a unique_ptr to hold the prototype: the destructor for + // DynamicMessage needs to know whether it is the prototype, and does so by + // looking back at this field. This would assume details about the + // implementation of unique_ptr. + const DynamicMessage* prototype; + int weak_field_map_offset; // The offset for the weak_field_map; + + TypeInfo() : prototype(nullptr) {} + + ~TypeInfo() { delete prototype; } +}; + +DynamicMessage::DynamicMessage(const DynamicMessageFactory::TypeInfo* type_info) + : type_info_(type_info), cached_byte_size_(0) { + SharedCtor(true); +} + +DynamicMessage::DynamicMessage(const DynamicMessageFactory::TypeInfo* type_info, + Arena* arena) + : Message(arena), type_info_(type_info), cached_byte_size_(0) { + SharedCtor(true); +} + +DynamicMessage::DynamicMessage(DynamicMessageFactory::TypeInfo* type_info, + bool lock_factory) + : type_info_(type_info), cached_byte_size_(0) { + // The prototype in type_info has to be set before creating the prototype + // instance on memory. e.g., message Foo { map<int32_t, Foo> a = 1; }. When + // creating prototype for Foo, prototype of the map entry will also be + // created, which needs the address of the prototype of Foo (the value in + // map). To break the cyclic dependency, we have to assign the address of + // prototype into type_info first. + type_info->prototype = this; + SharedCtor(lock_factory); +} + +inline void* DynamicMessage::MutableRaw(int i) { + return OffsetToPointer(type_info_->offsets[i]); +} +inline void* DynamicMessage::MutableExtensionsRaw() { + return OffsetToPointer(type_info_->extensions_offset); +} +inline void* DynamicMessage::MutableWeakFieldMapRaw() { + return OffsetToPointer(type_info_->weak_field_map_offset); +} +inline void* DynamicMessage::MutableOneofCaseRaw(int i) { + return OffsetToPointer(type_info_->oneof_case_offset + sizeof(uint32_t) * i); +} +inline void* DynamicMessage::MutableOneofFieldRaw(const FieldDescriptor* f) { + return OffsetToPointer(type_info_->offsets[type_info_->type->field_count() + + f->containing_oneof()->index()]); +} + +void DynamicMessage::SharedCtor(bool lock_factory) { + // 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; + // Initialize oneof cases. + int oneof_count = 0; + for (int i = 0; i < descriptor->oneof_decl_count(); ++i) { + if (descriptor->oneof_decl(i)->is_synthetic()) continue; + new (MutableOneofCaseRaw(oneof_count++)) uint32_t{0}; + } + + if (type_info_->extensions_offset != -1) { + new (MutableExtensionsRaw()) ExtensionSet(GetArenaForAllocation()); + } + for (int i = 0; i < descriptor->field_count(); i++) { + const FieldDescriptor* field = descriptor->field(i); + void* field_ptr = MutableRaw(i); + if (InRealOneof(field)) { + continue; + } + 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>(GetArenaForAllocation()); \ + } \ + break; + + HANDLE_TYPE(INT32, int32_t); + HANDLE_TYPE(INT64, int64_t); + HANDLE_TYPE(UINT32, uint32_t); + HANDLE_TYPE(UINT64, uint64_t); + 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>(GetArenaForAllocation()); + } + break; + + case FieldDescriptor::CPPTYPE_STRING: + switch (field->options().ctype()) { + default: // TODO(kenton): Support other string reps. + case FieldOptions::STRING: + if (!field->is_repeated()) { + ArenaStringPtr* asp = new (field_ptr) ArenaStringPtr(); + asp->InitDefault(); + } else { + new (field_ptr) + RepeatedPtrField<std::string>(GetArenaForAllocation()); + } + break; + } + break; + + case FieldDescriptor::CPPTYPE_MESSAGE: { + if (!field->is_repeated()) { + new (field_ptr) Message*(nullptr); + } else { + if (IsMapFieldInApi(field)) { + // We need to lock in most cases to avoid data racing. Only not lock + // when the constructor is called inside GetPrototype(), in which + // case we have already locked the factory. + if (lock_factory) { + if (GetArenaForAllocation() != nullptr) { + new (field_ptr) DynamicMapField( + type_info_->factory->GetPrototype(field->message_type()), + GetArenaForAllocation()); + if (GetOwningArena() != nullptr) { + // Needs to destroy the mutex member. + GetOwningArena()->OwnDestructor( + static_cast<DynamicMapField*>(field_ptr)); + } + } else { + new (field_ptr) DynamicMapField( + type_info_->factory->GetPrototype(field->message_type())); + } + } else { + if (GetArenaForAllocation() != nullptr) { + new (field_ptr) + DynamicMapField(type_info_->factory->GetPrototypeNoLock( + field->message_type()), + GetArenaForAllocation()); + if (GetOwningArena() != nullptr) { + // Needs to destroy the mutex member. + GetOwningArena()->OwnDestructor( + static_cast<DynamicMapField*>(field_ptr)); + } + } else { + new (field_ptr) + DynamicMapField(type_info_->factory->GetPrototypeNoLock( + field->message_type())); + } + } + } else { + new (field_ptr) RepeatedPtrField<Message>(GetArenaForAllocation()); + } + } + break; + } + } + } +} + +bool DynamicMessage::is_prototype() const { + return type_info_->prototype == this || + // If type_info_->prototype is nullptr, then we must be constructing + // the prototype now, which means we must be the prototype. + type_info_->prototype == nullptr; +} + +#if defined(__cpp_lib_destroying_delete) && defined(__cpp_sized_deallocation) +void DynamicMessage::operator delete(DynamicMessage* msg, + std::destroying_delete_t) { + const size_t size = msg->type_info_->size; + msg->~DynamicMessage(); + ::operator delete(msg, size); +} +#endif + +DynamicMessage::~DynamicMessage() { + const Descriptor* descriptor = type_info_->type; + + _internal_metadata_.Delete<UnknownFieldSet>(); + + if (type_info_->extensions_offset != -1) { + reinterpret_cast<ExtensionSet*>(MutableExtensionsRaw())->~ExtensionSet(); + } + + // We need to manually run the destructors for repeated fields and strings, + // just as we ran their constructors in the DynamicMessage constructor. + // We also need to manually delete oneof fields if it is set and is string + // or message. + // 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); + if (InRealOneof(field)) { + void* field_ptr = MutableOneofCaseRaw(field->containing_oneof()->index()); + if (*(reinterpret_cast<const int32_t*>(field_ptr)) == field->number()) { + field_ptr = MutableOneofFieldRaw(field); + if (field->cpp_type() == FieldDescriptor::CPPTYPE_STRING) { + switch (field->options().ctype()) { + default: + case FieldOptions::STRING: { + reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy(); + break; + } + } + } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) { + delete *reinterpret_cast<Message**>(field_ptr); + } + } + continue; + } + void* field_ptr = MutableRaw(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_t); + HANDLE_TYPE(INT64, int64_t); + HANDLE_TYPE(UINT32, uint32_t); + HANDLE_TYPE(UINT64, uint64_t); + 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<std::string>*>(field_ptr) + ->~RepeatedPtrField<std::string>(); + break; + } + break; + + case FieldDescriptor::CPPTYPE_MESSAGE: + if (IsMapFieldInApi(field)) { + reinterpret_cast<DynamicMapField*>(field_ptr)->~DynamicMapField(); + } else { + 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: { + reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy(); + break; + } + } + } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) { + if (!is_prototype()) { + Message* message = *reinterpret_cast<Message**>(field_ptr); + if (message != nullptr) { + 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); + if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE && + !field->options().weak() && !InRealOneof(field) && + !field->is_repeated()) { + void* field_ptr = MutableRaw(i); + // 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(Arena* arena) const { + if (arena != nullptr) { + void* new_base = Arena::CreateArray<char>(arena, type_info_->size); + memset(new_base, 0, type_info_->size); + return new (new_base) DynamicMessage(type_info_, arena); + } else { + void* new_base = 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_.load(std::memory_order_relaxed); +} + +void DynamicMessage::SetCachedSize(int size) const { + cached_byte_size_.store(size, std::memory_order_relaxed); +} + +Metadata DynamicMessage::GetMetadata() const { + Metadata metadata; + metadata.descriptor = type_info_->type; + metadata.reflection = type_info_->reflection.get(); + return metadata; +} + +// =================================================================== + +DynamicMessageFactory::DynamicMessageFactory() + : pool_(nullptr), delegate_to_generated_factory_(false) {} + +DynamicMessageFactory::DynamicMessageFactory(const DescriptorPool* pool) + : pool_(pool), delegate_to_generated_factory_(false) {} + +DynamicMessageFactory::~DynamicMessageFactory() { + for (auto iter = prototypes_.begin(); iter != prototypes_.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 TypeInfo** target = &prototypes_[type]; + if (*target != nullptr) { + // Already exists. + return (*target)->prototype; + } + + TypeInfo* type_info = new TypeInfo; + *target = type_info; + + type_info->type = type; + type_info->pool = (pool_ == nullptr) ? type->file()->pool() : pool_; + type_info->factory = this; + + // We need to construct all the structures passed to Reflection'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. + int real_oneof_count = 0; + for (int i = 0; i < type->oneof_decl_count(); i++) { + if (!type->oneof_decl(i)->is_synthetic()) { + real_oneof_count++; + } + } + + // Compute size and offsets. + uint32_t* offsets = new uint32_t[type->field_count() + real_oneof_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 = -1; + int max_hasbit = 0; + for (int i = 0; i < type->field_count(); i++) { + if (HasHasbit(type->field(i))) { + if (type_info->has_bits_offset == -1) { + // At least one field in the message requires a hasbit, so allocate + // hasbits. + type_info->has_bits_offset = size; + uint32_t* has_bits_indices = new uint32_t[type->field_count()]; + for (int j = 0; j < type->field_count(); j++) { + // Initialize to -1, fields that need a hasbit will overwrite. + has_bits_indices[j] = static_cast<uint32_t>(-1); + } + type_info->has_bits_indices.reset(has_bits_indices); + } + type_info->has_bits_indices[i] = max_hasbit++; + } + } + + if (max_hasbit > 0) { + int has_bits_array_size = DivideRoundingUp(max_hasbit, bitsizeof(uint32_t)); + size += has_bits_array_size * sizeof(uint32_t); + size = AlignOffset(size); + } + + // The oneof_case, if any. It is an array of uint32s. + if (real_oneof_count > 0) { + type_info->oneof_case_offset = size; + size += real_oneof_count * sizeof(uint32_t); + 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. + // + // TODO(b/31226269): Optimize the order of fields to minimize padding. + for (int i = 0; i < type->field_count(); i++) { + // Make sure field is aligned to avoid bus errors. + // Oneof fields do not use any space. + if (!InRealOneof(type->field(i))) { + int field_size = FieldSpaceUsed(type->field(i)); + size = AlignTo(size, std::min(kSafeAlignment, field_size)); + offsets[i] = size; + size += field_size; + } + } + + // The oneofs. + for (int i = 0; i < type->oneof_decl_count(); i++) { + if (!type->oneof_decl(i)->is_synthetic()) { + size = AlignTo(size, kSafeAlignment); + offsets[type->field_count() + i] = size; + size += kMaxOneofUnionSize; + } + } + + type_info->weak_field_map_offset = -1; + + // Align the final size to make sure no clever allocators think that + // alignment is not necessary. + type_info->size = size; + + // Construct the reflection object. + + // Compute the size of default oneof instance and offsets of default + // oneof fields. + for (int i = 0; i < type->oneof_decl_count(); i++) { + if (type->oneof_decl(i)->is_synthetic()) continue; + for (int j = 0; j < type->oneof_decl(i)->field_count(); j++) { + const FieldDescriptor* field = type->oneof_decl(i)->field(j); + // oneof fields are not accessed through offsets, but we still have the + // entry from a legacy implementation. This should be removed at some + // point. + // Mark the field to prevent unintentional access through reflection. + // Don't use the top bit because that is for unused fields. + offsets[field->index()] = internal::kInvalidFieldOffsetTag; + } + } + + // Allocate the prototype fields. + void* base = operator new(size); + memset(base, 0, size); + + // We have already locked the factory so we should not lock in the constructor + // of dynamic message to avoid dead lock. + DynamicMessage* prototype = new (base) DynamicMessage(type_info, false); + + internal::ReflectionSchema schema = { + type_info->prototype, + type_info->offsets.get(), + type_info->has_bits_indices.get(), + type_info->has_bits_offset, + PROTOBUF_FIELD_OFFSET(DynamicMessage, _internal_metadata_), + type_info->extensions_offset, + type_info->oneof_case_offset, + type_info->size, + type_info->weak_field_map_offset, + nullptr /* inlined_string_indices_ */, + 0 /* inlined_string_donated_offset_ */}; + + type_info->reflection.reset( + new Reflection(type_info->type, schema, type_info->pool, this)); + + // Cross link prototypes. + prototype->CrossLinkPrototypes(); + + return prototype; +} + +} // namespace protobuf +} // namespace google + +#include <google/protobuf/port_undef.inc> // NOLINT |