diff options
Diffstat (limited to 'third_party/protobuf/3.4.0/src/google/protobuf/arena_impl.h')
-rw-r--r-- | third_party/protobuf/3.4.0/src/google/protobuf/arena_impl.h | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/third_party/protobuf/3.4.0/src/google/protobuf/arena_impl.h b/third_party/protobuf/3.4.0/src/google/protobuf/arena_impl.h new file mode 100644 index 0000000000..b7f0c7b6ad --- /dev/null +++ b/third_party/protobuf/3.4.0/src/google/protobuf/arena_impl.h @@ -0,0 +1,214 @@ +// 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. + +// This file defines an Arena allocator for better allocation performance. + +#ifndef GOOGLE_PROTOBUF_ARENA_IMPL_H__ +#define GOOGLE_PROTOBUF_ARENA_IMPL_H__ + +#include <limits> + +#include <google/protobuf/stubs/atomic_sequence_num.h> +#include <google/protobuf/stubs/atomicops.h> +#include <google/protobuf/stubs/common.h> +#include <google/protobuf/stubs/logging.h> +#include <google/protobuf/stubs/mutex.h> +#include <google/protobuf/stubs/type_traits.h> + +namespace google { + +namespace protobuf { +namespace internal { + +inline size_t AlignUpTo8(size_t n) { + // Align n to next multiple of 8 (from Hacker's Delight, Chapter 3.) + return (n + 7) & -8; +} + +// This class provides the core Arena memory allocation library. Different +// implementations only need to implement the public interface below. +// Arena is not a template type as that would only be useful if all protos +// in turn would be templates, which will/cannot happen. However separating +// the memory allocation part from the cruft of the API users expect we can +// use #ifdef the select the best implementation based on hardware / OS. +class LIBPROTOBUF_EXPORT ArenaImpl { + public: + struct Options { + size_t start_block_size; + size_t max_block_size; + char* initial_block; + size_t initial_block_size; + void* (*block_alloc)(size_t); + void (*block_dealloc)(void*, size_t); + + template <typename O> + explicit Options(const O& options) + : start_block_size(options.start_block_size), + max_block_size(options.max_block_size), + initial_block(options.initial_block), + initial_block_size(options.initial_block_size), + block_alloc(options.block_alloc), + block_dealloc(options.block_dealloc) {} + }; + + template <typename O> + explicit ArenaImpl(const O& options) : options_(options) { + Init(); + } + + // Destructor deletes all owned heap allocated objects, and destructs objects + // that have non-trivial destructors, except for proto2 message objects whose + // destructors can be skipped. Also, frees all blocks except the initial block + // if it was passed in. + ~ArenaImpl(); + + uint64 Reset(); + + uint64 SpaceAllocated() const; + uint64 SpaceUsed() const; + + void* AllocateAligned(size_t n); + + void* AllocateAlignedAndAddCleanup(size_t n, void (*cleanup)(void*)); + + // Add object pointer and cleanup function pointer to the list. + void AddCleanup(void* elem, void (*cleanup)(void*)); + + private: + // Node contains the ptr of the object to be cleaned up and the associated + // cleanup function ptr. + struct CleanupNode { + void* elem; // Pointer to the object to be cleaned up. + void (*cleanup)(void*); // Function pointer to the destructor or deleter. + }; + + // Cleanup uses a chunked linked list, to reduce pointer chasing. + struct CleanupChunk { + static size_t SizeOf(size_t i) { + return sizeof(CleanupChunk) + (sizeof(CleanupNode) * (i - 1)); + } + size_t len; // Number of elements currently present. + size_t size; // Total elements in the list. + CleanupChunk* next; // Next node in the list. + CleanupNode nodes[1]; // True length is |size|. + }; + + // Blocks are variable length malloc-ed objects. The following structure + // describes the common header for all blocks. + struct Block { + void* owner; // &ThreadCache of thread that owns this block. + Block* next; // Next block in arena (may have different owner) + CleanupChunk* cleanup; // Head of cleanup list (may point to another block, + // but it must have the same owner). + // ((char*) &block) + pos is next available byte. It is always + // aligned at a multiple of 8 bytes. + size_t pos; + size_t size; // total size of the block. + GOOGLE_ATTRIBUTE_ALWAYS_INLINE size_t avail() const { return size - pos; } + // data follows + }; + + struct ThreadCache { + // The ThreadCache is considered valid as long as this matches the + // lifecycle_id of the arena being used. + int64 last_lifecycle_id_seen; + Block* last_block_used_; + }; + + // kHeaderSize is sizeof(Block), aligned up to the nearest multiple of 8 to + // protect the invariant that pos is always at a multiple of 8. + static const size_t kHeaderSize = (sizeof(Block) + 7) & -8; +#if LANG_CXX11 + static_assert(kHeaderSize % 8 == 0, "kHeaderSize must be a multiple of 8."); +#endif + static google::protobuf::internal::SequenceNumber lifecycle_id_generator_; +#if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL) + // Android ndk does not support GOOGLE_THREAD_LOCAL keyword so we use a custom thread + // local storage class we implemented. + // iOS also does not support the GOOGLE_THREAD_LOCAL keyword. + static ThreadCache& thread_cache(); +#elif defined(PROTOBUF_USE_DLLS) + // Thread local variables cannot be exposed through DLL interface but we can + // wrap them in static functions. + static ThreadCache& thread_cache(); +#else + static GOOGLE_THREAD_LOCAL ThreadCache thread_cache_; + static ThreadCache& thread_cache() { return thread_cache_; } +#endif + + void Init(); + + // Free all blocks and return the total space used which is the sums of sizes + // of the all the allocated blocks. + uint64 FreeBlocks(Block* head); + + void AddCleanupInBlock(Block* b, void* elem, void (*cleanup)(void*)); + Block* ExpandCleanupList(Block* b); + // Delete or Destruct all objects owned by the arena. + void CleanupList(Block* head); + uint64 ResetInternal(); + + inline void CacheBlock(Block* block) { + thread_cache().last_block_used_ = block; + thread_cache().last_lifecycle_id_seen = lifecycle_id_; + google::protobuf::internal::Release_Store(&hint_, reinterpret_cast<google::protobuf::internal::AtomicWord>(block)); + } + + google::protobuf::internal::AtomicWord blocks_; // Head of linked list of all allocated blocks + google::protobuf::internal::AtomicWord hint_; // Fast thread-local block access + uint64 space_allocated_; // Sum of sizes of all allocated blocks. + + bool owns_first_block_; // Indicates that arena owns the first block + mutable Mutex blocks_lock_; + + void AddBlock(Block* b); + // Access must be synchronized, either by blocks_lock_ or by being called from + // Init()/Reset(). + void AddBlockInternal(Block* b); + // Returns a block owned by this thread. + Block* GetBlock(size_t n); + Block* GetBlockSlow(void* me, Block* my_full_block, size_t n); + Block* FindBlock(void* me); + Block* NewBlock(void* me, Block* my_last_block, size_t min_bytes, + size_t start_block_size, size_t max_block_size); + static void* AllocFromBlock(Block* b, size_t n); + + int64 lifecycle_id_; // Unique for each arena. Changes on Reset(). + + Options options_; + + GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ArenaImpl); +}; + +} // namespace internal +} // namespace protobuf + +} // namespace google +#endif // GOOGLE_PROTOBUF_ARENA_IMPL_H__ |