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Diffstat (limited to 'include/rapidjson/allocators.h')
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diff --git a/include/rapidjson/allocators.h b/include/rapidjson/allocators.h new file mode 100644 index 0000000..12bc5ba --- /dev/null +++ b/include/rapidjson/allocators.h @@ -0,0 +1,692 @@ +// Tencent is pleased to support the open source community by making RapidJSON available. +// +// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. +// +// Licensed under the MIT License (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// http://opensource.org/licenses/MIT +// +// Unless required by applicable law or agreed to in writing, software distributed +// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR +// CONDITIONS OF ANY KIND, either express or implied. See the License for the +// specific language governing permissions and limitations under the License. + +#ifndef RAPIDJSON_ALLOCATORS_H_ +#define RAPIDJSON_ALLOCATORS_H_ + +#include "rapidjson.h" +#include "internal/meta.h" + +#include <memory> + +#if RAPIDJSON_HAS_CXX11 +#include <type_traits> +#endif + +RAPIDJSON_NAMESPACE_BEGIN + +/////////////////////////////////////////////////////////////////////////////// +// Allocator + +/*! \class rapidjson::Allocator + \brief Concept for allocating, resizing and freeing memory block. + + Note that Malloc() and Realloc() are non-static but Free() is static. + + So if an allocator need to support Free(), it needs to put its pointer in + the header of memory block. + +\code +concept Allocator { + static const bool kNeedFree; //!< Whether this allocator needs to call Free(). + + // Allocate a memory block. + // \param size of the memory block in bytes. + // \returns pointer to the memory block. + void* Malloc(size_t size); + + // Resize a memory block. + // \param originalPtr The pointer to current memory block. Null pointer is permitted. + // \param originalSize The current size in bytes. (Design issue: since some allocator may not book-keep this, explicitly pass to it can save memory.) + // \param newSize the new size in bytes. + void* Realloc(void* originalPtr, size_t originalSize, size_t newSize); + + // Free a memory block. + // \param pointer to the memory block. Null pointer is permitted. + static void Free(void *ptr); +}; +\endcode +*/ + + +/*! \def RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY + \ingroup RAPIDJSON_CONFIG + \brief User-defined kDefaultChunkCapacity definition. + + User can define this as any \c size that is a power of 2. +*/ + +#ifndef RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY +#define RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY (64 * 1024) +#endif + + +/////////////////////////////////////////////////////////////////////////////// +// CrtAllocator + +//! C-runtime library allocator. +/*! This class is just wrapper for standard C library memory routines. + \note implements Allocator concept +*/ +class CrtAllocator { +public: + static const bool kNeedFree = true; + void* Malloc(size_t size) { + if (size) // behavior of malloc(0) is implementation defined. + return RAPIDJSON_MALLOC(size); + else + return NULL; // standardize to returning NULL. + } + void* Realloc(void* originalPtr, size_t originalSize, size_t newSize) { + (void)originalSize; + if (newSize == 0) { + RAPIDJSON_FREE(originalPtr); + return NULL; + } + return RAPIDJSON_REALLOC(originalPtr, newSize); + } + static void Free(void *ptr) RAPIDJSON_NOEXCEPT { RAPIDJSON_FREE(ptr); } + + bool operator==(const CrtAllocator&) const RAPIDJSON_NOEXCEPT { + return true; + } + bool operator!=(const CrtAllocator&) const RAPIDJSON_NOEXCEPT { + return false; + } +}; + +/////////////////////////////////////////////////////////////////////////////// +// MemoryPoolAllocator + +//! Default memory allocator used by the parser and DOM. +/*! This allocator allocate memory blocks from pre-allocated memory chunks. + + It does not free memory blocks. And Realloc() only allocate new memory. + + The memory chunks are allocated by BaseAllocator, which is CrtAllocator by default. + + User may also supply a buffer as the first chunk. + + If the user-buffer is full then additional chunks are allocated by BaseAllocator. + + The user-buffer is not deallocated by this allocator. + + \tparam BaseAllocator the allocator type for allocating memory chunks. Default is CrtAllocator. + \note implements Allocator concept +*/ +template <typename BaseAllocator = CrtAllocator> +class MemoryPoolAllocator { + //! Chunk header for perpending to each chunk. + /*! Chunks are stored as a singly linked list. + */ + struct ChunkHeader { + size_t capacity; //!< Capacity of the chunk in bytes (excluding the header itself). + size_t size; //!< Current size of allocated memory in bytes. + ChunkHeader *next; //!< Next chunk in the linked list. + }; + + struct SharedData { + ChunkHeader *chunkHead; //!< Head of the chunk linked-list. Only the head chunk serves allocation. + BaseAllocator* ownBaseAllocator; //!< base allocator created by this object. + size_t refcount; + bool ownBuffer; + }; + + static const size_t SIZEOF_SHARED_DATA = RAPIDJSON_ALIGN(sizeof(SharedData)); + static const size_t SIZEOF_CHUNK_HEADER = RAPIDJSON_ALIGN(sizeof(ChunkHeader)); + + static inline ChunkHeader *GetChunkHead(SharedData *shared) + { + return reinterpret_cast<ChunkHeader*>(reinterpret_cast<uint8_t*>(shared) + SIZEOF_SHARED_DATA); + } + static inline uint8_t *GetChunkBuffer(SharedData *shared) + { + return reinterpret_cast<uint8_t*>(shared->chunkHead) + SIZEOF_CHUNK_HEADER; + } + + static const size_t kDefaultChunkCapacity = RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY; //!< Default chunk capacity. + +public: + static const bool kNeedFree = false; //!< Tell users that no need to call Free() with this allocator. (concept Allocator) + static const bool kRefCounted = true; //!< Tell users that this allocator is reference counted on copy + + //! Constructor with chunkSize. + /*! \param chunkSize The size of memory chunk. The default is kDefaultChunkSize. + \param baseAllocator The allocator for allocating memory chunks. + */ + explicit + MemoryPoolAllocator(size_t chunkSize = kDefaultChunkCapacity, BaseAllocator* baseAllocator = 0) : + chunk_capacity_(chunkSize), + baseAllocator_(baseAllocator ? baseAllocator : RAPIDJSON_NEW(BaseAllocator)()), + shared_(static_cast<SharedData*>(baseAllocator_ ? baseAllocator_->Malloc(SIZEOF_SHARED_DATA + SIZEOF_CHUNK_HEADER) : 0)) + { + RAPIDJSON_ASSERT(baseAllocator_ != 0); + RAPIDJSON_ASSERT(shared_ != 0); + if (baseAllocator) { + shared_->ownBaseAllocator = 0; + } + else { + shared_->ownBaseAllocator = baseAllocator_; + } + shared_->chunkHead = GetChunkHead(shared_); + shared_->chunkHead->capacity = 0; + shared_->chunkHead->size = 0; + shared_->chunkHead->next = 0; + shared_->ownBuffer = true; + shared_->refcount = 1; + } + + //! Constructor with user-supplied buffer. + /*! The user buffer will be used firstly. When it is full, memory pool allocates new chunk with chunk size. + + The user buffer will not be deallocated when this allocator is destructed. + + \param buffer User supplied buffer. + \param size Size of the buffer in bytes. It must at least larger than sizeof(ChunkHeader). + \param chunkSize The size of memory chunk. The default is kDefaultChunkSize. + \param baseAllocator The allocator for allocating memory chunks. + */ + MemoryPoolAllocator(void *buffer, size_t size, size_t chunkSize = kDefaultChunkCapacity, BaseAllocator* baseAllocator = 0) : + chunk_capacity_(chunkSize), + baseAllocator_(baseAllocator), + shared_(static_cast<SharedData*>(AlignBuffer(buffer, size))) + { + RAPIDJSON_ASSERT(size >= SIZEOF_SHARED_DATA + SIZEOF_CHUNK_HEADER); + shared_->chunkHead = GetChunkHead(shared_); + shared_->chunkHead->capacity = size - SIZEOF_SHARED_DATA - SIZEOF_CHUNK_HEADER; + shared_->chunkHead->size = 0; + shared_->chunkHead->next = 0; + shared_->ownBaseAllocator = 0; + shared_->ownBuffer = false; + shared_->refcount = 1; + } + + MemoryPoolAllocator(const MemoryPoolAllocator& rhs) RAPIDJSON_NOEXCEPT : + chunk_capacity_(rhs.chunk_capacity_), + baseAllocator_(rhs.baseAllocator_), + shared_(rhs.shared_) + { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + ++shared_->refcount; + } + MemoryPoolAllocator& operator=(const MemoryPoolAllocator& rhs) RAPIDJSON_NOEXCEPT + { + RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0); + ++rhs.shared_->refcount; + this->~MemoryPoolAllocator(); + baseAllocator_ = rhs.baseAllocator_; + chunk_capacity_ = rhs.chunk_capacity_; + shared_ = rhs.shared_; + return *this; + } + +#if RAPIDJSON_HAS_CXX11_RVALUE_REFS + MemoryPoolAllocator(MemoryPoolAllocator&& rhs) RAPIDJSON_NOEXCEPT : + chunk_capacity_(rhs.chunk_capacity_), + baseAllocator_(rhs.baseAllocator_), + shared_(rhs.shared_) + { + RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0); + rhs.shared_ = 0; + } + MemoryPoolAllocator& operator=(MemoryPoolAllocator&& rhs) RAPIDJSON_NOEXCEPT + { + RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0); + this->~MemoryPoolAllocator(); + baseAllocator_ = rhs.baseAllocator_; + chunk_capacity_ = rhs.chunk_capacity_; + shared_ = rhs.shared_; + rhs.shared_ = 0; + return *this; + } +#endif + + //! Destructor. + /*! This deallocates all memory chunks, excluding the user-supplied buffer. + */ + ~MemoryPoolAllocator() RAPIDJSON_NOEXCEPT { + if (!shared_) { + // do nothing if moved + return; + } + if (shared_->refcount > 1) { + --shared_->refcount; + return; + } + Clear(); + BaseAllocator *a = shared_->ownBaseAllocator; + if (shared_->ownBuffer) { + baseAllocator_->Free(shared_); + } + RAPIDJSON_DELETE(a); + } + + //! Deallocates all memory chunks, excluding the first/user one. + void Clear() RAPIDJSON_NOEXCEPT { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + for (;;) { + ChunkHeader* c = shared_->chunkHead; + if (!c->next) { + break; + } + shared_->chunkHead = c->next; + baseAllocator_->Free(c); + } + shared_->chunkHead->size = 0; + } + + //! Computes the total capacity of allocated memory chunks. + /*! \return total capacity in bytes. + */ + size_t Capacity() const RAPIDJSON_NOEXCEPT { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + size_t capacity = 0; + for (ChunkHeader* c = shared_->chunkHead; c != 0; c = c->next) + capacity += c->capacity; + return capacity; + } + + //! Computes the memory blocks allocated. + /*! \return total used bytes. + */ + size_t Size() const RAPIDJSON_NOEXCEPT { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + size_t size = 0; + for (ChunkHeader* c = shared_->chunkHead; c != 0; c = c->next) + size += c->size; + return size; + } + + //! Whether the allocator is shared. + /*! \return true or false. + */ + bool Shared() const RAPIDJSON_NOEXCEPT { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + return shared_->refcount > 1; + } + + //! Allocates a memory block. (concept Allocator) + void* Malloc(size_t size) { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + if (!size) + return NULL; + + size = RAPIDJSON_ALIGN(size); + if (RAPIDJSON_UNLIKELY(shared_->chunkHead->size + size > shared_->chunkHead->capacity)) + if (!AddChunk(chunk_capacity_ > size ? chunk_capacity_ : size)) + return NULL; + + void *buffer = GetChunkBuffer(shared_) + shared_->chunkHead->size; + shared_->chunkHead->size += size; + return buffer; + } + + //! Resizes a memory block (concept Allocator) + void* Realloc(void* originalPtr, size_t originalSize, size_t newSize) { + if (originalPtr == 0) + return Malloc(newSize); + + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + if (newSize == 0) + return NULL; + + originalSize = RAPIDJSON_ALIGN(originalSize); + newSize = RAPIDJSON_ALIGN(newSize); + + // Do not shrink if new size is smaller than original + if (originalSize >= newSize) + return originalPtr; + + // Simply expand it if it is the last allocation and there is sufficient space + if (originalPtr == GetChunkBuffer(shared_) + shared_->chunkHead->size - originalSize) { + size_t increment = static_cast<size_t>(newSize - originalSize); + if (shared_->chunkHead->size + increment <= shared_->chunkHead->capacity) { + shared_->chunkHead->size += increment; + return originalPtr; + } + } + + // Realloc process: allocate and copy memory, do not free original buffer. + if (void* newBuffer = Malloc(newSize)) { + if (originalSize) + std::memcpy(newBuffer, originalPtr, originalSize); + return newBuffer; + } + else + return NULL; + } + + //! Frees a memory block (concept Allocator) + static void Free(void *ptr) RAPIDJSON_NOEXCEPT { (void)ptr; } // Do nothing + + //! Compare (equality) with another MemoryPoolAllocator + bool operator==(const MemoryPoolAllocator& rhs) const RAPIDJSON_NOEXCEPT { + RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0); + RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0); + return shared_ == rhs.shared_; + } + //! Compare (inequality) with another MemoryPoolAllocator + bool operator!=(const MemoryPoolAllocator& rhs) const RAPIDJSON_NOEXCEPT { + return !operator==(rhs); + } + +private: + //! Creates a new chunk. + /*! \param capacity Capacity of the chunk in bytes. + \return true if success. + */ + bool AddChunk(size_t capacity) { + if (!baseAllocator_) + shared_->ownBaseAllocator = baseAllocator_ = RAPIDJSON_NEW(BaseAllocator)(); + if (ChunkHeader* chunk = static_cast<ChunkHeader*>(baseAllocator_->Malloc(SIZEOF_CHUNK_HEADER + capacity))) { + chunk->capacity = capacity; + chunk->size = 0; + chunk->next = shared_->chunkHead; + shared_->chunkHead = chunk; + return true; + } + else + return false; + } + + static inline void* AlignBuffer(void* buf, size_t &size) + { + RAPIDJSON_NOEXCEPT_ASSERT(buf != 0); + const uintptr_t mask = sizeof(void*) - 1; + const uintptr_t ubuf = reinterpret_cast<uintptr_t>(buf); + if (RAPIDJSON_UNLIKELY(ubuf & mask)) { + const uintptr_t abuf = (ubuf + mask) & ~mask; + RAPIDJSON_ASSERT(size >= abuf - ubuf); + buf = reinterpret_cast<void*>(abuf); + size -= abuf - ubuf; + } + return buf; + } + + size_t chunk_capacity_; //!< The minimum capacity of chunk when they are allocated. + BaseAllocator* baseAllocator_; //!< base allocator for allocating memory chunks. + SharedData *shared_; //!< The shared data of the allocator +}; + +namespace internal { + template<typename, typename = void> + struct IsRefCounted : + public FalseType + { }; + template<typename T> + struct IsRefCounted<T, typename internal::EnableIfCond<T::kRefCounted>::Type> : + public TrueType + { }; +} + +template<typename T, typename A> +inline T* Realloc(A& a, T* old_p, size_t old_n, size_t new_n) +{ + RAPIDJSON_NOEXCEPT_ASSERT(old_n <= SIZE_MAX / sizeof(T) && new_n <= SIZE_MAX / sizeof(T)); + return static_cast<T*>(a.Realloc(old_p, old_n * sizeof(T), new_n * sizeof(T))); +} + +template<typename T, typename A> +inline T *Malloc(A& a, size_t n = 1) +{ + return Realloc<T, A>(a, NULL, 0, n); +} + +template<typename T, typename A> +inline void Free(A& a, T *p, size_t n = 1) +{ + static_cast<void>(Realloc<T, A>(a, p, n, 0)); +} + +#ifdef __GNUC__ +RAPIDJSON_DIAG_PUSH +RAPIDJSON_DIAG_OFF(effc++) // std::allocator can safely be inherited +#endif + +template <typename T, typename BaseAllocator = CrtAllocator> +class StdAllocator : + public std::allocator<T> +{ + typedef std::allocator<T> allocator_type; +#if RAPIDJSON_HAS_CXX11 + typedef std::allocator_traits<allocator_type> traits_type; +#else + typedef allocator_type traits_type; +#endif + +public: + typedef BaseAllocator BaseAllocatorType; + + StdAllocator() RAPIDJSON_NOEXCEPT : + allocator_type(), + baseAllocator_() + { } + + StdAllocator(const StdAllocator& rhs) RAPIDJSON_NOEXCEPT : + allocator_type(rhs), + baseAllocator_(rhs.baseAllocator_) + { } + + template<typename U> + StdAllocator(const StdAllocator<U, BaseAllocator>& rhs) RAPIDJSON_NOEXCEPT : + allocator_type(rhs), + baseAllocator_(rhs.baseAllocator_) + { } + +#if RAPIDJSON_HAS_CXX11_RVALUE_REFS + StdAllocator(StdAllocator&& rhs) RAPIDJSON_NOEXCEPT : + allocator_type(std::move(rhs)), + baseAllocator_(std::move(rhs.baseAllocator_)) + { } +#endif +#if RAPIDJSON_HAS_CXX11 + using propagate_on_container_move_assignment = std::true_type; + using propagate_on_container_swap = std::true_type; +#endif + + /* implicit */ + StdAllocator(const BaseAllocator& allocator) RAPIDJSON_NOEXCEPT : + allocator_type(), + baseAllocator_(allocator) + { } + + ~StdAllocator() RAPIDJSON_NOEXCEPT + { } + + template<typename U> + struct rebind { + typedef StdAllocator<U, BaseAllocator> other; + }; + + typedef typename traits_type::size_type size_type; + typedef typename traits_type::difference_type difference_type; + + typedef typename traits_type::value_type value_type; + typedef typename traits_type::pointer pointer; + typedef typename traits_type::const_pointer const_pointer; + +#if RAPIDJSON_HAS_CXX11 + + typedef typename std::add_lvalue_reference<value_type>::type &reference; + typedef typename std::add_lvalue_reference<typename std::add_const<value_type>::type>::type &const_reference; + + pointer address(reference r) const RAPIDJSON_NOEXCEPT + { + return std::addressof(r); + } + const_pointer address(const_reference r) const RAPIDJSON_NOEXCEPT + { + return std::addressof(r); + } + + size_type max_size() const RAPIDJSON_NOEXCEPT + { + return traits_type::max_size(*this); + } + + template <typename ...Args> + void construct(pointer p, Args&&... args) + { + traits_type::construct(*this, p, std::forward<Args>(args)...); + } + void destroy(pointer p) + { + traits_type::destroy(*this, p); + } + +#else // !RAPIDJSON_HAS_CXX11 + + typedef typename allocator_type::reference reference; + typedef typename allocator_type::const_reference const_reference; + + pointer address(reference r) const RAPIDJSON_NOEXCEPT + { + return allocator_type::address(r); + } + const_pointer address(const_reference r) const RAPIDJSON_NOEXCEPT + { + return allocator_type::address(r); + } + + size_type max_size() const RAPIDJSON_NOEXCEPT + { + return allocator_type::max_size(); + } + + void construct(pointer p, const_reference r) + { + allocator_type::construct(p, r); + } + void destroy(pointer p) + { + allocator_type::destroy(p); + } + +#endif // !RAPIDJSON_HAS_CXX11 + + template <typename U> + U* allocate(size_type n = 1, const void* = 0) + { + return RAPIDJSON_NAMESPACE::Malloc<U>(baseAllocator_, n); + } + template <typename U> + void deallocate(U* p, size_type n = 1) + { + RAPIDJSON_NAMESPACE::Free<U>(baseAllocator_, p, n); + } + + pointer allocate(size_type n = 1, const void* = 0) + { + return allocate<value_type>(n); + } + void deallocate(pointer p, size_type n = 1) + { + deallocate<value_type>(p, n); + } + +#if RAPIDJSON_HAS_CXX11 + using is_always_equal = std::is_empty<BaseAllocator>; +#endif + + template<typename U> + bool operator==(const StdAllocator<U, BaseAllocator>& rhs) const RAPIDJSON_NOEXCEPT + { + return baseAllocator_ == rhs.baseAllocator_; + } + template<typename U> + bool operator!=(const StdAllocator<U, BaseAllocator>& rhs) const RAPIDJSON_NOEXCEPT + { + return !operator==(rhs); + } + + //! rapidjson Allocator concept + static const bool kNeedFree = BaseAllocator::kNeedFree; + static const bool kRefCounted = internal::IsRefCounted<BaseAllocator>::Value; + void* Malloc(size_t size) + { + return baseAllocator_.Malloc(size); + } + void* Realloc(void* originalPtr, size_t originalSize, size_t newSize) + { + return baseAllocator_.Realloc(originalPtr, originalSize, newSize); + } + static void Free(void *ptr) RAPIDJSON_NOEXCEPT + { + BaseAllocator::Free(ptr); + } + +private: + template <typename, typename> + friend class StdAllocator; // access to StdAllocator<!T>.* + + BaseAllocator baseAllocator_; +}; + +#if !RAPIDJSON_HAS_CXX17 // std::allocator<void> deprecated in C++17 +template <typename BaseAllocator> +class StdAllocator<void, BaseAllocator> : + public std::allocator<void> +{ + typedef std::allocator<void> allocator_type; + +public: + typedef BaseAllocator BaseAllocatorType; + + StdAllocator() RAPIDJSON_NOEXCEPT : + allocator_type(), + baseAllocator_() + { } + + StdAllocator(const StdAllocator& rhs) RAPIDJSON_NOEXCEPT : + allocator_type(rhs), + baseAllocator_(rhs.baseAllocator_) + { } + + template<typename U> + StdAllocator(const StdAllocator<U, BaseAllocator>& rhs) RAPIDJSON_NOEXCEPT : + allocator_type(rhs), + baseAllocator_(rhs.baseAllocator_) + { } + + /* implicit */ + StdAllocator(const BaseAllocator& baseAllocator) RAPIDJSON_NOEXCEPT : + allocator_type(), + baseAllocator_(baseAllocator) + { } + + ~StdAllocator() RAPIDJSON_NOEXCEPT + { } + + template<typename U> + struct rebind { + typedef StdAllocator<U, BaseAllocator> other; + }; + + typedef typename allocator_type::value_type value_type; + +private: + template <typename, typename> + friend class StdAllocator; // access to StdAllocator<!T>.* + + BaseAllocator baseAllocator_; +}; +#endif + +#ifdef __GNUC__ +RAPIDJSON_DIAG_POP +#endif + +RAPIDJSON_NAMESPACE_END + +#endif // RAPIDJSON_ENCODINGS_H_ |