247 lines
9.9 KiB
C++
247 lines
9.9 KiB
C++
// Copyright (C) 2011 Milo Yip
|
|
//
|
|
// Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
// of this software and associated documentation files (the "Software"), to deal
|
|
// in the Software without restriction, including without limitation the rights
|
|
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
// copies of the Software, and to permit persons to whom the Software is
|
|
// furnished to do so, subject to the following conditions:
|
|
//
|
|
// The above copyright notice and this permission notice shall be included in
|
|
// all copies or substantial portions of the Software.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
// THE SOFTWARE.
|
|
|
|
#ifndef RAPIDJSON_ALLOCATORS_H_
|
|
#define RAPIDJSON_ALLOCATORS_H_
|
|
|
|
#include "rapidjson.h"
|
|
|
|
namespace rapidjson {
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
// 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
|
|
*/
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
// 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) { return std::malloc(size); }
|
|
void* Realloc(void* originalPtr, size_t originalSize, size_t newSize) { (void)originalSize; return std::realloc(originalPtr, newSize); }
|
|
static void Free(void *ptr) { std::free(ptr); }
|
|
};
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
// 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 {
|
|
public:
|
|
static const bool kNeedFree = false; //!< Tell users that no need to call Free() with this allocator. (concept Allocator)
|
|
|
|
//! Constructor with chunkSize.
|
|
/*! \param chunkSize The size of memory chunk. The default is kDefaultChunkSize.
|
|
\param baseAllocator The allocator for allocating memory chunks.
|
|
*/
|
|
MemoryPoolAllocator(size_t chunkSize = kDefaultChunkCapacity, BaseAllocator* baseAllocator = 0) :
|
|
chunkHead_(0), chunk_capacity_(chunkSize), userBuffer_(0), baseAllocator_(baseAllocator), ownBaseAllocator_(0)
|
|
{
|
|
if (!baseAllocator_)
|
|
ownBaseAllocator_ = baseAllocator_ = new BaseAllocator();
|
|
AddChunk(chunk_capacity_);
|
|
}
|
|
|
|
//! 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) :
|
|
chunkHead_(0), chunk_capacity_(chunkSize), userBuffer_(buffer), baseAllocator_(baseAllocator), ownBaseAllocator_(0)
|
|
{
|
|
RAPIDJSON_ASSERT(buffer != 0);
|
|
RAPIDJSON_ASSERT(size > sizeof(ChunkHeader));
|
|
chunkHead_ = reinterpret_cast<ChunkHeader*>(buffer);
|
|
chunkHead_->capacity = size - sizeof(ChunkHeader);
|
|
chunkHead_->size = 0;
|
|
chunkHead_->next = 0;
|
|
}
|
|
|
|
//! Destructor.
|
|
/*! This deallocates all memory chunks, excluding the user-supplied buffer.
|
|
*/
|
|
~MemoryPoolAllocator() {
|
|
Clear();
|
|
delete ownBaseAllocator_;
|
|
}
|
|
|
|
//! Deallocates all memory chunks, excluding the user-supplied buffer.
|
|
void Clear() {
|
|
while(chunkHead_ != 0 && chunkHead_ != userBuffer_) {
|
|
ChunkHeader* next = chunkHead_->next;
|
|
baseAllocator_->Free(chunkHead_);
|
|
chunkHead_ = next;
|
|
}
|
|
}
|
|
|
|
//! Computes the total capacity of allocated memory chunks.
|
|
/*! \return total capacity in bytes.
|
|
*/
|
|
size_t Capacity() const {
|
|
size_t capacity = 0;
|
|
for (ChunkHeader* c = chunkHead_; c != 0; c = c->next)
|
|
capacity += c->capacity;
|
|
return capacity;
|
|
}
|
|
|
|
//! Computes the memory blocks allocated.
|
|
/*! \return total used bytes.
|
|
*/
|
|
size_t Size() const {
|
|
size_t size = 0;
|
|
for (ChunkHeader* c = chunkHead_; c != 0; c = c->next)
|
|
size += c->size;
|
|
return size;
|
|
}
|
|
|
|
//! Allocates a memory block. (concept Allocator)
|
|
void* Malloc(size_t size) {
|
|
size = RAPIDJSON_ALIGN(size);
|
|
if (chunkHead_ == 0 || chunkHead_->size + size > chunkHead_->capacity)
|
|
AddChunk(chunk_capacity_ > size ? chunk_capacity_ : size);
|
|
|
|
void *buffer = reinterpret_cast<char *>(chunkHead_ + 1) + chunkHead_->size;
|
|
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);
|
|
|
|
// 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 == (char *)(chunkHead_ + 1) + chunkHead_->size - originalSize) {
|
|
size_t increment = static_cast<size_t>(newSize - originalSize);
|
|
increment = RAPIDJSON_ALIGN(increment);
|
|
if (chunkHead_->size + increment <= chunkHead_->capacity) {
|
|
chunkHead_->size += increment;
|
|
return originalPtr;
|
|
}
|
|
}
|
|
|
|
// Realloc process: allocate and copy memory, do not free original buffer.
|
|
void* newBuffer = Malloc(newSize);
|
|
RAPIDJSON_ASSERT(newBuffer != 0); // Do not handle out-of-memory explicitly.
|
|
return std::memcpy(newBuffer, originalPtr, originalSize);
|
|
}
|
|
|
|
//! Frees a memory block (concept Allocator)
|
|
static void Free(void *ptr) { (void)ptr; } // Do nothing
|
|
|
|
private:
|
|
//! Copy constructor is not permitted.
|
|
MemoryPoolAllocator(const MemoryPoolAllocator& rhs) /* = delete */;
|
|
//! Copy assignment operator is not permitted.
|
|
MemoryPoolAllocator& operator=(const MemoryPoolAllocator& rhs) /* = delete */;
|
|
|
|
//! Creates a new chunk.
|
|
/*! \param capacity Capacity of the chunk in bytes.
|
|
*/
|
|
void AddChunk(size_t capacity) {
|
|
ChunkHeader* chunk = reinterpret_cast<ChunkHeader*>(baseAllocator_->Malloc(sizeof(ChunkHeader) + capacity));
|
|
chunk->capacity = capacity;
|
|
chunk->size = 0;
|
|
chunk->next = chunkHead_;
|
|
chunkHead_ = chunk;
|
|
}
|
|
|
|
static const int kDefaultChunkCapacity = 64 * 1024; //!< Default chunk capacity.
|
|
|
|
//! 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.
|
|
};
|
|
|
|
ChunkHeader *chunkHead_; //!< Head of the chunk linked-list. Only the head chunk serves allocation.
|
|
size_t chunk_capacity_; //!< The minimum capacity of chunk when they are allocated.
|
|
void *userBuffer_; //!< User supplied buffer.
|
|
BaseAllocator* baseAllocator_; //!< base allocator for allocating memory chunks.
|
|
BaseAllocator* ownBaseAllocator_; //!< base allocator created by this object.
|
|
};
|
|
|
|
} // namespace rapidjson
|
|
|
|
#endif // RAPIDJSON_ENCODINGS_H_
|