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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrMemoryPool_DEFINED
#define GrMemoryPool_DEFINED
#include "GrTypes.h"
/**
* Allocates memory in blocks and parcels out space in the blocks for allocation
* requests. It is optimized for allocate / release speed over memory
* effeciency. The interface is designed to be used to implement operator new
* and delete overrides. All allocations are expected to be released before the
* pool's destructor is called. Allocations will be 8-byte aligned.
*/
class GrMemoryPool {
public:
/**
* Prealloc size is the amount of space to make available at pool creation
* time and keep around until pool destruction. The min alloc size is the
* smallest allowed size of additional allocations.
*/
GrMemoryPool(size_t preallocSize, size_t minAllocSize);
~GrMemoryPool();
/**
* Allocates memory. The memory must be freed with release().
*/
void* allocate(size_t size);
/**
* p must have been returned by allocate()
*/
void release(void* p);
/**
* Returns true if there are no unreleased allocations.
*/
bool isEmpty() const { return fTail == fHead && !fHead->fLiveCount; }
private:
struct BlockHeader;
BlockHeader* CreateBlock(size_t size);
void DeleteBlock(BlockHeader* block);
void validate();
struct BlockHeader {
BlockHeader* fNext; ///< doubly-linked list of blocks.
BlockHeader* fPrev;
int fLiveCount; ///< number of outstanding allocations in the
///< block.
intptr_t fCurrPtr; ///< ptr to the start of blocks free space.
intptr_t fPrevPtr; ///< ptr to the last allocation made
size_t fFreeSize; ///< amount of free space left in the block.
};
enum {
// We assume this alignment is good enough for everybody.
kAlignment = 8,
kHeaderSize = GR_CT_ALIGN_UP(sizeof(BlockHeader), kAlignment),
kPerAllocPad = GR_CT_ALIGN_UP(sizeof(BlockHeader*), kAlignment),
};
size_t fPreallocSize;
size_t fMinAllocSize;
BlockHeader* fHead;
BlockHeader* fTail;
#if GR_DEBUG
int fAllocationCnt;
#endif
};
#endif
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