/*
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* Copyright 2012 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef GrMemoryPool_DEFINED
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#define GrMemoryPool_DEFINED
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#include "GrTypes.h"
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#include "SkRefCnt.h"
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#ifdef SK_DEBUG
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#include "SkTHash.h"
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#endif
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/**
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* Allocates memory in blocks and parcels out space in the blocks for allocation
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* requests. It is optimized for allocate / release speed over memory
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* efficiency. The interface is designed to be used to implement operator new
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* and delete overrides. All allocations are expected to be released before the
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* pool's destructor is called. Allocations will be 8-byte aligned.
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*/
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class GrMemoryPool {
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public:
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/**
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* Prealloc size is the amount of space to allocate at pool creation
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* time and keep around until pool destruction. The min alloc size is
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* the smallest allowed size of additional allocations. Both sizes are
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* adjusted to ensure that:
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* 1. they are are 8-byte aligned
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* 2. minAllocSize >= kSmallestMinAllocSize
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* 3. preallocSize >= minAllocSize
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*
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* Both sizes is what the pool will end up allocating from the system, and
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* portions of the allocated memory is used for internal bookkeeping.
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*/
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GrMemoryPool(size_t preallocSize, size_t minAllocSize);
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~GrMemoryPool();
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/**
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* Allocates memory. The memory must be freed with release().
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*/
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void* allocate(size_t size);
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/**
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* p must have been returned by allocate()
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*/
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void release(void* p);
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/**
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* Returns true if there are no unreleased allocations.
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*/
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bool isEmpty() const { return fTail == fHead && !fHead->fLiveCount; }
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/**
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* Returns the total allocated size of the GrMemoryPool minus any preallocated amount
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*/
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size_t size() const { return fSize; }
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/**
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* Returns the preallocated size of the GrMemoryPool
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*/
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size_t preallocSize() const { return fHead->fSize; }
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/**
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* Minimum value of minAllocSize constructor argument.
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*/
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constexpr static size_t kSmallestMinAllocSize = 1 << 10;
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private:
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struct BlockHeader;
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static BlockHeader* CreateBlock(size_t size);
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static void DeleteBlock(BlockHeader* block);
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void validate();
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struct BlockHeader {
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#ifdef SK_DEBUG
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uint32_t fBlockSentinal; ///< known value to check for bad back pointers to blocks
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#endif
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BlockHeader* fNext; ///< doubly-linked list of blocks.
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BlockHeader* fPrev;
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int fLiveCount; ///< number of outstanding allocations in the
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///< block.
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intptr_t fCurrPtr; ///< ptr to the start of blocks free space.
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intptr_t fPrevPtr; ///< ptr to the last allocation made
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size_t fFreeSize; ///< amount of free space left in the block.
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size_t fSize; ///< total allocated size of the block
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};
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static const uint32_t kAssignedMarker = 0xCDCDCDCD;
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static const uint32_t kFreedMarker = 0xEFEFEFEF;
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struct AllocHeader {
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#ifdef SK_DEBUG
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uint32_t fSentinal; ///< known value to check for memory stomping (e.g., (CD)*)
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int32_t fID; ///< ID that can be used to track down leaks by clients.
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#endif
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BlockHeader* fHeader; ///< pointer back to the block header in which an alloc resides
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};
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size_t fSize;
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size_t fMinAllocSize;
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BlockHeader* fHead;
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BlockHeader* fTail;
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#ifdef SK_DEBUG
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int fAllocationCnt;
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int fAllocBlockCnt;
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SkTHashSet<int32_t> fAllocatedIDs;
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#endif
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protected:
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enum {
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// We assume this alignment is good enough for everybody.
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kAlignment = 8,
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kHeaderSize = GR_CT_ALIGN_UP(sizeof(BlockHeader), kAlignment),
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kPerAllocPad = GR_CT_ALIGN_UP(sizeof(AllocHeader), kAlignment),
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};
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};
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class GrOp;
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// DDL TODO: for the DLL use case this could probably be the non-intrinsic-based style of
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// ref counting
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class GrOpMemoryPool : public SkRefCnt {
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public:
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GrOpMemoryPool(size_t preallocSize, size_t minAllocSize)
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: fMemoryPool(preallocSize, minAllocSize) {
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}
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template <typename Op, typename... OpArgs>
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std::unique_ptr<Op> allocate(OpArgs&&... opArgs) {
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char* mem = (char*) fMemoryPool.allocate(sizeof(Op));
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return std::unique_ptr<Op>(new (mem) Op(std::forward<OpArgs>(opArgs)...));
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}
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void* allocate(size_t size) {
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return fMemoryPool.allocate(size);
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}
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void release(std::unique_ptr<GrOp> op);
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bool isEmpty() const { return fMemoryPool.isEmpty(); }
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private:
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GrMemoryPool fMemoryPool;
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};
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#endif
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