0a73f822b1
Moving from external/webkit/Source/WebCore/platform/graphics/android/utils/ Change-Id: If91830aa9b207dbc8692b2ca7c4a0b76778addd5
98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
/*
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* Copyright 2012, The Android Open Source Project
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef ANDROID_LINEARALLOCATOR_H
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#define ANDROID_LINEARALLOCATOR_H
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#include <stddef.h>
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namespace android {
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/**
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* A memory manager that internally allocates multi-kbyte buffers for placing objects in. It avoids
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* the overhead of malloc when many objects are allocated. It is most useful when creating many
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* small objects with a similar lifetime, and doesn't add significant overhead for large
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* allocations.
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*/
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class LinearAllocator {
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public:
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LinearAllocator();
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~LinearAllocator();
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/**
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* Reserves and returns a region of memory of at least size 'size', aligning as needed.
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* Typically this is used in an object's overridden new() method or as a replacement for malloc.
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*
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* The lifetime of the returned buffers is tied to that of the LinearAllocator. If calling
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* delete() on an object stored in a buffer is needed, it should be overridden to use
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* rewindIfLastAlloc()
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*/
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void* alloc(size_t size);
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/**
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* Attempt to deallocate the given buffer, with the LinearAllocator attempting to rewind its
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* state if possible. No destructors are called.
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*/
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void rewindIfLastAlloc(void* ptr, size_t allocSize);
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/**
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* Dump memory usage statistics to the log (allocated and wasted space)
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*/
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void dumpMemoryStats(const char* prefix = "");
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/**
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* The number of bytes used for buffers allocated in the LinearAllocator (does not count space
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* wasted)
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*/
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size_t usedSize() const { return mTotalAllocated - mWastedSpace; }
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private:
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LinearAllocator(const LinearAllocator& other);
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class Page;
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Page* newPage(size_t pageSize);
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bool fitsInCurrentPage(size_t size);
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void ensureNext(size_t size);
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void* start(Page *p);
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void* end(Page* p);
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size_t mPageSize;
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size_t mMaxAllocSize;
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void* mNext;
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Page* mCurrentPage;
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Page* mPages;
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// Memory usage tracking
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size_t mTotalAllocated;
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size_t mWastedSpace;
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size_t mPageCount;
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size_t mDedicatedPageCount;
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};
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}; // namespace android
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#endif // ANDROID_LINEARALLOCATOR_H
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