kc3-lang/angle/src/common/MemoryBuffer.h

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• Hash : aa6dd50d
  Author :
  Date : 2020-02-03T17:10:58
  

  Share scratch buffers between contexts.
  
  The Display now owns scratch buffers and loans them out to contexts
  while they are current.  This allows us to to only allocate one scratch
  buffer in a single-threaded use case.
  
  Tick the scratch buffers every time a new context is made current.
  
  Lower the lifetime from 1000 to 64 to ensure that in the worst case,
  the buffers are cleared after not being used for ~1 second.
  
  BUG=chromium:1030835
  BUG=angleproject:4363
  
  Change-Id: I83552424e2beac62b9e41152876b04fc84f53692
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2031698
  Commit-Queue: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Zhenyao Mo <zmo@chromium.org>
  

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• src/common/MemoryBuffer.h

• //
  // Copyright 2014 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  #ifndef COMMON_MEMORYBUFFER_H_
  #define COMMON_MEMORYBUFFER_H_
  
  #include "common/Optional.h"
  #include "common/angleutils.h"
  #include "common/debug.h"
  
  #include <stdint.h>
  #include <cstddef>
  
  namespace angle
  {
  
  class MemoryBuffer final : NonCopyable
  {
    public:
      MemoryBuffer() = default;
      ~MemoryBuffer();
  
      MemoryBuffer(MemoryBuffer &&other);
      MemoryBuffer &operator=(MemoryBuffer &&other);
  
      ANGLE_NO_DISCARD bool resize(size_t size);
      void clear() { (void)resize(0); }
      size_t size() const { return mSize; }
      bool empty() const { return mSize == 0; }
  
      const uint8_t *data() const { return mData; }
      uint8_t *data()
      {
          ASSERT(mData);
          return mData;
      }
  
      uint8_t &operator[](size_t pos)
      {
          ASSERT(pos < mSize);
          return mData[pos];
      }
      const uint8_t &operator[](size_t pos) const
      {
          ASSERT(pos < mSize);
          return mData[pos];
      }
  
      void fill(uint8_t datum);
  
    private:
      size_t mSize   = 0;
      uint8_t *mData = nullptr;
  };
  
  class ScratchBuffer final : NonCopyable
  {
    public:
      // If we request a scratch buffer requesting a smaller size this many times, release and
      // recreate the scratch buffer. This ensures we don't have a degenerate case where we are stuck
      // hogging memory.
      ScratchBuffer();
      ScratchBuffer(uint32_t lifetime);
      ~ScratchBuffer();
  
      ScratchBuffer(ScratchBuffer &&other);
      ScratchBuffer &operator=(ScratchBuffer &&other);
  
      // Returns true with a memory buffer of the requested size, or false on failure.
      bool get(size_t requestedSize, MemoryBuffer **memoryBufferOut);
  
      // Same as get, but ensures new values are initialized to a fixed constant.
      bool getInitialized(size_t requestedSize, MemoryBuffer **memoryBufferOut, uint8_t initValue);
  
      // Ticks the release counter for the scratch buffer. Also done implicitly in get().
      void tick();
  
      void clear();
  
    private:
      bool getImpl(size_t requestedSize, MemoryBuffer **memoryBufferOut, Optional<uint8_t> initValue);
  
      uint32_t mLifetime;
      uint32_t mResetCounter;
      MemoryBuffer mScratchMemory;
  };
  
  }  // namespace angle
  
  #endif  // COMMON_MEMORYBUFFER_H_
  

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