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

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• Hash : b3af2e86
  Author :
  Date : 2024-12-31T08:51:37
  

  Enhance MemoryBuffer API
  
  Add support for -
  1. reserve - users can reserve sufficient capacity upfront to
               minimize subsequent reallocations due to resize
  2. append - to append data from a source so user doesn't need to
              track offsets explicitly
  
  Bug: angleproject:386749841
  Tests: MemoryBufferTest*
  Change-Id: Ibf2a3228d5a00ed34a7e0c5e3eb185e42677d676
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6135238
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Commit-Queue: mohan maiya <m.maiya@samsung.com>
  Reviewed-by: Shahbaz Youssefi <syoussefi@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);
  
      // Destroy underlying memory
      void destroy();
  
      // Updates mSize to newSize. Updates mCapacity iff newSize > mCapacity
      [[nodiscard]] bool resize(size_t newSize);
  
      // Resets mSize to 0. Reserves memory and updates mCapacity iff newSize > mCapacity
      [[nodiscard]] bool clearAndReserve(size_t newSize);
  
      // Updates mCapacity iff newSize > mCapacity
      [[nodiscard]] bool reserve(size_t newSize);
  
      // Appends content from "other" MemoryBuffer
      [[nodiscard]] bool append(const MemoryBuffer &other);
      // Appends content from "[buffer, buffer + bufferSize)"
      [[nodiscard]] bool appendRaw(const uint8_t *buffer, const size_t bufferSize);
  
      // Sets size bound by capacity.
      void setSize(size_t size)
      {
          ASSERT(size <= mCapacity);
          mSize = size;
      }
      void setSizeToCapacity() { setSize(mCapacity); }
  
      // Invalidate current content
      void clear() { (void)resize(0); }
  
      size_t size() const { return mSize; }
      size_t capacity() const { return mCapacity; }
      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(mData && pos < mSize);
          return mData[pos];
      }
      const uint8_t &operator[](size_t pos) const
      {
          ASSERT(mData && pos < mSize);
          return mData[pos];
      }
  
      void fill(uint8_t datum);
  
      // Only used by unit tests
      // Validate total bytes allocated during a resize
      void assertTotalAllocatedBytes(size_t totalAllocatedBytes) const
      {
  #if defined(ANGLE_ENABLE_ASSERTS)
          ASSERT(totalAllocatedBytes == mTotalAllocatedBytes);
  #endif  // ANGLE_ENABLE_ASSERTS
      }
      // Validate total bytes copied during a resize
      void assertTotalCopiedBytes(size_t totalCopiedBytes) const
      {
  #if defined(ANGLE_ENABLE_ASSERTS)
          ASSERT(totalCopiedBytes == mTotalCopiedBytes);
  #endif  // ANGLE_ENABLE_ASSERTS
      }
  
    private:
      size_t mSize     = 0;
      size_t mCapacity = 0;
      uint8_t *mData   = nullptr;
  #if defined(ANGLE_ENABLE_ASSERTS)
      size_t mTotalAllocatedBytes = 0;
      size_t mTotalCopiedBytes    = 0;
  #endif  // ANGLE_ENABLE_ASSERTS
  };
  
  class ScratchBuffer final : NonCopyable
  {
    public:
      ScratchBuffer();
      // 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(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();
  
      MemoryBuffer *getMemoryBuffer() { return &mScratchMemory; }
  
    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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