MemoryBuffer.h - mozsearch

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//

// 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);

    [[nodiscard]] 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_