1 files changed, 93 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/common/MemoryBuffer.h b/gfx/angle/checkout/src/common/MemoryBuffer.h
new file mode 100644
index 0000000000..75e83fc0a3
--- /dev/null
+++ b/gfx/angle/checkout/src/common/MemoryBuffer.h
@@ -0,0 +1,93 @@
+//
+// 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_