Implementing uploading of a WebRTC diagnostic log.

content/common/partial_circular_buffer.h

-// Copyright (c) 2013 The Chromium 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 CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_
-#define CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_
-
-#include "base/basictypes.h"
-#include "base/gtest_prod_util.h"
-#include "content/common/content_export.h"
-
-namespace content {
-
-// A wrapper around a memory buffer that allows circular read and write with a
-// selectable wrapping position. Buffer layout (after wrap; H is header):
-// -----------------------------------------------------------
-// | H | Beginning           | End           | Middle        |
-// -----------------------------------------------------------
-//  ^---- Non-wrapping -----^ ^--------- Wrapping ----------^
-// The non-wrapping part is never overwritten. The wrapping part will be
-// circular. The very first part is the header (see the BufferData struct
-// below). It consists of the following information:
-// - Length written to the buffer (not including header).
-// - Wrapping position.
-// - End position of buffer. (If the last byte is at x, this will be x + 1.)
-// Users of wrappers around the same underlying buffer must ensure that writing
-// is finished before reading is started.
-class CONTENT_EXPORT PartialCircularBuffer {
- public:
-  // Use for reading. |buffer_size| is in bytes and must be larger than the
-  // header size (see above).
-  PartialCircularBuffer(void* buffer, uint32 buffer_size);
-
-  // Use for writing. |buffer_size| is in bytes and must be larger than the
-  // header size (see above).
-  PartialCircularBuffer(void* buffer,
-                        uint32 buffer_size,
-                        uint32 wrap_position);
-
-  uint32 Read(void* buffer, uint32 buffer_size);
-  void Write(const void* buffer, uint32 buffer_size);
-
- private:
-  friend class PartialCircularBufferTest;
-
-#pragma pack(push)
-#pragma pack(4)
-  struct BufferData {
-    uint32 total_written;
-    uint32 wrap_position;
-    uint32 end_position;
-    uint8 data[1];
-  };
-#pragma pack(pop)
-
-  void DoWrite(void* dest, const void* src, uint32 num);
-
-  // Used for reading and writing.
-  BufferData* buffer_data_;
-  uint32 memory_buffer_size_;
-  uint32 data_size_;
-  uint32 position_;
-
-  // Used for reading.
-  uint32 total_read_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_