third_party/WebKit/Source/platform/SharedBuffer.h

/*
 * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
 * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef SharedBuffer_h
#define SharedBuffer_h

#include "platform/PlatformExport.h"
#include "third_party/skia/include/core/SkData.h"
#include "wtf/Forward.h"
#include "wtf/RefCounted.h"
#include "wtf/Vector.h"
#include "wtf/text/WTFString.h"

namespace blink {

class WebProcessMemoryDump;

class PLATFORM_EXPORT SharedBuffer : public RefCounted<SharedBuffer> {
 public:
  enum : unsigned { kSegmentSize = 0x1000 };

  static PassRefPtr<SharedBuffer> create() {
    return adoptRef(new SharedBuffer);
  }

  HAS_STRICTLY_TYPED_ARG
  static PassRefPtr<SharedBuffer> create(STRICTLY_TYPED_ARG(size)) {
    STRICT_ARG_TYPE(size_t);
    return adoptRef(new SharedBuffer(size));
  }

  HAS_STRICTLY_TYPED_ARG
  static PassRefPtr<SharedBuffer> create(const char* data,
                                         STRICTLY_TYPED_ARG(size)) {
    STRICT_ARG_TYPE(size_t);
    return adoptRef(new SharedBuffer(data, size));
  }

  HAS_STRICTLY_TYPED_ARG
  static PassRefPtr<SharedBuffer> create(const unsigned char* data,
                                         STRICTLY_TYPED_ARG(size)) {
    STRICT_ARG_TYPE(size_t);
    return adoptRef(new SharedBuffer(data, size));
  }

  static PassRefPtr<SharedBuffer> adoptVector(Vector<char>&);

  ~SharedBuffer();

  // Calling this function will force internal segmented buffers to be merged
  // into a flat buffer. Use getSomeData() whenever possible for better
  // performance.
  const char* data() const;

  size_t size() const;

  bool isEmpty() const { return !size(); }

  void append(PassRefPtr<SharedBuffer>);

  HAS_STRICTLY_TYPED_ARG
  void append(const char* data, STRICTLY_TYPED_ARG(size)) {
    ALLOW_NUMERIC_ARG_TYPES_PROMOTABLE_TO(size_t);
    appendInternal(data, size);
  }
  void append(const Vector<char>&);

  void clear();

  PassRefPtr<SharedBuffer> copy() const;

  // Return the number of consecutive bytes after "position". "data"
  // points to the first byte.
  // Return 0 when no more data left.
  // When extracting all data with getSomeData(), the caller should
  // repeat calling it until it returns 0.
  // Usage:
  //      const char* segment;
  //      size_t pos = 0;
  //      while (size_t length = sharedBuffer->getSomeData(segment, pos)) {
  //          // Use the data. for example: decoder->decode(segment, length);
  //          pos += length;
  //      }
  HAS_STRICTLY_TYPED_ARG
  size_t getSomeData(
      const char*& data,
      STRICTLY_TYPED_ARG(position) = static_cast<size_t>(0)) const {
    STRICT_ARG_TYPE(size_t);
    return getSomeDataInternal(data, position);
  }

  // Returns the content data into "dest" as a flat buffer. "byteLength" must
  // exactly match with size(). Returns true on success, otherwise the content
  // of "dest" is not guaranteed.
  HAS_STRICTLY_TYPED_ARG
  bool getAsBytes(void* dest, STRICTLY_TYPED_ARG(byteLength)) const {
    STRICT_ARG_TYPE(size_t);
    if (byteLength != size())
      return false;

    return getAsBytesInternal(dest, 0, byteLength);
  }

  // Copies "byteLength" bytes from "position"-th bytes (0 origin) of the
  // content data into "dest" as a flat buffer, Returns true on success,
  // otherwise the content of "dest" is not guaranteed.
  HAS_STRICTLY_TYPED_ARG
  bool getPartAsBytes(void* dest,
                      STRICTLY_TYPED_ARG(position),
                      STRICTLY_TYPED_ARG(byteLength)) const {
    STRICT_ARG_TYPE(size_t);
    return getAsBytesInternal(dest, position, byteLength);
  }

  // Creates an SkData and copies this SharedBuffer's contents to that
  // SkData without merging segmented buffers into a flat buffer.
  sk_sp<SkData> getAsSkData() const;

  void onMemoryDump(const String& dumpPrefix, WebProcessMemoryDump*) const;

 private:
  SharedBuffer();
  explicit SharedBuffer(size_t);
  SharedBuffer(const char*, size_t);
  SharedBuffer(const unsigned char*, size_t);

  // See SharedBuffer::data().
  void mergeSegmentsIntoBuffer() const;

  void appendInternal(const char* data, size_t);
  bool getAsBytesInternal(void* dest, size_t, size_t) const;
  size_t getSomeDataInternal(const char*& data, size_t position) const;

  size_t m_size;
  mutable Vector<char> m_buffer;
  mutable Vector<char*> m_segments;
};

}  // namespace blink

#endif  // SharedBuffer_h