| /* |
| * Copyright (C) 2015 Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * 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. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "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 THE COPYRIGHT |
| * OWNER 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 FastSharedBufferReader_h |
| #define FastSharedBufferReader_h |
| |
| #include "platform/PlatformExport.h" |
| #include "platform/SharedBuffer.h" |
| #include "wtf/PassRefPtr.h" |
| #include "wtf/RefPtr.h" |
| |
| namespace blink { |
| |
| // This class is used by image decoders to avoid memory consolidation and |
| // therefore minimizes the cost of memory copying when the decoders |
| // repeatedly read from a buffer that is continually growing due to network |
| // traffic. |
| class PLATFORM_EXPORT FastSharedBufferReader { |
| public: |
| FastSharedBufferReader(PassRefPtr<SharedBuffer> data); |
| |
| void setData(PassRefPtr<SharedBuffer>); |
| |
| // Returns a consecutive buffer that carries the data starting |
| // at |dataPosition| with |length| bytes. |
| // This method returns a pointer to a memory segment stored in |
| // |m_data| if such a consecutive buffer can be found. |
| // Otherwise copies into |buffer| and returns it. |
| // Caller must ensure there are enough bytes in |m_data| and |buffer|. |
| const char* getConsecutiveData(size_t dataPosition, size_t length, char* buffer); |
| |
| // Wraps SharedBuffer::getSomeData(). |
| size_t getSomeData(const char*& someData, size_t dataPosition); |
| |
| // Returns a byte at |dataPosition|. |
| // Caller must ensure there are enough bytes in |m_data|. |
| inline char getOneByte(size_t dataPosition) |
| { |
| return *getConsecutiveData(dataPosition, 1, 0); |
| } |
| |
| size_t size() const |
| { |
| return m_data->size(); |
| } |
| |
| private: |
| void getSomeDataInternal(unsigned dataPosition); |
| |
| RefPtr<SharedBuffer> m_data; |
| |
| // Caches the last segment of |m_data| accessed, since subsequent reads are |
| // likely to re-access it. |
| const char* m_segment; |
| size_t m_segmentLength; |
| |
| // Data position in |m_data| pointed to by |m_segment|. |
| size_t m_dataPosition; |
| }; |
| |
| } // namespace blink |
| |
| #endif |