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      1 /*
      2  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
      3  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     21  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     22  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 #ifndef SharedBuffer_h
     28 #define SharedBuffer_h
     29 
     30 #include "platform/PlatformExport.h"
     31 #include "third_party/skia/include/core/SkData.h"
     32 #include "wtf/ArrayBuffer.h"
     33 #include "wtf/Forward.h"
     34 #include "wtf/OwnPtr.h"
     35 #include "wtf/RefCounted.h"
     36 #include "wtf/Vector.h"
     37 #include "wtf/text/WTFString.h"
     38 
     39 namespace WebCore {
     40 
     41 class PurgeableBuffer;
     42 
     43 class PLATFORM_EXPORT SharedBuffer : public RefCounted<SharedBuffer> {
     44 public:
     45     static PassRefPtr<SharedBuffer> create() { return adoptRef(new SharedBuffer); }
     46     static PassRefPtr<SharedBuffer> create(size_t size) { return adoptRef(new SharedBuffer(size)); }
     47     static PassRefPtr<SharedBuffer> create(const char* c, int i) { return adoptRef(new SharedBuffer(c, i)); }
     48     static PassRefPtr<SharedBuffer> create(const unsigned char* c, int i) { return adoptRef(new SharedBuffer(c, i)); }
     49 
     50     static PassRefPtr<SharedBuffer> adoptVector(Vector<char>& vector);
     51 
     52     // The buffer must be in non-purgeable state before adopted to a SharedBuffer.
     53     // It will stay that way until released.
     54     static PassRefPtr<SharedBuffer> adoptPurgeableBuffer(PassOwnPtr<PurgeableBuffer>);
     55 
     56     ~SharedBuffer();
     57 
     58     // Calling this function will force internal segmented buffers
     59     // to be merged into a flat buffer. Use getSomeData() whenever possible
     60     // for better performance.
     61     const char* data() const;
     62 
     63     void moveTo(Vector<char>&);
     64 
     65     unsigned size() const;
     66 
     67     bool isEmpty() const { return !size(); }
     68 
     69     void append(SharedBuffer*);
     70     void append(const char*, unsigned);
     71     void append(const Vector<char>&);
     72 
     73     void clear();
     74 
     75     PassRefPtr<SharedBuffer> copy() const;
     76 
     77     bool hasPurgeableBuffer() const { return m_purgeableBuffer.get(); }
     78 
     79     // Ensure this buffer has no other clients before calling this.
     80     PassOwnPtr<PurgeableBuffer> releasePurgeableBuffer();
     81 
     82     // Return the number of consecutive bytes after "position". "data"
     83     // points to the first byte.
     84     // Return 0 when no more data left.
     85     // When extracting all data with getSomeData(), the caller should
     86     // repeat calling it until it returns 0.
     87     // Usage:
     88     //      const char* segment;
     89     //      unsigned pos = 0;
     90     //      while (unsigned length = sharedBuffer->getSomeData(segment, pos)) {
     91     //          // Use the data. for example: decoder->decode(segment, length);
     92     //          pos += length;
     93     //      }
     94     unsigned getSomeData(const char*& data, unsigned position = 0) const;
     95 
     96     void createPurgeableBuffer() const;
     97 
     98     // Creates an ArrayBuffer and copies this SharedBuffer's contents to that
     99     // ArrayBuffer without merging segmented buffers into a flat buffer.
    100     PassRefPtr<ArrayBuffer> getAsArrayBuffer() const;
    101 
    102     // Creates an SkData and copies this SharedBuffer's contents to that
    103     // SkData without merging segmented buffers into a flat buffer.
    104     PassRefPtr<SkData> getAsSkData() const;
    105 
    106 private:
    107     SharedBuffer();
    108     explicit SharedBuffer(size_t);
    109     SharedBuffer(const char*, int);
    110     SharedBuffer(const unsigned char*, int);
    111 
    112     // Calling this function will force internal segmented buffers
    113     // to be merged into a flat buffer. Use getSomeData() whenever possible
    114     // for better performance.
    115     // As well, be aware that this method does *not* return any purgeable
    116     // memory, which can be a source of bugs.
    117     const Vector<char>& buffer() const;
    118 
    119     unsigned m_size;
    120     mutable Vector<char> m_buffer;
    121     mutable Vector<char*> m_segments;
    122     mutable OwnPtr<PurgeableBuffer> m_purgeableBuffer;
    123 };
    124 
    125 } // namespace WebCore
    126 
    127 #endif // SharedBuffer_h
    128