third_party/WebKit/Source/platform/SharedBuffer.h

   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 "platform/PurgeableVector.h"
  32 #include "third_party/skia/include/core/SkData.h"
  33 #include "wtf/Forward.h"
  34 #include "wtf/OwnPtr.h"
  35 #include "wtf/RefCounted.h"
  36 #include "wtf/text/WTFString.h"
  37
  38 namespace blink {
  39
  40 class PLATFORM_EXPORT SharedBuffer : public RefCounted<SharedBuffer> {
  41 public:
  42     enum : unsigned { kSegmentSize = 0x1000 };
  43
  44     static PassRefPtr<SharedBuffer> create() { return adoptRef(new SharedBuffer); }
  45     static PassRefPtr<SharedBuffer> create(size_t size) { return adoptRef(new SharedBuffer(size)); }
  46     static PassRefPtr<SharedBuffer> create(const char* c, int i) { return adoptRef(new SharedBuffer(c, i)); }
  47     static PassRefPtr<SharedBuffer> create(const unsigned char* c, int i) { return adoptRef(new SharedBuffer(c, i)); }
  48
  49     static PassRefPtr<SharedBuffer> createPurgeable(const char* c, unsigned size) { return adoptRef(new SharedBuffer(c, size, PurgeableVector::Purgeable)); }
  50
  51     static PassRefPtr<SharedBuffer> adoptVector(Vector<char>&);
  52
  53     ~SharedBuffer();
  54
  55     // Calling this function will force internal segmented buffers to be merged
  56     // into a flat buffer. Use getSomeData() whenever possible for better
  57     // performance.
  58     const char* data() const;
  59
  60     unsigned size() const;
  61
  62     bool isEmpty() const { return !size(); }
  63
  64     void append(PassRefPtr<SharedBuffer>);
  65     void append(const char*, unsigned);
  66     void append(const Vector<char>&);
  67
  68     void clear();
  69
  70     PassRefPtr<SharedBuffer> copy() const;
  71
  72     // Return the number of consecutive bytes after "position". "data"
  73     // points to the first byte.
  74     // Return 0 when no more data left.
  75     // When extracting all data with getSomeData(), the caller should
  76     // repeat calling it until it returns 0.
  77     // Usage:
  78     //      const char* segment;
  79     //      unsigned pos = 0;
  80     //      while (unsigned length = sharedBuffer->getSomeData(segment, pos)) {
  81     //          // Use the data. for example: decoder->decode(segment, length);
  82     //          pos += length;
  83     //      }
  84     unsigned getSomeData(const char*& data, unsigned position = 0) const;
  85
  86     // Returns the content data into "dest" as a flat buffer. "byteLength" must
  87     // exactly match with size(). Returns true on success, otherwise the content
  88     // of "dest" is not guaranteed.
  89     bool getAsBytes(void* dest, unsigned byteLength) const;
  90
  91     // Creates an SkData and copies this SharedBuffer's contents to that
  92     // SkData without merging segmented buffers into a flat buffer.
  93     PassRefPtr<SkData> getAsSkData() const;
  94
  95     // See PurgeableVector::lock().
  96     bool lock();
  97
  98     // WARNING: Calling unlock() on a SharedBuffer that wasn't created with the
  99     // purgeability option does an extra memcpy(). Please use
 100     // SharedBuffer::createPurgeable() if you intend to call unlock().
 101     void unlock();
 102
 103     bool isLocked() const;
 104
 105 private:
 106     SharedBuffer();
 107     explicit SharedBuffer(size_t);
 108     SharedBuffer(const char*, int);
 109     SharedBuffer(const unsigned char*, int);
 110     SharedBuffer(const char*, unsigned, PurgeableVector::PurgeableOption);
 111
 112     // See SharedBuffer::data().
 113     void mergeSegmentsIntoBuffer() const;
 114
 115     unsigned m_size;
 116     mutable PurgeableVector m_buffer;
 117     mutable Vector<char*> m_segments;
 118 };
 119
 120 } // namespace blink
 121
 122 #endif // SharedBuffer_h