libsecurity_utilities/lib/bufferfifo.h

   1 /*
   2  * Copyright (c) 2000-2002,2004 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 //
  26 // bufferfifo - a Sink that queues data in a FIFO of buffers for retrieval
  27 //
  28 #ifndef _H_BUFFERFIFO
  29 #define _H_BUFFERFIFO
  30
  31 #include "streams.h"
  32 #include "buffers.h"
  33 #include <list>
  34 #include <queue>
  35
  36
  37 namespace Security {
  38
  39
  40 //
  41 // A BufferFifo acts as a First-in First-out queue of Buffer objects.
  42 // This is usually used as a flexible I/O buffer queue mechanism.
  43 // For convenience, a BufferFifo is a Sink, so you can push data
  44 // into it directly using the Sink mechanism.
  45 // Note that there is currently no mechanism for restricting the
  46 // memory footprint of a BufferFifo.
  47 //
  48 class BufferFifo : public Sink {
  49 public:
  50     BufferFifo(size_t es = 4096) : bufferLength(es) { }
  51     ~BufferFifo();
  52
  53     Buffer *top() const                 { assert(!mBuffers.empty()); return mBuffers.front(); }
  54     Buffer *pop();
  55     void push(Buffer *b)                { mBuffers.push(b); }
  56
  57     bool isEmpty() const                { return mBuffers.empty(); }
  58     size_t size() const                 { return mBuffers.size(); }
  59     size_t topLength() const    { assert(!isEmpty()); return mBuffers.front()->length(); }
  60
  61     // Sink implementation
  62     void consume(const void *data, size_t size);
  63     void clearBuffer();
  64
  65 private:
  66     typedef queue< Buffer *, list<Buffer *> > BufferQueue;
  67     BufferQueue mBuffers;
  68     const size_t bufferLength;
  69 };
  70
  71
  72
  73 }       // end namespace Security
  74
  75
  76 #endif /* _H_BUFFERFIFO */