cdsa/cdsa_utilities/bufferfifo.h

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // bufferfifo - a Sink that queues data in a FIFO of buffers for retrieval
  21 //
  22 #ifndef _H_BUFFERFIFO
  23 #define _H_BUFFERFIFO
  24
  25 #include "streams.h"
  26 #include "buffers.h"
  27 #include <list>
  28 #include <queue>
  29
  30
  31 namespace Security {
  32
  33
  34 //
  35 // A BufferFifo acts as a First-in First-out queue of Buffer objects.
  36 // This is usually used as a flexible I/O buffer queue mechanism.
  37 // For convenience, a BufferFifo is a Sink, so you can push data
  38 // into it directly using the Sink mechanism.
  39 // Note that there is currently no mechanism for restricting the
  40 // memory footprint of a BufferFifo.
  41 //
  42 class BufferFifo : public Sink {
  43 public:
  44     BufferFifo(size_t es = 4096) : bufferLength(es) { }
  45     ~BufferFifo();
  46
  47     Buffer *top() const                 { assert(!mBuffers.empty()); return mBuffers.front(); }
  48     Buffer *pop();
  49     void push(Buffer *b)                { mBuffers.push(b); }
  50
  51     bool isEmpty() const                { return mBuffers.empty(); }
  52     size_t size() const                 { return mBuffers.size(); }
  53     size_t topLength() const    { assert(!isEmpty()); return mBuffers.front()->length(); }
  54
  55     // Sink implementation
  56     void consume(const void *data, size_t size);
  57     void clearBuffer();
  58
  59 private:
  60     typedef queue< Buffer *, list<Buffer *> > BufferQueue;
  61     BufferQueue mBuffers;
  62     const size_t bufferLength;
  63 };
  64
  65
  66
  67 }       // end namespace Security
  68
  69
  70 #endif _H_BUFFERFIFO