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137 lines
2.7 KiB
137 lines
2.7 KiB
/*
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a thread safe ring buffer without dependencies
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Copyright (C) 1999 Martin Vogt
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation.
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For more information look at the file COPYRIGHT in this package
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*/
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#ifndef _SIMPLERINGBUFFER_H
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#define _SIMPLERINGBUFFER_H
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#include "../util/abstract/abs_thread.h"
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extern "C" {
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#include <stdio.h>
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}
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/**
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Note to parameter minLinBufSize in Constructor:
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<p>
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If the fillgrade is sufficient we can delivier at least
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this amount of bytes with one "fill"
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(If the fillgrade is not suffficient we can only deliever fillgrade)
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This values adresses the problem that a ring buffer cannot
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deliever linear memory the whole time(eg. if you read near the
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upper end)
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<p>
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If the requested Buffersize by the device is smaller than
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this number you can be sure that you get exactly
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your preferred buffersize. not more not less.(but
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only if the fillgrade allows this)
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*/
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class SimpleRingBuffer {
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public:
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SimpleRingBuffer(int ringBufferSize, int minLinBufferSize);
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virtual ~SimpleRingBuffer();
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// Writer thread can call these:
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int getWriteArea(char* &ptr,int &size);
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void forwardWritePtr(int bytes);
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int waitForSpace(int minSpace);
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void exitWaitForSpace();
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void setCanWaitForSpace(int lCanWaitForSpace);
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// Reader thread these:
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void forwardReadPtr(int bytes);
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int getReadArea(char* &ptr,int &size);
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int waitForData(int minData);
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void exitWaitForData();
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void setCanWaitForData(int lCanWaitForData);
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int getCanWaitForData();
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// and the lockPos
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void forwardLockPtr(int bytes);
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// both:
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int getFillgrade(); // return how much buffer between reader/writer
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void emptyBuffer(); // frees the space between them
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int getFreeRead();
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int getFreeWrite();
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int getSize();
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int getReadBytes();
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int getWriteBytes();
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// make sure that no one calls getReadArea/getWriteArea
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void resizeBuffer(int changeSize);
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private:
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void updateCanWrite();
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void updateCanRead();
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int size;
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int lockgrade;
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int fillgrade;
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char* readPos;
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char* writePos;
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char* lockPos;
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char* startPos;
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char* lastPos;
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char* eofPos;
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int canWrite;
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int canRead;
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int waitMinData;
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int waitMinSpace;
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abs_thread_mutex_t mut;
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abs_thread_cond_t dataCond;
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abs_thread_cond_t spaceCond;
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int insertBlock;
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int readBlock;
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int linAvail;
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char* minLinBuf;
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int minLinBufSize;
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int lWaitForData;
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int lWaitForSpace;
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// statistic purpose:
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int readBytes;
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int writeBytes;
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int lCanWaitForSpace;
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int lCanWaitForData;
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int instance;
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};
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#endif
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