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wefts_semaphore.h

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00001 /*
00002    wefts_semaphore.h
00003    Semaphore object header file.
00004 
00005    $Id: wefts_semaphore.h,v 1.3 2004/03/10 14:57:04 jonnymind Exp $
00006 ---------------------------------------
00007    Begin      : Mon, 08 Mar 2004 21:52:32 +0100
00008    Author     : Giancarlo Niccolai
00009 
00010    Last modified because:
00011    Implementing OS independent base threading
00012 */
00013 
00014 /**************************************************************************
00015 *   This program is free software; you can redistribute it and/or modify  *
00016 *   it under the terms of the GNU Library General Public License as       *
00017 *   published by the Free Software Foundation; either version 2.1 of the  *
00018 *   License, or (at your option) any later version.                       *
00019 ***************************************************************************/
00020 
00021 #ifndef WT_SEMAPHORE_H
00022 #define WT_SEMAPHORE_H
00023 
00024 #include <wefts_fastcond.h>
00025 
00026 namespace Wefts {
00027 
00048 class Semaphore: public CleanupHandler
00049 {
00050 private:
00051    int m_count;
00052    int m_waiting;
00053    FastCondition m_cond;
00054    
00055 public:
00071    Semaphore( int initial_count = 1 )
00072    {
00073       m_count = initial_count;
00074       m_waiting = 0;
00075    }
00076    
00084    inline int value() { return m_count; }
00085    
00093    inline int waiters() { return m_waiting; }
00094    
00108    inline void post(int amount=1) {
00109       m_cond.lock();
00110       m_count+=amount;
00111       // todo: would be greatly optimized if signal would not do a broadcast.
00112       if ( m_waiting > 0 ) 
00113       {
00114          if ( m_count == 1 )
00115             m_cond.signalOne();
00116          else if ( m_count > 1 )
00117             m_cond.signal();
00118       }
00119       m_cond.unlock();
00120    }
00121    
00142    void wait(CleanupHandler *handler = 0, int position = 0);
00143       
00158    bool wait( double seconds, CleanupHandler *handler = 0, int position = 0 );
00159    
00167    bool tryWait()
00168    {
00169       bool ret;
00170       m_cond.lock();
00171       if ( m_count > 0 ) { 
00172          m_count --;
00173          ret = true;
00174       }
00175       else
00176          ret = false;
00177       m_cond.unlock();
00178       
00179       return ret;
00180    }
00181       
00182    virtual void handleCleanup( int code, void *caller=0 );  
00183 };
00184 
00185 }
00186 #endif
00187 /* end of wefts_semaphore.h */

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