Panda3D
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psemaphore.h
00001 // Filename: psemaphore.h
00002 // Created by:  drose (13Oct08)
00003 //
00004 ////////////////////////////////////////////////////////////////////
00005 //
00006 // PANDA 3D SOFTWARE
00007 // Copyright (c) Carnegie Mellon University.  All rights reserved.
00008 //
00009 // All use of this software is subject to the terms of the revised BSD
00010 // license.  You should have received a copy of this license along
00011 // with this source code in a file named "LICENSE."
00012 //
00013 ////////////////////////////////////////////////////////////////////
00014 
00015 #ifndef PSEMAPHORE_H
00016 #define PSEMAPHORE_H
00017 
00018 #include "pandabase.h"
00019 #include "pmutex.h"
00020 #include "conditionVar.h"
00021 
00022 ////////////////////////////////////////////////////////////////////
00023 //       Class : Semaphore
00024 // Description : A classic semaphore synchronization primitive.  
00025 //
00026 //               A semaphore manages an internal counter which is
00027 //               decremented by each acquire() call and incremented by
00028 //               each release() call. The counter can never go below
00029 //               zero; when acquire() finds that it is zero, it
00030 //               blocks, waiting until some other thread calls
00031 //               release().
00032 ////////////////////////////////////////////////////////////////////
00033 class EXPCL_PANDA_PIPELINE Semaphore {
00034 PUBLISHED:
00035   INLINE Semaphore(int initial_count = 1);
00036   INLINE ~Semaphore();
00037 private:
00038   INLINE Semaphore(const Semaphore &copy);
00039   INLINE void operator = (const Semaphore &copy);
00040 
00041 PUBLISHED:
00042   BLOCKING INLINE void acquire();
00043   BLOCKING INLINE bool try_acquire();
00044   INLINE int release();
00045 
00046   INLINE int get_count() const;
00047   void output(ostream &out) const;
00048 
00049 private:
00050   Mutex _lock;
00051   ConditionVar _cvar;
00052   int _count;
00053 };
00054 
00055 INLINE ostream &
00056 operator << (ostream &out, const Semaphore &sem) {
00057   sem.output(out);
00058   return out;
00059 }
00060 
00061 #include "psemaphore.I"
00062 
00063 #endif
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