60 lines
1.4 KiB
C++
60 lines
1.4 KiB
C++
/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file psemaphore.h
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* @author drose
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* @date 2008-10-13
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*/
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#ifndef PSEMAPHORE_H
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#define PSEMAPHORE_H
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#include "pandabase.h"
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#include "pmutex.h"
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#include "conditionVar.h"
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#include "mutexHolder.h"
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/**
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* A classic semaphore synchronization primitive.
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*
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* A semaphore manages an internal counter which is decremented by each
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* acquire() call and incremented by each release() call. The counter can
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* never go below zero; when acquire() finds that it is zero, it blocks,
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* waiting until some other thread calls release().
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*/
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class EXPCL_PANDA_PIPELINE Semaphore {
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PUBLISHED:
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INLINE explicit Semaphore(int initial_count = 1);
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Semaphore(const Semaphore ©) = delete;
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~Semaphore() = default;
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Semaphore &operator = (const Semaphore ©) = delete;
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PUBLISHED:
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BLOCKING INLINE void acquire();
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BLOCKING INLINE bool try_acquire();
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INLINE int release();
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INLINE int get_count() const;
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void output(std::ostream &out) const;
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private:
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Mutex _lock;
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ConditionVar _cvar;
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int _count;
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};
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INLINE std::ostream &
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operator << (std::ostream &out, const Semaphore &sem) {
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sem.output(out);
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return out;
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}
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#include "psemaphore.I"
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#endif
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