Blame IlmThread/IlmThreadSemaphore.h

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///////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2005-2012, Industrial Light & Magic, a division of Lucas
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// Digital Ltd. LLC
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// 
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// All rights reserved.
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// 
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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// *       Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// *       Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// *       Neither the name of Industrial Light & Magic nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission. 
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// 
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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///////////////////////////////////////////////////////////////////////////
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#ifndef INCLUDED_ILM_THREAD_SEMAPHORE_H
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#define INCLUDED_ILM_THREAD_SEMAPHORE_H
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//-----------------------------------------------------------------------------
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//
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//	class Semaphore -- a wrapper class for
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//	system-dependent counting semaphores
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//
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//-----------------------------------------------------------------------------
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#include "IlmBaseConfig.h"
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#include "IlmThreadExport.h"
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#include "IlmThreadNamespace.h"
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#if defined _WIN32 || defined _WIN64
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    #ifdef NOMINMAX
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        #undef NOMINMAX
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    #endif
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    #define NOMINMAX
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    #include <windows.h>
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#elif HAVE_PTHREAD && !HAVE_POSIX_SEMAPHORES
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    #include <pthread.h>
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#elif HAVE_PTHREAD && HAVE_POSIX_SEMAPHORES
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    #include <semaphore.h>
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#endif
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
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class ILMTHREAD_EXPORT Semaphore
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{
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  public:
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    Semaphore (unsigned int value = 0);
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    virtual ~Semaphore();
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    void	wait();
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    bool	tryWait();
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    void	post();
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    int		value() const;
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  private:
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    #if defined _WIN32 || defined _WIN64
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	mutable HANDLE _semaphore;
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    #elif HAVE_PTHREAD && !HAVE_POSIX_SEMAPHORES
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	//
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	// If the platform has Posix threads but no semapohores,
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	// then we implement them ourselves using condition variables
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	//
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	struct sema_t
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	{
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	    unsigned int count;
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	    unsigned long numWaiting;
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	    pthread_mutex_t mutex;
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	    pthread_cond_t nonZero;
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	};
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	mutable sema_t _semaphore;
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    #elif HAVE_PTHREAD && HAVE_POSIX_SEMAPHORES
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	mutable sem_t _semaphore;
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    #endif
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    void operator = (const Semaphore& s);	// not implemented
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    Semaphore (const Semaphore& s);		// not implemented
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};
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
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#endif // INCLUDED_ILM_THREAD_SEMAPHORE_H