112 lines
2.8 KiB
C
112 lines
2.8 KiB
C
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//
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// SPDX-License-Identifier: BSD-3-Clause
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// Copyright (c) Contributors to the OpenEXR Project.
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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 "IlmThreadExport.h"
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#include "IlmThreadConfig.h"
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#include "IlmThreadNamespace.h"
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//
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// Decipher the platform-specific threading support.
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// Set the ILMTHREAD_SEMAPHORE_* defines to indicate the corresponding
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// implementation of the Semaphore class. Only one of these should be
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// defined.
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//
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#if ILMTHREAD_THREADING_ENABLED
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# if ILMTHREAD_HAVE_POSIX_SEMAPHORES
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# include <semaphore.h>
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# define ILMTHREAD_SEMAPHORE_POSIX 1
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# elif defined(__APPLE__)
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# include <AvailabilityMacros.h>
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# if MAC_OS_X_VERSION_MIN_REQUIRED > 1050 && !defined(__ppc__)
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# include <dispatch/dispatch.h>
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# define ILMTHREAD_SEMAPHORE_OSX 1
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# else
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# include <condition_variable>
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# include <mutex>
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# define ILMTHREAD_SEMAPHORE_OTHER 1
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# endif
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# elif (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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# define ILMTHREAD_SEMAPHORE_WINDOWS 1
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# else
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# include <condition_variable>
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# include <mutex>
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# define ILMTHREAD_SEMAPHORE_OTHER 1
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# endif
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#else
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# define ILMTHREAD_SEMAPHORE_DISABLED 1
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#endif
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
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class ILMTHREAD_EXPORT_TYPE Semaphore
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{
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public:
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ILMTHREAD_EXPORT Semaphore (unsigned int value = 0);
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ILMTHREAD_EXPORT virtual ~Semaphore ();
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ILMTHREAD_EXPORT void wait ();
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ILMTHREAD_EXPORT bool tryWait ();
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ILMTHREAD_EXPORT void post ();
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ILMTHREAD_EXPORT int value () const;
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private:
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#if ILMTHREAD_SEMAPHORE_POSIX
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mutable sem_t _semaphore;
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#elif ILMTHREAD_SEMAPHORE_OSX
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mutable dispatch_semaphore_t _semaphore;
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#elif ILMTHREAD_SEMAPHORE_WINDOWS
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mutable HANDLE _semaphore;
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#elif ILMTHREAD_SEMAPHORE_OTHER
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//
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// If the platform has threads but no semaphores,
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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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std::mutex mutex;
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std::condition_variable nonZero;
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};
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mutable sema_t _semaphore;
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#endif
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void operator= (const Semaphore& s) = delete;
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Semaphore (const Semaphore& s) = delete;
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void operator= (Semaphore&& s) = delete;
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Semaphore (Semaphore&& s) = delete;
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};
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
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#endif // INCLUDED_ILM_THREAD_SEMAPHORE_H
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