181 lines
4.9 KiB
C++
181 lines
4.9 KiB
C++
///////////////////////////////////////////////////////////////////////////
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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_MUTEX_H
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#define INCLUDED_ILM_THREAD_MUTEX_H
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//-----------------------------------------------------------------------------
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//
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// class Mutex, class Lock
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//
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// Class Mutex is a wrapper for a system-dependent mutual exclusion
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// mechanism. Actual locking and unlocking of a Mutex object must
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// be performed using an instance of a Lock (defined below).
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//
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// Class lock provides safe locking and unlocking of mutexes even in
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// the presence of C++ exceptions. Constructing a Lock object locks
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// the mutex; destroying the Lock unlocks the mutex.
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//
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// Lock objects are not themselves thread-safe. You should never
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// share a Lock object among multiple threads.
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//
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// Typical usage:
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//
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// Mutex mtx; // Create a Mutex object that is visible
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// //to multiple threads
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//
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// ... // create some threads
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//
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// // Then, within each thread, construct a critical section like so:
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//
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// {
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// Lock lock (mtx); // Lock constructor locks the mutex
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// ... // do some computation on shared data
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// } // leaving the block unlocks the mutex
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//
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//-----------------------------------------------------------------------------
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#include "IlmThreadExport.h"
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#include "IlmBaseConfig.h"
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#include "IlmThreadNamespace.h"
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#ifdef ILMBASE_FORCE_CXX03
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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
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# include <pthread.h>
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# endif
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#else
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# include <mutex>
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#endif
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
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// in c++11, this can just be
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//
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// using Mutex = std::mutex;
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// unfortunately we can't use std::unique_lock as a replacement for Lock since
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// they have different API.
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//
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// if we decide to break the API, we can just
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//
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// using Lock = std::lock_guard<std::mutex>;
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// or
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// using Lock = std::unique_lock<std::mutex>;
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//
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// (or eliminate the type completely and have people use the std library)
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#ifdef ILMBASE_FORCE_CXX03
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class Lock;
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class ILMTHREAD_EXPORT Mutex
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{
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public:
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Mutex ();
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virtual ~Mutex ();
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private:
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void lock () const;
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void unlock () const;
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#if defined _WIN32 || defined _WIN64
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mutable CRITICAL_SECTION _mutex;
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#elif HAVE_PTHREAD
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mutable pthread_mutex_t _mutex;
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#endif
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void operator = (const Mutex& M); // not implemented
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Mutex (const Mutex& M); // not implemented
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friend class Lock;
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};
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#else
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using Mutex = std::mutex;
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#endif
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class ILMTHREAD_EXPORT Lock
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{
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public:
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Lock (const Mutex& m, bool autoLock = true):
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_mutex (const_cast<Mutex &>(m)), _locked (false)
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{
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if (autoLock)
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{
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_mutex.lock();
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_locked = true;
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}
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}
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~Lock ()
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{
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if (_locked)
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_mutex.unlock();
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}
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void acquire ()
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{
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_mutex.lock();
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_locked = true;
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}
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void release ()
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{
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_mutex.unlock();
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_locked = false;
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}
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bool locked ()
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{
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return _locked;
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}
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private:
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Mutex & _mutex;
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bool _locked;
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};
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ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
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#endif // INCLUDED_ILM_THREAD_MUTEX_H
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