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///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2005-2012, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_ILM_THREAD_MUTEX_H
#define INCLUDED_ILM_THREAD_MUTEX_H
//-----------------------------------------------------------------------------
//
// class Mutex, class Lock
//
// Class Mutex is a wrapper for a system-dependent mutual exclusion
// mechanism. Actual locking and unlocking of a Mutex object must
// be performed using an instance of a Lock (defined below).
//
// Class lock provides safe locking and unlocking of mutexes even in
// the presence of C++ exceptions. Constructing a Lock object locks
// the mutex; destroying the Lock unlocks the mutex.
//
// Lock objects are not themselves thread-safe. You should never
// share a Lock object among multiple threads.
//
// Typical usage:
//
// Mutex mtx; // Create a Mutex object that is visible
// //to multiple threads
//
// ... // create some threads
//
// // Then, within each thread, construct a critical section like so:
//
// {
// Lock lock (mtx); // Lock constructor locks the mutex
// ... // do some computation on shared data
// } // leaving the block unlocks the mutex
//
//-----------------------------------------------------------------------------
#include "IlmThreadExport.h"
#include "IlmBaseConfig.h"
#include "IlmThreadNamespace.h"
#ifdef ILMBASE_FORCE_CXX03
# if defined _WIN32 || defined _WIN64
# ifdef NOMINMAX
# undef NOMINMAX
# endif
# define NOMINMAX
# include <windows.h>
# elif HAVE_PTHREAD
# include <pthread.h>
# endif
#else
# include <mutex>
#endif
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
// in c++11, this can just be
//
// using Mutex = std::mutex;
// unfortunately we can't use std::unique_lock as a replacement for Lock since
// they have different API.
//
// if we decide to break the API, we can just
//
// using Lock = std::lock_guard<std::mutex>;
// or
// using Lock = std::unique_lock<std::mutex>;
//
// (or eliminate the type completely and have people use the std library)
#ifdef ILMBASE_FORCE_CXX03
class Lock;
class ILMTHREAD_EXPORT Mutex
{
public:
Mutex ();
virtual ~Mutex ();
private:
void lock () const;
void unlock () const;
#if defined _WIN32 || defined _WIN64
mutable CRITICAL_SECTION _mutex;
#elif HAVE_PTHREAD
mutable pthread_mutex_t _mutex;
#endif
void operator = (const Mutex& M); // not implemented
Mutex (const Mutex& M); // not implemented
friend class Lock;
};
#else
using Mutex = std::mutex;
#endif
class ILMTHREAD_EXPORT Lock
{
public:
Lock (const Mutex& m, bool autoLock = true):
_mutex (const_cast<Mutex &>(m)), _locked (false)
{
if (autoLock)
{
_mutex.lock();
_locked = true;
}
}
~Lock ()
{
if (_locked)
_mutex.unlock();
}
void acquire ()
{
_mutex.lock();
_locked = true;
}
void release ()
{
_mutex.unlock();
_locked = false;
}
bool locked ()
{
return _locked;
}
private:
Mutex & _mutex;
bool _locked;
};
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
#endif // INCLUDED_ILM_THREAD_MUTEX_H
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