text: ///////////////////////////////////////////////////////////////////////////
  //
  // Copyright (c) 2005, 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 "IlmBaseConfig.h"
  
  #if defined _WIN32 || defined _WIN64
      #ifdef NOMINMAX
          #undef NOMINMAX
      #endif
      #define NOMINMAX
      #include <windows.h>
  #elif HAVE_PTHREAD
      #include <pthread.h>
  #endif
  
  namespace IlmThread {
  
  class Lock;
  
  
  class 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;
  };
  
  
  class Lock
  {
    public:
  
      Lock (const Mutex& m, bool autoLock = true):
  	_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:
  
      const Mutex &	_mutex;
      bool		_locked;
  };
  
  
  } // namespace IlmThread
  
  #endif
  