itkConditionVariable.h

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkConditionVariable.h,v $
  Language:  C++
  Date:      $Date: 2004/12/11 17:31:47 $
  Version:   $Revision: 1.8 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef  _itkConditionVariable_h_
#define  _itkConditionVariable_h_

#include "itkConfigure.h"

// This implementation uses a routine called SignalObjectAndWait()
// which is only defined on WinNT 4.0 or greater systems.  We need to
// define this symbol in order to get the prototype for the
// routine. This needs to be done before we load any system headers.
#ifdef ITK_USE_WIN32_THREADS
#undef _WIN32_WINNT
#define _WIN32_WINNT 0x0400
#endif

#include "itkMutexLock.h"
#include "itkLightObject.h"


namespace itk {

class ITKCommon_EXPORT ConditionVariable : public LightObject
{
public:
  typedef ConditionVariable Self;
  typedef LightObject Superclass;
  typedef SmartPointer<Self> Pointer;
  typedef SmartPointer<const Self> ConstPointer;
  
  itkNewMacro(Self);
  
  itkTypeMacro(ConditionVariable, LightObject);

  void Wait(SimpleMutexLock * mutex);

  void Signal();

  void Broadcast();

protected:
  ConditionVariable();
  ~ConditionVariable();

private:
  ConditionVariable(const Self & other);
  const Self & operator=( const Self & );
#ifdef ITK_USE_PTHREADS
  pthread_cond_t m_ConditionVariable;
  MutexType m_Mutex;
#else
  int m_NumberOfWaiters;                   // number of waiting threads
#ifdef WIN32
  CRITICAL_SECTION m_NumberOfWaitersLock;  // Serialize access to m_NumberOfWaiters

  HANDLE m_Semaphore;                      // Semaphore to queue threads 
  HANDLE m_WaitersAreDone;                 // Auto-reset event used by the
                                           // broadcast/signal thread to
                                           // wait for all the waiting
                                           // threads to wake up and
                                           // release the semaphore

  size_t m_WasBroadcast;                   // Keeps track of whether we
                                           // were broadcasting or signaling
#endif
#endif
};

}//end of itk namespace

#endif

---