MutexNSPR.h

Go to the documentation of this file.

/****************** <VPR heading BEGIN do not edit this line> *****************
 *
 * VR Juggler Portable Runtime
 *
 * Original Authors:
 *   Allen Bierbaum, Patrick Hartling, Kevin Meinert, Carolina Cruz-Neira
 *
 * -----------------------------------------------------------------
 * File:          $RCSfile$
 * Date modified: $Date: 2005-01-17 22:34:01 -0600 (Mon, 17 Jan 2005) $
 * Version:       $Revision: 16635 $
 * -----------------------------------------------------------------
 *
 ****************** <VPR heading END do not edit this line> ******************/

/*************** <auto-copyright.pl BEGIN do not edit this line> **************
 *
 * VR Juggler is (C) Copyright 1998-2005 by Iowa State University
 *
 * Original Authors:
 *   Allen Bierbaum, Christopher Just,
 *   Patrick Hartling, Kevin Meinert,
 *   Carolina Cruz-Neira, Albert Baker
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 *************** <auto-copyright.pl END do not edit this line> ***************/

#ifndef _VPR_MUTEX_NSPR_H_
#define _VPR_MUTEX_NSPR_H_

#include <vpr/vprConfig.h>

#include <stdio.h>
#include <stdlib.h>
#include <prlock.h>

#include <vpr/Util/Assert.h>
#include <vpr/Util/ReturnStatus.h>


namespace vpr
{

class VPR_CLASS_API MutexNSPR
{
public:
   MutexNSPR() : mLocked(0)
   {
      // ----- Allocate the mutex ----- //
      mMutex = PR_NewLock();
      vprASSERT(mMutex != NULL);
   }

   ~MutexNSPR()
   {
      PR_DestroyLock(mMutex);
   }

   vpr::ReturnStatus acquire()
   {
      PR_Lock(mMutex);
      mLocked = 1;

      return vpr::ReturnStatus();
   }

   vpr::ReturnStatus acquireRead()
   {
      return this->acquire();
   }

   vpr::ReturnStatus acquireWrite()
   {
      return this->acquire();
   }

   vpr::ReturnStatus tryAcquire()
   {
      // XXX: Possible race condition exists in this function implementation
      if ( mLocked == 0 )
      {
         this->acquire();
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

   vpr::ReturnStatus tryAcquireRead()
   {
      return this->tryAcquire();
   }

   vpr::ReturnStatus tryAcquireWrite()
   {
      return this->tryAcquire();
   }

   vpr::ReturnStatus release()
   {
      mLocked = 0;
      if ( PR_Unlock(mMutex) == PR_SUCCESS )
      {
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

   int test() const
   {
      return mLocked;
   }

   // Allow the vpr::CondNSPR class to access the private and protected
   // members of this class.  Specifically, direct access is needed to the
   // mutex variable.
   friend class CondVarNSPR;

protected:
   PRLock* mMutex;     
   int     mLocked;    
   // = Prevent assignment and initialization.
   MutexNSPR& operator=(const MutexNSPR& r)
   {
      mMutex = r.mMutex;
      mLocked = r.mLocked;
      return *this;
   }

   MutexNSPR(const MutexNSPR &)
   {
      /* Do nothing. */ ;
   }
};

} // End of vpr namespace


#endif   /* ifdef _VPR_MUTEX_NSPR_H_ */

---