RWMutexPosix.h

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/****************** <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_RWMUTEX_POSIX_H_
#define _VPR_RWMUTEX_POSIX_H_

#include <vpr/vprConfig.h>

#include <stdio.h>
#include <pthread.h>
#include <errno.h>

#include <vpr/Util/ReturnStatus.h>


namespace vpr
{

class RWMutexPosix
{
public:
   RWMutexPosix() : mLocked(0)
   {
      // Initialize the mutex.
      pthread_rwlock_init(&mRWMutex, NULL);
   }

   ~RWMutexPosix()
   {
      // Destroy the mutex.
      if ( pthread_rwlock_destroy(&mRWMutex) == -1 )
      {
         pthread_rwlock_unlock(&mRWMutex);
         pthread_rwlock_destroy(&mRWMutex);
      }
   }

   vpr::ReturnStatus acquire()
   { 
      return acquireWrite();
   }

   vpr::ReturnStatus acquireRead()
   {
      int retval = pthread_rwlock_rdlock(&mRWMutex);

      // Locking succeeded.
      if ( retval == 0 )
      {
         mLocked = 1;
         return vpr::ReturnStatus();
      }
#ifdef _DEBUG
      // This thread tried to lock the mutex twice and a deadlock condition
      // was reported.
      else if ( retval == EDEADLK )
      {
         perror("Tried to lock mutex twice (RWMutexPosix.h:146)");
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
#endif
      // Some other error occurred.
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

   vpr::ReturnStatus acquireWrite()
   {
      int retval = pthread_rwlock_wrlock(&mRWMutex);

      // Locking succeeded.
      if ( retval == 0 )
      {
         mLocked = 1;
         return vpr::ReturnStatus();
      }
#ifdef _DEBUG
      // This thread tried to lock the mutex twice and a deadlock condition
      // was reported.
      else if ( retval == EDEADLK )
      {
         perror("Tried to lock mutex twice (RWMutexPosix.h:184)");
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
#endif
      // Some other error occurred.
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

   vpr::ReturnStatus tryAcquire()
   {
      return tryAcquireWrite();
   }

   vpr::ReturnStatus tryAcquireRead()
   {
      if ( pthread_rwlock_tryrdlock(&mRWMutex) == 0 )
      {
         mLocked = 1;
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }

   }

   vpr::ReturnStatus tryAcquireWrite()
   {
      if ( pthread_rwlock_trywrlock(&mRWMutex) == 0 )
      {
         mLocked = 1;
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }

   }

   vpr::ReturnStatus release()
   {
      mLocked = 0;
      if ( pthread_rwlock_unlock(&mRWMutex) == 0 )
      {
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

   int test()
   {
      return mLocked;
   }

protected:
   pthread_rwlock_t  mRWMutex;    
   int               mLocked;     
   // = Prevent assignment and initialization.
   void operator= (const RWMutexPosix &) {;}
   RWMutexPosix (const RWMutexPosix &) {;}
};

} // End of vpr namespace


#endif  /* ifdef _VPR_RWMUTEX_POSIX_H_ */

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