OpenWalnut  1.4.0
WConditionOneShot.h
00001 //---------------------------------------------------------------------------
00002 //
00003 // Project: OpenWalnut ( http://www.openwalnut.org )
00004 //
00005 // Copyright 2009 OpenWalnut Community, BSV@Uni-Leipzig and CNCF@MPI-CBS
00006 // For more information see http://www.openwalnut.org/copying
00007 //
00008 // This file is part of OpenWalnut.
00009 //
00010 // OpenWalnut is free software: you can redistribute it and/or modify
00011 // it under the terms of the GNU Lesser General Public License as published by
00012 // the Free Software Foundation, either version 3 of the License, or
00013 // (at your option) any later version.
00014 //
00015 // OpenWalnut is distributed in the hope that it will be useful,
00016 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00018 // GNU Lesser General Public License for more details.
00019 //
00020 // You should have received a copy of the GNU Lesser General Public License
00021 // along with OpenWalnut. If not, see <http://www.gnu.org/licenses/>.
00022 //
00023 //---------------------------------------------------------------------------
00024 
00025 #ifndef WCONDITIONONESHOT_H
00026 #define WCONDITIONONESHOT_H
00027 
00028 #include <boost/thread.hpp>
00029 
00030 #include "WCondition.h"
00031 
00032 
00033 /**
00034  * Implements a WCondition, but can be fired only ONCE. This is useful if you want to have a thread waiting for a condition but
00035  * you can not assure that the thread already waits when you set the condition. This would cause the thread to wait endlessly
00036  * because he does not know that you already fired it. Implementation is simple. The constructor uses a unique lock (write lock)
00037  * on a mutex. All waiting threads try to get a read lock which is not possible as long it is write-locked. The notify method
00038  * releases the write lock and all waiting threads can continue.
00039  */
00040 class WConditionOneShot: public WCondition
00041 {
00042     friend class WConditionOneShot_test;
00043 public:
00044     /**
00045      * Default constructor.
00046      */
00047     WConditionOneShot();
00048 
00049     /**
00050      * Destructor.
00051      */
00052     virtual ~WConditionOneShot();
00053 
00054     /**
00055      * Wait for the condition. Sets the calling thread asleep.
00056      */
00057     virtual void wait() const;
00058 
00059     /**
00060      * Notifies all waiting threads.
00061      */
00062     virtual void notify();
00063 
00064 protected:
00065     /**
00066      * Locked as long the condition was not fired.
00067      */
00068     boost::unique_lock<boost::shared_mutex> m_lock;
00069 
00070 private:
00071 };
00072 
00073 #endif  // WCONDITIONONESHOT_H
00074