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 #include "WExportCommon.h"
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 OWCOMMON_EXPORT WConditionOneShot: public WCondition
00041 {
00042     friend class WConditionOneShot_test;
00043 public:
00044 
00045     /**
00046      * Default constructor.
00047      */
00048     WConditionOneShot();
00049 
00050     /**
00051      * Destructor.
00052      */
00053     virtual ~WConditionOneShot();
00054 
00055     /**
00056      * Wait for the condition. Sets the calling thread asleep.
00057      */
00058     virtual void wait() const;
00059 
00060     /**
00061      * Notifies all waiting threads.
00062      */
00063     virtual void notify();
00064 
00065 protected:
00066 
00067     /**
00068      * Locked as long the condition was not fired.
00069      */
00070     boost::unique_lock<boost::shared_mutex> m_lock;
00071 
00072 private:
00073 };
00074 
00075 #endif  // WCONDITIONONESHOT_H
00076 
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