source: XMLIO_V2/external/src/POCO/Foundation.save/Poco/Condition.h @ 80

//
// Condition.h
//
// $Id: //poco/1.3/Foundation/include/Poco/Condition.h#1 $
//
// Library: Foundation
// Package: Threading
// Module:  Condition
//
// Definition of the Condition class template.
//
// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Condition_INCLUDED
#define Foundation_Condition_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include "Poco/ScopedUnlock.h"
#include "Poco/Event.h"
#include "Poco/Exception.h"
#include <deque>


namespace Poco {


class Foundation_API Condition
        /// A Condition is a synchronization object used to block a thread 
        /// until a particular condition is met. 
        /// A Condition object is always used in conjunction with
        /// a Mutex (or FastMutex) object.
        ///
        /// Condition objects are similar to POSIX condition variables, which the
        /// difference that Condition is not subject to spurious wakeups.
        ///
        /// Threads waiting on a Condition are resumed in FIFO order.
{
public:
        Condition();
                /// Creates the Condition.
        
        ~Condition();
                /// Destroys the Condition.
        
        template <class Mtx>
        void wait(Mtx& mutex)
                /// Unlocks the mutex (which must be locked upon calling
                /// wait()) and waits until the Condition is signalled.
                ///
                /// The given mutex will be locked again upon 
                /// leaving the function, even in case of an exception.
        {
                ScopedUnlock<Mtx> unlock(mutex, false);
                Event event;
                {
                        FastMutex::ScopedLock lock(_mutex);
                        mutex.unlock();
                        enqueue(event);
                }
                event.wait();
        }
        
        template <class Mtx>
        void wait(Mtx& mutex, long milliseconds)
                /// Unlocks the mutex (which must be locked upon calling
                /// wait()) and waits for the given time until the Condition is signalled.
                ///
                /// The given mutex will be locked again upon successfully leaving the 
                /// function, even in case of an exception.
                ///
                /// Throws a TimeoutException if the Condition is not signalled
                /// within the given time interval.
        {
                if (!tryWait(mutex, milliseconds))
                        throw TimeoutException();
        }
        
        template <class Mtx>
        bool tryWait(Mtx& mutex, long milliseconds)
                /// Unlocks the mutex (which must be locked upon calling
                /// tryWait()) and waits for the given time until the Condition is signalled.
                ///
                /// The given mutex will be locked again upon leaving the 
                /// function, even in case of an exception.
                ///
                /// Returns true if the Condition has been signalled
                /// within the given time interval, otherwise false.
        {
                ScopedUnlock<Mtx> unlock(mutex, false);
                Event event;
                {
                        FastMutex::ScopedLock lock(_mutex);
                        mutex.unlock();
                        enqueue(event);
                }
                if (!event.tryWait(milliseconds))
                {
                        FastMutex::ScopedLock lock(_mutex);
                        dequeue(event);
                        return false;
                }
                return true;
        }
        
        void signal();
                /// Signals the Condition and allows one waiting thread
                /// to continue execution.

        void broadcast();
                /// Signals the Condition and allows all waiting
                /// threads to continue their execution.

protected:
        void enqueue(Event& event);
        void dequeue();
        void dequeue(Event& event);
        
private:
        Condition(const Condition&);
        Condition& operator = (const Condition&);
        
        typedef std::deque<Event*> WaitQueue;
        
        FastMutex _mutex;
        WaitQueue _waitQueue;
};


} // namespace Poco


#endif // Foundation_Condition_INCLUDED