source: XMLIO_V2/external/include/Poco/Activity.h @ 80

//
// Activity.h
//
// $Id: //poco/1.3/Foundation/include/Poco/Activity.h#2 $
//
// Library: Foundation
// Package: Threading
// Module:  ActiveObjects
//
// Definition of the Activity template class.
//
// Copyright (c) 2004-2006, 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_Activity_INCLUDED
#define Foundation_Activity_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/RunnableAdapter.h"
#include "Poco/ThreadPool.h"
#include "Poco/Event.h"
#include "Poco/Mutex.h"


namespace Poco {


template <class C>
class Activity: public Runnable
        /// This template class helps to implement active objects.
        /// An active object uses threads to decouple method
        /// execution from method invocation, or to perform tasks
        /// autonomously, without intervention of a caller.
        ///
        /// An activity is a (typically longer running) method
        /// that executes within its own task. Activities can
        /// be started automatically (upon object construction)
        /// or manually at a later time. Activities can also
        /// be stopped at any time. However, to make stopping
        /// an activity work, the method implementing the
        /// activity has to check periodically whether it
        /// has been requested to stop, and if so, return. 
        /// Activities are stopped before the object they belong to is
        /// destroyed. Methods implementing activities cannot have arguments
        /// or return values. 
        ///
        /// Activity objects are used as follows:
        ///
        ///     class ActiveObject
        ///     {
        ///     public:
        ///         ActiveObject(): 
        ///             _activity(this, &ActiveObject::runActivity)
        ///         {
        ///             ...
        ///         }
        ///   
        ///         ...
        ///  
        ///     protected:
        ///         void runActivity()
        ///         {
        ///             while (!_activity.isStopped())
        ///             {
        ///                 ...
        ///             }
        ///         }
        ///
        ///     private:
        ///         Activity<ActiveObject> _activity;
        ///     };
{
public:
        typedef RunnableAdapter<C> RunnableAdapterType;
        typedef typename RunnableAdapterType::Callback Callback;

        Activity(C* pOwner, Callback method):
                _pOwner(pOwner),
                _runnable(*pOwner, method),
                _stopped(true),
                _running(false),
                _done(false)
                /// Creates the activity. Call start() to
                /// start it.
        {
                poco_check_ptr (pOwner);
        }
        
        ~Activity()
                /// Stops and destroys the activity.
        {
                stop();
                wait();
        }
        
        void start()
                /// Starts the activity by acquiring a
                /// thread for it from the default thread pool.
        {
                FastMutex::ScopedLock lock(_mutex);
                
                if (!_running)
                {
                        _done.reset();
                        _stopped = false;
                        _running = true;
                        try
                        {
                                ThreadPool::defaultPool().start(*this);
                        }
                        catch (...)
                        {
                                _running = false;
                                throw;
                        }
                }
        }
        
        void stop()
                /// Requests to stop the activity.
        {
                FastMutex::ScopedLock lock(_mutex);

                _stopped = true;
        }
        
        void wait()
                /// Waits for the activity to complete.
        {
                if (_running)
                {
                        _done.wait();
                }
        }

        void wait(long milliseconds)
                /// Waits the given interval for the activity to complete.
                /// An TimeoutException is thrown if the activity does not
                /// complete within the given interval.
        {
                if (_running)
                {
                        _done.wait(milliseconds);
                }
        }
        
        bool isStopped() const
                /// Returns true if the activity has been requested to stop.
        {
                return _stopped;
        }
        
        bool isRunning() const
                /// Returns true if the activity is running.
        {
                return _running;
        }

protected:
        void run()
        {
                try
                {
                        _runnable.run();
                }
                catch (...)
                {
                        _running = false;
                        _done.set();
                        throw;
                }
                _running = false;
                _done.set();
        }
        
private:
        Activity();
        Activity(const Activity&);
        Activity& operator = (const Activity&);

        C*                  _pOwner;
        RunnableAdapterType _runnable;
        volatile bool       _stopped;
        volatile bool       _running;
        Event               _done;
        FastMutex           _mutex;
};


} // namespace Poco


#endif // Foundation_Activity_INCLUDED