activity.h

This software aims to create an applet and panel tools to manage a wireless interface card, such as

//
// Activity.h
//
// $Id: //poco/Main/Foundation/include/Foundation/Activity.h#5 $
//
// Definition of the Activity template class.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef Foundation_Activity_INCLUDED
#define Foundation_Activity_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef Foundation_RunnableAdapter_INCLUDED
#include "Foundation/RunnableAdapter.h"
#endif
#ifndef Foundation_ThreadPool_INCLUDED
#include "Foundation/ThreadPool.h"
#endif
#ifndef Foundation_Event_INCLUDED
#include "Foundation/Event.h"
#endif
#ifndef Foundation_Mutex_INCLUDED
#include "Foundation/Mutex.h"
#endif


Foundation_BEGIN


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 (_stopped)
		{
			_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;
};


Foundation_END


#endif // Foundation_Activity_INCLUDED