notificationqueue.h

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

//
// NotificationQueue.h
//
// $Id: //poco/Main/Foundation/include/Foundation/NotificationQueue.h#5 $
//
// Definition of the NotificationQueue 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_NotificationQueue_INCLUDED
#define Foundation_NotificationQueue_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef Foundation_Mutex_INCLUDED
#include "Foundation/Mutex.h"
#endif
#ifndef Foundation_Event_INCLUDED
#include "Foundation/Event.h"
#endif
#ifndef STD_DEQUE_INCLUDED
#include <deque>
#define STD_DEQUE_INCLUDED
#endif


Foundation_BEGIN


class Notification;
class NotificationCenter;


class Foundation_API NotificationQueue
	/// A NotificationQueue object provides a way to implement asynchronous
	/// notifications. This is especially useful for sending notifications
	/// from one thread to another, for example from a background thread to 
	/// the main (user interface) thread. 
	/// 
	/// The NotificationQueue can also be used to distribute work from
	/// a controlling thread to one or more worker threads. Each worker thread
	/// repeatedly calls waitDequeueNotification() and processes the
	/// returned notification. Special care must be taken when shutting
	/// down a queue with worker threads waiting for notifications.
	/// The recommended sequence to shut down and destroy the queue is to
	///   1. set a termination flag for every worker thread
	///   2. call the wakeUpAll() method
	///   3. join each worker thread
	///   4. destroy the notification queue.
{
public:
	NotificationQueue();
		/// Creates the NotificationQueue.

	~NotificationQueue();
		/// Destroys the NotificationQueue.

	void enqueueNotification(Notification* pNotification);
		/// Enqueues the given notification.
		/// The queue takes ownership of the notification, thus
		/// a call like
		///     notificationQueue.enqueueNotification(new MyNotification);
		/// does not result in a memory leak.

	Notification* dequeueNotification();
		/// Dequeues the next pending notification.
		/// Returns 0 (null) if no notification is available.
		/// The caller gains ownership of the notification and
		/// is expected to release it when done with it.

	Notification* waitDequeueNotification();
		/// Dequeues the next pending notification.
		/// If no notification is available, waits for a notification
		/// to be enqueued. 
		/// The caller gains ownership of the notification and
		/// is expected to release it when done with it.
		/// This method returns 0 (null) if wakeUpWaitingThreads()
		/// has been called by another thread.

	Notification* waitDequeueNotification(long milliseconds);
		/// Dequeues the next pending notification.
		/// If no notification is available, waits for a notification
		/// to be enqueued up to the specified time.
		/// Returns 0 (null) if no notification is available.
		/// The caller gains ownership of the notification and
		/// is expected to release it when done with it.

	void dispatch(NotificationCenter& notificationCenter);
		/// Dispatches all queued notifications to the given
		/// notification center.

	void wakeUpAll();
		/// Wakes up all threads that wait for a notification.
	
	bool empty() const;
		/// Returns true iff the queue is empty.
		
	int size() const;
		/// Returns the number of notifications in the queue.

	static NotificationQueue& defaultQueue();
		/// Returns a reference to the default
		/// NotificationQueue.

protected:
	Notification* dequeueOne();
	
private:
	typedef std::deque<Notification*> NfQueue;
	struct WaitInfo
	{
		Notification* pNf;
		Event         nfAvailable;
	};
	typedef std::deque<WaitInfo*> WaitQueue;

	NfQueue           _nfQueue;
	WaitQueue         _waitQueue;
	mutable FastMutex _mutex;
};


Foundation_END


#endif // Foundation_NotificationQueue_INCLUDED