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

//
// TimedNotificationQueue.h
//
// $Id: //poco/1.3/Foundation/include/Poco/TimedNotificationQueue.h#4 $
//
// Library: Foundation
// Package: Notifications
// Module:  TimedNotificationQueue
//
// Definition of the TimedNotificationQueue class.
//
// Copyright (c) 2009, 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_TimedNotificationQueue_INCLUDED
#define Foundation_TimedNotificationQueue_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Notification.h"
#include "Poco/Mutex.h"
#include "Poco/Event.h"
#include "Poco/Timestamp.h"
#include <map>


namespace Poco {


class Foundation_API TimedNotificationQueue
        /// A TimedNotificationQueue object provides a way to implement timed, 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 TimedNotificationQueue is quite similar to the NotificationQueue class.
        /// The only difference to NotificationQueue is that each Notification is tagged
        /// with a Timestamp. When inserting a Notification into the queue, the
        /// Notification is inserted according to the given Timestamp, with 
        /// lower Timestamp values being inserted before higher ones.
        ///
        /// Notifications are dequeued in order of their timestamps.
        ///
        /// TimedNotificationQueue has some restrictions regarding multithreaded use.
        /// While multiple threads may enqueue notifications, only one thread at a
        /// time may dequeue notifications from the queue.
        ///
        /// If two threads try to dequeue a notification simultaneously, the results
        /// are undefined.
{
public:
        TimedNotificationQueue();
                /// Creates the TimedNotificationQueue.

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

        void enqueueNotification(Notification::Ptr pNotification, Timestamp timestamp);
                /// Enqueues the given notification by adding it to
                /// the queue according to the given timestamp.
                /// Lower timestamp values are inserted before higher ones.
                /// The queue takes ownership of the notification, thus
                /// a call like
                ///     notificationQueue.enqueueNotification(new MyNotification, someTime);
                /// does not result in a memory leak.

        Notification* dequeueNotification();
                /// Dequeues the next pending notification with a timestamp
                /// less than or equal to the current 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.
                ///
                /// It is highly recommended that the result is immediately
                /// assigned to a Notification::Ptr, to avoid potential
                /// memory management issues.
                
        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.
                ///
                /// It is highly recommended that the result is immediately
                /// assigned to a Notification::Ptr, to avoid potential
                /// memory management issues.

        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.
                ///
                /// It is highly recommended that the result is immediately
                /// assigned to a Notification::Ptr, to avoid potential
                /// memory management issues.

        bool empty() const;
                /// Returns true iff the queue is empty.
                
        int size() const;
                /// Returns the number of notifications in the queue.

        void clear();
                /// Removes all notifications from the queue.
                ///
                /// Calling clear() while another thread executes one of
                /// the dequeue member functions will result in undefined
                /// behavior.

protected:
        typedef std::multimap<Timestamp, Notification::Ptr> NfQueue;
        Notification::Ptr dequeueOne(NfQueue::iterator& it);
        bool wait(Timestamp::TimeDiff interval);
        
private:
        NfQueue _nfQueue;
        Event   _nfAvailable;
        mutable FastMutex _mutex;
};


} // namespace Poco


#endif // Foundation_TimedNotificationQueue_INCLUDED