source: XMLIO_V2/external/src/POCO/Foundation/TimedNotificationQueue.cpp @ 80

//
// TimedNotificationQueue.cpp
//
// $Id: //poco/1.3/Foundation/src/TimedNotificationQueue.cpp#5 $
//
// Library: Foundation
// Package: Notifications
// Module:  TimedNotificationQueue
//
// 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.
//


#include <Poco/TimedNotificationQueue.h>
#include <Poco/Notification.h>
#include <limits>


namespace Poco {


TimedNotificationQueue::TimedNotificationQueue()
{
}


TimedNotificationQueue::~TimedNotificationQueue()
{
        clear();
}


void TimedNotificationQueue::enqueueNotification(Notification::Ptr pNotification, Timestamp timestamp)
{
        poco_check_ptr (pNotification);

        FastMutex::ScopedLock lock(_mutex);
        _nfQueue.insert(NfQueue::value_type(timestamp, pNotification));
        _nfAvailable.set();
}


Notification* TimedNotificationQueue::dequeueNotification()
{
        FastMutex::ScopedLock lock(_mutex);

        NfQueue::iterator it = _nfQueue.begin();
        if (it != _nfQueue.end())
        {
                Timestamp::TimeDiff sleep = -it->first.elapsed();
                if (sleep <= 0)
                {
                        Notification::Ptr pNf = it->second;
                        _nfQueue.erase(it);
                        return pNf.duplicate();
                }
        }
        return 0;
}


Notification* TimedNotificationQueue::waitDequeueNotification()
{
        for (;;)
        {
                _mutex.lock();
                NfQueue::iterator it = _nfQueue.begin();
                if (it != _nfQueue.end())
                {
                        _mutex.unlock();
                        Timestamp::TimeDiff sleep = -it->first.elapsed();
                        if (sleep <= 0)
                        {
                                return dequeueOne(it).duplicate();
                        }
                        else if (!wait(sleep))
                        {
                                return dequeueOne(it).duplicate();
                        }
                        else continue;
                }
                else
                {
                        _mutex.unlock();
                }
                _nfAvailable.wait();
        }
}


Notification* TimedNotificationQueue::waitDequeueNotification(long milliseconds)
{
        while (milliseconds >= 0)
        {
                _mutex.lock();
                NfQueue::iterator it = _nfQueue.begin();
                if (it != _nfQueue.end())
                {
                        _mutex.unlock();
                        Poco::Timestamp now;
                        Timestamp::TimeDiff sleep = it->first - now;
                        if (sleep <= 0)
                        {
                                return dequeueOne(it).duplicate();
                        }
                        else if (sleep <= 1000*Timestamp::TimeDiff(milliseconds))
                        {
                                if (!wait(sleep))
                                {
                                        return dequeueOne(it).duplicate();
                                }
                                else 
                                {
                                        milliseconds -= static_cast<long>((now.elapsed() + 999)/1000);
                                        continue;
                                }
                        }
                }
                else
                {
                        _mutex.unlock();
                }
                if (milliseconds > 0)
                {
                        Poco::Timestamp now;
                        _nfAvailable.tryWait(milliseconds);
                        milliseconds -= static_cast<long>((now.elapsed() + 999)/1000);
                }
                else return 0;
        }
        return 0;
}


bool TimedNotificationQueue::wait(Timestamp::TimeDiff interval)
{
        const Timestamp::TimeDiff MAX_SLEEP = 8*60*60*Timestamp::TimeDiff(1000000); // sleep at most 8 hours at a time
        while (interval > 0)
        {
                Timestamp now;
                Timestamp::TimeDiff sleep = interval <= MAX_SLEEP ? interval : MAX_SLEEP;
                if (_nfAvailable.tryWait(static_cast<long>((sleep + 999)/1000)))
                        return true;
                interval -= now.elapsed();
        }
        return false;
}


bool TimedNotificationQueue::empty() const
{
        FastMutex::ScopedLock lock(_mutex);
        return _nfQueue.empty();
}

        
int TimedNotificationQueue::size() const
{
        FastMutex::ScopedLock lock(_mutex);
        return static_cast<int>(_nfQueue.size());
}


void TimedNotificationQueue::clear()
{
        FastMutex::ScopedLock lock(_mutex);
        _nfQueue.clear();       
}


Notification::Ptr TimedNotificationQueue::dequeueOne(NfQueue::iterator& it)
{
        FastMutex::ScopedLock lock(_mutex);
        Notification::Ptr pNf = it->second;
        _nfQueue.erase(it);
        return pNf;
}


} // namespace Poco