001/*
002 * GWTEventService
003 * Copyright (c) 2011 and beyond, strawbill UG (haftungsbeschr?nkt)
004 *
005 * This is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU Lesser General Public License as
007 * published by the Free Software Foundation; either version 3 of
008 * the License, or (at your option) any later version.
009 * Other licensing for GWTEventService may also be possible on request.
010 * Please view the license.txt of the project for more information.
011 *
012 * This software is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this software; if not, write to the Free
019 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021 */
022package de.novanic.eventservice.service.registry.user;
023
024import de.novanic.eventservice.service.UserTimeoutListener;
025import de.novanic.eventservice.util.PlatformUtil;
026
027import java.util.*;
028import java.util.concurrent.ConcurrentLinkedQueue;
029
030/**
031 * UserActivityScheduler observes the activities of the users/clients and can report timeouts.
032 * To observe the users/clients, the UserActivityScheduler must be started with the start method
033 * ({@link UserActivityScheduler#start(boolean)}).
034 *
035 * @author sstrohschein
036 *         <br>Date: 20.01.2009
037 *         <br>Time: 23:30:47
038 */
039public class UserActivityScheduler
040{
041    private final Collection<UserInfo> myUserInfoCollection;
042    private final Queue<UserTimeoutListener> myTimeoutListeners;
043    private final long myTimeoutInterval;
044    private Timer myTimer;
045    private TimeoutTimerTask myTimeoutTimerTask;
046    private boolean myIsAutoClean;
047    private boolean isActive;
048
049    /**
050     * Creates a new UserActivityScheduler with a reference to a Collection of {@link UserInfo}.
051     * @param aUserInfoCollection all UserInfo instances to observe
052     * @param aTimeoutInterval milliseconds to the timeout
053     */
054    protected UserActivityScheduler(Collection<UserInfo> aUserInfoCollection, long aTimeoutInterval) {
055        myUserInfoCollection = aUserInfoCollection;
056        myTimeoutInterval = aTimeoutInterval;
057        myTimeoutListeners = new ConcurrentLinkedQueue<UserTimeoutListener>();
058    }
059
060    /**
061     * Adds a {@link de.novanic.eventservice.service.UserTimeoutListener} to the {@link de.novanic.eventservice.service.registry.user.UserActivityScheduler}.
062     * @param aTimeoutListener listener to get reported timeouts
063     */
064    public void addTimeoutListener(UserTimeoutListener aTimeoutListener) {
065        myTimeoutListeners.add(aTimeoutListener);
066    }
067
068    /**
069     * Removes a {@link de.novanic.eventservice.service.UserTimeoutListener} from the {@link de.novanic.eventservice.service.registry.user.UserActivityScheduler}.
070     * @param aTimeoutListener listener to get reported timeouts
071     */
072    public void removeTimeoutListener(UserTimeoutListener aTimeoutListener) {
073        myTimeoutListeners.remove(aTimeoutListener);
074    }
075
076    /**
077     * Removes all {@link de.novanic.eventservice.service.UserTimeoutListener} from the {@link de.novanic.eventservice.service.registry.user.UserActivityScheduler}.
078     */
079    public void removeTimeoutListeners() {
080        myTimeoutListeners.clear();
081    }
082
083    /**
084     * That method starts the UserActivityScheduler to observe the users/clients. The activities will be checked like
085     * the timeout interval is configured ({@link de.novanic.eventservice.config.EventServiceConfiguration#getTimeoutTime()}).
086     * @param isAutoClean when set to true, the users/clients are removed automatically on timeout
087     */
088    public void start(boolean isAutoClean) {
089        if(!isActive) {
090            myIsAutoClean = isAutoClean;
091            myTimer = new Timer("GWTEventService-UserActivityScheduler", true);
092            myTimeoutTimerTask = new TimeoutTimerTask();
093            isActive = true;
094            schedule(myTimer, myTimeoutTimerTask, myTimeoutInterval);
095        }
096    }
097
098    /**
099     * Stops the UserActivityScheduler. At that point, the users/clients won't be observed anymore.
100     */
101    public void stop() {
102        if(isActive) {
103            isActive = false;
104
105            if(myTimer != null) {
106                myTimer.cancel();
107            }
108            if(myTimeoutTimerTask != null) {
109                myTimeoutTimerTask.cancel();
110            }
111            if(myTimer != null) {
112                myTimer.purge();
113            }
114        }
115    }
116
117    /**
118     * Returns the state of the UserActivityScheduler. Returns true when the UserActivityScheduler is started
119     * ({@link UserActivityScheduler#start(boolean)}) and false when the UserActivityScheduler isn't started or stopped
120     * ({@link de.novanic.eventservice.service.registry.user.UserActivityScheduler#stop()}).
121     * @return true when running/started, false when running (not started or stopped)
122     */
123    public boolean isActive() {
124        return isActive;
125    }
126
127    /**
128     * Returns the configured timeout time/interval. The user activity is checked in that interval.
129     * @return timeout time/interval
130     */
131    public long getTimeoutInterval() {
132        return myTimeoutInterval;
133    }
134
135    /**
136     * That method must be called to report a user activity and protects the user from a timeout for the time of the
137     * timeout interval ({@link de.novanic.eventservice.config.EventServiceConfiguration#getTimeoutTime()}).
138     * @param aUserInfo user/client to refresh
139     */
140    public void reportUserActivity(UserInfo aUserInfo) {
141        aUserInfo.reportUserActivity();
142    }
143
144    /**
145     * That method is used to measure the timeout and it will remove the user automatically, if configured with the start method
146     * ({@link de.novanic.eventservice.service.registry.user.UserActivityScheduler#start(boolean)}).
147     * @param aTimer timer to schedule
148     * @param aTimeoutTimerTask TimeoutTimerTask
149     * @param aTimeoutInterval interval to check for timeouts
150     */
151    private void schedule(Timer aTimer, TimeoutTimerTask aTimeoutTimerTask, long aTimeoutInterval) {
152        aTimer.schedule(aTimeoutTimerTask, 0L, aTimeoutInterval);
153    }
154
155    /**
156     * The TimeoutTimerTask runs in the interval which is configured with {@link de.novanic.eventservice.config.EventServiceConfiguration#getTimeoutTime()}.
157     * All added {@link de.novanic.eventservice.service.UserTimeoutListener} get informed about the occurred timeout
158     * with the execution of that {@link java.util.TimerTask}. The TimeoutTimerTask starts when the UserActivityScheduler
159     * is started ({@link de.novanic.eventservice.service.registry.user.UserActivityScheduler#start(boolean)}) and stops when
160     * the UserActivityScheduler is stopped ({@link de.novanic.eventservice.service.registry.user.UserActivityScheduler#stop()}).
161     */
162    private class TimeoutTimerTask extends TimerTask
163    {
164        public void run() {
165            final long theTimeoutCriteriaTime = PlatformUtil.getCurrentTime() - myTimeoutInterval;
166
167            Iterator<UserInfo> theUserInfoIterator = myUserInfoCollection.iterator();
168            while(theUserInfoIterator.hasNext()) {
169                UserInfo theUserInfo = theUserInfoIterator.next();
170                if(isTimeout(theUserInfo, theTimeoutCriteriaTime)) {
171                    //report about user timeout
172                    for(UserTimeoutListener theTimeoutListener: myTimeoutListeners) {
173                        theTimeoutListener.onTimeout(theUserInfo);
174                    }
175                    //remove the user/client automatically if auto-clean is switched on
176                    if(myIsAutoClean) {
177                        theUserInfoIterator.remove();
178                    }
179                }
180            }
181        }
182
183        /**
184         * Reports a timeout when {@link UserInfo#getLastActivityTime()} is greater than the max. timeout time (the
185         * current time + {@link de.novanic.eventservice.config.EventServiceConfiguration#getTimeoutTime()}).  
186         * @param aUserInfo user/client to check for a timeout
187         * @param aTimeoutCriteriaTime timeout time to compare {@link UserInfo#getLastActivityTime()}
188         * @return True if the {@link UserInfo#getLastActivityTime()} is too long ago, otherwise true
189         */
190        private boolean isTimeout(UserInfo aUserInfo, long aTimeoutCriteriaTime) {
191            return (aUserInfo.getLastActivityTime() <= aTimeoutCriteriaTime);
192        }
193    }
194}