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/*
* Copyright 2005 Joe Walker
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.directwebremoting.impl;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
import org.directwebremoting.Container;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.event.ScriptSessionEvent;
import org.directwebremoting.event.ScriptSessionListener;
import org.directwebremoting.extend.ConverterManager;
import org.directwebremoting.extend.InitializingBean;
import org.directwebremoting.extend.PageNormalizer;
import org.directwebremoting.extend.RealScriptSession;
import org.directwebremoting.extend.ScriptSessionManager;
import org.directwebremoting.extend.UninitializingBean;
import org.directwebremoting.util.Loggers;
/**
* A default implementation of ScriptSessionManager.
* You should note that {@link DefaultScriptSession} and
* {@link DefaultScriptSessionManager} make calls to each other and you should
* take care not to break any constraints in inheriting from these classes.
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/
public class DefaultScriptSessionManager implements ScriptSessionManager, InitializingBean, UninitializingBean
{
/* (non-Javadoc)
* @see org.directwebremoting.extend.InitializingBean#afterContainerSetup(org.directwebremoting.Container)
*/
public void afterContainerSetup(Container container)
{
Runnable runnable = new Runnable()
{
public void run()
{
maybeCheckTimeouts();
}
};
future = executor.scheduleWithFixedDelay(runnable, 60, 60, TimeUnit.SECONDS);
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.UninitializingBean#destroy()
*/
public void destroy()
{
future.cancel(true);
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getScriptSession(java.lang.String)
*/
public RealScriptSession getOrCreateScriptSession(String sentScriptId, String page, HttpSession httpSession)
{
maybeCheckTimeouts();
DefaultScriptSession scriptSession;
// We only use a "full" script session when we got an id from the
// client layer. When there is no script session id we just create
// a temporary script session for the duration of the call
if ("".equals(sentScriptId))
{
scriptSession = createScriptSession("", page);
Loggers.SESSION.debug("Creating temporary script session on " + scriptSession.getPage());
}
else
{
scriptSession = sessionMap.get(sentScriptId);
if (scriptSession == null)
{
scriptSession = createScriptSession(sentScriptId, page);
Loggers.SESSION.debug("Creating " + scriptSession + " on " + scriptSession.getPage());
sessionMap.putIfAbsent(sentScriptId, scriptSession);
// See notes on synchronization in invalidate()
fireScriptSessionCreatedEvent(scriptSession);
}
else
{
// This could be called from a poll or an rpc call, so this is a
// good place to update the session access time
scriptSession.updateLastAccessedTime();
String storedPage = scriptSession.getPage();
if (!storedPage.equals(page))
{
scriptSession.setPage(page);
}
}
final String httpSessionId = (httpSession != null ? httpSession.getId() : null);
// Keep ScriptSession association to its HttpSession (if any)
synchronized (scriptSession)
{
if (scriptSession.getHttpSessionId() != null && !scriptSession.getHttpSessionId().equals(httpSessionId))
{
disassociateScriptSessionAndHttpSession(scriptSession, httpSessionId);
}
if (httpSessionId != null && !httpSessionId.equals(scriptSession.getHttpSessionId()))
{
associateScriptSessionAndHttpSession(scriptSession, httpSessionId);
}
}
// Listen for HttpSession invalidation to update association to ScriptSession
if (httpSession != null)
{
HttpSessionBindingListener invalidationListener = (HttpSessionBindingListener) httpSession.getAttribute(ATTRIBUTE_INVALIDATIONLISTENER);
if (invalidationListener == null)
{
synchronized (this)
{
// This is a valid use of DCL as the getAttribute() calls are synchronized
invalidationListener = (HttpSessionBindingListener) httpSession.getAttribute(ATTRIBUTE_INVALIDATIONLISTENER);
if (invalidationListener == null)
{
httpSession.setAttribute(ATTRIBUTE_INVALIDATIONLISTENER, new InvalidationListener(this, httpSessionId));
}
}
}
}
}
// Maybe we should update the access time of the ScriptSession?
// scriptSession.updateLastAccessedTime();
// Since this call could come from outside of a call from the
// browser, it's not really an indication that this session is still
// alive, so we don't.
return scriptSession;
}
/**
* Extension point allowing for custom implementations of the DefaultScriptSession.
* @param sentScriptId The script ID that was sent by the browser, and should
* likely be used to create the DefaultScripSession.
* @param page The page for which the scriptsession needs to be created.
* @return the DefaultScriptSession object for this sentScriptId
* and page
*/
protected DefaultScriptSession createScriptSession(String sentScriptId, String page)
{
return new DefaultScriptSession(sentScriptId, this, page, converterManager, jsonOutput);
}
/**
* Link a script session and an http session in some way
* Exactly what we should do here is still something of a mystery. We don't
* really have much experience on the best way to handle this, so currently
* we're just setting a script session attribute that points at the
* http session id, and not exposing it.
*
This method is an ideal point to override and do something better.
* @param scriptSession The script session to be linked to an http session
* @param httpSessionId The http session from the browser with the given scriptSession
*/
protected void associateScriptSessionAndHttpSession(DefaultScriptSession scriptSession, String httpSessionId)
{
if (httpSessionId == null)
{
return;
}
// We may have to retry as we are (deliberately) not locking the parent map
boolean done = false;
do {
Set scriptSessions = httpSessionXref.get(httpSessionId);
if (scriptSessions == null)
{
scriptSessions = new HashSet();
httpSessionXref.putIfAbsent(httpSessionId, scriptSessions);
}
// We use the lock on the script session set to coordinate both access
// to the set AND to lock the map key pointing to it
synchronized (scriptSessions)
{
if (httpSessionXref.get(httpSessionId) != scriptSessions) {
// The key mapping was changed by another thread before we
// managed to lock it.
// Retry by taking another spin in the loop.
}
else
{
// We have a lock on the script session set and we know it is
// mapped by the key, so safe to add the new script session and
// consider us done
scriptSessions.add(scriptSession);
done = true;
}
}
} while(!done);
// Update field on ScriptSession outside synchronized block to avoid deadlocks
scriptSession.setHttpSessionId(httpSessionId);
}
/**
* Unlink any http sessions from this script session
*/
protected void disassociateScriptSessionAndHttpSession(DefaultScriptSession scriptSession, String httpSessionId)
{
if (httpSessionId == null)
{
return;
}
Set scriptSessions = httpSessionXref.get(httpSessionId);
if (scriptSessions == null)
{
return;
}
// We use the lock on the script session set to coordinate both access
// to the set AND to lock the map key pointing to it
synchronized (scriptSessions)
{
if (!scriptSessions.contains(scriptSession))
{
return;
}
scriptSessions.remove(scriptSession);
if (scriptSessions.size() == 0)
{
httpSessionXref.remove(httpSessionId);
}
}
// Update field on ScriptSession outside synchronized block to avoid deadlocks
scriptSession.setHttpSessionId(null);
}
private void disassociateAllScriptSessionsFromHttpSession(String httpSessionId)
{
if (httpSessionId == null)
{
return;
}
Set scriptSessions = httpSessionXref.get(httpSessionId);
if (scriptSessions == null)
{
return;
}
// We use the lock on the script session set to coordinate both access
// to the set AND to lock the map key pointing to it
Set copy = new HashSet();
synchronized (scriptSessions)
{
copy.addAll(scriptSessions);
scriptSessions.clear();
httpSessionXref.remove(httpSessionId);
}
// Update field on all the ScriptSessions outside synchronized block to avoid deadlocks
for(DefaultScriptSession scriptSession : copy)
{
synchronized (scriptSession)
{
if (httpSessionId.equals(scriptSession.getHttpSessionId()))
{
scriptSession.setHttpSessionId(null);
}
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.ScriptSessionManager#getScriptSessionById(java.lang.String)
*/
public ScriptSession getScriptSessionById(String scriptSessionId)
{
return sessionMap.get(scriptSessionId);
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.ScriptSessionManager#getScriptSessionsByHttpSessionId(java.lang.String)
*/
public Collection getScriptSessionsByHttpSessionId(String httpSessionId)
{
Collection reply = new HashSet();
Set scriptSessions = httpSessionXref.get(httpSessionId);
if (scriptSessions != null)
{
// We need to lock the set to keep it stable from updates in associate()
// and disassociate() while we loop
synchronized (scriptSessions)
{
reply.addAll(scriptSessions);
}
}
return reply;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getAllScriptSessions()
*/
public Collection getAllScriptSessions()
{
Set reply = new HashSet();
reply.addAll(sessionMap.values());
return reply;
}
/**
* Remove the given session from the list of sessions that we manage, and
* leave it for the GC vultures to pluck.
* @param scriptSession The session to get rid of
*/
protected void invalidate(DefaultScriptSession scriptSession)
{
Loggers.SESSION.debug("Invalidating " + scriptSession + " from " + scriptSession.getPage());
// Due to the way systems get a number of script sessions for a page
// and the perform a number of actions on them, we may get a number
// of invalidation checks, and therefore calls to invalidate().
// We could protect ourselves from this by having a
// 'hasBeenInvalidated' flag, but we're taking the simple option
// here of just allowing multiple invalidations.
sessionMap.remove(scriptSession.getId());
synchronized (scriptSession)
{
disassociateScriptSessionAndHttpSession(scriptSession, scriptSession.getHttpSessionId());
}
// Are there any risks from doing this outside the locks?
// The initial analysis is that 'Destroyed' is past tense so you would
// have expected it to have happened already.
fireScriptSessionDestroyedEvent(scriptSession);
}
/**
* If we call {@link #checkTimeouts()} too often is could bog things down so
* we only check every one in a while (default 30 secs); this checks to see
* of we need to check, and checks if we do.
*/
protected void maybeCheckTimeouts()
{
long now = System.currentTimeMillis();
if (now - scriptSessionCheckTime > lastSessionCheckAt)
{
checkTimeouts();
lastSessionCheckAt = now;
}
}
/**
* Do a check on all the known sessions to see if and have timeout and need
* removing.
*/
protected void checkTimeouts()
{
long now = System.currentTimeMillis();
List timeouts = new ArrayList();
for (DefaultScriptSession session : sessionMap.values())
{
if (session.isInvalidated())
{
continue;
}
long age = now - session.getLastAccessedTime();
if (age > scriptSessionTimeout)
{
timeouts.add(session);
}
}
for (ScriptSession scriptSession : timeouts)
{
DefaultScriptSession session = (DefaultScriptSession) scriptSession;
session.invalidate();
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.ScriptSessionManager#addScriptSessionListener(org.directwebremoting.event.ScriptSessionListener)
*/
public void addScriptSessionListener(ScriptSessionListener li)
{
scriptSessionListeners.add(li);
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.ScriptSessionManager#removeScriptSessionListener(org.directwebremoting.event.ScriptSessionListener)
*/
public void removeScriptSessionListener(ScriptSessionListener li)
{
scriptSessionListeners.remove(li);
}
/**
* This should be called whenever a {@link ScriptSession} is created
* @param scriptSession The newly created ScriptSession
*/
protected void fireScriptSessionCreatedEvent(ScriptSession scriptSession)
{
ScriptSessionEvent ev = null;
for (int i = scriptSessionListeners.size() - 1; i >= 0; i--)
{
if (ev == null)
{
ev = new ScriptSessionEvent(scriptSession);
}
scriptSessionListeners.get(i).sessionCreated(ev);
}
}
/**
* This should be called whenever a {@link ScriptSession} is destroyed
* @param scriptSession The newly destroyed ScriptSession
*/
protected void fireScriptSessionDestroyedEvent(ScriptSession scriptSession)
{
ScriptSessionEvent ev = null;
for (int i = scriptSessionListeners.size() - 1; i >= 0; i--)
{
if (ev == null)
{
ev = new ScriptSessionEvent(scriptSession);
}
scriptSessionListeners.get(i).sessionDestroyed(ev);
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.ScriptSessionManager#getInitCode()
*/
public String getInitCode()
{
return "dwr.engine._execute(dwr.engine._pathToDwrServlet, '__System', 'pageLoaded', [ function() { dwr.engine._ordered = false; }]);";
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getScriptSessionTimeout()
*/
public long getScriptSessionTimeout()
{
return scriptSessionTimeout;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#setScriptSessionTimeout(long)
*/
public void setScriptSessionTimeout(long scriptSessionTimeout)
{
this.scriptSessionTimeout = scriptSessionTimeout;
}
/**
* How long do we wait before we timeout script sessions?
*/
private long scriptSessionTimeout = DEFAULT_TIMEOUT_MILLIS;
/**
* How we turn pages into the canonical form.
* @param pageNormalizer The new PageNormalizer
*/
public void setPageNormalizer(PageNormalizer pageNormalizer)
{
this.pageNormalizer = pageNormalizer;
}
/**
* @see #setPageNormalizer(PageNormalizer)
*/
protected PageNormalizer pageNormalizer;
/**
* How often do we check for script sessions that need timing out
*/
public void setScriptSessionCheckTime(long scriptSessionCheckTime)
{
this.scriptSessionCheckTime = scriptSessionCheckTime;
}
/**
* @see #setScriptSessionCheckTime(long)
*/
protected long scriptSessionCheckTime = DEFAULT_SESSION_CHECK_TIME;
/**
* How often do we check for script sessions that need timing out
*/
public void setScheduledThreadPoolExecutor(ScheduledThreadPoolExecutor executor)
{
this.executor = executor;
}
/*
* Accessor for the ConverterManager that we configure
* @param converterManager
*/
public void setConverterManager(ConverterManager converterManager)
{
this.converterManager = converterManager;
}
/**
* How we convert parameters
*/
protected ConverterManager converterManager = null;
/**
* @param jsonOutput Are we outputting in JSON mode?
*/
public void setJsonOutput(boolean jsonOutput)
{
this.jsonOutput = jsonOutput;
}
/**
* Are we outputting in JSON mode?
*/
protected boolean jsonOutput = false;
/**
* @see #setScheduledThreadPoolExecutor(ScheduledThreadPoolExecutor)
*/
protected ScheduledThreadPoolExecutor executor;
/**
* HttpSession attribute that stores the invalidation listener
*/
protected static final String ATTRIBUTE_INVALIDATIONLISTENER = DefaultScriptSessionManager.class.getName() + ".InvalidationListener";
/**
* By default we check for sessions that need expiring every 30 seconds
*/
protected static final long DEFAULT_SESSION_CHECK_TIME = 30000;
/**
* The list of current {@link ScriptSessionListener}s
*/
protected List scriptSessionListeners = new CopyOnWriteArrayList();
/**
* The session timeout checker function so we can shutdown cleanly
*/
private volatile ScheduledFuture future;
/**
* We check for sessions that need timing out every
* {@link #scriptSessionCheckTime}; this is when we last checked.
*/
protected volatile long lastSessionCheckAt = System.currentTimeMillis();
/**
* The map of all the known sessions.
* The key is the script session id, the value is the session data
*/
protected final ConcurrentMap sessionMap = new ConcurrentHashMap();
/**
* Allows us to associate script sessions with http sessions.
* The key is an http session id, the value is a set of script sessions
*/
protected final ConcurrentMap> httpSessionXref = new ConcurrentHashMap>();
/**
* BindingListener used to detect session destroy so we can clean up our ScriptSession cross-reference.
* @author Mike Wilson
*/
private static class InvalidationListener implements HttpSessionBindingListener, Serializable
{
private final transient DefaultScriptSessionManager scriptSessionManager;
private final transient String httpSessionId;
public InvalidationListener(DefaultScriptSessionManager scriptSessionManager, String httpSessionId)
{
this.scriptSessionManager = scriptSessionManager;
this.httpSessionId = httpSessionId;
}
public void valueBound(HttpSessionBindingEvent arg0)
{
// NOP
}
public void valueUnbound(HttpSessionBindingEvent arg0)
{
if (scriptSessionManager != null && httpSessionId != null)
{
scriptSessionManager.disassociateAllScriptSessionsFromHttpSession(httpSessionId);
}
}
}
}