org.directwebremoting.impl.DefaultScriptSessionManager Maven / Gradle / Ivy
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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.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import org.directwebremoting.extend.PageNormalizer;
import org.directwebremoting.extend.RealScriptSession;
import org.directwebremoting.extend.ScriptSessionManager;
import org.directwebremoting.util.Logger;
/**
* A default implmentation of ScriptSessionManager.
* There are synchronization constraints on this class that could be broken
* by subclasses. Specifically anyone accessing either sessionMap,
* sessionPageMap or pageSessionMap must do this while
* synchronizing on the respective Map. Locking several Maps at the same time
* should be avoided and if doing this care must be taken to avoid deadlocks.
* When accessing pageSessionMap value Sets the respective Set must be
* synchronized on. If desired to lock both a value Set and pageSessionMap then
* the Map must be locked first to avoid deadlocks.
*
In addition 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
{
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getScriptSession(java.lang.String)
*/
public RealScriptSession getScriptSession(String id)
{
maybeCheckTimeouts();
synchronized (this.sessionMap)
{
DefaultScriptSession scriptSession = (DefaultScriptSession) sessionMap.get(id);
if (scriptSession == null)
{
scriptSession = new DefaultScriptSession(id, this);
sessionMap.put(id, scriptSession);
}
else
{
scriptSession.updateLastAccessedTime();
}
return scriptSession;
}
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#setPageForScriptSession(org.directwebremoting.extend.RealScriptSession, java.lang.String)
*/
public void setPageForScriptSession(RealScriptSession scriptSession, String page)
{
String normalizedPage = pageNormalizer.normalizePage(page);
// pageSessionMap
synchronized (this.pageSessionMap)
{
Set pageSessions = (Set) pageSessionMap.get(normalizedPage);
if (pageSessions == null)
{
pageSessions = new HashSet();
pageSessionMap.put(normalizedPage, pageSessions);
}
synchronized (pageSessions)
{
if (!pageSessions.contains(scriptSession)) {
pageSessions.add(scriptSession);
}
}
}
// sessionPageMap
synchronized (sessionPageMap)
{
String currentPage = (String) sessionPageMap.get(scriptSession.getId());
if (currentPage == null || !currentPage.equals(normalizedPage)) {
sessionPageMap.put(scriptSession.getId(), normalizedPage);
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getScriptSessionsByPage(java.lang.String)
*/
public Collection getScriptSessionsByPage(String page)
{
String normalizedPage = pageNormalizer.normalizePage(page);
synchronized (this.pageSessionMap)
{
Set pageSessions = (Set) pageSessionMap.get(normalizedPage);
if (pageSessions == null)
{
pageSessions = new HashSet();
}
Set reply = new HashSet();
synchronized (pageSessions)
{
reply.addAll(pageSessions);
}
return reply;
}
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getAllScriptSessions()
*/
public Collection getAllScriptSessions()
{
synchronized (this.sessionMap)
{
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(RealScriptSession scriptSession)
{
// Remove from sessionMap
synchronized (sessionMap)
{
RealScriptSession removed = (RealScriptSession) sessionMap.remove(scriptSession.getId());
if (!scriptSession.equals(removed))
{
log.debug("ScriptSession already removed from manager. scriptSession=" + scriptSession + " removed=" + removed);
}
}
// Remove from sessionPageMap
String page = null;
synchronized (sessionPageMap)
{
page = (String) sessionPageMap.remove(scriptSession.getId());
}
// Remove from pageSessionMap
synchronized (pageSessionMap) {
Set pageSessions = (Set) pageSessionMap.get(page);
if (pageSessions != null) {
synchronized (pageSessions) {
pageSessions.remove(scriptSession);
if (pageSessions.isEmpty()) {
pageSessionMap.remove(page);
}
}
}
}
}
/**
* 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
* if 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();
Set scriptSessions;
synchronized (sessionMap) {
scriptSessions = new HashSet(sessionMap.values());
}
for (Iterator it = scriptSessions.iterator(); it.hasNext();)
{
DefaultScriptSession session = (DefaultScriptSession) it.next();
if (session.isInvalidated())
{
continue;
}
long age = now - session.getLastAccessedTime();
if (age > scriptSessionTimeout)
{
session.invalidate();
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#getScriptSessionTimeout()
*/
public long getScriptSessionTimeout()
{
return scriptSessionTimeout;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSessionManager#setScriptSessionTimeout(long)
*/
public void setScriptSessionTimeout(long timeout)
{
this.scriptSessionTimeout = timeout;
}
/**
* Accessfor for the PageNormalizer.
* @param pageNormalizer The new PageNormalizer
*/
public void setPageNormalizer(PageNormalizer pageNormalizer)
{
this.pageNormalizer = pageNormalizer;
}
/**
* @param scriptSessionCheckTime the scriptSessionCheckTime to set
*/
public void setScriptSessionCheckTime(long scriptSessionCheckTime)
{
this.scriptSessionCheckTime = scriptSessionCheckTime;
}
/**
* By default we check for sessions that need expiring every 30 seconds
*/
protected static final long DEFAULT_SESSION_CHECK_TIME = 30000;
/**
* How we turn pages into the canonical form.
*/
protected PageNormalizer pageNormalizer;
/**
* How long do we wait before we timeout script sessions?
*/
protected volatile long scriptSessionTimeout = DEFAULT_TIMEOUT_MILLIS;
/**
* How often do we check for script sessions that need timing out
*/
protected volatile long scriptSessionCheckTime = DEFAULT_SESSION_CHECK_TIME;
/**
* 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
* Map
*/
protected Map sessionMap = new HashMap();
/**
* The map of sessions and their associated page
* Map
*/
protected Map sessionPageMap = new HashMap();
/**
* The map of pages that have sessions
* Map>
*/
protected Map pageSessionMap = new HashMap();
/**
* The log stream
*/
private static final Logger log = Logger.getLogger(DefaultScriptSessionManager.class);
}