org.directwebremoting.impl.DefaultScriptSession 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.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import org.directwebremoting.ScriptBuffer;
import org.directwebremoting.extend.MarshallException;
import org.directwebremoting.extend.RealScriptSession;
import org.directwebremoting.extend.ScriptConduit;
import org.directwebremoting.util.Logger;
/**
* An implementation of ScriptSession and RealScriptSession.
* There are synchronization constraints on this class. See the field
* comments of the type: GuardedBy("lock").
*
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 DefaultScriptSession implements RealScriptSession
{
/**
* Simple constructor
* @param id The new unique identifier for this session
* @param manager The manager that created us
*/
protected DefaultScriptSession(String id, DefaultScriptSessionManager manager)
{
this.id = id;
if (id == null)
{
throw new IllegalArgumentException("id can not be null");
}
this.manager = manager;
this.creationTime = System.currentTimeMillis();
this.lastAccessedTime = creationTime;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#getAttribute(java.lang.String)
*/
public Object getAttribute(String name)
{
checkNotInvalidated();
return attributes.get(name);
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#setAttribute(java.lang.String, java.lang.Object)
*/
public void setAttribute(String name, Object value)
{
checkNotInvalidated();
attributes.put(name, value);
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#removeAttribute(java.lang.String)
*/
public void removeAttribute(String name)
{
checkNotInvalidated();
attributes.remove(name);
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#getAttributeNames()
*/
public Iterator getAttributeNames()
{
checkNotInvalidated();
Set keys = Collections.unmodifiableSet(attributes.keySet());
return keys.iterator();
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#invalidate()
*/
public void invalidate()
{
invalidated = true;
manager.invalidate(this);
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#isInvalidated()
*/
public boolean isInvalidated()
{
return invalidated;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#getId()
*/
public String getId()
{
return id;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#getCreationTime()
*/
public long getCreationTime()
{
checkNotInvalidated();
return creationTime;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#getLastAccessedTime()
*/
public long getLastAccessedTime()
{
// For many accesses here we check to see if we should invalidate
// ourselves, but getLastAccessedTime() is used as part of the process
// that DefaultScriptSessionManager goes through in order to check
// everything for validity. So if we do this check here then DSSM will
// give a ConcurrentModificationException if anything does timeout
// checkNotInvalidated();
return lastAccessedTime;
}
/* (non-Javadoc)
* @see org.directwebremoting.ScriptSession#addScript(java.lang.String)
*/
public void addScript(ScriptBuffer script)
{
checkNotInvalidated();
if (script == null)
{
throw new NullPointerException("null script");
}
// log.debug("addScript() to " + this);
// First we try to add the script to an existing conduit
synchronized (this.scripts)
{
if (conduits.size() == 0)
{
// There are no conduits, just store it until there are
scripts.add(script);
// log.debug("- No conduits. Adding script to waiting list");
}
else
{
// Try all the conduits, starting with the first
boolean written = false;
// The conduit.addScript call is an external call which eventually makes its way back here
// and into the removeScriptConduit method. Since removeScriptConduit may modify the conduits
// collection we need to make a protective copy here to prevent ConcurrentModExceptions.
List conduitsList;
synchronized (conduits)
{
conduitsList = new ArrayList(conduits);
} // lock synchronized wrapper
for (Iterator it = conduitsList.iterator(); !written && it.hasNext();)
{
ScriptConduit conduit = (ScriptConduit) it.next();
try
{
written = conduit.addScript(script);
// log.debug("- Adding script to conduit (written=" + written + "): " + conduit);
}
catch (Exception ex)
{
it.remove();
log.debug("Failed to write to ScriptConduit, removing from list: " + conduit);
}
}
if (!written)
{
scripts.add(script);
// log.debug("- No conduits passed it on. Adding script to waiting list");
}
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.RealScriptSession#addScriptConduit(org.directwebremoting.extend.ScriptConduit)
*/
public void addScriptConduit(ScriptConduit conduit) throws IOException
{
checkNotInvalidated();
synchronized (this.scripts)
{
writeScripts(conduit);
conduits.add(conduit);
// log.debug("Adding Conduit: conduit=" + conduit + " scriptsession=" + this);
// log.debug("-- conduits=" + conduits);
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.RealScriptSession#writeScripts(org.directwebremoting.extend.ScriptConduit)
*/
public void writeScripts(ScriptConduit conduit) throws IOException
{
checkNotInvalidated();
synchronized (this.scripts)
{
for (Iterator it = scripts.iterator(); it.hasNext();)
{
ScriptBuffer script = (ScriptBuffer) it.next();
try
{
if (conduit.addScript(script))
{
// log.debug("Adding stored script to conduit: " + conduit);
it.remove();
}
else
{
// If we didn't write this one, don't bother with any more
break;
}
}
catch (MarshallException ex)
{
log.warn("Failed to convert data. Dropping Javascript: " + script, ex);
}
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.RealScriptSession#removeScriptConduit(org.directwebremoting.extend.ScriptConduit)
*/
public void removeScriptConduit(ScriptConduit conduit)
{
checkNotInvalidated();
synchronized (this.scripts)
{
boolean removed = conduits.remove(conduit);
if (!removed)
{
log.debug("Removing unattached ScriptConduit: " + conduit);
debug();
}
}
// log.debug("Removing Conduit: conduit=" + conduit + " scriptsession=" + this);
// log.debug("-- conduits=" + conduits);
}
/* (non-Javadoc)
* @see org.directwebremoting.extend.RealScriptSession#hasWaitingScripts()
*/
public boolean hasWaitingScripts()
{
synchronized (this.scripts)
{
return !scripts.isEmpty();
}
}
/**
* Called whenever a browser accesses this data using DWR
*/
protected void updateLastAccessedTime()
{
lastAccessedTime = System.currentTimeMillis();
}
/**
* Check that we are still valid and throw an IllegalStateException if not.
* At the same time set the lastAccessedTime flag.
* @throws IllegalStateException If this object has become invalid
*/
protected void checkNotInvalidated()
{
long now = System.currentTimeMillis();
long age = now - lastAccessedTime;
if (age > manager.getScriptSessionTimeout())
{
invalidate();
}
if (invalidated)
{
log.debug("ScriptSession has been invalidated.");
}
}
/**
* Some debug output
*/
private void debug()
{
if (log.isDebugEnabled())
{
log.debug("Known ScriptConduits:");
for (Iterator it = conduits.iterator(); it.hasNext();)
{
ScriptConduit c = (ScriptConduit) it.next();
log.debug("- " + c);
}
}
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
public int hashCode()
{
return 572 + id.hashCode();
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object obj)
{
if (obj == null)
{
return false;
}
if (obj == this)
{
return true;
}
if (!this.getClass().equals(obj.getClass()))
{
return false;
}
DefaultScriptSession that = (DefaultScriptSession) obj;
if (!this.id.equals(that.id))
{
return false;
}
return true;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
public String toString()
{
return "DefaultScriptSession[id=" + id + "]";
}
/**
* The server side attributes for this page.
*
GuardedBy("attributes")
*/
protected final Map attributes = Collections.synchronizedMap(new HashMap());
/**
* When the the web page that we represent last contact us using DWR?
*
GuardedBy("invalidLock")
*/
protected volatile long lastAccessedTime = 0L;
/**
* Have we been made invalid?
*
GuardedBy("invalidLock")
*/
protected volatile boolean invalidated = false;
/**
* The script conduits that we can use to transfer data to the browser.
*
GuardedBy("scriptLock")
*/
protected final SortedSet conduits = new TreeSet();
/**
* The list of waiting scripts.
*
GuardedBy("scriptLock")
*/
protected final List scripts = Collections.synchronizedList(new ArrayList());
/**
* What is our page session id?
*
This should not need careful synchronization since it is unchanging
*/
protected final String id;
/**
* When we we created?
*
This should not need careful synchronization since it is unchanging
*/
protected final long creationTime;
/**
* The session manager that collects sessions together
*
This should not need careful synchronization since it is unchanging
*/
protected final DefaultScriptSessionManager manager;
/**
* The log stream
*/
private static final Logger log = Logger.getLogger(DefaultScriptSession.class);
}