/*
* JBoss, Home of Professional Open Source.
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.ejb.plugins;
import java.rmi.RemoteException;
import javax.ejb.EJBException;
import org.jboss.deployment.DeploymentException;
import org.jboss.ejb.EnterpriseContext;
import org.jboss.ejb.StatelessSessionEnterpriseContext;
import org.jboss.metadata.MetaData;
import org.w3c.dom.Element;
/**
* Singleton pool for session beans. This lets you have
* singletons in EJB!
*
* @author Rickard Oberg
* @version $Revision: 89152 $
*/
public class SingletonStatelessSessionInstancePool extends AbstractInstancePool
{
// Constants -----------------------------------------------------
// Attributes ----------------------------------------------------
EnterpriseContext ctx;
boolean inUse = false;
boolean isSynchronized = true;
// Static --------------------------------------------------------
// Constructors --------------------------------------------------
// Public --------------------------------------------------------
/**
* Get the singleton instance
*
* @return Context /w instance
* @exception Exception
*/
public synchronized EnterpriseContext get()
throws Exception
{
boolean intr = false;
try
{
// Wait while someone else is using it
while(inUse && isSynchronized)
{
try { this.wait(); } catch (InterruptedException e) { intr = true; }
}
// Create if not already created (or it has been discarded)
if (ctx == null)
{
try
{
ctx = create(getContainer().createBeanClassInstance());
} catch (InstantiationException e)
{
throw new EJBException("Could not instantiate bean", e);
} catch (IllegalAccessException e)
{
throw new EJBException("Could not instantiate bean", e);
}
}
else
{
}
// Lock and return instance
inUse = true;
return ctx;
}
finally
{
if (intr) Thread.currentThread().interrupt();
}
}
/**
* Return an instance after invocation.
*
* Called in 2 cases:
* a) Done with finder method
* b) Just removed
*
* @param ctx
*/
public synchronized void free(EnterpriseContext ctx)
{
// Notify waiters
inUse = false;
this.notifyAll();
}
public synchronized void discard(EnterpriseContext ctx)
{
// Throw away
try
{
ctx.discard();
} catch (RemoteException e)
{
// DEBUG Logger.exception(e);
}
// Notify waiters
inUse = false;
this.notifyAll();
}
/**
* Add a instance in the pool
*/
public void add()
throws Exception
{
// Empty
}
public int getCurrentSize()
{
return 1;
}
public int getMaxSize()
{
return 1;
}
public long getAvailableCount()
{
return 1;
}
// Z implementation ----------------------------------------------
// XmlLoadable implementation
public void importXml(Element element) throws DeploymentException
{
Element synch = MetaData.getUniqueChild(element, "Synchronized");
isSynchronized = Boolean.valueOf(MetaData.getElementContent(synch)).booleanValue();
}
// Package protected ---------------------------------------------
// Protected -----------------------------------------------------
protected EnterpriseContext create(Object instance)
throws Exception
{
// The instance is created by the caller and is a newInstance();
return new StatelessSessionEnterpriseContext(instance, getContainer());
}
// Private -------------------------------------------------------
// Inner classes -------------------------------------------------
}