package org.jacorb.poa;
/*
* JacORB - a free Java ORB
*
* Copyright (C) 1997-2004 Gerald Brose.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
import java.util.*;
import org.apache.avalon.framework.logger.Logger;
import org.apache.avalon.framework.configuration.*;
import org.jacorb.orb.dsi.ServerRequest;
import org.jacorb.poa.except.ResourceLimitReachedException;
import org.jacorb.poa.util.StringPair;
/**
* This class manages a queue of ServerRequest objects.
*
* @author Reimo Tiedemann, FU Berlin
* @version $Id: RequestQueue.java,v 1.19 2006/06/04 11:27:26 andre.spiegel Exp $
*/
public class RequestQueue
implements Configurable
{
private RequestQueueListener queueListener;
private RequestController controller;
/** the configuration object for this queue */
private org.jacorb.config.Configuration configuration = null;
private Logger logger;
private int queueMin;
private int queueMax;
private boolean queueWait;
private List queueListeners;
private boolean configured = false;
private List queue =
new ArrayList (POAConstants.QUEUE_CAPACITY_INI);
// POAConstants.QUEUE_CAPACITY_INC);
protected RequestQueue(RequestController controller)
{
this.controller = controller;
}
public synchronized void configure(Configuration myConfiguration)
throws ConfigurationException
{
if (configured) return;
this.configuration = (org.jacorb.config.Configuration)myConfiguration;
logger = configuration.getNamedLogger("jacorb.poa.queue");
queueMax = configuration.getAttributeAsInteger("jacorb.poa.queue_max", 100);
queueMin = configuration.getAttributeAsInteger("jacorb.poa.queue_min", 10);
queueWait = configuration.getAttributeAsBoolean("jacorb.poa.queue_wait",false);
queueListeners = configuration.getAttributeList("jacorb.poa.queue_listeners");
configured = true;
for (Iterator i = queueListeners.iterator(); i.hasNext();) {
String className = (String)i.next();
try
{
RequestQueueListener rql = (RequestQueueListener)
org.jacorb.util.ObjectUtil.classForName(className).newInstance();
addRequestQueueListener(rql);
}
catch (Exception ex)
{
throw new ConfigurationException ("could not instantiate queue listener",
ex);
}
}
}
/**
* Adds a request to this queue. The properties
* <code>jacorb.poa.queue_{min,max,wait}</code> specify what happens
* when the queue is full, i.e. when it already contains
* <code>queue_max</code> requests. If <code>queue_wait</code> is
* <i>off</i>, then this method does not add the request and throws a
* <code>ResourceLimitReachedException</code>. If <code>queue_wait</code>
* is <i>on</i>, then this method blocks until no more than
* <code>queue_min</code> requests are in the queue; it then adds the
* request, and returns.
*/
protected synchronized void add(ServerRequest request)
throws ResourceLimitReachedException
{
if (!configured)
throw new Error("RQ.add(): not configured!");
if (queue.size() >= queueMax )
{
if (logger.isWarnEnabled())
{
logger.warn("Request queue is full, consider increasing "
+ "jacorb.poa.queue_max (currently: "
+ queueMax + ")");
}
if ( queueWait )
{
while (queue.size() > queueMin )
{
try
{
this.wait();
}
catch (InterruptedException ex)
{
// ignore
}
}
}
else
{
throw new ResourceLimitReachedException();
}
}
queue.add(request);
if (queue.size() == 1)
{
controller.continueToWork();
}
if (logger.isDebugEnabled())
{
logger.debug("rid: " + request.requestId() +
" opname: " + request.operation() +
" is queued (queue size: " + queue.size() + ")");
}
// notify a queue listener
if (queueListener != null)
queueListener.requestAddedToQueue(request, queue.size());
}
protected synchronized void addRequestQueueListener(RequestQueueListener listener)
{
if (!configured)
throw new Error("RQ.add(): not configured!");
queueListener = EventMulticaster.add(queueListener, listener);
}
protected synchronized StringPair[] deliverContent()
{
if (!configured)
throw new Error("RQ.add(): not configured!");
StringPair[] result = new StringPair[queue.size()];
Iterator en = queue.iterator();
ServerRequest sr;
for (int i=0; i<result.length; i++)
{
sr = (ServerRequest) en.next();
result[i] = new StringPair(sr.requestId()+"", new String( sr.objectId() ) );
}
return result;
}
protected synchronized ServerRequest getElementAndRemove(int rid)
{
if (!configured)
throw new Error("RQ.add(): not configured!");
if (!queue.isEmpty())
{
Iterator en = queue.iterator();
ServerRequest result;
while (en.hasNext())
{
result = (ServerRequest) en.next();
if (result.requestId() == rid)
{
en.remove();
this.notifyAll();
// notify a queue listener
if (queueListener != null)
queueListener.requestRemovedFromQueue(result, queue.size());
return result;
}
}
}
return null;
}
protected synchronized ServerRequest getFirst()
{
if (!configured)
throw new Error("RQ.add(): not configured!");
if (!queue.isEmpty())
{
return (ServerRequest) queue.get(0);
}
return null;
}
protected boolean isEmpty()
{
if (!configured)
throw new Error("RQ.add(): not configured!");
return queue.isEmpty();
}
protected synchronized ServerRequest removeFirst()
{
if (!configured)
throw new Error("RQ.add(): not configured!");
if (!queue.isEmpty())
{
ServerRequest result = (ServerRequest) queue.get(0);
queue.remove(0);
this.notifyAll();
// notify a queue listener
if (queueListener != null)
queueListener.requestRemovedFromQueue(result, queue.size());
return result;
}
return null;
}
protected synchronized ServerRequest removeLast()
{
if (!configured)
throw new Error("RQ.add(): not configured!");
if (!queue.isEmpty())
{
int index = queue.size() - 1;
ServerRequest result = (ServerRequest) queue.get(index);
queue.remove(index);
this.notifyAll();
// notify a queue listener
if (queueListener != null)
queueListener.requestRemovedFromQueue(result, queue.size());
return result;
}
return null;
}
protected synchronized void removeRequestQueueListener(RequestQueueListener listener)
{
if (!configured)
throw new Error("RQ.add(): not configured!");
queueListener = EventMulticaster.remove(queueListener, listener);
}
protected int size()
{
return queue.size();
}
}