/*
* 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.monitor;
import java.io.Serializable;
/**
* Simple thread-safe POJO encapsulating locking stats.
*
* Turned this class to Serializable to be able to
* return copies of instances of this class over RMI.
*
* In this case it becomes detached from the EntityLockMonitor
* factory.
*
* @author <a href="mailto:bill@jboss.org">Bill Burke</a>
* @author <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
* @version $Revision: 81030 $
*/
public class LockMonitor implements Serializable
{
// Private -------------------------------------------------------
/** @since 4.0.2 */
private static final long serialVersionUID = -6710878502772579272L;
/* Lock Stats */
private long totalTime;
private long numContentions;
private long timeouts;
private long maxContenders;
private long currentContenders;
/** Back reference to the non-Serializable LockMonitor factory */
private transient EntityLockMonitor parent;
// Constructors --------------------------------------------------
/**
* @param parent factory
*/
public LockMonitor(EntityLockMonitor parent)
{
this.parent = parent;
}
// Accessors -----------------------------------------------------
public synchronized long getTotalTime()
{
return totalTime;
}
public synchronized long getNumContentions()
{
return numContentions;
}
public synchronized long getTimeouts()
{
return timeouts;
}
public synchronized long getMaxContenders()
{
return maxContenders;
}
public synchronized long getCurrentContenders()
{
return currentContenders;
}
// Modifiers -----------------------------------------------------
/**
* Adjust the counters to indicate a contetion conditions.
*
* If the parent EntityLockMonitor has been initialized
* the total stats will be updated, as well.
*/
public void contending()
{
synchronized(this)
{
++numContentions;
++currentContenders;
if (currentContenders > maxContenders)
{
maxContenders = currentContenders;
}
}
// Remark Ulf Schroeter: DO NOT include following call into the
// synchronization block because it will cause deadlocks between
// LockMonitor methods and EntityLockMonitor.clearMonitor() call!
if (parent != null)
{
parent.incrementContenders();
}
}
/**
* Adjust the counters to indicate that contention is over
*
* If the parent EntityLockMonitor has been initialized
* the total stats will be updated, too.
*/
public void finishedContending(long time)
{
synchronized(this)
{
totalTime += time;
--currentContenders;
}
// Remark Ulf Schroeter: DO NOT include following call into the
// synchronization block because it will cause deadlocks between
// LockMonitor methods and EntityLockMonitor.clearMonitor() call!
if (parent != null)
{
parent.decrementContenders(time);
}
}
/**
* Increase the timeouts on this lock
*/
public void increaseTimeouts()
{
synchronized(this)
{
++timeouts;
}
}
/**
* Reset the counters.
*
* CurrentContenders stays unchanged and
* MaxCondenders is set to CurrentContenders
*/
public void reset()
{
synchronized(this)
{
timeouts = 0;
totalTime = 0;
numContentions = 0;
// maxContenders always >= currentContenders
maxContenders = currentContenders;
}
}
// Object overrides ----------------------------------------------
public String toString()
{
StringBuffer sbuf = new StringBuffer(128);
sbuf.append(super.toString())
.append("[ ")
.append("totalTime=").append(getTotalTime())
.append(", numContentions=").append(getNumContentions())
.append(", timeouts=").append(getTimeouts())
.append(", maxContenders=").append(getMaxContenders())
.append(", currentContenders=").append(getCurrentContenders())
.append(" ]");
return sbuf.toString();
}
}