/*
* JBoss, Home of Professional Open Source.
* Copyright 2000 - 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.cache.cluster;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jboss.cache.RPCManager;
import org.jboss.cache.commands.CommandsFactory;
import org.jboss.cache.commands.ReplicableCommand;
import org.jboss.cache.commands.remote.ReplicateCommand;
import org.jboss.cache.config.Configuration;
import org.jboss.cache.factories.annotations.Inject;
import org.jboss.cache.factories.annotations.Start;
import org.jboss.cache.factories.annotations.Stop;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Periodically (or when certain size is exceeded) takes elements and replicates them.
*
* @author <a href="mailto:bela@jboss.org">Bela Ban</a> May 24, 2003
* @version $Revision: 5197 $
*/
public class ReplicationQueue
{
private static final Log log = LogFactory.getLog(ReplicationQueue.class);
/**
* Max elements before we flush
*/
private long max_elements = 500;
/**
* Holds the replication jobs: LinkedList<MethodCall>
*/
final List<ReplicableCommand> elements = new LinkedList<ReplicableCommand>();
/**
* For periodical replication
*/
private ScheduledExecutorService scheduledExecutor = null;
private RPCManager rpcManager;
private Configuration configuration;
private boolean enabled;
private CommandsFactory commandsFactory;
private static final AtomicInteger counter = new AtomicInteger(0);
public boolean isEnabled()
{
return enabled;
}
@Inject
void injectDependencies(RPCManager rpcManager, Configuration configuration, CommandsFactory commandsFactory)
{
this.rpcManager = rpcManager;
this.configuration = configuration;
this.commandsFactory = commandsFactory;
// this is checked again in Start
enabled = configuration.isUseReplQueue() && (configuration.getBuddyReplicationConfig() == null || !configuration.getBuddyReplicationConfig().isEnabled());
}
/**
* Starts the asynchronous flush queue.
*/
@Start
public synchronized void start()
{
long interval = configuration.getReplQueueInterval();
this.max_elements = configuration.getReplQueueMaxElements();
// check again
enabled = configuration.isUseReplQueue() && (configuration.getBuddyReplicationConfig() == null || !configuration.getBuddyReplicationConfig().isEnabled());
if (enabled && interval > 0 && scheduledExecutor == null)
{
scheduledExecutor = Executors.newSingleThreadScheduledExecutor(new ThreadFactory()
{
public Thread newThread(Runnable r)
{
return new Thread(r, "ReplicationQueue-periodicProcessor-" + counter.getAndIncrement());
}
});
scheduledExecutor.scheduleWithFixedDelay(new Runnable()
{
public void run()
{
flush();
}
}, 500l, interval, TimeUnit.MILLISECONDS);
}
}
/**
* Stops the asynchronous flush queue.
*/
@Stop
public synchronized void stop()
{
if (scheduledExecutor != null)
{
scheduledExecutor.shutdownNow();
}
scheduledExecutor = null;
}
/**
* Adds a new method call.
*/
public void add(ReplicateCommand job)
{
if (job == null)
throw new NullPointerException("job is null");
synchronized (elements)
{
elements.add(job);
if (elements.size() >= max_elements)
flush();
}
}
/**
* Flushes existing method calls.
*/
public void flush()
{
List<ReplicableCommand> toReplicate;
synchronized (elements)
{
if (log.isTraceEnabled())
log.trace("flush(): flushing repl queue (num elements=" + elements.size() + ")");
toReplicate = new ArrayList<ReplicableCommand>(elements);
elements.clear();
}
if (toReplicate.size() > 0)
{
try
{
ReplicateCommand replicateCommand = commandsFactory.buildReplicateCommand(toReplicate);
// send to all live nodes in the cluster
rpcManager.callRemoteMethods(null, replicateCommand, false, configuration.getSyncReplTimeout(), false);
}
catch (Throwable t)
{
log.error("failed replicating " + toReplicate.size() + " elements in replication queue", t);
}
}
}
}