/*
* JBoss, Home of Professional Open Source.
* Copyright 2009, 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.ha.framework.server.lock;
import java.io.Serializable;
import org.jboss.ha.framework.interfaces.ClusterNode;
import org.jboss.ha.framework.interfaces.HAPartition;
/**
* Support class for cluster locking scenarios where threads cannot acquire
* a local lock unless the node owns a cluster-wide lock, but where the node
* owning the cluster-wide lock will yield it to another node if no thread
* has a local lock. Use case for this is scenarios like session management
* where a node needs to acquire ownership of a cluster-wide lock for a session,
* but then once acquired wishes to handle multiple calls for the session without
* make cluster-wide locking calls. The node handling the session would acquire
* the cluster-wide lock if it doesn't have it and thereafter would only use
* local locks; if another node received a request for the session it would
* request the lock and the first node would release it if no local locks are
* held.
*
* @author Brian Stansberry
*/
public class YieldingGloballyExclusiveClusterLockSupport extends AbstractClusterLockSupport
{
public YieldingGloballyExclusiveClusterLockSupport(String serviceHAName,
HAPartition partition,
LocalLockHandler handler)
{
super(serviceHAName, partition, handler);
}
// ------------------------------------------------------ ClusterLockManager
public void unlock(Serializable lockId)
{
ClusterNode myself = getLocalClusterNode();
if (myself == null)
{
throw new IllegalStateException("Must call start() before first call to unlock()");
}
ClusterLockState category = getClusterLockState(lockId, false);
if (category != null && myself.equals(category.getHolder()))
{
category.invalidate();
getLocalHandler().unlockFromCluster(lockId, myself);
removeLockState(category);
}
}
// --------------------------------------------------------------- Protected
@Override
protected ClusterLockState getClusterLockState(Serializable categoryName)
{
return getClusterLockState(categoryName, false);
}
@Override
protected RemoteLockResponse yieldLock(ClusterLockState lockState, ClusterNode caller, long timeout)
{
if (getLocalClusterNode().equals(lockState.getHolder()))
{
return getLock(lockState.lockId, lockState, caller, timeout);
}
else
{
return new RemoteLockResponse(getLocalClusterNode(), RemoteLockResponse.Flag.REJECT, lockState.getHolder());
}
}
@Override
protected RemoteLockResponse handleLockSuccess(ClusterLockState lockState, ClusterNode caller)
{
if (getLocalClusterNode().equals(caller))
{
recordLockHolder(lockState, caller);
}
else
{
// Caller succeeded, but since this node doesn't hold the
// lock we don't want to hold the category in our map any longer
lockState.invalidate();
removeLockState(lockState);
}
return new RemoteLockResponse(getLocalClusterNode(), RemoteLockResponse.Flag.OK);
}
// ----------------------------------------------------------------- Private
}