/*
* JBoss, Home of Professional Open Source
* Copyright 2011 Red Hat Inc. and/or its affiliates and other
* contributors as indicated by the @author tags. All rights reserved.
* See the copyright.txt 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.infinispan.util;
import org.infinispan.manager.EmbeddedCacheManager;
import org.infinispan.notifications.Listener;
import org.infinispan.notifications.cachemanagerlistener.annotation.ViewChanged;
import org.infinispan.notifications.cachemanagerlistener.event.ViewChangedEvent;
import org.infinispan.remoting.transport.Address;
import org.infinispan.remoting.transport.Transport;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
/**
* This class generates ids guaranteed to be unique cluster wide.
*
* @author Galder Zamarreno
* @author Mircea Markus
* @since 4.1
*/
public class ClusterIdGenerator {
private static final Log log = LogFactory.getLog(ClusterIdGenerator.class);
// TODO: Possibly seed version counter on capped System.currentTimeMillis, to avoid issues with clients holding to versions in between restarts
private final AtomicInteger versionCounter = new AtomicInteger();
private final AtomicLong versionPrefix = new AtomicLong();
public ClusterIdGenerator(EmbeddedCacheManager cm, Transport transport) {
if (cm != null) cm.addListener(new RankCalculator());
if (transport != null) {
calculateRank(transport.getAddress(), transport.getMembers(), transport.getViewId());
}
}
public long newVersion(boolean isClustered) {
if (isClustered && versionPrefix.get() == 0)
throw new IllegalStateException("If clustered, version prefix cannot be 0. Rank calculator probably not in use.");
long counter = versionCounter.incrementAndGet();
// Version counter occupies the least significant 4 bytes of the version
if (isClustered) {
return versionPrefix.get() | counter;
} else {
return counter;
}
}
void resetCounter() {
versionCounter.compareAndSet(versionCounter.get(), 0);
}
private int findAddressRank(Address address, List<Address> members, int rank) {
if (address.equals(members.get(0))) return rank;
else return findAddressRank(address, members.subList(1, members.size()), rank + 1);
}
protected long calculateRank(Address address, List<Address> members, long viewId) {
long rank = findAddressRank(address, members, 1);
// Version is composed of: <view id (2 bytes)><rank (2 bytes)><version counter (4 bytes)>
// View id and rank form the prefix which is updated on a view change.
long newVersionPrefix = (viewId << 48) | (rank << 32);
// TODO: Deal with compareAndSet failures?
versionPrefix.compareAndSet(versionPrefix.get(), newVersionPrefix);
return versionPrefix.get();
}
@Listener
public class RankCalculator {
@ViewChanged
public void calculateRank(ViewChangedEvent e) {
long rank = ClusterIdGenerator.this
.calculateRank(e.getLocalAddress(), e.getNewMembers(), e.getViewId());
if (log.isTraceEnabled())
log.tracef("Calculated rank based on view %s and result was %d", e, rank);
}
}
}