/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* JBoss, Home of Professional Open Source
* Copyright 2012 Red Hat Inc. and/or its affiliates and other contributors
* as indicated by the @authors tag. All rights reserved.
* See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License, v. 2.1.
* This program is distributed in the hope that it will be useful, but WITHOUT A
* 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,
* v.2.1 along with this distribution; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
package org.hibernate.search.engine.impl;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
import org.hibernate.search.engine.spi.TimingSource;
/**
* Default implementation for a {@link org.hibernate.search.engine.spi.TimingSource}
*
* @author Sanne Grinovero <sanne@hibernate.org> (C) 2012 Red Hat Inc.
* @since 4.1
*/
public final class DefaultTimingSource implements TimingSource {
private static final long INVALID_TIME = -1;
//lazily initialize it, so we don't start a thread for those who don't use timeouts
//guarded by synchronization on this
private Timer timer = null;
private volatile long currentTimeApproximation = INVALID_TIME;
@Override
public long getMonotonicTimeEstimate() {
// This method is very performance critical:
// it's invoked once for each Lucene match during a query collection.
// That's why we read the volatile resorting to a Timer and
// approximating rather than invoking
// the currentTime() directly.
long currentValue = currentTimeApproximation;
if ( currentValue == INVALID_TIME ) {
throw new IllegalStateException( "Timing source was not started" );
}
return currentValue;
}
@Override
public synchronized void ensureInitialized() {
if ( timer == null ) {
timer = new Timer( "HibernateSearch_QueryTimeoutMonitor", true );
timer.schedule( new TriggerTask(), 5, 5 );
currentTimeApproximation = currentTime();
}
}
@Override
public synchronized void stop() {
if ( timer != null ) {
timer.cancel();
}
currentTimeApproximation = INVALID_TIME;
}
private class TriggerTask extends TimerTask {
public void run() {
DefaultTimingSource.this.currentTimeApproximation = currentTime();
}
}
private static long currentTime() {
return TimeUnit.MILLISECONDS.convert( System.nanoTime(), TimeUnit.NANOSECONDS );
}
}