/**
* Copyright (c) 2002-2010 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.util;
import org.neo4j.kernel.DeadlockDetectedException;
/**
* Encapsulates a block of code which is, sort of, expected to throw Neo4j
* {@link DeadlockDetectedException} and provides a means of performing that
* code block a number of times in order to succeed.
* @author mattias
*
* @param <T> The result type of the result from {@link #run()}, if any.
*/
public abstract class DeadlockCapsule<T>
{
private int maxNumberOfTries;
private long millisToSleepBetweenTries;
public DeadlockCapsule( String name )
{
this( name, 5 );
}
public DeadlockCapsule( String name, int maxNumberOfTries )
{
this( name, maxNumberOfTries, 20 );
}
public DeadlockCapsule( String name, int maxNumberOfTries,
long millisToSleepBetweenTries )
{
this.maxNumberOfTries = maxNumberOfTries;
this.millisToSleepBetweenTries = millisToSleepBetweenTries;
}
public abstract T tryOnce();
public final T run()
{
int tries = 0;
do
{
tries++;
try
{
return tryOnce();
}
catch ( DeadlockDetectedException e )
{
try
{
Thread.sleep( millisToSleepBetweenTries );
}
catch ( InterruptedException ie )
{
Thread.interrupted();
ie.printStackTrace();
}
}
}
while ( tries < maxNumberOfTries );
return null;
}
}