package org.neo4j.util;
import org.neo4j.kernel.impl.transaction.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;
}
}