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MultiRetryStrategy.java
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MultiRetryStrategy.java
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/*
* Copyright (c) 2002-2018 "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.causalclustering.discovery;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
/**
* Implementation of the RetryStrategy that repeats the retriable function until the correct result has been retrieved or the limit of retries has been
* encountered.
* There is a fixed delay between each retry.
*
* @param <INPUT> the type of input of the retriable function
* @param <OUTPUT> the type of output of the retriable function
*/
public class MultiRetryStrategy<INPUT, OUTPUT> implements RetryStrategy<INPUT,OUTPUT>
{
private final long delayInMillis;
private final long retries;
private final LogProvider logProvider;
private final Consumer<Long> sleeper;
/**
* @param delayInMillis number of milliseconds between each attempt at getting the desired result
* @param retries the number of attempts to perform before giving up
* @param logProvider {@see LogProvider}
*/
public MultiRetryStrategy( long delayInMillis, long retries, LogProvider logProvider, Consumer<Long> sleeper )
{
this.delayInMillis = delayInMillis;
this.retries = retries;
this.logProvider = logProvider;
this.sleeper = sleeper;
}
/**
* {@inheritDoc}
*/
@Override
public OUTPUT apply( INPUT retriableInput, Function<INPUT,OUTPUT> retriable, Predicate<OUTPUT> wasRetrySuccessful )
{
Log log = logProvider.getLog( MultiRetryStrategy.class );
OUTPUT result = retriable.apply( retriableInput );
int currentIteration = 0;
while ( !wasRetrySuccessful.test( result ) && currentIteration++ < retries )
{
log.debug( "Try attempt was unsuccessful for input: %s\n", retriableInput );
sleeper.accept( delayInMillis );
result = retriable.apply( retriableInput );
}
return result;
}
}