net.logstash.logback.appender.destination.RoundRobinDestinationConnectionStrategy Maven / Gradle / Ivy

/*
 * Copyright 2013-2022 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.logstash.logback.appender.destination;


/**
 * This strategy attempts connections to the destination in round robin order.
 * If a connection fails, the next destination is attempted.
 *
 * The connectionTTL can be set to gracefully close connections after a specific duration.
 * This will force the the appender to reattempt to connect to the next destination.
 */
public class RoundRobinDestinationConnectionStrategy extends DestinationConnectionStrategyWithTtl {

    /**
     * The destinationIndex to be returned on the next call to {@link #selectNextDestinationIndex(int, int)}.
     */
    private volatile int nextDestinationIndex = 0;

    @Override
    public int selectNextDestinationIndex(int previousDestinationIndex, int numDestinations) {
        return nextDestinationIndex++ % numDestinations;
    }

}