/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.flink.runtime.io.network.api.writer;
import org.apache.flink.core.io.IOReadableWritable;
/**
* This is the default implementation of the {@link ChannelSelector} interface. It represents a simple round-robin
* strategy, i.e. regardless of the record every attached exactly one output channel is selected at a time.
* @param <T>
* the type of record which is sent through the attached output gate
*/
public class RoundRobinChannelSelector<T extends IOReadableWritable> implements ChannelSelector<T> {
/**
* Stores the index of the channel to send the next record to.
*/
private final int[] nextChannelToSendTo = new int[1];
/**
* Constructs a new default channel selector.
*/
public RoundRobinChannelSelector() {
this.nextChannelToSendTo[0] = 0;
}
@Override
public int[] selectChannels(final T record, final int numberOfOutputChannels) {
this.nextChannelToSendTo[0] = (this.nextChannelToSendTo[0] + 1) % numberOfOutputChannels;
return this.nextChannelToSendTo;
}
}