org.apache.flink.runtime.io.network.api.writer.ChannelSelector Maven / Gradle / Ivy
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* 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
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* 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,
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* 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;
/**
* The {@link ChannelSelector} determines to which logical channels a record
* should be written to.
*
* @param the type of record which is sent through the attached output gate
*/
public interface ChannelSelector {
/**
* Initializes the channel selector with the number of output channels.
*
* @param numberOfChannels the total number of output channels which are attached
* to respective output gate.
*/
void setup(int numberOfChannels);
/**
* Returns the logical channel index, to which the given record should be written. It is
* illegal to call this method for broadcast channel selectors and this method can remain
* not implemented in that case (for example by throwing {@link UnsupportedOperationException}).
*
* @param record the record to determine the output channels for.
* @return an integer number which indicates the index of the output
* channel through which the record shall be forwarded.
*/
int selectChannel(T record);
/**
* Returns whether the channel selector always selects all the output channels.
*
* @return true if the selector is for broadcast mode.
*/
boolean isBroadcast();
}