org.apache.flink.runtime.leaderretrieval.LeaderRetrievalEventHandler Maven / Gradle / Ivy
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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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*/
package org.apache.flink.runtime.leaderretrieval;
import org.apache.flink.runtime.leaderelection.LeaderInformation;
/**
* Interface which should be implemented to notify to {@link LeaderInformation} changes in {@link
* LeaderRetrievalDriver}.
*
* Important: The {@link LeaderRetrievalDriver} could not guarantee that there
* is no {@link LeaderRetrievalEventHandler} callbacks happen after {@link
* LeaderRetrievalDriver#close()}. This means that the implementor of {@link
* LeaderRetrievalEventHandler} is responsible for filtering out spurious callbacks(e.g. after close
* has been called on {@link LeaderRetrievalDriver}).
*/
public interface LeaderRetrievalEventHandler {
/**
* Called by specific {@link LeaderRetrievalDriver} to notify leader address.
*
*
Duplicated leader change events could happen, so the implementation should check whether
* the passed leader information is truly changed with last stored leader information.
*
* @param leaderInformation the new leader information to notify {@link LeaderRetrievalService}.
* It could be {@link LeaderInformation#empty()} if the leader address does not exist in the
* external storage.
*/
void notifyLeaderAddress(LeaderInformation leaderInformation);
}