org.apache.flink.runtime.leaderretrieval.StandaloneLeaderRetrievalService Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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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.leaderretrieval;
import org.apache.flink.util.Preconditions;
/**
* Standalone implementation of the {@link LeaderRetrievalService}. The standalone implementation
* assumes that there is only a single {@link org.apache.flink.runtime.jobmanager.JobManager} whose
* address is given to the service when creating it. This address is directly given to the
* {@link LeaderRetrievalListener} when the service is started.
*/
public class StandaloneLeaderRetrievalService implements LeaderRetrievalService {
/** Address of the only JobManager */
private final String jobManagerAddress;
/** Listener which wants to be notified about the new leader */
private LeaderRetrievalListener leaderListener;
/**
* Creates a StandaloneLeaderRetrievalService with the given JobManager address.
*
* @param jobManagerAddress The JobManager's address which is returned to the
* {@link LeaderRetrievalListener}
*/
public StandaloneLeaderRetrievalService(String jobManagerAddress) {
this.jobManagerAddress = jobManagerAddress;
}
@Override
public void start(LeaderRetrievalListener listener) {
Preconditions.checkNotNull(listener, "Listener must not be null.");
Preconditions.checkState(leaderListener == null, "StandaloneLeaderRetrievalService can " +
"only be started once.");
leaderListener = listener;
// directly notify the listener, because we already know the leading JobManager's address
leaderListener.notifyLeaderAddress(jobManagerAddress, null);
}
@Override
public void stop() {}
}