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
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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package org.apache.flink.runtime.leaderretrieval;
import org.apache.flink.runtime.highavailability.HighAvailabilityServices;
import java.util.UUID;
import static org.apache.flink.util.Preconditions.checkNotNull;
import static org.apache.flink.util.Preconditions.checkState;
/**
* Standalone implementation of the {@link LeaderRetrievalService}. This implementation assumes that
* there is only a single contender for leadership (e.g., a single JobManager or ResourceManager
* process) and that this process is reachable under a constant address.
*
* As soon as this service is started, it immediately notifies the leader listener of the leader
* contender with the pre-configured address.
*/
public class StandaloneLeaderRetrievalService implements LeaderRetrievalService {
private final Object startStopLock = new Object();
/** The fix address of the leader. */
private final String leaderAddress;
/** The fix leader ID (leader lock fencing token). */
private final UUID leaderId;
/** Flag whether this service is started. */
private boolean started;
/**
* Creates a StandaloneLeaderRetrievalService with the given leader address. The leaderId will
* be null.
*
* @param leaderAddress The leader's pre-configured address
* @deprecated Use {@link #StandaloneLeaderRetrievalService(String, UUID)} instead
*/
@Deprecated
public StandaloneLeaderRetrievalService(String leaderAddress) {
this.leaderAddress = checkNotNull(leaderAddress);
this.leaderId = HighAvailabilityServices.DEFAULT_LEADER_ID;
}
/**
* Creates a StandaloneLeaderRetrievalService with the given leader address.
*
* @param leaderAddress The leader's pre-configured address
* @param leaderId The constant leaderId.
*/
public StandaloneLeaderRetrievalService(String leaderAddress, UUID leaderId) {
this.leaderAddress = checkNotNull(leaderAddress);
this.leaderId = checkNotNull(leaderId);
}
// ------------------------------------------------------------------------
@Override
public void start(LeaderRetrievalListener listener) {
checkNotNull(listener, "Listener must not be null.");
synchronized (startStopLock) {
checkState(!started, "StandaloneLeaderRetrievalService can only be started once.");
started = true;
// directly notify the listener, because we already know the leading JobManager's
// address
listener.notifyLeaderAddress(leaderAddress, leaderId);
}
}
@Override
public void stop() {
synchronized (startStopLock) {
started = false;
}
}
}