net.kuujo.copycat.election.internal.DefaultLeaderElection Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of copycat-leader-election Show documentation
The newest version!
/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed 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 net.kuujo.copycat.election.internal;

import net.kuujo.copycat.EventListener;
import net.kuujo.copycat.cluster.ElectionEvent;
import net.kuujo.copycat.cluster.Member;
import net.kuujo.copycat.election.LeaderElection;
import net.kuujo.copycat.resource.internal.AbstractResource;
import net.kuujo.copycat.resource.internal.ResourceManager;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CompletableFuture;

/**
 * Default leader election implementation.
 *
 * @author Jordan Halterman
 */
public class DefaultLeaderElection extends AbstractResource implements LeaderElection {
  private final Map, EventListener> listeners = new HashMap<>();

  public DefaultLeaderElection(ResourceManager context) {
    super(context);
  }

  @Override
  public synchronized LeaderElection addListener(EventListener listener) {
    if (!listeners.containsKey(listener)) {
      EventListener wrapper = event -> listener.accept(event.winner());
      listeners.put(listener, wrapper);
      context.cluster().addElectionListener(wrapper);
    }
    return this;
  }

  @Override
  public synchronized LeaderElection removeListener(EventListener listener) {
    EventListener wrapper = listeners.remove(listener);
    if (wrapper != null) {
      context.cluster().removeElectionListener(wrapper);
    }
    return this;
  }

  @Override
  public synchronized CompletableFuture open() {
    return runStartupTasks()
      .thenCompose(v -> context.open())
      .thenApply(v -> this);
  }

  @Override
  public synchronized CompletableFuture close() {
    return context.close()
      .thenCompose(v -> runShutdownTasks());
  }

}