leader.LeaderSelectorExample Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of curator-examples Show documentation
Example usages of various Curator features.
There is a newer version: 5.7.1
/**
 * 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
 * regarding copyright ownership.  The ASF licenses this file
 * 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, 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 leader;

import com.google.common.collect.Lists;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.test.TestingServer;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.List;

public class LeaderSelectorExample
{
    private static final int        CLIENT_QTY = 10;

    private static final String     PATH = "/examples/leader";

    public static void main(String[] args) throws Exception
    {
        // all of the useful sample code is in ExampleClient.java

        System.out.println("Create " + CLIENT_QTY + " clients, have each negotiate for leadership and then wait a random number of seconds before letting another leader election occur.");
        System.out.println("Notice that leader election is fair: all clients will become leader and will do so the same number of times.");

        List  clients = Lists.newArrayList();
        List     examples = Lists.newArrayList();
        TestingServer           server = new TestingServer();
        try
        {
            for ( int i = 0; i < CLIENT_QTY; ++i )
            {
                CuratorFramework    client = CuratorFrameworkFactory.newClient(server.getConnectString(), new ExponentialBackoffRetry(1000, 3));
                clients.add(client);

                ExampleClient       example = new ExampleClient(client, PATH, "Client #" + i);
                examples.add(example);

                client.start();
                example.start();
            }

            System.out.println("Press enter/return to quit\n");
            new BufferedReader(new InputStreamReader(System.in)).readLine();
        }
        finally
        {
            System.out.println("Shutting down...");

            for ( ExampleClient exampleClient : examples )
            {
                CloseableUtils.closeQuietly(exampleClient);
            }
            for ( CuratorFramework client : clients )
            {
                CloseableUtils.closeQuietly(client);
            }

            CloseableUtils.closeQuietly(server);
        }
    }
}