leader.LeaderSelectorExample Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2012 Netflix, Inc.
 *
 *    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 leader;

import com.google.common.collect.Lists;
import com.google.common.io.Closeables;
import com.netflix.curator.framework.CuratorFramework;
import com.netflix.curator.framework.CuratorFrameworkFactory;
import com.netflix.curator.retry.ExponentialBackoffRetry;
import com.netflix.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 )
            {
                Closeables.closeQuietly(exampleClient);
            }
            for ( CuratorFramework client : clients )
            {
                Closeables.closeQuietly(client);
            }

            Closeables.closeQuietly(server);
        }
    }
}