Cassandra Leadership Election

Client.java

package com.github.craigleonard.leadershipelection;

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.Session;

import java.net.InetSocketAddress;

public class Client {

    static final long LEASE_TIME = 10;
    static final long HEARTBEAT_TIME = 7;
    static final String ELECTION_NAME = "test-election";

    public static void main(String[] args) throws InterruptedException {
        String clientName = args[0];
        Session session = Cluster.builder().addContactPointsWithPorts(new InetSocketAddress("127.0.0.1", 9042)).build().connect();
        PreparedStatement tryAcquire = session.prepare("INSERT INTO LE.ELECTIONS (ELECTION, WINNER) VALUES (?,?) IF NOT EXISTS USING TTL " + LEASE_TIME);
        PreparedStatement heartbeat = session.prepare("UPDATE LE.ELECTIONS USING TTL " + LEASE_TIME + " SET WINNER = ? WHERE ELECTION = ? IF WINNER = ?");

        while (true) {
            // try acquire lock
            boolean isLeader = session.execute(tryAcquire.bind(ELECTION_NAME, clientName)).wasApplied();

            while (isLeader) {
                System.out.println("Client " + clientName + " is the leader");
                Thread.sleep(HEARTBEAT_TIME * 1000);
                isLeader = session.execute(heartbeat.bind(clientName, ELECTION_NAME, clientName)).wasApplied();
            }

            System.out.println("Client " + clientName + " is not the leader");
            Thread.sleep(LEASE_TIME * 1000);
        }
    }
}
}

tables.cql

CREATE KEYSPACE LE WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', 'datacenter1' : 1 };

CREATE TABLE IF NOT EXISTS LE.ELECTIONS (
  ELECTION TEXT,
  WINNER TEXT
  PRIMARY KEY(ELECTION)
);