Demonstrating locking abilities via etcdv3 client.

EtcdV3Client.java

package etcd;

import io.etcd.jetcd.*;
import io.etcd.jetcd.kv.GetResponse;
import io.etcd.jetcd.kv.PutResponse;
import io.etcd.jetcd.lease.LeaseGrantResponse;
import io.etcd.jetcd.lease.LeaseRevokeResponse;
import io.etcd.jetcd.lock.LockResponse;
import io.etcd.jetcd.lock.UnlockResponse;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 *  Added dependency
 *         <!-- https://mvnrepository.com/artifact/io.etcd/jetcd-core -->
 *         <dependency>
 *             <groupId>io.etcd</groupId>
 *             <artifactId>jetcd-core</artifactId>
 *             <version>0.5.7</version>
 *         </dependency>
 *
 */
public class EtcdV3Client {
    public static void main(String[] args) throws Exception {
        Client client = Client.builder().endpoints("http://172.17.42.1:4001").build();
        KV kvClient = client.getKVClient();
        Lease leaseClient = client.getLeaseClient();
        CompletableFuture<LeaseGrantResponse> grant = leaseClient.grant(200);
        LeaseGrantResponse leaseGrantResponse = grant.get();
        long leaseId = leaseGrantResponse.getID();
        System.out.println("Lease ID : " + leaseId);

        Lock lockClient = client.getLockClient();

        String lockId = "Lock4";
        CompletableFuture<LockResponse> lock = lockClient.lock(ByteSequence.from(lockId.getBytes()), leaseId);

        LockResponse lockResponse = null;
        boolean isLockGranted = false;
        try {
            lockResponse = lock.get(5, TimeUnit.SECONDS);
            isLockGranted = true;
        }catch (TimeoutException e){
            System.out.println(e.getMessage());
        }

        if(isLockGranted) {
            System.out.println("Lock acquired : " + new String(lockResponse.getKey().getBytes()));

            ByteSequence key = ByteSequence.from("test_key".getBytes());
            ByteSequence value = ByteSequence.from("test_value".getBytes());

            PutResponse putResponse = kvClient.put(key, value).get();
            System.out.println("PUT response");
            System.out.println(putResponse.toString());

            CompletableFuture<UnlockResponse> unlock = lockClient.unlock(ByteSequence.from(lockId.getBytes()));
            UnlockResponse unlockResponse = unlock.get();
            System.out.println("Lock released : " + unlockResponse.toString());
            System.out.println(unlockResponse);

            CompletableFuture<GetResponse> getFuture = kvClient.get(key);
            GetResponse response = getFuture.get();
//        System.out.println("Response______________________");
//        System.out.println(response.toString());

            CompletableFuture<LeaseRevokeResponse> revoke = leaseClient.revoke(leaseId);
            LeaseRevokeResponse leaseRevokeResponse = revoke.get();
            System.out.println("Lease revoked :" + leaseRevokeResponse);


            lockClient.close();
            kvClient.close();
            client.close();
        }else{
            System.out.println("Unable to acquire lock");
        }

        System.out.println("Done");
    }
}