exec/java-exec/src/main/java/org/apache/drill/exec/coord/zk/ZkDistributedSemaphore.java

/*
 * 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 org.apache.drill.exec.coord.zk;

import java.util.concurrent.TimeUnit;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.locks.InterProcessSemaphoreV2;
import org.apache.curator.framework.recipes.locks.Lease;
import org.apache.drill.exec.coord.DistributedSemaphore;

public class ZkDistributedSemaphore implements DistributedSemaphore{
  static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ZkDistributedSemaphore.class);

  final InterProcessSemaphoreV2 semaphore;

  public ZkDistributedSemaphore(CuratorFramework client, String path, int numberOfLeases) {
    this.semaphore = new InterProcessSemaphoreV2(client, path, numberOfLeases);
  }

  @Override
  public DistributedLease acquire(long time, TimeUnit unit) throws Exception {
    Lease lease = semaphore.acquire(time, unit);
    if(lease != null){
      return new LeaseHolder(lease);
    }else{
      return null;
    }
  }

  private class LeaseHolder implements DistributedLease{
    Lease lease;

    public LeaseHolder(Lease lease) {
      super();
      this.lease = lease;
    }

    @Override
    public void close() throws Exception {
      lease.close();
    }

  }
}