drill-yarn/src/main/java/org/apache/drill/yarn/appMaster/AMRegistrar.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.yarn.appMaster;

/**
 * Interface to register the AM. Registration prevents two AMs from running for
 * the same Drill cluster. A normal return means that this AM now "owns" the
 * cluster. An exception means this is a duplicate AM (or something went wrong.)
 * <p>
 * Although the interface contains a deregister call, the implementation should
 * automatically deregister on death of the AM to prevent zombie registrations.
 * (The production system, ZK, handles this via ephemeral znodes.)
 */

public interface AMRegistrar {
  public static class AMRegistrationException extends Exception {
    private static final long serialVersionUID = 1L;

    public AMRegistrationException(Exception e) {
      super(e.getMessage(), e);
    }
  }

  void register(String amHost, int amPort, String appId)
      throws AMRegistrationException;

  void deregister();
}