lang/java/reef-runtime-yarn/src/main/java/org/apache/reef/runtime/yarn/driver/ApplicationMasterRegistration.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.reef.runtime.yarn.driver;

import org.apache.hadoop.yarn.api.protocolrecords.RegisterApplicationMasterResponse;
import org.apache.reef.util.Optional;

import javax.inject.Inject;

/**
 * Helper class that holds on to the AM registration.
 */
final class ApplicationMasterRegistration {

  private Optional<RegisterApplicationMasterResponse> registration = Optional.empty();

  @Inject
  ApplicationMasterRegistration() {
  }

  /**
   * @return the registered registration.
   */
  synchronized RegisterApplicationMasterResponse getRegistration() {
    return registration.get();
  }

  /**
   * Set the registration information. This is a set-once field.
   *
   * @param registration
   */
  synchronized void setRegistration(final RegisterApplicationMasterResponse registration) {
    if (this.isPresent()) {
      throw new RuntimeException("Trying to re-register the AM");
    }
    this.registration = Optional.of(registration);
  }

  /**
   * @return true, if a registration was set.
   */
  synchronized boolean isPresent() {
    return this.registration.isPresent();
  }
}