001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package org.apache.hadoop.yarn.event;
020
021 import org.apache.hadoop.classification.InterfaceAudience.Public;
022 import org.apache.hadoop.classification.InterfaceStability.Evolving;
023
024 /**
025 * Event Dispatcher interface. It dispatches events to registered
026 * event handlers based on event types.
027 *
028 */
029 @SuppressWarnings("rawtypes")
030 @Public
031 @Evolving
032 public interface Dispatcher {
033
034 // Configuration to make sure dispatcher crashes but doesn't do system-exit in
035 // case of errors. By default, it should be false, so that tests are not
036 // affected. For all daemons it should be explicitly set to true so that
037 // daemons can crash instead of hanging around.
038 public static final String DISPATCHER_EXIT_ON_ERROR_KEY =
039 "yarn.dispatcher.exit-on-error";
040
041 public static final boolean DEFAULT_DISPATCHER_EXIT_ON_ERROR = false;
042
043 EventHandler getEventHandler();
044
045 void register(Class<? extends Enum> eventType, EventHandler handler);
046
047 }