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.state;
020    
021    import org.apache.hadoop.classification.InterfaceAudience.Public;
022    import org.apache.hadoop.classification.InterfaceStability.Evolving;
023    
024    /**
025     * Hook for Transition. 
026     * Post state is decided by Transition hook. Post state must be one of the 
027     * valid post states registered in StateMachine.
028     */
029    @Public
030    @Evolving
031    public interface MultipleArcTransition
032            <OPERAND, EVENT, STATE extends Enum<STATE>> {
033    
034      /**
035       * Transition hook.
036       * @return the postState. Post state must be one of the 
037       *                      valid post states registered in StateMachine.
038       * @param operand the entity attached to the FSM, whose internal 
039       *                state may change.
040       * @param event causal event
041       */
042      public STATE transition(OPERAND operand, EVENT event);
043    
044    }