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
019package org.apache.hadoop.yarn.state;
020
021import org.apache.hadoop.classification.InterfaceAudience.Public;
022import 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
031public 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}