| /** |
| * 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.hadoop.mapred; |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableUtils; |
| |
| /** |
| * A generic directive from the {@link org.apache.hadoop.mapred.JobTracker} |
| * to the {@link org.apache.hadoop.mapred.TaskTracker} to take some 'action'. |
| * |
| */ |
| abstract class TaskTrackerAction implements Writable { |
| |
| /** |
| * Ennumeration of various 'actions' that the {@link JobTracker} |
| * directs the {@link TaskTracker} to perform periodically. |
| * |
| */ |
| public static enum ActionType { |
| /** Launch a new task. */ |
| LAUNCH_TASK, |
| |
| /** Kill a task. */ |
| KILL_TASK, |
| |
| /** Kill any tasks of this job and cleanup. */ |
| KILL_JOB, |
| |
| /** Reinitialize the tasktracker. */ |
| REINIT_TRACKER, |
| |
| /** Ask a task to save its output. */ |
| COMMIT_TASK |
| }; |
| |
| /** |
| * A factory-method to create objects of given {@link ActionType}. |
| * @param actionType the {@link ActionType} of object to create. |
| * @return an object of {@link ActionType}. |
| */ |
| public static TaskTrackerAction createAction(ActionType actionType) { |
| TaskTrackerAction action = null; |
| |
| switch (actionType) { |
| case LAUNCH_TASK: |
| { |
| action = new LaunchTaskAction(); |
| } |
| break; |
| case KILL_TASK: |
| { |
| action = new KillTaskAction(); |
| } |
| break; |
| case KILL_JOB: |
| { |
| action = new KillJobAction(); |
| } |
| break; |
| case REINIT_TRACKER: |
| { |
| action = new ReinitTrackerAction(); |
| } |
| break; |
| case COMMIT_TASK: |
| { |
| action = new CommitTaskAction(); |
| } |
| break; |
| } |
| |
| return action; |
| } |
| |
| private ActionType actionType; |
| |
| protected TaskTrackerAction(ActionType actionType) { |
| this.actionType = actionType; |
| } |
| |
| /** |
| * Return the {@link ActionType}. |
| * @return the {@link ActionType}. |
| */ |
| ActionType getActionId() { |
| return actionType; |
| } |
| |
| public void write(DataOutput out) throws IOException { |
| WritableUtils.writeEnum(out, actionType); |
| } |
| |
| public void readFields(DataInput in) throws IOException { |
| actionType = WritableUtils.readEnum(in, ActionType.class); |
| } |
| } |