| /** |
| * 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.IOException; |
| import java.util.Collection; |
| import java.util.List; |
| |
| import org.apache.hadoop.conf.Configurable; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.server.jobtracker.TaskTracker; |
| |
| /** |
| * Used by a {@link JobTracker} to schedule {@link Task}s on |
| * {@link TaskTracker}s. |
| * <p> |
| * {@link TaskScheduler}s typically use one or more |
| * {@link JobInProgressListener}s to receive notifications about jobs. |
| * <p> |
| * It is the responsibility of the {@link TaskScheduler} |
| * to initialize tasks for a job, by calling {@link JobInProgress#initTasks()} |
| * between the job being added (when |
| * {@link JobInProgressListener#jobAdded(JobInProgress)} is called) |
| * and tasks for that job being assigned (by |
| * {@link #assignTasks(TaskTracker)}). |
| * @see EagerTaskInitializationListener |
| */ |
| abstract class TaskScheduler implements Configurable { |
| |
| protected Configuration conf; |
| protected TaskTrackerManager taskTrackerManager; |
| |
| public Configuration getConf() { |
| return conf; |
| } |
| |
| public void setConf(Configuration conf) { |
| this.conf = conf; |
| } |
| |
| public synchronized void setTaskTrackerManager( |
| TaskTrackerManager taskTrackerManager) { |
| this.taskTrackerManager = taskTrackerManager; |
| } |
| |
| /** |
| * Lifecycle method to allow the scheduler to start any work in separate |
| * threads. |
| * @throws IOException |
| */ |
| public void start() throws IOException { |
| // do nothing |
| } |
| |
| /** |
| * Lifecycle method to allow the scheduler to stop any work it is doing. |
| * @throws IOException |
| */ |
| public void terminate() throws IOException { |
| // do nothing |
| } |
| |
| /** |
| * Returns the tasks we'd like the TaskTracker to execute right now. |
| * |
| * @param taskTracker The TaskTracker for which we're looking for tasks. |
| * @return A list of tasks to run on that TaskTracker, possibly empty. |
| */ |
| public abstract List<Task> assignTasks(TaskTracker taskTracker) |
| throws IOException; |
| |
| /** |
| * Returns a collection of jobs in an order which is specific to |
| * the particular scheduler. |
| * @param queueName |
| * @return |
| */ |
| public abstract Collection<JobInProgress> getJobs(String queueName); |
| |
| /** |
| * Refresh the configuration of the scheduler. |
| */ |
| public void refresh() throws IOException {} |
| |
| |
| /** |
| * Subclasses can override to provide any scheduler-specific checking |
| * mechanism for job submission. |
| * @param job |
| * @throws IOException |
| */ |
| public void checkJobSubmission(JobInProgress job) throws IOException{ |
| } |
| |
| } |