Event model Hadoop1.X job submission

1 Overview

In hadoop1.X the job is submitted to JobTracker, with a very typical event model, the source abstract it.

2 listeners

A listener interfaces: need to focus on behavior

2 listeners: implementation class

public interface Listener {

	/**
	 * 监听作业添加
	 * 
	 * @param job 作业对象
	 */
	public void jobAdded(Job job);

	/**
	 * 监听作业删除
	 * 
	 * @param job 作业对象
	 */
	public void jobDeleted(Job job);
}

/**
 * 作业初始化监听器
 * 
 * 源码中调用jobTracker的initJob方法
 * 
 */
public class EagerTaskInitializationListener implements Listener {

	public void jobAdded(Job job) {
		System.out.println("作业被添加:" + job.getName() + " 执行操作1........");
	}

	public void jobDeleted(Job job) {
		System.out.println("作业被删除:" + job.getName() + " 执行操作1........");

	}
}

/**
 * 排序监听器
 */
public class JobQueueJobInProgressListener implements Listener {

	public void jobAdded(Job job) {
		System.out.println("作业被添加:" + job.getName() + " 执行操作2........");
	}

	public void jobDeleted(Job job) {
		System.out.println("作业被删除:" + job.getName() + " 执行操作2........");
	}
}

Scheduler 3

A scheduler Abstract

A particular scheduler

public abstract class TaskScheduler {
	protected TaskTrackerManager taskTrackerManager;

	public void setTaskTrackerManager(TaskTrackerManager taskTrackerManager) {
		// 该对象就是JobTracker对象
		this.taskTrackerManager = taskTrackerManager;
	}

	public void start() {

	}
}

public class JobQueueScheduler extends TaskScheduler {

	// 监听器1
	private EagerTaskInitializationListener jobInProgressListener1;

	// 监听器2
	private JobQueueJobInProgressListener jobInProgressListener2;

	/**
	 * 初始化并注册监听器
	 */
	public void start() {
		jobInProgressListener1 = new EagerTaskInitializationListener();
		jobInProgressListener2 = new JobQueueJobInProgressListener();

		// taskTrackerManager为父类中的对象，其实就是JobTracker
		taskTrackerManager.addJobInProgressListener(jobInProgressListener1);
		taskTrackerManager.addJobInProgressListener(jobInProgressListener2);
	}
}

4 Tacker related

An abstract class Job

Add a listener interface

1 specific JobTracker

public class Job {

	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
}


public interface TaskTrackerManager {
	// 添加监听者
	public void addJobInProgressListener(Listener listener);
}

public class JobTracker implements TaskTrackerManager {

	// 调度器
	private TaskScheduler scheduler;

	// 所有监听者
	private List<Listener> jobInProgressListeners = new CopyOnWriteArrayList<Listener>();

	/**
	 * 启动时创建调度器
	 */
	public JobTracker() {
		scheduler = new JobQueueScheduler();
	}

	/**
	 * 启动JobTracker
	 */
	public void startTracker() {
		// 将自身对象传给调度器
		scheduler.setTaskTrackerManager(this);
		// 启动调度器
		scheduler.start();
	}

	/**
	 * 作业被添加。通知所有注册的监听器
	 * 
	 * @param job 作业对象
	 */
	public void addJob(Job job) {
		for (Listener listener : jobInProgressListeners) {
			listener.jobAdded(job);
		}
	}

	/**
	 * 作业被删除。通知所有注册的监听器
	 * 
	 * @param job 作业对象
	 */
	public void deleteJob(Job job) {
		for (Listener listener : jobInProgressListeners) {
			listener.jobDeleted(job);
		}
	}

	/**
	 * 添加监听器
	 */
	@Override
	public void addJobInProgressListener(Listener listener) {
		jobInProgressListeners.add(listener);
	}
}

5 Test

public class TestJobTracker {

	public static void main(String[] args) {
		// 初始化
		JobTracker jobTracker = new JobTracker();
		jobTracker.startTracker();
		
		// 添加作业
		Job job = new Job();
		job.setName("xy job");
		jobTracker.addJob(job);
		// 删除作业
		jobTracker.deleteJob(job);
	}
}