Java--高效的定时任务设计
相信你在日常的开发中肯定遇到过这种问题: 需要对实体类的状态信息进行管理,比如一定时间后修改它为XXX状态.
举个例子: 订单服务,当用户提交了订单后,如果在30分钟内没有支付,自动取消订单,这就是一个对状态的管理;
再举一个我实际开发的例子: 消息管道的例子,用户来拉取消息后,如果在30s内没有提交,那么修改他的订阅状态为:未订阅,这样其他的实例可以建立连接继续读取.
整理设计图:
核心就是: 一个Thread + 一个Queue;Thread不断从队列中取出数据, 如果队列中为空或者里边的任务没到期,则线程卡住wait(timeOut).
二 详细设计
先是简单的有状态的实体类:ConsumerInfoState,这个类的核心是状态(订阅到期时间),所以得有对状态的查询设置,查询距到期还要多久等等....
import java.io.Serializable;
public class ConsumerInfoState implements Serializable {
/**
* 序列化ID
*/
private static final long serialVersionUID = 1L;
/**
* 过期时间20s
*/
protected long expiration;
private String topic;
private String userId;
private boolean isSubscribed = false;
private long CONSUMER_INSTANCE_TIMEOUT_MS_DEFAULT = 5000;
public ConsumerInfoState(String userId) {
this.userId = userId;
this.expiration = System.currentTimeMillis() + CONSUMER_INSTANCE_TIMEOUT_MS_DEFAULT;
}
public ConsumerInfoState(String topic, String userId) {
super();
this.topic = topic;
this.userId = userId;
this.expiration = System.currentTimeMillis() + CONSUMER_INSTANCE_TIMEOUT_MS_DEFAULT;
}
/**
*是否过期
*/
public boolean expired(long nowMs) {
return expiration <= nowMs;
}
/**
* <p>
* 更新订阅过期时间
* </p>
*/
public void updateExpiration() {
this.expiration = System.currentTimeMillis() + CONSUMER_INSTANCE_TIMEOUT_MS_DEFAULT;
}
/**
* <p>
* 到指定时间还有多久
* </p>
*/
public long untilExpiration(long nowMs) {
return this.expiration - nowMs;
}
public String getUserId() {
return userId;
}
public String getTopic() {
return topic;
}
public void setTopic(String topic) {
this.topic = topic;
}
public void setSubscribed(boolean isSubscribed) {
this.isSubscribed = isSubscribed;
}
public boolean hasSubscribed() {
return isSubscribed;
}
}
这个类还是很清晰的..
核心类: ConsumerInfoManager
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ConsumerInfoManager {
Logger logger = LoggerFactory.getLogger(ConsumerInfoManager.class);
//任务队列
private final PriorityQueue<ConsumerInfoState> consumersByExpiration = new PriorityQueue<ConsumerInfoState>(
new Comparator<ConsumerInfoState>() {
//小的在前
public int compare(ConsumerInfoState o1, ConsumerInfoState o2) {
if (o1.expiration < o2.expiration) {
return -1;
} else if (o1.expiration == o2.expiration) {
return 0;
} else {
return 1;
}
}
});
private ExpirationThread expirationThread;
public ConsumerInfoManager() {
//启动线程
this.expirationThread = new ExpirationThread();
this.expirationThread.start();
}
//加入任务队列
public synchronized void addConsumerInfoSate(ConsumerInfoState consumerInfoSate) {
consumersByExpiration.add(consumerInfoSate);
this.notifyAll();
}
@SuppressWarnings("unused")
public synchronized void updateExpiration(ConsumerInfoState state) {
// 先删除在放里边,重新排序
consumersByExpiration.remove(state);
state.updateExpiration();
consumersByExpiration.add(state);
this.notifyAll();
}
public void shutdown() {
logger.debug("Shutting down consumers");
expirationThread.shutdown();
synchronized (this) {
consumersByExpiration.clear();
}
}
/**
* <p>
* 检查consumerInfo的过期时间,过期就从缓存中删除
* </p>
* @author jiangyuechao 2018年1月13日 下午2:04:30
*/
@SuppressWarnings("unused")
private class ExpirationThread extends Thread {
AtomicBoolean isRunning = new AtomicBoolean(true);
CountDownLatch shutdownLatch = new CountDownLatch(1);
public ExpirationThread() {
super("Consumer Expiration Thread");
setDaemon(true);
}
@Override
public void run() {
synchronized (ConsumerInfoManager.this) {
try {
while (isRunning.get()) {
long now = System.currentTimeMillis();
//队列空和最近一个任务是否到期的判断
while (!consumersByExpiration.isEmpty() && consumersByExpiration.peek().expired(now)) {
final ConsumerInfoState state = consumersByExpiration.remove();
//{你自己的业务处理}
state.setSubscribed(false);
logger.info("任务已到期,topic:{}, userID:{},subscribed:{}",state.getTopic(),state.getUserId(),state.hasSubscribed());
}
//需要等待的时间
long timeout = consumersByExpiration.isEmpty() ? Long.MAX_VALUE
: consumersByExpiration.peek().untilExpiration(now);
ConsumerInfoManager.this.wait(timeout);
}
} catch (InterruptedException e) {
// Interrupted by other thread, do nothing to allow this thread to exit
logger.error("ExpirationThread线程中断", e);
}
}
shutdownLatch.countDown();
}
public void shutdown() {
try {
isRunning.set(false);
this.interrupt();
shutdownLatch.await();
} catch (InterruptedException e) {
throw new Error("Interrupted when shutting down consumer worker thread.");
}
}
}
public void join(){
try {
expirationThread.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
代码就这些,我进行了删减,删除了不重要的部分, 一般ConsumerInfoManager还需要一个缓存Cache,Cache中是存储所有的实体类,queue中是Cache中的一部分,一般queue中的任务到期,需要从Cache中删除或取出执行一些操作.
当然加Cache是复杂点的,核心思想就这些,额外的代码就删除了..
最后测试一下
public class ManagerTest {
static ConsumerInfoManager consumerInfoManager;
static String userId = "dhsajkdsajkdsjh1";
static Logger logger = LoggerFactory.getLogger(ManagerTest.class);
public static void main(String[] args) throws InterruptedException {
//实例化
setUp();
for(int i = 0;i<3;i++){
ConsumerInfoState consumerInfoState = new ConsumerInfoState("chao-"+i, userId);
consumerInfoState.setSubscribed(true);
consumerInfoManager.addConsumerInfoSate(consumerInfoState);
logger.info("任务"+i+"加入队列");
Thread.sleep(1000);
}
consumerInfoManager.join();
}
public static void setUp(){
consumerInfoManager = new ConsumerInfoManager();
}
}
输出结果: 符合预期...
2018-01-17 10:07:27,450 [main] INFO ManagerTest - 任务0加入队列
2018-01-17 10:07:28,451 [main] INFO ManagerTest - 任务1加入队列
2018-01-17 10:07:29,451 [main] INFO ManagerTest - 任务2加入队列
2018-01-17 10:07:32,451 [Consumer Expiration Thread] INFO ConsumerInfoManager - 任务已到期,topic:chao-0, userID:dhsajkdsajkdsjh1,subscribed:false
2018-01-17 10:07:33,485 [Consumer Expiration Thread] INFO ConsumerInfoManager - 任务已到期,topic:chao-1, userID:dhsajkdsajkdsjh1,subscribed:false
2018-01-17 10:07:34,452 [Consumer Expiration Thread] INFO ConsumerInfoManager - 任务已到期,topic:chao-2, userID:dhsajkdsajkdsjh1,subscribed:false
