java – 按顺序处理异步事件和发布结果
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了java – 按顺序处理异步事件和发布结果，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含4706字，纯文字阅读大概需要7分钟。
内容图文
我的目标是按顺序发布异步事件,这些事件也按顺序到达并花费任意时间进行处理.所以下面是我目前的实现只使用wait和notify. MyThread处理事件,通过id将结果放入哈希表中,如果在按顺序发布此事件之前被阻塞,则通知Scheduler线程.
使用java.util.concurrent包实现此功能会有什么更好,更简洁的方法？
import java.util.Map;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;
public class AsyncHandler {
private final Map<Integer, Object> locks = new ConcurrentHashMap<Integer, Object>();
private final Map<Integer, Result> results = new ConcurrentHashMap<Integer, Result>();
private static final Random rand = new Random();
public AsyncHandler () {
new Scheduler(this, locks, results).start();
}
public void handleEvent(Event event) {
System.out.println("handleEvent(" + event.id + ")");
new MyThread(this, event, locks, results).start();
}
public Result processEvent (Event event) {
System.out.println("processEvent(" + event.id + ")");
locks.put(event.id, new Object());
try {
Thread.sleep(rand.nextInt(10000));
} catch (InterruptedException e) {
System.out.println(e);
}
return new Result(event.id);
}
public void postProcessEvent (Result result) {
System.out.println(result.id);
}
public static void main (String[] args) {
AsyncHandler async = new AsyncHandler();
for (int i = 0; i < 100; i++) {
async.handleEvent(new Event(i));
}
}
}
class Event {
int id;
public Event (int id) {
this.id = id;
}
}
class Result {
int id;
public Result (int id) {
this.id = id;
}
}
class MyThread extends Thread {
private final Event event;
private final Map<Integer, Object> locks;
private final Map<Integer, Result> results;
private final AsyncHandler async;
public MyThread (AsyncHandler async, Event event, Map<Integer, Object> locks, Map<Integer, Result> results) {
this.async = async;
this.event = event;
this.locks = locks;
this.results = results;
}
@Override
public void run () {
Result res = async.processEvent(event);
results.put(event.id, res);
Object lock = locks.get(event.id);
synchronized (lock) {
lock.notifyAll();
}
}
}
class Scheduler extends Thread {
private int curId = 0;
private final AsyncHandler async;
private final Map<Integer, Object> locks;
private final Map<Integer, Result> results;
public Scheduler (AsyncHandler async, Map<Integer, Object> locks, Map<Integer, Result> results) {
this.async = async;
this.locks = locks;
this.results = results;
}
@Override
public void run () {
while (true) {
Result res = results.get(curId);
if (res == null) {
Object lock = locks.get(curId);
//TODO: eliminate busy waiting
if (lock == null) {
continue;
}
synchronized (lock) {
try {
lock.wait();
} catch (InterruptedException e) {
System.out.println(e);
System.exit(1);
}
}
res = results.get(curId);
}
async.postProcessEvent(res);
results.remove(curId);
locks.remove(curId);
curId++;
}
}
}
解决方法:
是的并发库会简单得多.
ExecutorService旨在包装线程池和队列,以便为每个任务返回Future,并提供等待结果的任何线程.
如果您想按顺序处理结果,请按顺序处理未来结果的线程.
按顺序处理异步结果
public class Main {
public static void main(String[] args) {
Main main = new Main();
for (int i = 0; i < 1000; i++) {
final int finalI = i;
main.submitTask(new Callable<Long>() {
@Override
public Long call() throws Exception {
long millis = (long) (Math.pow(2000, Math.random()));
Thread.sleep(millis);
return millis;
}
}, new ResultHandler<Long>() {
@Override
public void onFuture(Future<Long> future) throws ExecutionException, InterruptedException {
System.out.println(new Date() + ": " + finalI + " - Slept for " + future.get() + " millis");
}
});
}
main.shutdown();
}
public interface ResultHandler<T> {
void onFuture(Future<T> future) throws Exception;
}
private final ExecutorService pool = Executors.newFixedThreadPool(10);
private final ExecutorService result = Executors.newSingleThreadExecutor();
public synchronized <T> void submitTask(Callable<T> callable, final ResultHandler<T> resultHandler) {
final Future<T> future = pool.submit(callable);
result.submit(new Runnable() {
@Override
public void run() {
try {
resultHandler.onFuture(future);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public void shutdown() {
pool.shutdown();
result.shutdown();
}
}
版画
Wed Oct 02 16:32:07 CEST 2013: 0 - Slept for 1 millis
Wed Oct 02 16:32:07 CEST 2013: 1 - Slept for 1899 millis
Wed Oct 02 16:32:09 CEST 2013: 2 - Slept for 32 millis
Wed Oct 02 16:32:09 CEST 2013: 3 - Slept for 32 millis
Wed Oct 02 16:32:09 CEST 2013: 4 - Slept for 214 millis
Wed Oct 02 16:32:09 CEST 2013: 5 - Slept for 366 millis
... many deleted ...
Wed Oct 02 16:32:09 CEST 2013: 82 - Slept for 6 millis
Wed Oct 02 16:32:09 CEST 2013: 83 - Slept for 1636 millis
Wed Oct 02 16:32:10 CEST 2013: 84 - Slept for 44 millis
Wed Oct 02 16:32:10 CEST 2013: 85 - Slept for 1 millis
您可以看到,虽然某些任务比其他任务花费的时间长,但输出的顺序是添加任务的顺序.您还可以看到它在同一秒内处理许多任务(同时)
内容总结
以上是互联网集市为您收集整理的java – 按顺序处理异步事件和发布结果全部内容，希望文章能够帮你解决java – 按顺序处理异步事件和发布结果所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错，欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 gblab@vip.qq.com 举报，一经查实，本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。
来源：【匿名】