package com.taobao.tddl.common.utils.thread;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;
/**
* 多线程执行器模板代码,otter中好多地方都写多线程,比较多的都是重复的逻辑代码,抽象一下做个模板把
*
* <pre>
* 示例代码:
* ExecutorTemplate template = new ExecutorTemplate(executor);
* ...
* try {
* for ( ....) {
* template.submit(new Runnable() {})
* }
*
* List<?> result = template.waitForResult();
* // do result
* } finally {
* template.clear();
* }
*
* 注意:该模板工程,不支持多业务并发调用,会出现数据混乱
* </pre>
*
* @author jianghang 2013-2-26 下午10:46:43
*/
public class ExecutorTemplate {
private volatile ExecutorCompletionService completionService = null;
private volatile List<Future> futures = null;
public ExecutorTemplate(ThreadPoolExecutor executor){
completionService = new ExecutorCompletionService(executor);
futures = Collections.synchronizedList(new ArrayList<Future>());
}
public void submit(Callable<Exception> task) {
Future future = completionService.submit(task);
futures.add(future);
check(future);// 立即check下,fast-fail
}
public void submit(Runnable task) {
Future future = completionService.submit(task, null);
futures.add(future);
check(future);// 立即check下,fast-fail
}
private void check(Future future) {
if (future.isDone()) {
// 立即判断一次,因为使用了CallerRun可能当场跑出结果,针对有异常时快速响应,而不是等跑完所有的才抛异常
try {
future.get();
} catch (InterruptedException e) {
cancel();// 取消完之后立马退出
throw new RuntimeException(e);
} catch (Throwable e) {
cancel(); // 取消完之后立马退出
throw new RuntimeException(e);
}
}
}
public synchronized List<?> waitForResult() {
List result = new ArrayList();
RuntimeException exception = null;
// 开始处理结果
int index = 0;
while (index < futures.size()) { // 循环处理发出去的所有任务
try {
Future future = completionService.take();// 它也可能被打断
result.add(future.get());
} catch (InterruptedException e) {
exception = new RuntimeException(e);
break;// 如何一个future出现了异常,就退出
} catch (Throwable e) {
exception = new RuntimeException(e);
break;// 如何一个future出现了异常,就退出
}
index++;
}
if (exception != null) {
// 小于代表有错误,需要对未完成的记录进行cancel操作,对已完成的结果进行收集,做重复录入过滤记录
cancel();
throw exception;
} else {
return result;
}
}
public void cancel() {
for (int i = 0; i < futures.size(); i++) {
Future future = futures.get(i);
if (!future.isDone() && !future.isCancelled()) {
future.cancel(true);
}
}
}
public void clear() {
futures.clear();
}
}