guava中线程同步的代码

  1 /**
  2  * 
  3  */
  4 package com.qunar.qfc.guanyingpiao.basic.concurrent;
  5 
  6 import com.google.common.base.Function;
  7 import com.google.common.util.concurrent.AsyncFunction;
  8 import com.google.common.util.concurrent.FutureCallback;
  9 import com.google.common.util.concurrent.Futures;
 10 import com.google.common.util.concurrent.ListenableFuture;
 11 import com.google.common.util.concurrent.ListeningExecutorService;
 12 import com.google.common.util.concurrent.MoreExecutors;
 13 import org.slf4j.Logger;
 14 import org.slf4j.LoggerFactory;
 15 
 16 import java.util.ArrayList;
 17 import java.util.List;
 18 import java.util.concurrent.Callable;
 19 import java.util.concurrent.ExecutionException;
 20 import java.util.concurrent.ExecutorService;
 21 import java.util.concurrent.Executors;
 22 import java.util.concurrent.ThreadLocalRandom;
 23 import java.util.concurrent.atomic.AtomicInteger;
 24 
 25 /**
 26  * 
 27  *
 28  * @author Guanying Piao
 29  *
 30  * 2018-06-30
 31  */
 32 public class FuturesDemo {
 33 
 34     private static Logger logger = LoggerFactory.getLogger(FuturesDemo.class);
 35     
 36     public static void main(String[] args) {
 37         AtomicInteger threadIndex = new AtomicInteger(0);//设置一个原子的自增变量
 38         ExecutorService executorService = Executors.newFixedThreadPool(5, r -> new Thread(r, "thread-" + threadIndex.getAndIncrement()));//创建线程池
 39         ListeningExecutorService listeningExecutorService = MoreExecutors.listeningDecorator(executorService);//管理着线程池
 40         ExecutorService finishExecutorService = Executors.newSingleThreadExecutor(r -> new Thread(r, "finisher"));//这是一个单独的线程
 41         int jobCount = 5;
 42         List<ListenableFuture<String>> listenableFutures = new ArrayList<>(jobCount); 
 43         for (int i = 0; i < jobCount; i++) {
 44             //这里往线程池中循环的投递任务
 45             ListenableFuture<Long> firstFuture = listeningExecutorService.submit(() -> {
 46                 try {
 47                     Thread.sleep(ThreadLocalRandom.current().nextLong(1000L));//并发情况下这个随机数生成器效率更好
 48                 } catch (InterruptedException e) {
 49                     logger.warn("Interrupted while waiting for permit");
 50                 }
 51                 return 123L;
 52             });
 53 
 54            /* ListenableFuture<Long> firstFuture = listeningExecutorService.submit(new Callable<Long>() {
 55 
 56                 public Long call() throws Exception {
 57                     try {
 58                         Thread.sleep(ThreadLocalRandom.current().nextLong(1000L));//并发情况下这个随机数生成器效率更好
 59                     } catch (InterruptedException e) {
 60                         logger.warn("Interrupted while waiting for permit");
 61                     }
 62                     return System.currentTimeMillis();
 63                 }
 64             });*/
 65             try {
 66                 Thread.sleep(1000);
 67             }catch (InterruptedException e){
 68 
 69             }
 70             //对前面的firstFuture任务进行监听，如果firstFutrue任务结束了，在listeningExecutorService线程池中，调用中间的这个回调函数
 71             //由于是transformAsync，所以后面new的是AsyncFunction，同时返回值不能是Long，只能是ListenableFuture<Long>，所以我们下面要return listeningExecutorService.submit
 72             //相当于继续往线程池中投递任务
 73             ListenableFuture<Long> secondFuture = Futures.transformAsync(firstFuture, new AsyncFunction<Long, Long>() {
 74                 @Override
 75                 public ListenableFuture<Long> apply(Long input) throws Exception {
 76                     return listeningExecutorService.submit(() -> {
 77                         try {
 78                             Thread.sleep(ThreadLocalRandom.current().nextLong(1000L));
 79                         } catch (InterruptedException e) {
 80                             logger.warn("Interrupted while waiting for permit");
 81                         }
 82                         return input;
 83                     });
 84                 }                
 85             }, listeningExecutorService);
 86             //下面是对secondFuture进行监听，如果结束了，在finishExecutorService这个线程中执行回调函数
 87             //由于是同步的，所以返回值就可以是正常的值了
 88             ListenableFuture<String> thirdFuture = Futures.transform(secondFuture, new Function<Long, String>() {
 89                 @Override
 90                 public String apply(Long input) {
 91                     return String.valueOf(input);
 92                 }
 93             }, finishExecutorService);
 94             listenableFutures.add(thirdFuture);//将返回的ListenableFutrue装在一个链表中
 95         }
 96         //将这个链表中的每一个ListenableFuture判断，用null代替失败，然后将其装入ListenableFuture<List<String>>中
 97         //里层的链表应该就是代表之前成功的返回值
 98         ListenableFuture<List<String>> allFuture = Futures.successfulAsList(listenableFutures);
 99         //如果allFuture这里面里层的链表都执行完了，在finishExecutorService线程调用回调函数
100         Futures.addCallback(allFuture, new FutureCallback<List<String>>() {
101             @Override
102             public void onSuccess(List<String> result) {
103                 logger.info("job done times:{}", result);
104             }
105             @Override
106             public void onFailure(Throwable t) {
107                 logger.warn("Got exception:{}", t.getMessage());
108             }            
109         }, finishExecutorService);
110         
111         try {
112             allFuture.get();
113         } catch (InterruptedException | ExecutionException e) {
114             logger.warn("Failed to wait for jobs to end");
115         }
116         executorService.shutdown();
117         finishExecutorService.shutdown();
118     }
119 
120 }