content: /*
   * Copyright (C) 2010-2101 Alibaba Group Holding Limited.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.otter.shared.common.utils.thread;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.ArrayBlockingQueue;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorCompletionService;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.DisposableBean;
  import org.springframework.beans.factory.InitializingBean;
  
  /**
   * 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
   * 
   * @author jianghang 2013-2-26 下午10:46:43
   * @version 4.1.7
   */
  public class ExecutorTemplate implements InitializingBean, DisposableBean {
  
      private static final Logger                logger            = LoggerFactory.getLogger(ExecutorTemplate.class);
      private String                             name              = "ExecutorTemplate";
      private static final int                   DEFAULT_POOL_SIZE = 5;
      private int                                poolSize          = DEFAULT_POOL_SIZE;
      private ExecutorService                    executor;
  
      private volatile ExecutorCompletionService completionService = null;
      private volatile List<Future>              futures           = null;
  
      public void start() {
          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 (index < futures.size()) {
              // 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() {
          logger.info("canal Futures[{}]", futures.size());
          for (int i = 0; i < futures.size(); i++) {
              Future future = futures.get(i);
              if (!future.isDone() && !future.isCancelled()) {
                  future.cancel(true);
              }
          }
      }
  
      // 调整一下线程池
      public void adjustPoolSize(int newPoolSize) {
          if (newPoolSize != poolSize) {
              poolSize = newPoolSize;
              if (executor instanceof ThreadPoolExecutor) {
                  ThreadPoolExecutor pool = (ThreadPoolExecutor) executor;
                  pool.setCorePoolSize(newPoolSize);
                  pool.setMaximumPoolSize(newPoolSize);
              }
          }
      }
  
      public void afterPropertiesSet() throws Exception {
          executor = new ThreadPoolExecutor(poolSize, poolSize, 0L, TimeUnit.MILLISECONDS,
                                            new ArrayBlockingQueue(poolSize * 4), new NamedThreadFactory(name),
                                            new ThreadPoolExecutor.CallerRunsPolicy());
      }
  
      public void destroy() throws Exception {
          if (futures != null) {
              futures.clear();
          }
  
          executor.shutdownNow(); // 立即关闭
      }
  
      public void setPoolSize(int poolSize) {
          this.poolSize = poolSize;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
  }
  