content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.jstorm.event;
  
  import com.alibaba.jstorm.callback.RunnableCallback;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.atomic.AtomicInteger;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Event Manager, drop one event from queue, then execute the event.
   */
  public class EventManagerImp extends RunnableCallback implements EventManager {
      private static final Logger LOG = LoggerFactory.getLogger(EventManagerImp.class);
  
      private AtomicInteger added = new AtomicInteger();
      private AtomicInteger processed = new AtomicInteger();
  
      private LinkedBlockingQueue<RunnableCallback> queue = new LinkedBlockingQueue<>();
  
      private Exception e;
  
      public void processInc() {
          processed.incrementAndGet();
      }
  
      @Override
      public void add(RunnableCallback event_fn) {
          added.incrementAndGet();
          queue.add(event_fn);
      }
  
      @Override
      public boolean waiting() {
          return (processed.get() == added.get());
      }
  
      @Override
      public Exception error() {
          return e;
      }
  
      @Override
      public void run() {
          try {
              RunnableCallback r = queue.take();
              if (r == null) {
                  return;
              }
              r.run();
              e = r.error();
              processInc();
          } catch (InterruptedException e) {
              LOG.info("Interrupted when processing event.");
          }
      }
  }
  