/**
 * 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 org.apache.hadoop.yarn.event;

import static org.mockito.Mockito.doThrow;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.spy;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
import org.junit.Assert;
import org.junit.Test;

public class TestAsyncDispatcher {

  /* This test checks whether dispatcher hangs on close if following two things
   * happen :
   * 1. A thread which was putting event to event queue is interrupted.
   * 2. Event queue is empty on close.
   */
  @SuppressWarnings({ "unchecked", "rawtypes" })
  @Test(timeout=10000)
  public void testDispatcherOnCloseIfQueueEmpty() throws Exception {
    BlockingQueue<Event> eventQueue = spy(new LinkedBlockingQueue<Event>());
    Event event = mock(Event.class);
    doThrow(new InterruptedException()).when(eventQueue).put(event);
    DrainDispatcher disp = new DrainDispatcher(eventQueue);
    disp.init(new Configuration());
    disp.setDrainEventsOnStop();
    disp.start();
    // Wait for event handler thread to start and begin waiting for events.
    disp.waitForEventThreadToWait();
    try {
      disp.getEventHandler().handle(event);
    } catch (YarnRuntimeException e) {
    }
    // Queue should be empty and dispatcher should not hang on close
    Assert.assertTrue("Event Queue should have been empty",
        eventQueue.isEmpty());
    disp.close();
  }
}

