/**
    *
    * 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.
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  package org.apache.hadoop.hbase.util;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNull;
  import static org.junit.Assert.assertTrue;
  
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  
  @Category(SmallTests.class)
  public class TestStealJobQueue {
  
    StealJobQueue<Integer> stealJobQueue;
    BlockingQueue<Integer> stealFromQueue;
  
    @Before
    public void setup() {
      stealJobQueue = new StealJobQueue<>();
      stealFromQueue = stealJobQueue.getStealFromQueue();
  
    }
  
  
    @Test
    public void testTake() throws InterruptedException {
      stealJobQueue.offer(3);
      stealFromQueue.offer(10);
      stealJobQueue.offer(15);
      stealJobQueue.offer(4);
      assertEquals(3, stealJobQueue.take().intValue());
      assertEquals(4, stealJobQueue.take().intValue());
      assertEquals("always take from the main queue before trying to steal", 15,
              stealJobQueue.take().intValue());
      assertEquals(10, stealJobQueue.take().intValue());
      assertTrue(stealFromQueue.isEmpty());
      assertTrue(stealJobQueue.isEmpty());
    }
  
    @Test
    public void testOfferInStealQueueFromShouldUnblock() throws InterruptedException {
      final AtomicInteger taken = new AtomicInteger();
      Thread consumer = new Thread() {
        @Override
        public void run() {
          try {
            Integer n = stealJobQueue.take();
            taken.set(n);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
      };
      consumer.start();
      stealFromQueue.offer(3);
      consumer.join(1000);
      assertEquals(3, taken.get());
      consumer.interrupt(); //Ensure the consumer thread will stop.
    }
  
  
    @Test
    public void testOfferInStealJobQueueShouldUnblock() throws InterruptedException {
      final AtomicInteger taken = new AtomicInteger();
      Thread consumer = new Thread() {
        @Override
        public void run() {
          try {
            Integer n = stealJobQueue.take();
            taken.set(n);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
       }
     };
     consumer.start();
     stealJobQueue.offer(3);
     consumer.join(1000);
     assertEquals(3, taken.get());
     consumer.interrupt(); //Ensure the consumer thread will stop.
   }
 
 
   @Test
   public void testPoll() throws InterruptedException {
     stealJobQueue.offer(3);
     stealFromQueue.offer(10);
     stealJobQueue.offer(15);
     stealJobQueue.offer(4);
     assertEquals(3, stealJobQueue.poll(1, TimeUnit.SECONDS).intValue());
     assertEquals(4, stealJobQueue.poll(1, TimeUnit.SECONDS).intValue());
     assertEquals("always take from the main queue before trying to steal", 15,
             stealJobQueue.poll(1, TimeUnit.SECONDS).intValue());
     assertEquals(10, stealJobQueue.poll(1, TimeUnit.SECONDS).intValue());
     assertTrue(stealFromQueue.isEmpty());
     assertTrue(stealJobQueue.isEmpty());
     assertNull(stealJobQueue.poll(10, TimeUnit.MILLISECONDS));
   }
 
   @Test
   public void testPutInStealQueueFromShouldUnblockPoll() throws InterruptedException {
     final AtomicInteger taken = new AtomicInteger();
     Thread consumer = new Thread() {
       @Override
       public void run() {
         try {
           Integer n = stealJobQueue.poll(3, TimeUnit.SECONDS);
           taken.set(n);
         } catch (InterruptedException e) {
           e.printStackTrace();
         }
       }
     };
     consumer.start();
     stealFromQueue.put(3);
     consumer.join(1000);
     assertEquals(3, taken.get());
     consumer.interrupt(); //Ensure the consumer thread will stop.
 
   }
 
 
   @Test
   public void testAddInStealJobQueueShouldUnblockPoll() throws InterruptedException {
     final AtomicInteger taken = new AtomicInteger();
     Thread consumer = new Thread() {
       @Override
       public void run() {
         try {
           Integer n = stealJobQueue.poll(3, TimeUnit.SECONDS);
           taken.set(n);
         } catch (InterruptedException e) {
           e.printStackTrace();
         }
       }
     };
     consumer.start();
     stealJobQueue.add(3);
     consumer.join(1000);
     assertEquals(3, taken.get());
     consumer.interrupt(); //Ensure the consumer thread will stop.
   }
 
 
   @Test
   public void testInteractWithThreadPool() throws InterruptedException {
     StealJobQueue<Runnable> stealTasksQueue = new StealJobQueue<>();
     final CountDownLatch stealJobCountDown = new CountDownLatch(3);
     final CountDownLatch stealFromCountDown = new CountDownLatch(3);
     ThreadPoolExecutor stealPool = new ThreadPoolExecutor(3, 3, 1, TimeUnit.DAYS, stealTasksQueue) {
       @Override
       protected void afterExecute(Runnable r, Throwable t) {
         super.afterExecute(r, t);
         stealJobCountDown.countDown();
       }
 
     };
 
     //This is necessary otherwise no worker will be running and stealing job
     stealPool.prestartAllCoreThreads();
 
     ThreadPoolExecutor stealFromPool = new ThreadPoolExecutor(3, 3, 1, TimeUnit.DAYS,
             stealTasksQueue.getStealFromQueue()) {
       @Override
       protected void afterExecute(Runnable r, Throwable t) {
         super.afterExecute(r, t);
         stealFromCountDown.countDown();
       }
     };
 
     for (int i = 0; i < 4; i++) {
       TestTask task = new TestTask();
       stealFromPool.execute(task);
     }
 
     for (int i = 0; i < 2; i++) {
       TestTask task = new TestTask();
       stealPool.execute(task);
     }
 
     stealJobCountDown.await(1, TimeUnit.SECONDS);
     stealFromCountDown.await(1, TimeUnit.SECONDS);
     assertEquals(0, stealFromCountDown.getCount());
     assertEquals(0, stealJobCountDown.getCount());
   }
 
   class TestTask extends Thread implements Comparable<TestTask> {
     @Override
     public int compareTo(TestTask o) {
       return 0;
     }
 
     @Override
     public void run() {
       try {
         Thread.sleep(200);
       } catch (InterruptedException e) {
         e.printStackTrace();
       }
     }
   }
 
 }