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      1 /*
      2  * Copyright (C) 2008 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.testing;
     18 
     19 import com.google.common.annotations.GwtCompatible;
     20 import com.google.common.annotations.GwtIncompatible;
     21 
     22 import junit.framework.TestCase;
     23 
     24 import java.util.concurrent.Callable;
     25 import java.util.concurrent.CountDownLatch;
     26 import java.util.concurrent.ExecutorService;
     27 import java.util.concurrent.Executors;
     28 import java.util.concurrent.TimeUnit;
     29 
     30 /**
     31  * Unit test for {@link FakeTicker}.
     32  *
     33  * @author benyu (at) google.com (Jige Yu)
     34  */
     35 @GwtCompatible(emulated = true)
     36 public class FakeTickerTest extends TestCase {
     37 
     38   public void testAdvance() {
     39     FakeTicker ticker = new FakeTicker();
     40     assertEquals(0, ticker.read());
     41     assertSame(ticker, ticker.advance(10));
     42     assertEquals(10, ticker.read());
     43     ticker.advance(1, TimeUnit.MILLISECONDS);
     44     assertEquals(1000010L, ticker.read());
     45   }
     46 
     47   @GwtIncompatible("concurrency")
     48 
     49   public void testConcurrentAdvance() throws Exception {
     50     final FakeTicker ticker = new FakeTicker();
     51 
     52     int numberOfThreads = 64;
     53     ExecutorService executorService = Executors.newFixedThreadPool(numberOfThreads);
     54     final CountDownLatch startLatch = new CountDownLatch(numberOfThreads);
     55     final CountDownLatch doneLatch = new CountDownLatch(numberOfThreads);
     56     for (int i = numberOfThreads; i > 0; i--) {
     57       executorService.submit(new Callable<Void>() {
     58         @Override
     59         public Void call() throws Exception {
     60           // adds two nanoseconds to the ticker
     61           startLatch.countDown();
     62           startLatch.await();
     63           ticker.advance(1L);
     64           Thread.sleep(10);
     65           ticker.advance(1L);
     66           doneLatch.countDown();
     67           return null;
     68         }
     69       });
     70     }
     71     doneLatch.await();
     72     assertEquals(numberOfThreads * 2, ticker.read());
     73   }
     74 }
     75