//
// ========================================================================
// Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.util.statistic;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThanOrEqualTo;
import static org.junit.Assert.assertThat;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import org.junit.Test;
/* ------------------------------------------------------------ */
public class CounterStatisticTest
{
@Test
public void testCounter()
throws Exception
{
CounterStatistic count = new CounterStatistic();
assertThat(count.getCurrent(),equalTo(0L));
assertThat(count.getMax(),equalTo(0L));
assertThat(count.getTotal(),equalTo(0L));
count.increment();
count.increment();
count.decrement();
count.add(4);
count.add(-2);
assertThat(count.getCurrent(),equalTo(3L));
assertThat(count.getMax(),equalTo(5L));
assertThat(count.getTotal(),equalTo(6L));
count.reset();
assertThat(count.getCurrent(),equalTo(3L));
assertThat(count.getMax(),equalTo(3L));
assertThat(count.getTotal(),equalTo(3L));
count.increment();
count.decrement();
count.add(-2);
count.decrement();
assertThat(count.getCurrent(),equalTo(0L));
assertThat(count.getMax(),equalTo(4L));
assertThat(count.getTotal(),equalTo(4L));
count.decrement();
assertThat(count.getCurrent(),equalTo(-1L));
assertThat(count.getMax(),equalTo(4L));
assertThat(count.getTotal(),equalTo(4L));
count.increment();
assertThat(count.getCurrent(),equalTo(0L));
assertThat(count.getMax(),equalTo(4L));
assertThat(count.getTotal(),equalTo(5L));
}
@Test
public void testCounterContended()
throws Exception
{
final CounterStatistic counter = new CounterStatistic();
final int N=100;
final int L=1000;
final Thread[] threads = new Thread[N];
final CyclicBarrier incBarrier = new CyclicBarrier(N);
final CountDownLatch decBarrier = new CountDownLatch(N/2);
for (int i=N;i-->0;)
{
final int I = i;
threads[i]=(i>=N/2)
?new Thread()
{
@Override
public void run()
{
try
{
incBarrier.await();
decBarrier.await();
}
catch (Exception e)
{
throw new RuntimeException(e);
}
Random random = new Random();
for (int l=L;l-->0;)
{
counter.decrement();
if (random.nextInt(5)==0)
Thread.yield();
}
}
}
:new Thread()
{
@Override
public void run()
{
try
{
incBarrier.await();
}
catch (Exception e)
{
throw new RuntimeException(e);
}
Random random = new Random();
for (int l=L;l-->0;)
{
counter.increment();
if (l==L/2)
decBarrier.countDown();
if (random.nextInt(5)==0)
Thread.yield();
}
}
};
threads[i].start();
}
for (int i=N;i-->0;)
threads[i].join();
assertThat(counter.getCurrent(),equalTo(0L));
assertThat(counter.getTotal(),equalTo(N*L/2L));
assertThat(counter.getMax(),greaterThanOrEqualTo((N/2)*(L/2L)));
}
}