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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.yolean.concurrent;
import org.junit.Test;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
/**
* @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
*/
public class ThreadRobustListTestCase {
private final static int NUM_THREADS = 64;
private final static int NUM_ITEMS_TO_WRITE = 1000000;
private final static int NUM_TIMES_TO_READ = 10;
@Test
public void requireThatListIsThreadRobust() throws Exception {
final CountDownLatch latch = new CountDownLatch(NUM_THREADS);
final ThreadRobustList<Integer> sharedList = new ThreadRobustList<>();
List<Callable<Boolean>> tasks = new ArrayList<>(NUM_THREADS);
tasks.add(new WriterTask(latch, sharedList));
for (int i = 1; i < NUM_THREADS; ++i) {
tasks.add(new ReaderTask(latch, sharedList));
}
for (Future<Boolean> result : Executors.newFixedThreadPool(NUM_THREADS).invokeAll(tasks)) {
assertTrue(result.get(60, TimeUnit.SECONDS));
}
}
@Test
public void requireThatAccessorsWork() {
ThreadRobustList<Object> lst = new ThreadRobustList<>();
assertTrue(lst.isEmpty());
assertFalse(lst.iterator().hasNext());
Object foo = new Object();
lst.add(foo);
assertFalse(lst.isEmpty());
Iterator<Object> it = lst.iterator();
assertNotNull(it);
assertTrue(it.hasNext());
assertSame(foo, it.next());
assertFalse(it.hasNext());
Object bar = new Object();
lst.add(bar);
assertFalse(lst.isEmpty());
assertNotNull(it = lst.iterator());
assertTrue(it.hasNext());
assertSame(foo, it.next());
assertTrue(it.hasNext());
assertSame(bar, it.next());
assertFalse(it.hasNext());
}
@Test
public void requireThatIteratorNextThrowsNoSuchElementExceptionWhenDone() {
ThreadRobustList<Object> lst = new ThreadRobustList<>();
Iterator<Object> it = lst.iterator();
assertFalse(it.hasNext());
try {
it.next();
fail();
} catch (NoSuchElementException e) {
}
}
@Test
public void requireThatIteratorRemoveIsNotSupported() {
ThreadRobustList<Object> lst = new ThreadRobustList<>();
Object obj = new Object();
lst.add(obj);
Iterator<Object> it = lst.iterator();
assertTrue(it.hasNext());
assertSame(obj, it.next());
try {
it.remove();
fail();
} catch (UnsupportedOperationException e) {
}
}
private static class WriterTask implements Callable<Boolean> {
final CountDownLatch latch;
final ThreadRobustList<Integer> sharedList;
WriterTask(CountDownLatch latch, ThreadRobustList<Integer> sharedList) {
this.latch = latch;
this.sharedList = sharedList;
}
@Override
public Boolean call() throws Exception {
latch.countDown();
assertTrue(latch.await(60, TimeUnit.SECONDS));
for (int i = 0; i < NUM_ITEMS_TO_WRITE; ++i) {
sharedList.add(i);
}
return true;
}
}
private static class ReaderTask implements Callable<Boolean> {
final CountDownLatch latch;
final ThreadRobustList<Integer> sharedList;
ReaderTask(CountDownLatch latch, ThreadRobustList<Integer> sharedList) {
this.latch = latch;
this.sharedList = sharedList;
}
@Override
public Boolean call() throws Exception {
latch.countDown();
assertTrue(latch.await(60, TimeUnit.SECONDS));
for (int i = 0; i < NUM_TIMES_TO_READ; ++i) {
Iterator<Integer> it = sharedList.iterator();
for (int j = 0; it.hasNext(); ++j) {
assertEquals(j, it.next().intValue());
}
}
return true;
}
}
}
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