/*******************************************************************************
* Copyright (c) 2007 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.tests.internal;
import java.util.EmptyStackException;
import org.eclipse.jpt.utility.internal.SimpleStack;
import org.eclipse.jpt.utility.internal.Stack;
import org.eclipse.jpt.utility.internal.SynchronizedStack;
public class SynchronizedStackTests extends SimpleStackTests {
private volatile SynchronizedStack<String> ss;
private volatile boolean exCaught;
private volatile boolean timeoutOccurred;
private volatile long startTime;
private volatile long endTime;
private volatile Object poppedObject;
static final String ITEM_1 = new String();
static final String ITEM_2 = new String();
public SynchronizedStackTests(String name) {
super(name);
}
@Override
protected void setUp() throws Exception {
super.setUp();
this.ss = new SynchronizedStack<String>();
this.exCaught = false;
this.timeoutOccurred = false;
this.startTime = 0;
this.endTime = 0;
this.poppedObject = null;
}
/**
* test first with an unsynchronized stack,
* then with a synchronized stack
*/
public void testConcurrentAccess() throws Exception {
this.verifyConcurrentAccess(new SlowSimpleStack<String>(), "second");
this.verifyConcurrentAccess(new SlowSynchronizedStack<String>(), "first");
}
private void verifyConcurrentAccess(SlowStack<String> slowStack, String expected) throws Exception {
slowStack.push("first");
slowStack.push("second");
new Thread(this.buildRunnable(slowStack)).start();
Thread.sleep(200);
assertEquals(expected, slowStack.pop());
}
private Runnable buildRunnable(final SlowStack<String> slowStack) {
return new Runnable() {
public void run() {
slowStack.slowPop();
}
};
}
private interface SlowStack<E> extends Stack<E> {
Object slowPop();
}
private class SlowSimpleStack<E> extends SimpleStack<E> implements SlowStack<E> {
SlowSimpleStack() {
super();
}
public Object slowPop() {
try {
Thread.sleep(500);
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
}
return this.pop();
}
}
private class SlowSynchronizedStack<E> extends SynchronizedStack<E> implements SlowStack<E> {
SlowSynchronizedStack() {
super();
}
public synchronized Object slowPop() {
try {
Thread.sleep(100);
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
}
return this.pop();
}
}
// ********** waits **********
public void testWaitToPop() throws Exception {
this.verifyWaitToPop(0);
// no timeout occurs...
assertFalse(this.timeoutOccurred);
// ...and an item should have been popped by t2...
assertSame(ITEM_1, this.poppedObject);
// ...and the stack should be empty
assertTrue(this.ss.isEmpty());
// make a reasonable guess about how long t2 took
assertTrue(this.elapsedTime() > 150);
}
public void testWaitToPopTimeout() throws Exception {
this.verifyWaitToPop(20);
// timeout occurs...
assertTrue(this.timeoutOccurred);
// ...and the stack was never popped...
assertNull(this.poppedObject);
// ...and it still holds the item
assertSame(ITEM_1, this.ss.peek());
// make a reasonable guess about how long t2 took
assertTrue(this.elapsedTime() < 150);
}
private void verifyWaitToPop(long timeout) throws Exception {
Runnable r1 = this.buildRunnable(this.buildPushCommand(), this.ss, 200);
Runnable r2 = this.buildRunnable(this.buildWaitToPopCommand(timeout), this.ss, 0);
Thread t1 = new Thread(r1);
Thread t2 = new Thread(r2);
t1.start();
t2.start();
while (t1.isAlive() || t2.isAlive()) {
Thread.sleep(50);
}
assertFalse(this.exCaught);
}
public void testWaitToPush() throws Exception {
this.verifyWaitToPush(0);
// no timeout occurs...
assertFalse(this.timeoutOccurred);
// ...and the stack gets popped by t1...
assertSame(ITEM_1, this.poppedObject);
// ...and an item is pushed on to the stack by t2
assertFalse(this.ss.isEmpty());
assertSame(ITEM_2, this.ss.peek());
// make a reasonable guess about how long t2 took
assertTrue(this.elapsedTime() > 150);
}
public void testWaitToPushTimeout() throws Exception {
this.verifyWaitToPush(20);
// timeout occurs...
assertTrue(this.timeoutOccurred);
// ...and the stack is eventually popped by t1...
assertSame(ITEM_1, this.poppedObject);
// ...but nothing is pushed on to the stack by t2
assertTrue(this.ss.isEmpty());
// make a reasonable guess about how long t2 took
assertTrue(this.elapsedTime() < 150);
}
private void verifyWaitToPush(long timeout) throws Exception {
this.ss.push(ITEM_1);
Runnable r1 = this.buildRunnable(this.buildPopCommand(), this.ss, 200);
Runnable r2 = this.buildRunnable(this.buildWaitToPushCommand(timeout), this.ss, 0);
Thread t1 = new Thread(r1);
Thread t2 = new Thread(r2);
t1.start();
t2.start();
while (t1.isAlive() || t2.isAlive()) {
Thread.sleep(50);
}
assertFalse(this.exCaught);
}
private Command buildPushCommand() {
return new Command() {
public void execute(SynchronizedStack<String> synchronizedStack) {
synchronizedStack.push(ITEM_1);
}
};
}
private Command buildWaitToPopCommand(final long timeout) {
return new Command() {
public void execute(SynchronizedStack<String> synchronizedStack) throws Exception {
SynchronizedStackTests.this.setStartTime(System.currentTimeMillis());
try {
SynchronizedStackTests.this.setPoppedObject(synchronizedStack.waitToPop(timeout));
} catch (EmptyStackException ex) {
SynchronizedStackTests.this.setTimeoutOccurred(true);
}
SynchronizedStackTests.this.setEndTime(System.currentTimeMillis());
}
};
}
private Command buildPopCommand() {
return new Command() {
public void execute(SynchronizedStack<String> synchronizedStack) {
SynchronizedStackTests.this.setPoppedObject(synchronizedStack.pop());
}
};
}
private Command buildWaitToPushCommand(final long timeout) {
return new Command() {
public void execute(SynchronizedStack<String> synchronizedStack) throws Exception {
SynchronizedStackTests.this.setStartTime(System.currentTimeMillis());
SynchronizedStackTests.this.setTimeoutOccurred( ! synchronizedStack.waitToPush(ITEM_2, timeout));
SynchronizedStackTests.this.setEndTime(System.currentTimeMillis());
}
};
}
private Runnable buildRunnable(final Command command, final SynchronizedStack<String> synchronizedStack, final long sleep) {
return new Runnable() {
public void run() {
try {
if (sleep != 0) {
Thread.sleep(sleep);
}
command.execute(synchronizedStack);
} catch (Exception ex) {
SynchronizedStackTests.this.setExCaught(true);
}
}
};
}
void setExCaught(boolean exCaught) {
this.exCaught = exCaught;
}
void setTimeoutOccurred(boolean timeoutOccurred) {
this.timeoutOccurred = timeoutOccurred;
}
void setStartTime(long startTime) {
this.startTime = startTime;
}
void setEndTime(long endTime) {
this.endTime = endTime;
}
void setPoppedObject(Object poppedObject) {
this.poppedObject = poppedObject;
}
long elapsedTime() {
return this.endTime - this.startTime;
}
// ********** Command interface **********
private interface Command {
void execute(SynchronizedStack<String> synchronizedStack) throws Exception;
}
}
