/*

* Copyright (c) 2004-2013 Tada AB and other contributors, as listed below.

*

* All rights reserved. This program and the accompanying materials

* are made available under the terms of the The BSD 3-Clause License

* which accompanies this distribution, and is available at

* http://opensource.org/licenses/BSD-3-Clause

*

* Contributors:

* Tada AB

*/

package org.postgresql.pljava.example;

import java.util.logging.Level;

import java.util.logging.Logger;

/**

* This class contains thread related methods.

*

* @author Thomas Hallgren

*/

public class Threads {

static class Locker extends Thread {

private final String m_name;

private final String m_first;

private final String m_second;

Locker(String name, String first, String second) {

m_name = name;

m_first = first;

m_second = second;

}

@Override

public void run() {

Logger log = Logger.getAnonymousLogger();

try {

log.info("Thread " + m_name + " wants " + m_first);

synchronized (m_first) {

log.info("Thread " + m_name + " got " + m_first);

Thread.sleep(100);

log.info("Thread " + m_name + " wants " + m_second);

synchronized (m_second) {

log.info("Thread " + m_name + " got " + m_second);

}

}

} catch (Exception e) {

log.log(Level.INFO, "Thread " + m_name + " got exception: ", e);

}

}

}

private final static String s_lockOne = "lock number one";

private final static String s_lockTwo = "lock number two";

public static void forceDeadlock() {

// Cause a deadlock.

//

Locker x = new Locker("x", s_lockOne, s_lockTwo);

Locker y = new Locker("y", s_lockTwo, s_lockOne);

x.start();

y.start();

// Sleep for a while. The logger will fail if trying to access the

// backend when it is not in a Java call.

//

try {

Logger.getAnonymousLogger().log(Level.INFO,

"Main thread sleeps a while");

Thread.sleep(1000);

} catch (Exception e) {

Logger.getAnonymousLogger().log(Level.INFO,

"Main thread interrupted while sleeping: ", e);

}

}

}