jstrachan 2003/08/27 09:28:31
Added: messenger/src/java/org/apache/commons/messenger Lock.java
messenger/src/test/org/apache/commons/messenger
LockTest.java
Log:
added a simple Lock class which I'm about to use in another Messenger imnplementation
Revision Changes Path
1.1
jakarta-commons-sandbox/messenger/src/java/org/apache/commons/messenger/Lock.java
Index: Lock.java
===================================================================
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE file.
*
* $Id: Lock.java,v 1.1 2003/08/27 16:28:31 jstrachan Exp $
*/
package org.apache.commons.messenger;
import javax.jms.JMSException;
/** <p><code>Lock</code> is a simple lock.
*
* @author <a href="mailto:[EMAIL PROTECTED]">James Strachan</a>
* @version $Revision: 1.1 $
*/
public class Lock {
private Thread owner;
private int count;
/**
* Acquires the lock, blocking until the lock can be acquired
* @throws InterruptedException
*/
public void acquire() {
Thread caller = Thread.currentThread();
synchronized (this) {
if (caller == owner) {
count++;
}
else {
while (owner != null) {
try {
wait();
}
catch (InterruptedException ex) {
// ignore
}
}
owner = caller;
count = 1;
}
}
}
/**
* Release the lock.
**/
public synchronized void release() throws JMSException {
if (Thread.currentThread() != owner) {
throw new JMSException("Cannot release lock - not the current owner");
}
else {
if (--count == 0) {
owner = null;
notify();
}
}
}
/**
* @return
*/
public synchronized boolean hasLock() {
return Thread.currentThread() == owner;
}
}
1.1
jakarta-commons-sandbox/messenger/src/test/org/apache/commons/messenger/LockTest.java
Index: LockTest.java
===================================================================
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE file.
*
* $Id: LockTest.java,v 1.1 2003/08/27 16:28:31 jstrachan Exp $
*/
package org.apache.commons.messenger;
import javax.jms.JMSException;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import junit.textui.TestRunner;
/** Test harness for the Lock class
*
* @author <a href="mailto:[EMAIL PROTECTED]">James Strachan</a>
* @version $Revision: 1.1 $
*/
public class LockTest extends TestCase {
public static Test suite() {
return new TestSuite(LockTest.class);
}
public static void main(String[] args) {
TestRunner.run(suite());
}
public LockTest(String testName) {
super(testName);
}
public void testNormalLockOperation() throws Exception {
Lock lock = new Lock();
assertFalse("should not have the lock yet", lock.hasLock());
lock.acquire();
assertTrue("have lock", lock.hasLock());
lock.release();
assertFalse("have released the lock", lock.hasLock());
try {
lock.release();
fail("Should have thrown an exception");
}
catch (JMSException e) {
// ignore
}
}
public void testNestedLockOperation() throws Exception {
Lock lock = new Lock();
lock.acquire();
assertTrue("have lock", lock.hasLock());
lock.acquire();
assertTrue("have lock", lock.hasLock());
lock.release();
assertTrue("have lock", lock.hasLock());
lock.release();
assertFalse("have released the lock", lock.hasLock());
try {
lock.release();
fail("Should have thrown an exception");
}
catch (JMSException e) {
// ignore
}
}
public void testReleaseBeforeAcquireShouldFail() throws Exception {
Lock lock = new Lock();
try {
lock.release();
fail("Should have thrown an exception");
}
catch (JMSException e) {
// ignore
}
}
}
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