org.jboss.as.ejb3.tx.OwnableReentrantLock Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source
* Copyright 2009 Red Hat Inc. and/or its affiliates and other
* contributors as indicated by the @author tags. All rights reserved.
* See the copyright.txt in the distribution for a full listing of
* individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.ejb3.tx;
import org.wildfly.common.Assert;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
/**
* A lock that supports reentrancy based on owner (and not on current thread).
*
* @author Stuart Douglas
*/
public class OwnableReentrantLock {
private static final long serialVersionUID = 493297473462848792L;
/**
* Current owner
*/
private Object owner;
private final Object lock = new Object();
private int lockCount = 0;
private int waiters = 0;
/**
* Creates a new lock instance.
*/
public OwnableReentrantLock() {
}
public void lock(Object owner) {
Assert.checkNotNullParam("owner", owner);
synchronized (this.lock) {
if (Objects.equals(owner, this.owner)) {
lockCount++;
} else if (this.owner == null) {
this.owner = owner;
lockCount ++;
} else {
while (this.owner != null) {
try {
waiters++;
try {
lock.wait();
} finally {
--waiters;
}
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
this.owner = owner;
lockCount ++;
}
}
}
public boolean tryLock(long timeValue, TimeUnit timeUnit, Object owner) {
Assert.checkNotNullParam("owner", owner);
synchronized (this.lock) {
if (Objects.equals(owner, this.owner)) {
lockCount++;
return true;
} else if (this.owner == null) {
this.owner = owner;
lockCount ++;
return true;
} else {
long endTime = System.currentTimeMillis() + timeUnit.toMillis(timeValue);
while (this.owner != null && System.currentTimeMillis() < endTime) {
try {
waiters++;
try {
lock.wait(endTime - System.currentTimeMillis());
} finally {
waiters--;
}
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
if(this.owner == null) {
this.owner = owner;
lockCount++;
return true;
} else {
return false;
}
}
}
}
public void unlock(Object owner) {
Assert.checkNotNullParam("owner", owner);
synchronized (this.lock) {
if (!Objects.equals(owner,this.owner)) {
throw new IllegalMonitorStateException();
} else {
if (--lockCount == 0) {
this.owner = null;
if (waiters > 0) {
lock.notifyAll();
}
}
}
}
}
/**
* Returns a string identifying this lock, as well as its lock state. The state, in brackets, includes either the
* String "Unlocked" or the String "Locked by" followed by the String representation of the lock
* owner.
*
* @return a string identifying this lock, as well as its lock state.
*/
public String toString() {
return super.toString() + ((owner == null) ?
"[Unlocked]" :
"[Locked by " + owner + "]");
}
}