/*
* Copyright (c) 2013 Cisco Systems, Inc. and others. 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
*/
package org.opendaylight.yangtools.concepts;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
/**
* Utility registration handle. It is a convenience for register-style method
* which can return an AutoCloseable realized by a subclass of this class.
* Invoking the close() method triggers unregistration of the state the method
* installed.
*/
public abstract class AbstractRegistration implements AutoCloseable {
private static final AtomicIntegerFieldUpdater<AbstractRegistration> CLOSED_UPDATER =
AtomicIntegerFieldUpdater.newUpdater(AbstractRegistration.class, "closed");
private volatile int closed = 0;
/**
* Remove the state referenced by this registration. This method is
* guaranteed to be called at most once. The referenced state must be
* retained until this method is invoked.
*/
protected abstract void removeRegistration();
/**
* Query the state of this registration. Returns true if it was
* closed.
*
* @return true if the registration was closed, false otherwise.
*/
protected final boolean isClosed() {
return closed != 0;
}
@Override
public final void close() {
if (CLOSED_UPDATER.compareAndSet(this, 0, 1)) {
removeRegistration();
}
}
}