pekko/akka-actor/src/main/java/akka/dispatch/AbstractMailbox.java

/**
 * Copyright (C) 2009-2011 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.dispatch;

import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;

abstract class AbstractMailbox {
    private volatile int _status; // not initialized because this is faster: 0 == Open
    protected final static AtomicIntegerFieldUpdater<AbstractMailbox> updater =
      AtomicIntegerFieldUpdater.newUpdater(AbstractMailbox.class, "_status");

    private volatile SystemMessage _systemQueue; // not initialized because this is faster
    protected final static AtomicReferenceFieldUpdater<AbstractMailbox, SystemMessage> systemQueueUpdater =
      AtomicReferenceFieldUpdater.newUpdater(AbstractMailbox.class, SystemMessage.class, "_systemQueue");
}