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Standard library for the Scala Programming Language

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/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala.collection.concurrent;

import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;

abstract class MainNode extends BasicNode {

    @SuppressWarnings("rawtypes")
    public static final AtomicReferenceFieldUpdater updater =
            AtomicReferenceFieldUpdater.newUpdater(MainNode.class, MainNode.class, "prev");

    public volatile MainNode prev = null;

    public abstract int cachedSize(Object ct);

    public boolean CAS_PREV(MainNode oldval, MainNode nval) {
	return updater.compareAndSet(this, oldval, nval);
    }

    public void WRITE_PREV(MainNode nval) {
	updater.set(this, nval);
    }

    // do we need this? unclear in the javadocs...
    // apparently not - volatile reads are supposed to be safe
    // irregardless of whether there are concurrent ARFU updates
    @Deprecated @SuppressWarnings("unchecked")
    public MainNode READ_PREV() {
	return updater.get(this);
    }

}