Java in a Nutshell, 5th Edition

Name

AtomicMarkableReference<V>

Synopsis

This threadsafe class holds a mutable reference to an object of type V and also holds a mutable boolean value or “mark.” It defines atomic operations and volatile access semantics for the reference and the mark. The set( ) method unconditionally sets the reference and mark value. The get( ) method queries both, returning the reference as its return value, and storing the current value of the mark in element 0 of the specified boolean array. The reference and mark can also be queried individually (and nonatomically) with getReference( ) and isMarked( ).

The atomic compareAndSet( ) and weakCompareAndSet( ) methods take expected and new values for both the reference and the mark, and neither is set to its new value unless both match their expected values. attemptMark( ) atomically sets the value of the mark but only if the reference is equal to the expected value. Like weakCompareAndSet( ), this method may fail spuriously, even if the reference does equal the expected value. Repeated invocation eventually succeeds, however, as long as the expected value is correct, and other threads are not continuously changing the reference value.

public class AtomicMarkableReference<V> {
// Public Constructors
     public AtomicMarkableReference(V initialRef, boolean initialMark);  
// Public Instance Methods
     public boolean attemptMark(V expectedReference, boolean newMark);  
     public boolean compareAndSet(V expectedReference, V newReference, 
        boolean expectedMark, boolean ...