 java.lang.Object

 java.util.concurrent.atomic.AtomicMarkableReference<V>

 Type Parameters:
V
 The type of object referred to by this reference
public class AtomicMarkableReference<V> extends Object
AnAtomicMarkableReference
maintains an object reference along with a mark bit, that can be updated atomically.Implementation note: This implementation maintains markable references by creating internal objects representing "boxed" [reference, boolean] pairs.
 Since:
 1.5


Constructor Summary
Constructors Constructor Description AtomicMarkableReference(V initialRef, boolean initialMark)
Creates a newAtomicMarkableReference
with the given initial values.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
attemptMark(V expectedReference, boolean newMark)
Atomically sets the value of the mark to the given update value if the current reference is==
to the expected reference.boolean
compareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)
Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.V
get(boolean[] markHolder)
Returns the current values of both the reference and the mark.V
getReference()
Returns the current value of the reference.boolean
isMarked()
Returns the current value of the mark.void
set(V newReference, boolean newMark)
Unconditionally sets the value of both the reference and mark.boolean
weakCompareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)
Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.



Constructor Detail

AtomicMarkableReference
public AtomicMarkableReference(V initialRef, boolean initialMark)
Creates a newAtomicMarkableReference
with the given initial values. Parameters:
initialRef
 the initial referenceinitialMark
 the initial mark


Method Detail

getReference
public V getReference()
Returns the current value of the reference. Returns:
 the current value of the reference

isMarked
public boolean isMarked()
Returns the current value of the mark. Returns:
 the current value of the mark

get
public V get(boolean[] markHolder)
Returns the current values of both the reference and the mark. Typical usage isboolean[1] holder; ref = v.get(holder);
. Parameters:
markHolder
 an array of size of at least one. On return,markHolder[0]
will hold the value of the mark. Returns:
 the current value of the reference

weakCompareAndSet
public boolean weakCompareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)
Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to
compareAndSet
. Parameters:
expectedReference
 the expected value of the referencenewReference
 the new value for the referenceexpectedMark
 the expected value of the marknewMark
 the new value for the mark Returns:
true
if successful

compareAndSet
public boolean compareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)
Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark. Parameters:
expectedReference
 the expected value of the referencenewReference
 the new value for the referenceexpectedMark
 the expected value of the marknewMark
 the new value for the mark Returns:
true
if successful

set
public void set(V newReference, boolean newMark)
Unconditionally sets the value of both the reference and mark. Parameters:
newReference
 the new value for the referencenewMark
 the new value for the mark

attemptMark
public boolean attemptMark(V expectedReference, boolean newMark)
Atomically sets the value of the mark to the given update value if the current reference is==
to the expected reference. Any given invocation of this operation may fail (returnfalse
) spuriously, but repeated invocation when the current value holds the expected value and no other thread is also attempting to set the value will eventually succeed. Parameters:
expectedReference
 the expected value of the referencenewMark
 the new value for the mark Returns:
true
if successful

