java.lang.Object
java.util.concurrent.atomic.AtomicStampedReference<V>
 Type Parameters:
V
 The type of object referred to by this reference
public class AtomicStampedReference<V> extends Object
An
AtomicStampedReference
maintains an object reference
along with an integer "stamp", that can be updated atomically.
Implementation note: This implementation maintains stamped references by creating internal objects representing "boxed" [reference, integer] pairs.
 Since:
 1.5

Constructor Summary
Constructors Constructor Description AtomicStampedReference(V initialRef, int initialStamp)
Creates a newAtomicStampedReference
with the given initial values. 
Method Summary
Modifier and Type Method Description boolean
attemptStamp(V expectedReference, int newStamp)
Atomically sets the value of the stamp to the given update value if the current reference is==
to the expected reference.boolean
compareAndSet(V expectedReference, V newReference, int expectedStamp, int newStamp)
Atomically sets the value of both the reference and stamp to the given update values if the current reference is==
to the expected reference and the current stamp is equal to the expected stamp.V
get(int[] stampHolder)
Returns the current values of both the reference and the stamp.V
getReference()
Returns the current value of the reference.int
getStamp()
Returns the current value of the stamp.void
set(V newReference, int newStamp)
Unconditionally sets the value of both the reference and stamp.boolean
weakCompareAndSet(V expectedReference, V newReference, int expectedStamp, int newStamp)
Atomically sets the value of both the reference and stamp to the given update values if the current reference is==
to the expected reference and the current stamp is equal to the expected stamp.

Constructor Details

AtomicStampedReference
Creates a newAtomicStampedReference
with the given initial values. Parameters:
initialRef
 the initial referenceinitialStamp
 the initial stamp


Method Details

getReference
Returns the current value of the reference. Returns:
 the current value of the reference

getStamp
public int getStamp()Returns the current value of the stamp. Returns:
 the current value of the stamp

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

weakCompareAndSet
public boolean weakCompareAndSet(V expectedReference, V newReference, int expectedStamp, int newStamp)Atomically sets the value of both the reference and stamp to the given update values if the current reference is==
to the expected reference and the current stamp is equal to the expected stamp. This operation may fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative tocompareAndSet
. Parameters:
expectedReference
 the expected value of the referencenewReference
 the new value for the referenceexpectedStamp
 the expected value of the stampnewStamp
 the new value for the stamp Returns:
true
if successful

compareAndSet
Atomically sets the value of both the reference and stamp to the given update values if the current reference is==
to the expected reference and the current stamp is equal to the expected stamp. Parameters:
expectedReference
 the expected value of the referencenewReference
 the new value for the referenceexpectedStamp
 the expected value of the stampnewStamp
 the new value for the stamp Returns:
true
if successful

set
Unconditionally sets the value of both the reference and stamp. Parameters:
newReference
 the new value for the referencenewStamp
 the new value for the stamp

attemptStamp
Atomically sets the value of the stamp 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 referencenewStamp
 the new value for the stamp Returns:
true
if successful
