public class AtomicStampedReference
extends java.lang.Object
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.
Constructor and Description |
---|
AtomicStampedReference(java.lang.Object initialRef,
int initialStamp)
Creates a new
AtomicStampedReference with the given
initial values. |
Modifier and Type | Method and Description |
---|---|
boolean |
attemptStamp(java.lang.Object 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(java.lang.Object expectedReference,
java.lang.Object 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. |
java.lang.Object |
get(int[] stampHolder)
Returns the current values of both the reference and the stamp.
|
java.lang.Object |
getReference()
Returns the current value of the reference.
|
int |
getStamp()
Returns the current value of the stamp.
|
void |
set(java.lang.Object newReference,
int newStamp)
Unconditionally sets the value of both the reference and stamp.
|
boolean |
weakCompareAndSet(java.lang.Object expectedReference,
java.lang.Object 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. |
public AtomicStampedReference(java.lang.Object initialRef, int initialStamp)
AtomicStampedReference
with the given
initial values.initialRef
- the initial referenceinitialStamp
- the initial stamppublic java.lang.Object getReference()
public int getStamp()
public java.lang.Object get(int[] stampHolder)
int[1] holder; ref = v.get(holder);
.stampHolder
- an array of size of at least one. On return,
stampholder[0]
will hold the value of the stamp.public boolean weakCompareAndSet(java.lang.Object expectedReference, java.lang.Object newReference, int expectedStamp, int newStamp)
==
to the expected reference
and the current stamp is equal to the expected stamp.
May fail spuriously
and does not provide ordering guarantees, so is only rarely an
appropriate alternative to compareAndSet
.
expectedReference
- the expected value of the referencenewReference
- the new value for the referenceexpectedStamp
- the expected value of the stampnewStamp
- the new value for the stamppublic boolean compareAndSet(java.lang.Object expectedReference, java.lang.Object newReference, int expectedStamp, int newStamp)
==
to the expected reference
and the current stamp is equal to the expected stamp.expectedReference
- the expected value of the referencenewReference
- the new value for the referenceexpectedStamp
- the expected value of the stampnewStamp
- the new value for the stamppublic void set(java.lang.Object newReference, int newStamp)
newReference
- the new value for the referencenewStamp
- the new value for the stamppublic boolean attemptStamp(java.lang.Object expectedReference, int newStamp)
==
to the expected
reference. Any given invocation of this operation may fail
(return false
) 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.expectedReference
- the expected value of the referencenewStamp
- the new value for the stamp