AtomicStampedReference
public
class
AtomicStampedReference
extends Object
java.lang.Object  
↳  java.util.concurrent.atomic.AtomicStampedReference<V> 
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.
Summary
Public constructors  

AtomicStampedReference(V initialRef, int initialStamp)
Creates a new 
Public methods  

boolean

attemptStamp(V expectedReference, int newStamp)
Atomically sets the value of the stamp to the given update value
if the current reference is 
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 
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 
Inherited methods  

Public constructors
AtomicStampedReference
AtomicStampedReference (V initialRef, int initialStamp)
Creates a new AtomicStampedReference
with the given
initial values.
Parameters  

initialRef 
V : the initial reference 
initialStamp 
int : the initial stamp

Public methods
attemptStamp
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. 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.
Parameters  

expectedReference 
V : the expected value of the reference 
newStamp 
int : the new value for the stamp 
Returns  

boolean 
true if successful

compareAndSet
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.
Parameters  

expectedReference 
V : the expected value of the reference 
newReference 
V : the new value for the reference 
expectedStamp 
int : the expected value of the stamp 
newStamp 
int : the new value for the stamp 
Returns  

boolean 
true if successful

get
V get (int[] stampHolder)
Returns the current values of both the reference and the stamp.
Typical usage is int[1] holder; ref = v.get(holder);
.
Parameters  

stampHolder 
int : an array of size of at least one. On return,
stampHolder[0] will hold the value of the stamp. 
Returns  

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

V 
the current value of the reference 
getStamp
int getStamp ()
Returns the current value of the stamp.
Returns  

int 
the current value of the stamp 
set
void set (V newReference, int newStamp)
Unconditionally sets the value of both the reference and stamp.
Parameters  

newReference 
V : the new value for the reference 
newStamp 
int : the new value for the stamp

weakCompareAndSet
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.
May fail
spuriously and does not provide ordering guarantees, so is
only rarely an appropriate alternative to compareAndSet
.
Parameters  

expectedReference 
V : the expected value of the reference 
newReference 
V : the new value for the reference 
expectedStamp 
int : the expected value of the stamp 
newStamp 
int : the new value for the stamp 
Returns  

boolean 
true if successful
