edu.emory.mathcs.backport.java.util.concurrent.atomic
Class AtomicStampedReference
java.lang.Object
edu.emory.mathcs.backport.java.util.concurrent.atomic.AtomicStampedReference
public class AtomicStampedReference
extends java.lang.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.
AtomicStampedReference(Object initialRef, int initialStamp) - Creates a new AtomicStampedReference with the given
initial values.
|
boolean | attemptStamp(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(Object expectedReference, 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.
|
Object | get(int[] stampHolder) - Returns the current values of both the reference and the stamp.
|
Object | getReference() - Returns the current value of the reference.
|
int | getStamp() - Returns the current value of the stamp.
|
void | set(Object newReference, int newStamp) - Unconditionally sets the value of both the reference and stamp.
|
boolean | weakCompareAndSet(Object expectedReference, 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.
|
AtomicStampedReference
public AtomicStampedReference(Object initialRef,
int initialStamp)
Creates a new AtomicStampedReference with the given
initial values.
initialRef
- the initial referenceinitialStamp
- the initial stamp
attemptStamp
public boolean attemptStamp(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. 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
compareAndSet
public boolean compareAndSet(Object expectedReference,
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.
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
get
public Object get(int[] stampHolder)
Returns the current values of both the reference and the stamp.
Typical usage is 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.
- the current value of the reference
getReference
public Object getReference()
Returns the current value of the reference.
- the current value of the reference
getStamp
public int getStamp()
Returns the current value of the stamp.
- the current value of the stamp
set
public void set(Object newReference,
int newStamp)
Unconditionally sets the value of both the reference and stamp.
newReference
- the new value for the referencenewStamp
- the new value for the stamp
weakCompareAndSet
public boolean weakCompareAndSet(Object expectedReference,
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. 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 referencenewReference
- the new value for the referenceexpectedStamp
- the expected value of the stampnewStamp
- the new value for the stamp