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
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Constructor Summary
ConstructorDescriptionAtomicStampedReference(V initialRef, int initialStamp)
Creates a newAtomicStampedReference
with the given initial values. -
Method Summary
Modifier and TypeMethodDescriptionboolean
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.get(int[] stampHolder)
Returns the current values of both the reference and the stamp.Returns the current value of the reference.int
getStamp()
Returns the current value of the stamp.void
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.
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Constructor Details
-
AtomicStampedReference
Creates a newAtomicStampedReference
with the given initial values.- Parameters:
initialRef
- the initial referenceinitialStamp
- the initial stamp
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Method Details
-
getReference
Returns the current value of the reference.- Returns:
- the current value of the reference
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getStamp
public int getStamp()Returns the current value of the stamp.- Returns:
- the current value of the stamp
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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
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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
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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
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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
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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
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