Class AtomicMarkableReference<V>
java.lang.Object
java.util.concurrent.atomic.AtomicMarkableReference<V>
- Type Parameters:
V
- The type of object referred to by this reference
An
AtomicMarkableReference
maintains an object reference
along with a mark bit, that can be updated atomically.
Implementation note: This implementation maintains markable references by creating internal objects representing "boxed" [reference, boolean] pairs.
- Since:
- 1.5
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Constructor Summary
ConstructorDescriptionAtomicMarkableReference
(V initialRef, boolean initialMark) Creates a newAtomicMarkableReference
with the given initial values. -
Method Summary
Modifier and TypeMethodDescriptionboolean
attemptMark
(V expectedReference, boolean newMark) Atomically sets the value of the mark to the given update value if the current reference is==
to the expected reference.boolean
compareAndSet
(V expectedReference, V newReference, boolean expectedMark, boolean newMark) Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.get
(boolean[] markHolder) Returns the current values of both the reference and the mark.Returns the current value of the reference.boolean
isMarked()
Returns the current value of the mark.void
Unconditionally sets the value of both the reference and mark.boolean
weakCompareAndSet
(V expectedReference, V newReference, boolean expectedMark, boolean newMark) Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.
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Constructor Details
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AtomicMarkableReference
Creates a newAtomicMarkableReference
with the given initial values.- Parameters:
initialRef
- the initial referenceinitialMark
- the initial mark
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Method Details
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getReference
Returns the current value of the reference.- Returns:
- the current value of the reference
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isMarked
public boolean isMarked()Returns the current value of the mark.- Returns:
- the current value of the mark
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get
Returns the current values of both the reference and the mark. Typical usage isboolean[1] holder; ref = v.get(holder);
.- Parameters:
markHolder
- an array of size of at least one. On return,markHolder[0]
will hold the value of the mark.- Returns:
- the current value of the reference
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weakCompareAndSet
public boolean weakCompareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark) Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark. 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 referenceexpectedMark
- the expected value of the marknewMark
- the new value for the mark- Returns:
true
if successful
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compareAndSet
public boolean compareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark) Atomically sets the value of both the reference and mark to the given update values if the current reference is==
to the expected reference and the current mark is equal to the expected mark.- Parameters:
expectedReference
- the expected value of the referencenewReference
- the new value for the referenceexpectedMark
- the expected value of the marknewMark
- the new value for the mark- Returns:
true
if successful
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set
Unconditionally sets the value of both the reference and mark.- Parameters:
newReference
- the new value for the referencenewMark
- the new value for the mark
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attemptMark
Atomically sets the value of the mark 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 referencenewMark
- the new value for the mark- Returns:
true
if successful
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