AtomicMarkableReferencepublic class AtomicMarkableReference extends Object 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. |
Fields Summary |
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private final AtomicReference | atomicRef |
Constructors Summary |
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public AtomicMarkableReference(V initialRef, boolean initialMark)Creates a new AtomicMarkableReference with the given
initial values.
atomicRef = new AtomicReference<ReferenceBooleanPair<V>> (new ReferenceBooleanPair<V>(initialRef, initialMark));
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Methods Summary |
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public boolean | 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. 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.
ReferenceBooleanPair current = atomicRef.get();
return expectedReference == current.reference &&
(newMark == current.bit ||
atomicRef.compareAndSet
(current, new ReferenceBooleanPair<V>(expectedReference,
newMark)));
| 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.
ReferenceBooleanPair current = atomicRef.get();
return expectedReference == current.reference &&
expectedMark == current.bit &&
((newReference == current.reference && newMark == current.bit) ||
atomicRef.compareAndSet(current,
new ReferenceBooleanPair<V>(newReference,
newMark)));
| public V | get(boolean[] markHolder)Returns the current values of both the reference and the mark.
Typical usage is boolean[1] holder; ref = v.get(holder); .
ReferenceBooleanPair<V> p = atomicRef.get();
markHolder[0] = p.bit;
return p.reference;
| public V | getReference()Returns the current value of the reference.
return atomicRef.get().reference;
| public boolean | isMarked()Returns the current value of the mark.
return atomicRef.get().bit;
| public void | set(V newReference, boolean newMark)Unconditionally sets the value of both the reference and mark.
ReferenceBooleanPair current = atomicRef.get();
if (newReference != current.reference || newMark != current.bit)
atomicRef.set(new ReferenceBooleanPair<V>(newReference, newMark));
| 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. 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.
ReferenceBooleanPair current = atomicRef.get();
return expectedReference == current.reference &&
expectedMark == current.bit &&
((newReference == current.reference && newMark == current.bit) ||
atomicRef.weakCompareAndSet(current,
new ReferenceBooleanPair<V>(newReference,
newMark)));
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