edu.emory.mathcs.backport.java.util.concurrent.atomic
Class AtomicMarkableReference
java.lang.Object
edu.emory.mathcs.backport.java.util.concurrent.atomic.AtomicMarkableReference
public class AtomicMarkableReference
extends java.lang.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.
AtomicMarkableReference(Object initialRef, boolean initialMark) - Creates a new AtomicMarkableReference with the given
initial values.
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boolean | attemptMark(Object expectedReference, boolean newMark) - Atomically sets the value of the mark to the given update value
if the current reference is == to the expected
reference.
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boolean | compareAndSet(Object expectedReference, Object 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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Object | get(boolean[] markHolder) - Returns the current values of both the reference and the mark.
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Object | getReference() - Returns the current value of the reference.
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boolean | isMarked() - Returns the current value of the mark.
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void | set(Object newReference, boolean newMark) - Unconditionally sets the value of both the reference and mark.
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boolean | weakCompareAndSet(Object expectedReference, Object 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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AtomicMarkableReference
public AtomicMarkableReference(Object initialRef,
boolean initialMark)
Creates a new AtomicMarkableReference with the given
initial values.
initialRef
- the initial referenceinitialMark
- the initial mark
attemptMark
public boolean attemptMark(Object 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.
expectedReference
- the expected value of the referencenewMark
- the new value for the mark
compareAndSet
public boolean compareAndSet(Object expectedReference,
Object 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.
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
get
public Object get(boolean[] markHolder)
Returns the current values of both the reference and the mark.
Typical usage is boolean[1] holder; ref = v.get(holder); .
markHolder
- an array of size of at least one. On return,
markholder[0] will hold the value of the mark.
- the current value of the reference
getReference
public Object getReference()
Returns the current value of the reference.
- the current value of the reference
isMarked
public boolean isMarked()
Returns the current value of the mark.
- the current value of the mark
set
public void set(Object newReference,
boolean newMark)
Unconditionally sets the value of both the reference and mark.
newReference
- the new value for the referencenewMark
- the new value for the mark
weakCompareAndSet
public boolean weakCompareAndSet(Object expectedReference,
Object 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.
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