java.util.concurrent.atomic

Class AtomicMarkableReference<V>

  • Type Parameters:
    V - The type of object referred to by this reference 

    public class AtomicMarkableReference<V>
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.

    Since:
    1.5

    • Constructor Summary

      Constructors

      Constructor and Description
      AtomicMarkableReference(V initialRef, boolean initialMark)
      Creates a new AtomicMarkableReference with the given initial values.

    • Method Summary

      Modifier and Type Method and Description
      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.
      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.
      V get(boolean[] markHolder)
      Returns the current values of both the reference and the mark.
      V getReference()
      Returns the current value of the reference.
      boolean isMarked()
      Returns the current value of the mark.
      void set(V newReference, boolean newMark)
      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.

    • Constructor Detail

      • AtomicMarkableReference

        public AtomicMarkableReference(V initialRef,
                               boolean initialMark)
        Creates a new AtomicMarkableReference with the given initial values.
        Parameters:
        initialRef - the initial reference
        initialMark - the initial mark

    • Method Detail

      • getReference

        public V getReference()
        Returns the current value of the reference.
        Returns:
        the current value of the reference

      • isMarked

        public boolean isMarked()
        Returns the current value of the mark.
        Returns:
        the current value of the mark

      • get

        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); .
        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

      • 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.

        May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.

        Parameters:
        expectedReference - the expected value of the reference
        newReference - the new value for the reference
        expectedMark - the expected value of the mark
        newMark - the new value for the mark
        Returns:
        true if successful

      • 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 reference
        newReference - the new value for the reference
        expectedMark - the expected value of the mark
        newMark - the new value for the mark
        Returns:
        true if successful

      • set

        public void set(V newReference,
                boolean newMark)
        Unconditionally sets the value of both the reference and mark.
        Parameters:
        newReference - the new value for the reference
        newMark - the new value for the mark

      • attemptMark

        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.
        Parameters:
        expectedReference - the expected value of the reference
        newMark - the new value for the mark
        Returns:
        true if successful