java.util.concurrent.atomic

Class 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

    • Constructor Summary

      Constructors

      Constructor and Description
      AtomicStampedReference(V initialRef, int initialStamp)
      Creates a new AtomicStampedReference with the given initial values.

    • Method Summary

      Modifier and Type Method and Description
      boolean 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.
      V get(int[] stampHolder)
      Returns the current values of both the reference and the stamp.
      V getReference()
      Returns the current value of the reference.
      int getStamp()
      Returns the current value of the stamp.
      void set(V newReference, int newStamp)
      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.

    • Constructor Detail

      • AtomicStampedReference

        public AtomicStampedReference(V initialRef,
                              int initialStamp)
        Creates a new AtomicStampedReference with the given initial values.
        Parameters:
        initialRef - the initial reference
        initialStamp - the initial stamp

    • Method Detail

      • getReference

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

      • getStamp

        public int getStamp()
        Returns the current value of the stamp.
        Returns:
        the current value of the stamp

      • get

        public V get(int[] stampHolder)
        Returns the current values of both the reference and the stamp. Typical usage is int[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

      • 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.

        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
        expectedStamp - the expected value of the stamp
        newStamp - the new value for the stamp
        Returns:
        true if successful

      • compareAndSet

        public 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.
        Parameters:
        expectedReference - the expected value of the reference
        newReference - the new value for the reference
        expectedStamp - the expected value of the stamp
        newStamp - the new value for the stamp
        Returns:
        true if successful

      • set

        public void set(V newReference,
                int newStamp)
        Unconditionally sets the value of both the reference and stamp.
        Parameters:
        newReference - the new value for the reference
        newStamp - the new value for the stamp

      • attemptStamp

        public boolean 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. 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
        newStamp - the new value for the stamp
        Returns:
        true if successful