jsr166e

Class LongMaxUpdater

  • All Implemented Interfaces:
    Serializable 

    public class LongMaxUpdater
extends Number
implements Serializable
    One or more variables that together maintain a running long maximum with initial value Long.MIN_VALUE. When updates (method update(long)) are contended across threads, the set of variables may grow dynamically to reduce contention. Method max() (or, equivalently, longValue()) returns the current maximum across the variables maintaining updates.

    This class extends Number, but does not define methods such as equals, hashCode and compareTo because instances are expected to be mutated, and so are not useful as collection keys.

    jsr166e note: This class is targeted to be placed in java.util.concurrent.atomic.

    Since:
    1.8
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors

      Constructor and Description
      LongMaxUpdater()
      Creates a new instance with initial maximum of Long.MIN_VALUE.

    • Constructor Detail

      • LongMaxUpdater

        public LongMaxUpdater()
        Creates a new instance with initial maximum of Long.MIN_VALUE.

    • Method Detail

      • update

        public void update(long x)
        Updates the maximum to be at least the given value.
        Parameters:
        x - the value to update

      • max

        public long max()
        Returns the current maximum. The returned value is NOT an atomic snapshot; invocation in the absence of concurrent updates returns an accurate result, but concurrent updates that occur while the value is being calculated might not be incorporated.
        Returns:
        the maximum

      • reset

        public void reset()
        Resets variables maintaining updates to Long.MIN_VALUE. This method may be a useful alternative to creating a new updater, but is only effective if there are no concurrent updates. Because this method is intrinsically racy, it should only be used when it is known that no threads are concurrently updating.

      • maxThenReset

        public long maxThenReset()
        Equivalent in effect to max() followed by reset(). This method may apply for example during quiescent points between multithreaded computations. If there are updates concurrent with this method, the returned value is not guaranteed to be the final value occurring before the reset.
        Returns:
        the maximum

      • toString

        public String toString()
        Returns the String representation of the max().
        Overrides:
        toString in class  Object
        Returns:
        the String representation of the max()

      • longValue

        public long longValue()
        Equivalent to max().
        Specified by:
        longValue in class  Number
        Returns:
        the maximum

      • intValue

        public int intValue()
        Returns the max() as an int after a narrowing primitive conversion.

      • floatValue

        public float floatValue()
        Returns the max() as a float after a widening primitive conversion.

      • doubleValue

        public double doubleValue()
        Returns the max() as a double after a widening primitive conversion.