Package edu.rit.pj.reduction

Class SharedLong

java.lang.Object
java.lang.Number
edu.rit.pj.reduction.SharedLong
All Implemented Interfaces:
Serializable
public class SharedLong extends Number
Class SharedLong provides a reduction variable for a value of type long.

Class SharedLong is multiple thread safe. The methods use lock-free atomic compare-and-set.

Note: Class SharedLong is implemented using class java.util.concurrent.atomic.AtomicLong.

Version:
07-Jun-2007
Author:
Alan Kaminsky
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    SharedLong()
    Construct a new long reduction variable with the initial value 0.
    SharedLong(long initialValue)
    Construct a new long reduction variable with the given initial value.

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    addAndGet(long value)
    Add the given value to this reduction variable and return the new value.
    boolean
    compareAndSet(long expect, long update)
    Atomically set this reduction variable to the given updated value if the current value equals the expected value.
    long
    decrementAndGet()
    Subtract one from this reduction variable and return the new value.
    double
    doubleValue()
    Returns this reduction variable's current value converted to type double.
    float
    floatValue()
    Returns this reduction variable's current value converted to type float.
    long
    get()
    Returns this reduction variable's current value.
    long
    getAndAdd(long value)
    Add the given value to this reduction variable and return the previous value.
    long
    getAndDecrement()
    Subtract one from this reduction variable and return the previous value.
    long
    getAndIncrement()
    Add one to this reduction variable and return the previous value.
    long
    getAndSet(long value)
    Set this reduction variable to the given value and return the previous value.
    long
    incrementAndGet()
    Add one to this reduction variable and return the new value.
    int
    intValue()
    Returns this reduction variable's current value converted to type int.
    long
    longValue()
    Returns this reduction variable's current value converted to type long.
    long
    reduce(long value, LongOp op)
    Combine this reduction variable with the given value using the given operation.
    void
    set(long value)
    Set this reduction variable to the given value.
    String
    toString()
    Returns a string version of this reduction variable.
    boolean
    weakCompareAndSet(long expect, long update)
    Atomically set this reduction variable to the given updated value if the current value equals the expected value.

    Methods inherited from class java.lang.Number

    byteValue, shortValue

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Constructor Details

    • SharedLong

      public SharedLong()
      Construct a new long reduction variable with the initial value 0.

    • SharedLong

      public SharedLong(long initialValue)
      Construct a new long reduction variable with the given initial value.
      Parameters:
      initialValue - Initial value.

  • Method Details

    • get

      public long get()
      Returns this reduction variable's current value.
      Returns:
      Current value.

    • set

      public void set(long value)
      Set this reduction variable to the given value.
      Parameters:
      value - New value.

    • getAndSet

      public long getAndSet(long value)
      Set this reduction variable to the given value and return the previous value.
      Parameters:
      value - New value.
      Returns:
      Previous value.

    • compareAndSet

      public boolean compareAndSet(long expect, long update)
      Atomically set this reduction variable to the given updated value if the current value equals the expected value.
      Parameters:
      expect - Expected value.
      update - Updated value.
      Returns:
      True if the update happened, false otherwise.

    • weakCompareAndSet

      public boolean weakCompareAndSet(long expect, long update)
      Atomically set this reduction variable to the given updated value if the current value equals the expected value. May fail spuriously.
      Parameters:
      expect - Expected value.
      update - Updated value.
      Returns:
      True if the update happened, false otherwise.

    • getAndIncrement

      public long getAndIncrement()
      Add one to this reduction variable and return the previous value.
      Returns:
      Previous value.

    • getAndDecrement

      public long getAndDecrement()
      Subtract one from this reduction variable and return the previous value.
      Returns:
      Previous value.

    • getAndAdd

      public long getAndAdd(long value)
      Add the given value to this reduction variable and return the previous value.
      Parameters:
      value - Value to add.
      Returns:
      Previous value.

    • incrementAndGet

      public long incrementAndGet()
      Add one to this reduction variable and return the new value.
      Returns:
      New value.

    • decrementAndGet

      public long decrementAndGet()
      Subtract one from this reduction variable and return the new value.
      Returns:
      New value.

    • addAndGet

      public long addAndGet(long value)
      Add the given value to this reduction variable and return the new value.
      Parameters:
      value - Value to add.
      Returns:
      New value.

    • reduce

      public long reduce(long value, LongOp op)
      Combine this reduction variable with the given value using the given operation. The result is stored back into this reduction variable and is returned.
      Parameters:
      value - Value.
      op - Binary operation.
      Returns:
      (This variable) op (value).

    • toString

      public String toString()
      Returns a string version of this reduction variable.
      Overrides:
      toString in class Object
      Returns:
      String version.

    • intValue

      public int intValue()
      Returns this reduction variable's current value converted to type int.
      Specified by:
      intValue in class Number
      Returns:
      Current value.

    • longValue

      public long longValue()
      Returns this reduction variable's current value converted to type long.
      Specified by:
      longValue in class Number
      Returns:
      Current value.

    • floatValue

      public float floatValue()
      Returns this reduction variable's current value converted to type float.
      Specified by:
      floatValue in class Number
      Returns:
      Current value.

    • doubleValue

      public double doubleValue()
      Returns this reduction variable's current value converted to type double.
      Specified by:
      doubleValue in class Number
      Returns:
      Current value.