Package edu.rit.pj.reduction

Class SharedInteger

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

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

Note: Class SharedInteger is implemented using class java.util.concurrent.atomic.AtomicInteger.

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

  • Constructor Summary

    Constructors
    Constructor
    Description
    SharedInteger()
    Construct a new integer reduction variable with the initial value 0.
    SharedInteger(int initialValue)
    Construct a new integer reduction variable with the given initial value.

  • Method Summary

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

    • SharedInteger

      public SharedInteger()
      Construct a new integer reduction variable with the initial value 0.

    • SharedInteger

      public SharedInteger(int initialValue)
      Construct a new integer reduction variable with the given initial value.
      Parameters:
      initialValue - Initial value.

  • Method Details

    • get

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

    • set

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

    • getAndSet

      public int getAndSet(int 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(int expect, int 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(int expect, int 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 int getAndIncrement()
      Add one to this reduction variable and return the previous value.
      Returns:
      Previous value.

    • getAndDecrement

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

    • getAndAdd

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

    • incrementAndGet

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

    • decrementAndGet

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

    • addAndGet

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

    • reduce

      public int reduce(int value, IntegerOp 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.