Class SharedObject<T>

java.lang.Object
edu.rit.pj.reduction.SharedObject<T>
Type Parameters:
T - Object data type.
public class SharedObject<T> extends Object
Class SharedObject provides a reduction variable for a value of an object type.

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

Note: Class SharedObject is implemented using class java.util.concurrent.atomic.AtomicReference.

Version:
20-Jun-2007
Author:
Alan Kaminsky

  • Constructor Summary

    Constructors
    Constructor
    Description
    SharedObject()
    Construct a new object reduction variable with the initial value null.
    SharedObject(T initialValue)
    Construct a new object reduction variable with the given initial value.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    compareAndSet(T expect, T update)
    Atomically set this reduction variable to the given updated value if the current value equals the expected value.
    T
    get()
    Returns this reduction variable's current value.
    T
    getAndSet(T value)
    Set this reduction variable to the given value and return the previous value.
    T
    reduce(T value, ObjectOp<T> op)
    Combine this reduction variable with the given value using the given operation.
    void
    set(T value)
    Set this reduction variable to the given value.
    String
    toString()
    Returns a string version of this reduction variable.
    boolean
    weakCompareAndSet(T expect, T update)
    Atomically set this reduction variable to the given updated value if the current value equals the expected value.

    Methods inherited from class Object

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

  • Constructor Details

    • SharedObject

      public SharedObject()
      Construct a new object reduction variable with the initial value null.

    • SharedObject

      public SharedObject(T initialValue)
      Construct a new object reduction variable with the given initial value.
      Parameters:
      initialValue - Initial value.

  • Method Details

    • get

      public T get()
      Returns this reduction variable's current value.
      Returns:
      Current value.

    • set

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

    • getAndSet

      public T getAndSet(T 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(T expect, T 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(T expect, T 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.

    • reduce

      public T reduce(T value, ObjectOp<T> 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.