pu.RedLib

Class Reducible<E>

java.lang.Object

pu.RedLib.Reducible<E>

public class Reducible<E>
extends java.lang.Object

Defines a Reducible. This essentials behaves like a thread-local variable, with the addition of a reduction function at the end that may be executed by any of the threads.

Note that the number of thread-local values used in the reduction is determined according to the number of unique Threads that set(Object) a value.

Author:

Nasser Giacaman, Oliver Sinnen

Constructor Summary

Constructors

Constructor and Description
Reducible() A new Reducible without an initial value for any of the threads.
Reducible(E initialValue) Creates a Reducible with the specified initial value for all threads.

Method Summary

Modifier and Type	Method and Description
int	countOfThreadLocalValues() Returns the number of thread-local values currently stored.
E	get() Returns the thread-local value for the current thread.
E	reduce(Reduction<E> reduction) Performs the specified reduction, as defined by the reduction instance.
void	set(E value) Sets the thread-local value of the current thread to value.

Methods inherited from class java.lang.Object

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

Constructor Detail

Reducible

public Reducible()

A new Reducible without an initial value for any of the threads. Therefore, each thread must call set(Object) before attempting to get() its thread-local value.

Reducible

public Reducible(E initialValue)

Creates a Reducible with the specified initial value for all threads.

Parameters:

initialValue - The initial value to set for all threads.

Method Detail

set

public void set(E value)

Sets the thread-local value of the current thread to value.

Parameters:

value - The value to set for the current thread.

get

public E get()

Returns the thread-local value for the current thread. This implies that the user has either specified a default initial value (in the constructor), and/or has already called set(Object) for the current thread.

Returns:

The thread-local value for the current thread.

Throws:

java.lang.RuntimeException - If no initial value was supplied in the constructor and no value has been set(Object) for the current thread.

countOfThreadLocalValues

public int countOfThreadLocalValues()

Returns the number of thread-local values currently stored. Note that the initial value, if there is one, does not get included in this count. In other words, this is the number of calls made by unique threads to set(Object) .

Returns:

The number of thread-local values currently stored.

reduce

public E reduce(Reduction<E> reduction)

Performs the specified reduction, as defined by the reduction instance.

This method should be called at the end when all thread-local values are ready. Note that a reduction is only calculated once, therefore subsequent calls to this method result in the pre-calculated value being returned.

Parameters:

reduction - The reduction to perform.

Returns:

The final reduced value after performing the reduction over all thread-local values.

Throws:

java.lang.RuntimeException - If attempting to perform a reduction but there are no values that have been set (either by specifying an initial value or using set(Object)).