edu.rice.hj.api

Interface HjDataDrivenFuture<V>

Type Parameters:

V - the type of the value wrapped in the futureNb object.

All Superinterfaces:

HjFuture<V>

All Known Implementing Classes:

ParallelDataDrivenFuture

public interface HjDataDrivenFuture<V>
extends HjFuture<V>

A Future that may be explicitly completed by setting its value using the put() method.

A DDF can be viewed as a container with a full/empty state that obeys a dynamic single-assignment rule. The runtime scheduler will then ensure that a task is only scheduled when all the DDFs in its await clause become available (full). There is no constraint on which task performs a put() operation on a DDF.

DDFs provide a first-class construct for expressing data-dependences among dynamic tasks, thereby decoupling the roles of the control parent and data parents. DDFs can also be used to enforce control dependences. A control dependence can be expressed with a DDF with dummy data.

It is illegal to perform a get() operation on an empty DDF; instead, a task can safely perform a get() on any DDF in its await clause. Refer to Module0.asyncNbAwait(HjFuture, HjRunnable) for the await clause and the creation of data-driven tasks.

Details: Data-Driven Tasks and their Implementation. Sagnak Tasirlar, Vivek Sarkar. Proceedings of the International Conference on Parallel Processing (ICPP) 2011, September 2011.

Author:

Shams Imam (shams@rice.edu)

Nested Class Summary

Nested classes/interfaces inherited from interface edu.rice.hj.api.HjFuture

HjFuture.CancelledException

Method Summary

Modifier and Type	Method and Description
boolean	cancel() Cancels the Data-driven futureNb, equivalent to a failed(new CancelledException()).
void	failed(Exception failedEx) Associates the specified Exception as the reason of failure while computing the result of the HjDataDrivenFuture.
V	get() Returns the value wrapped in the DDF.
void	put(V value) Associates the specified value with the HjDataDrivenFuture.
V	safeGet() Returns the value wrapped in the DDF.

Methods inherited from interface edu.rice.hj.api.HjFuture

failed, resolved

Method Detail

get

V get()
throws SuspendableException

Returns the value wrapped in the DDF.

It is illegal to perform a get() operation on an empty DDF; instead, a task can safely perform a get() on any DDF in its await clause. Refer to Module0.asyncNbAwait(HjFuture, HjRunnable) and related variants for the await clause and the creation of data-driven tasks.

Specified by:

get in interface HjFuture<V>

Returns:

The value wrapped in the futureNb.

Throws:

SuspendableException

safeGet

V safeGet()

Returns the value wrapped in the DDF.

It is illegal to perform a safeGet() operation on an empty DDF; instead, a task can safely perform a safeGet() on any DDF in its await clause. Refer to Module0.asyncNbAwait(HjFuture, HjRunnable) and related variants for the await clause and the creation of data-driven tasks.

Specified by:

safeGet in interface HjFuture<V>

Returns:

The value wrapped in the futureNb.

cancel

boolean cancel()

Cancels the Data-driven futureNb, equivalent to a failed(new CancelledException()).

Specified by:

cancel in interface HjFuture<V>

Returns:

false if the task could not be cancelled, typically because it has already been resolved; true otherwise

Throws:

IllegalStateException - if called when the DDF has already been resolved

put

void put(V value)

Associates the specified value with the HjDataDrivenFuture. This operation may fail if the single assignment property is violated.

Parameters:

value - The value to store into the DDF.

failed

void failed(Exception failedEx)

Associates the specified Exception as the reason of failure while computing the result of the HjDataDrivenFuture. This operation may fail if the single assignment property is violated.

Parameters:

failedEx - The exception incurred while computing the result.