com.ibm.cos.v2.utils

Class CompletableFutureUtils

java.lang.Object

com.ibm.cos.v2.utils.CompletableFutureUtils

public final class CompletableFutureUtils
extends Object

Utility class for working with CompletableFuture.

Method Summary

Modifier and Type	Method and Description
static CompletableFuture<Void>	allOfExceptionForwarded(CompletableFuture<?>[] futures) Similar to CompletableFuture.allOf(CompletableFuture[]), but when any future is completed exceptionally, forwards the exception to other futures.
static CompletionException	errorAsCompletionException(Throwable t) Wraps the given error in a CompletionException if necessary.
static <U> CompletableFuture<U>	failedFuture(Throwable t) Convenience method for creating a future that is immediately completed exceptionally with the given Throwable.
static <T> CompletableFuture<T>	forwardExceptionTo(CompletableFuture<T> src, CompletableFuture<?> dst) Forward the Throwable from src to dst.
static <T> CompletableFuture<T>	forwardResultTo(CompletableFuture<T> src, CompletableFuture<T> dst) Completes the dst future based on the result of the src future asynchronously on the provided Executor and return the src future.
static <T> CompletableFuture<T>	forwardResultTo(CompletableFuture<T> src, CompletableFuture<T> dst, Executor executor) Completes the dst future based on the result of the src future asynchronously on the provided Executor and return the src future.
static <T> CompletableFuture<T>	forwardTransformedExceptionTo(CompletableFuture<T> src, CompletableFuture<?> dst, Function<Throwable,Throwable> transformationFunction) Forward the Throwable that can be transformed as per the transformationFunction from src to dst.
static <SourceT,DestT> CompletableFuture<SourceT>	forwardTransformedResultTo(CompletableFuture<SourceT> src, CompletableFuture<DestT> dst, Function<SourceT,DestT> function) Completes the dst future based on the result of the src future, synchronously, after applying the provided transformation Function if successful.
static <T> T	joinInterruptibly(CompletableFuture<T> future)
static void	joinInterruptiblyIgnoringFailures(CompletableFuture<?> future)
static <T> T	joinLikeSync(CompletableFuture<T> future) Joins (interruptibly) on the future, and re-throws any RuntimeExceptions or Errors just like the async task would have thrown if it was executed synchronously.

Methods inherited from class java.lang.Object

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

Method Detail

failedFuture

public static <U> CompletableFuture<U> failedFuture(Throwable t)

Convenience method for creating a future that is immediately completed exceptionally with the given Throwable.

Similar to CompletableFuture#failedFuture which was added in Java 9.

Type Parameters:

U - The type of the element.

Parameters:

t - The failure.

Returns:

The failed future.

errorAsCompletionException

public static CompletionException errorAsCompletionException(Throwable t)

Wraps the given error in a CompletionException if necessary. Useful if an exception needs to be rethrown from within CompletableFuture.handle(java.util.function.BiFunction) or similar methods.

Parameters:

t - The error.

Returns:

The error as a CompletionException.

forwardExceptionTo

public static <T> CompletableFuture<T> forwardExceptionTo(CompletableFuture<T> src,
                                                          CompletableFuture<?> dst)

Forward the Throwable from src to dst.

Parameters:

src - The source of the Throwable.

dst - The destination where the Throwable will be forwarded to.

Returns:

src.

forwardTransformedExceptionTo

public static <T> CompletableFuture<T> forwardTransformedExceptionTo(CompletableFuture<T> src,
                                                                     CompletableFuture<?> dst,
                                                                     Function<Throwable,Throwable> transformationFunction)

Forward the Throwable that can be transformed as per the transformationFunction from src to dst.

Parameters:

src - The source of the Throwable.

dst - The destination where the Throwable will be forwarded to

transformationFunction - Transformation function taht will be applied on to the forwarded exception.

Returns:

forwardResultTo

public static <T> CompletableFuture<T> forwardResultTo(CompletableFuture<T> src,
                                                       CompletableFuture<T> dst)

Completes the dst future based on the result of the src future asynchronously on the provided Executor and return the src future.

Parameters:

src - The source CompletableFuture

dst - The destination where the Throwable or response will be forwarded to.

Returns:

the src future.

forwardResultTo

public static <T> CompletableFuture<T> forwardResultTo(CompletableFuture<T> src,
                                                       CompletableFuture<T> dst,
                                                       Executor executor)

Completes the dst future based on the result of the src future asynchronously on the provided Executor and return the src future.

Parameters:

src - The source CompletableFuture

dst - The destination where the Throwable or response will be forwarded to.

executor - the executor to complete the des future

Returns:

the src future.

forwardTransformedResultTo

public static <SourceT,DestT> CompletableFuture<SourceT> forwardTransformedResultTo(CompletableFuture<SourceT> src,
                                                                                    CompletableFuture<DestT> dst,
                                                                                    Function<SourceT,DestT> function)

Completes the dst future based on the result of the src future, synchronously, after applying the provided transformation Function if successful. If the function threw an exception, the destination future will be completed exceptionally with that exception.

Parameters:

src - The source CompletableFuture

dst - The destination where the Throwable or transformed result will be forwarded to.

Returns:

the src future.

allOfExceptionForwarded

public static CompletableFuture<Void> allOfExceptionForwarded(CompletableFuture<?>[] futures)

Similar to CompletableFuture.allOf(CompletableFuture[]), but when any future is completed exceptionally, forwards the exception to other futures.

Parameters:

futures - The futures.

Returns:

The new future that is completed when all the futures in futures are.

joinInterruptibly

public static <T> T joinInterruptibly(CompletableFuture<T> future)

joinInterruptiblyIgnoringFailures

public static void joinInterruptiblyIgnoringFailures(CompletableFuture<?> future)

joinLikeSync

public static <T> T joinLikeSync(CompletableFuture<T> future)

Joins (interruptibly) on the future, and re-throws any RuntimeExceptions or Errors just like the async task would have thrown if it was executed synchronously.