Package com.spotify.futures

Class CompletableFuturesExtra

java.lang.Object

com.spotify.futures.CompletableFuturesExtra

public class CompletableFuturesExtra
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static enum	CompletableFuturesExtra.Identity
private static enum	CompletableFuturesExtra.WrapFunction

Constructor Summary

Constructors

Modifier	Constructor	Description
private	CompletableFuturesExtra()

Method Summary

Modifier and Type	Method	Description
static <T> void	checkCompleted(CompletionStage<T> stage)	check that a stage is completed.
static <T> CompletionStage<T>	dereference(CompletionStage<? extends CompletionStage<T>> stage)	This takes a stage of a stage of a value and returns a plain stage of a value.
static <T> CompletableFuture<T>	exceptionallyCompletedFuture(Throwable throwable)	Returns a new CompletableFuture that is already exceptionally completed with the given exception.
static <T> CompletionStage<T>	exceptionallyCompose(CompletionStage<T> stage, Function<Throwable,? extends CompletionStage<T>> fn)	Returns a new stage that, when this stage completes exceptionally, is executed with this stage's exception as the argument to the supplied function.
static <T> T	getCompleted(CompletionStage<T> stage)	Get the value of a completed stage.
static Throwable	getCompletedException(CompletionStage<?> stage)	Get the exception from an exceptionally completed stage.
static <T, U> CompletionStage<U>	handleCompose(CompletionStage<T> stage, BiFunction<? super T,Throwable,? extends CompletionStage<U>> fn)	Returns a new stage that, when this stage completes either normally or exceptionally, is executed with this stage's result and exception as arguments to the supplied function.
static <V> com.google.api.core.ApiFuture<V>	toApiFuture(CompletionStage<V> future)	Wrap a CompletionStage in a ApiFuture.
static <V> CompletableFuture<V>	toCompletableFuture(com.google.api.core.ApiFuture<V> future)	Deprecated. - see ApiFuturesExtra.toCompletableFuture(ApiFuture)
static <V> CompletableFuture<V>	toCompletableFuture(com.google.api.core.ApiFuture<V> future, Executor executor)	Deprecated. - see ApiFuturesExtra.toCompletableFuture(ApiFuture)
static <V> CompletableFuture<V>	toCompletableFuture(com.google.common.util.concurrent.ListenableFuture<V> future)	Deprecated. - see ListenableFuturesExtra.toCompletableFuture(ListenableFuture)
static <V> com.google.common.util.concurrent.ListenableFuture<V>	toListenableFuture(CompletableFuture<V> future)	Wrap a CompletableFuture in a ListenableFuture.
static <V> com.google.common.util.concurrent.ListenableFuture<V>	toListenableFuture(CompletionStage<V> future)	Wrap a CompletionStage in a ListenableFuture.
private static <T> CompletionStage<CompletionStage<T>>	wrap(CompletionStage<T> future)

Methods inherited from class java.lang.Object

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

Constructor Details

CompletableFuturesExtra

private CompletableFuturesExtra()

Method Details

toListenableFuture

public static <V>
com.google.common.util.concurrent.ListenableFuture<V> toListenableFuture(CompletableFuture<V> future)

Wrap a CompletableFuture in a ListenableFuture. The returned future will complete with the same result or failure as the original future.

Parameters:

future - The CompletableFuture to wrap in a ListenableFuture.

Returns:

A ListenableFuture that completes when the original future completes.

toListenableFuture

public static <V>
com.google.common.util.concurrent.ListenableFuture<V> toListenableFuture(CompletionStage<V> future)

Wrap a CompletionStage in a ListenableFuture. The returned future will complete with the same result or failure as the original future.

Parameters:

future - The CompletionStage to wrap in a ListenableFuture.

Returns:

A ListenableFuture that completes when the original future completes.

toCompletableFuture

@Deprecated
public static <V> CompletableFuture<V> toCompletableFuture(com.google.common.util.concurrent.ListenableFuture<V> future)

Deprecated.

- see ListenableFuturesExtra.toCompletableFuture(ListenableFuture)

Wrap a ListenableFuture in a CompletableFuture. The returned future will complete with the same result or failure as the original future. Completing the returned future does not complete the original future.

Parameters:

future - The ListenableFuture to wrap in a CompletableFuture.

Returns:

A CompletableFuture that completes when the original future completes.

toCompletableFuture

@Deprecated
public static <V> CompletableFuture<V> toCompletableFuture(com.google.api.core.ApiFuture<V> future)

Deprecated.

- see ApiFuturesExtra.toCompletableFuture(ApiFuture)

Converts an ApiFuture to a CompletableFuture.

Parameters:

future - the ApiFuture to wrap.

Returns:

a CompletableFuture that completes when the original future completes.

toCompletableFuture

@Deprecated
public static <V> CompletableFuture<V> toCompletableFuture(com.google.api.core.ApiFuture<V> future,
 Executor executor)

Deprecated.

- see ApiFuturesExtra.toCompletableFuture(ApiFuture)

Converts an ApiFuture to a CompletableFuture.

Parameters:

future - the ApiFuture to wrap.

executor - the executor where the listener is running.

Returns:

a CompletableFuture that completes when the original future completes.

toApiFuture

public static <V> com.google.api.core.ApiFuture<V> toApiFuture(CompletionStage<V> future)

Wrap a CompletionStage in a ApiFuture. The returned future will complete with the same result or failure as the original future.

Parameters:

future - The CompletionStage to wrap in a ApiFuture.

Returns:

A ApiFuture that completes when the original future completes.

exceptionallyCompletedFuture

public static <T> CompletableFuture<T> exceptionallyCompletedFuture(Throwable throwable)

Returns a new CompletableFuture that is already exceptionally completed with the given exception.

Parameters:

throwable - the exception

Returns:

the exceptionally completed CompletableFuture

handleCompose

public static <T,
U> CompletionStage<U> handleCompose(CompletionStage<T> stage,
 BiFunction<? super T,Throwable,? extends CompletionStage<U>> fn)

Returns a new stage that, when this stage completes either normally or exceptionally, is executed with this stage's result and exception as arguments to the supplied function.

When this stage is complete, the given function is invoked with the result (or null if none) and the exception (or null if none) of this stage as arguments, and the function's result is used to complete the returned stage.

This differs from CompletionStage.handle(java.util.function.BiFunction) in that the function should return a CompletionStage rather than the value directly.

Type Parameters:

U - the function's return type

Parameters:

stage - the CompletionStage to compose

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

exceptionallyCompose

public static <T> CompletionStage<T> exceptionallyCompose(CompletionStage<T> stage,
 Function<Throwable,? extends CompletionStage<T>> fn)

Returns a new stage that, when this stage completes exceptionally, is executed with this stage's exception as the argument to the supplied function. Otherwise, if this stage completes normally, then the returned stage also completes normally with the same value.

This differs from CompletionStage.exceptionally(java.util.function.Function) in that the function should return a CompletionStage rather than the value directly.

Parameters:

stage - the CompletionStage to compose

fn - the function to use to compute the value of the returned CompletionStage if this stage completed exceptionally

Returns:

the new CompletionStage

checkCompleted

public static <T> void checkCompleted(CompletionStage<T> stage)

check that a stage is completed.

Parameters:

stage - a CompletionStage.

Throws:

IllegalStateException - if the stage is not completed.

getCompleted

public static <T> T getCompleted(CompletionStage<T> stage)

Get the value of a completed stage.

Parameters:

stage - a completed CompletionStage.

Returns:

the value of the stage if it has one.

Throws:

IllegalStateException - if the stage is not completed.

CompletionException - if the future completed exceptionally.

getCompletedException

public static Throwable getCompletedException(CompletionStage<?> stage)

Get the exception from an exceptionally completed stage.

Parameters:

stage - a completed CompletionStage.

Returns:

the exception of the stage if it has one.

Throws:

IllegalStateException - if the stage is not completed, or not completed exceptionally.

dereference

public static <T> CompletionStage<T> dereference(CompletionStage<? extends CompletionStage<T>> stage)

This takes a stage of a stage of a value and returns a plain stage of a value.

Parameters:

stage - a CompletionStage of a CompletionStage of a value

Returns:

the CompletionStage of the value

wrap

private static <T>
CompletionStage<CompletionStage<T>> wrap(CompletionStage<T> future)