Package org.cometd.bayeux

Interface Promise<C>

Type Parameters:

C - the type of the result value

All Known Implementing Classes:

Promise.Completable

public interface Promise<C>

The future result of an operation, either a value if the operation succeeded, or a failure if the operation failed.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	Promise.Completable<S>	A CompletableFuture that is also a Promise.

Field Summary

Fields

Modifier and Type	Field	Description
static final Promise<?>	NOOP	Shared instance whose methods are implemented empty,

Method Summary

Modifier and Type	Method	Description
default BiConsumer<C,Throwable>	complete()	Returns a BiConsumer that, when invoked, completes this Promise.
static <T> Promise<T>	complete(BiConsumer<T,Throwable> fn)	Returns a Promise that, when completed, invokes the given BiConsumer function.
default void	fail(Throwable failure)	Callback to invoke when the operation fails.
static <T> Promise<T>	from(Consumer<T> succeed, Consumer<Throwable> fail)
static <T> Promise<T>	noop()
default void	succeed(C result)	Callback to invoke when the operation succeeds.

Field Details

NOOP

static final Promise<?> NOOP

Shared instance whose methods are implemented empty,

use noop() to ease type inference.

Method Details

succeed

default void succeed(C result)

Callback to invoke when the operation succeeds.

Parameters:

result - the result

See Also:

• fail(Throwable)

fail

default void fail(Throwable failure)

Callback to invoke when the operation fails.

Parameters:

failure - the operation failure

complete

default BiConsumer<C,Throwable> complete()

Returns a BiConsumer that, when invoked, completes this Promise.

Typical usage is with CompletableFuture:

 public void process(ServerMessage message, Promise<Boolean> promise) {
     CompletableFuture.supplyAsync(() -> asyncOperation(message))
             .whenComplete(promise.complete());
 }
 

Returns:

a BiConsumer that completes this Promise

See Also:

• Promise.Completable

noop

static <T> Promise<T> noop()

Type Parameters:

T - the type of the empty result

Returns:

a Promise whose methods are implemented empty.

from

static <T> Promise<T> from(Consumer<T> succeed,
 Consumer<Throwable> fail)

Type Parameters:

T - the type of the result value

Parameters:

succeed - the Consumer to call in case of successful completion

fail - the Consumer to call in case of failed completion

Returns:

a Promise from the given consumers

complete

static <T> Promise<T> complete(BiConsumer<T,Throwable> fn)

Returns a Promise that, when completed, invokes the given BiConsumer function.

Type Parameters:

T - the type of the result value

Parameters:

fn - the function to invoke when the Promise is completed

Returns:

a Promise that invokes the BiConsumer function