| // |
| // ======================================================================== |
| // Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd. |
| // ------------------------------------------------------------------------ |
| // All rights reserved. This program and the accompanying materials |
| // are made available under the terms of the Eclipse Public License v1.0 |
| // and Apache License v2.0 which accompanies this distribution. |
| // |
| // The Eclipse Public License is available at |
| // http://www.eclipse.org/legal/epl-v10.html |
| // |
| // The Apache License v2.0 is available at |
| // http://www.opensource.org/licenses/apache2.0.php |
| // |
| // You may elect to redistribute this code under either of these licenses. |
| // ======================================================================== |
| // |
| |
| package org.eclipse.jetty.util; |
| |
| import java.util.concurrent.CompletableFuture; |
| |
| import org.eclipse.jetty.util.log.Log; |
| |
| /** |
| * <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p> |
| * |
| * @param <C> the type of the context object |
| */ |
| public interface Promise<C> |
| { |
| /** |
| * <p>Callback invoked when the operation completes.</p> |
| * |
| * @param result the context |
| * @see #failed(Throwable) |
| */ |
| default void succeeded(C result) |
| { |
| } |
| |
| /** |
| * <p>Callback invoked when the operation fails.</p> |
| * |
| * @param x the reason for the operation failure |
| */ |
| default void failed(Throwable x) |
| { |
| } |
| |
| /** |
| * <p>Empty implementation of {@link Promise}.</p> |
| * |
| * @param <U> the type of the result |
| */ |
| class Adapter<U> implements Promise<U> |
| { |
| @Override |
| public void succeeded(U result) |
| { |
| } |
| |
| @Override |
| public void failed(Throwable x) |
| { |
| Log.getLogger(this.getClass()).warn(x); |
| } |
| } |
| |
| /** |
| * <p>Creates a promise from the given incomplete CompletableFuture.</p> |
| * <p>When the promise completes, either succeeding or failing, the |
| * CompletableFuture is also completed, respectively via |
| * {@link CompletableFuture#complete(Object)} or |
| * {@link CompletableFuture#completeExceptionally(Throwable)}.</p> |
| * |
| * @param completable the CompletableFuture to convert into a promise |
| * @return a promise that when completed, completes the given CompletableFuture |
| */ |
| static <T> Promise<T> from(CompletableFuture<? super T> completable) |
| { |
| if (completable instanceof Promise) |
| return (Promise<T>)completable; |
| |
| return new Promise<T>() |
| { |
| @Override |
| public void succeeded(T result) |
| { |
| completable.complete(result); |
| } |
| |
| @Override |
| public void failed(Throwable x) |
| { |
| completable.completeExceptionally(x); |
| } |
| }; |
| } |
| |
| /** |
| * <p>A CompletableFuture that is also a Promise.</p> |
| * |
| * @param <S> the type of the result |
| */ |
| class Completable<S> extends CompletableFuture<S> implements Promise<S> |
| { |
| @Override |
| public void succeeded(S result) |
| { |
| complete(result); |
| } |
| |
| @Override |
| public void failed(Throwable x) |
| { |
| completeExceptionally(x); |
| } |
| } |
| } |