481717 - Make Callback and Promise CompletableFuture-friendly.
Introduced methods from(CompletableFuture) and subclass Completable.
diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/Callback.java b/jetty-util/src/main/java/org/eclipse/jetty/util/Callback.java
index 3cc9b10..e9c5104 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/Callback.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/Callback.java
@@ -16,24 +16,10 @@
// ========================================================================
//
-/*
- * Copyright (c) 2012 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
package org.eclipse.jetty.util;
+import java.util.concurrent.CompletableFuture;
+
/**
* <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p>
*
@@ -72,6 +58,56 @@
}
/**
+ * <p>Creates a non-blocking callback from the given incomplete CompletableFuture.</p>
+ * <p>When the callback 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 callback
+ * @return a callback that when completed, completes the given CompletableFuture
+ */
+ static Callback from(CompletableFuture<?> completable)
+ {
+ return from(completable, false);
+ }
+
+ /**
+ * <p>Creates a callback from the given incomplete CompletableFuture,
+ * with the given {@code blocking} characteristic.</p>
+ *
+ * @param completable the CompletableFuture to convert into a callback
+ * @param blocking whether the callback is blocking
+ * @return a callback that when completed, completes the given CompletableFuture
+ */
+ static Callback from(CompletableFuture<?> completable, boolean blocking)
+ {
+ if (completable instanceof Callback)
+ return (Callback)completable;
+
+ return new Callback()
+ {
+ @Override
+ public void succeeded()
+ {
+ completable.complete(null);
+ }
+
+ @Override
+ public void failed(Throwable x)
+ {
+ completable.completeExceptionally(x);
+ }
+
+ @Override
+ public boolean isNonBlocking()
+ {
+ return !blocking;
+ }
+ };
+ }
+
+ /**
* Callback interface that declares itself as non-blocking
*/
interface NonBlocking extends Callback
@@ -82,4 +118,40 @@
return true;
}
}
+
+ /**
+ * <p>A CompletableFuture that is also a Callback.</p>
+ */
+ class Completable extends CompletableFuture<Void> implements Callback
+ {
+ private final boolean blocking;
+
+ public Completable()
+ {
+ this(false);
+ }
+
+ public Completable(boolean blocking)
+ {
+ this.blocking = blocking;
+ }
+
+ @Override
+ public void succeeded()
+ {
+ complete(null);
+ }
+
+ @Override
+ public void failed(Throwable x)
+ {
+ completeExceptionally(x);
+ }
+
+ @Override
+ public boolean isNonBlocking()
+ {
+ return !blocking;
+ }
+ }
}
diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/Promise.java b/jetty-util/src/main/java/org/eclipse/jetty/util/Promise.java
index 30ed7f1..a20c0d1 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/Promise.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/Promise.java
@@ -18,6 +18,8 @@
package org.eclipse.jetty.util;
+import java.util.concurrent.CompletableFuture;
+
import org.eclipse.jetty.util.log.Log;
/**
@@ -33,25 +35,28 @@
* @param result the context
* @see #failed(Throwable)
*/
- public abstract void succeeded(C result);
+ default void succeeded(C result)
+ {
+ }
/**
* <p>Callback invoked when the operation fails.</p>
*
* @param x the reason for the operation failure
*/
- public void failed(Throwable x);
-
+ default void failed(Throwable x)
+ {
+ }
/**
- * <p>Empty implementation of {@link Promise}</p>
+ * <p>Empty implementation of {@link Promise}.</p>
*
- * @param <C> the type of the context object
+ * @param <U> the type of the result
*/
- public static class Adapter<C> implements Promise<C>
+ class Adapter<U> implements Promise<U>
{
@Override
- public void succeeded(C result)
+ public void succeeded(U result)
{
}
@@ -62,4 +67,54 @@
}
}
+ /**
+ * <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);
+ }
+ }
}
