1 files changed, 89 insertions, 11 deletions
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 8c8f543bc8..b32d6260f0 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
@@ -18,6 +18,8 @@
 
 package org.eclipse.jetty.util;
 
+import java.util.concurrent.CompletableFuture;
+
 /**
  * <p>A callback abstraction that handles completed/failed events of asynchronous operations.</p>
  *
@@ -30,8 +32,7 @@ public interface Callback
      * Instance of Adapter that can be used when the callback methods need an empty
      * implementation without incurring in the cost of allocating a new Adapter object.
      */
-    static Callback NOOP = new Callback(){};
-
+    Callback NOOP = new Callback(){};
 
     /**
      * <p>Callback invoked when the operation completes.</p>
@@ -55,25 +56,102 @@ public interface Callback
     {
         return false;
     }
-    
-    
+
+    /**
+     * <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
     {
         @Override
-        public default boolean isNonBlocking()
+        default boolean isNonBlocking()
         {
             return true;
         }
     }
-    
-    
+
     /**
-     * <p>Empty implementation of {@link Callback}</p>
+     * <p>A CompletableFuture that is also a Callback.</p>
      */
-    @Deprecated
-    static class Adapter implements Callback
-    {}
+    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;
+        }
+    }
 }