Introduced CompletableCallback to handle asynchronous content on clients.

jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java

@@ -20,7 +20,6 @@ package org.eclipse.jetty.client.http;
 
 import java.io.EOFException;
 import java.nio.ByteBuffer;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.eclipse.jetty.client.HttpClient;
 import org.eclipse.jetty.client.HttpExchange;
@@ -34,7 +33,7 @@ import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.io.ByteBufferPool;
 import org.eclipse.jetty.io.EndPoint;
 import org.eclipse.jetty.util.BufferUtil;
-import org.eclipse.jetty.util.Callback;
+import org.eclipse.jetty.util.CompletableCallback;
 
 public class HttpReceiverOverHTTP extends HttpReceiver implements HttpParser.ResponseHandler<ByteBuffer>
 {
@@ -226,27 +225,22 @@ public class HttpReceiverOverHTTP extends HttpReceiver implements HttpParser.Res
         if (exchange == null)
             return false;
 
-        final AtomicBoolean completed = new AtomicBoolean();
-        Callback callback = new Callback()
+        CompletableCallback callback = new CompletableCallback()
         {
             @Override
-            public void succeeded()
+            public void resume()
             {
-                if (!completed.compareAndSet(false, true))
-                {
-                    LOG.debug("Content consumed asynchronously, resuming processing");
-                    process();
-                }
+                LOG.debug("Content consumed asynchronously, resuming processing");
+                process();
             }
 
-            @Override
-            public void failed(Throwable x)
+            public void abort(Throwable x)
             {
                 failAndClose(x);
             }
         };
         responseContent(exchange, buffer, callback);
-        return completed.compareAndSet(false, true);
+        return callback.tryComplete();
     }
 
     @Override

jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientAsyncContentTest.java

@@ -19,7 +19,6 @@
 package org.eclipse.jetty.client;
 
 import java.io.IOException;
-import java.net.Socket;
 import java.nio.ByteBuffer;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -86,7 +85,7 @@ public class HttpClientAsyncContentTest extends AbstractHttpClientServerTest
                     }
                 });
 
-        Assert.assertTrue(contentLatch.get().await(555, TimeUnit.SECONDS));
+        Assert.assertTrue(contentLatch.get().await(5, TimeUnit.SECONDS));
         Callback callback = callbackRef.get();
 
         // Wait a while to be sure that the parsing does not proceed.
@@ -99,7 +98,7 @@ public class HttpClientAsyncContentTest extends AbstractHttpClientServerTest
         contentLatch.set(new CountDownLatch(1));
         callback.succeeded();
 
-        Assert.assertTrue(contentLatch.get().await(555, TimeUnit.SECONDS));
+        Assert.assertTrue(contentLatch.get().await(5, TimeUnit.SECONDS));
         callback = callbackRef.get();
 
         // Wait a while to be sure that the parsing does not proceed.
@@ -116,12 +115,4 @@ public class HttpClientAsyncContentTest extends AbstractHttpClientServerTest
         Assert.assertTrue(completeLatch.await(5, TimeUnit.SECONDS));
         Assert.assertEquals(2, contentCount.get());
     }
-
-    public void test() throws Exception
-    {
-        try (Socket socket = new Socket())
-        {
-            System.out.println("socket = " + socket);
-        }
-    }
 }

jetty-util/src/main/java/org/eclipse/jetty/util/CompletableCallback.java

@@ -0,0 +1,100 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2014 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.atomic.AtomicBoolean;
+
+/**
+ * A callback to be used by driver code that needs to know whether the callback has been
+ * succeeded or failed (that is, completed) just after the asynchronous operation or not,
+ * typically because further processing depends on the callback being completed.
+ * The driver code competes with the asynchronous operation to complete the callback.
+ * <p />
+ * If the callback is already completed, the driver code continues the processing,
+ * otherwise it suspends it. If it is suspended, the callback will be completed some time
+ * later, and {@link #resume()} or {@link #abort(Throwable)} will be called to allow the
+ * application to resume the processing.
+ * <p />
+ * Typical usage:
+ * <pre>
+ * CompletableCallback callback = new CompletableCallback()
+ * {
+ *     &#64;Override
+ *     public void resume()
+ *     {
+ *         // continue processing
+ *     }
+ *
+ *     &#64;Override
+ *     public void abort(Throwable failure)
+ *     {
+ *         // abort processing
+ *     }
+ * }
+ * asyncOperation(callback);
+ * boolean completed = callback.tryComplete();
+ * if (completed)
+ *     // suspend processing, async operation not done yet
+ * else
+ *     // continue processing, async operation already done
+ * </pre>
+ */
+public abstract class CompletableCallback implements Callback
+{
+    private final AtomicBoolean completed = new AtomicBoolean();
+
+    @Override
+    public void succeeded()
+    {
+        if (!tryComplete())
+            resume();
+    }
+
+    @Override
+    public void failed(Throwable x)
+    {
+        if (!tryComplete())
+            abort(x);
+    }
+
+    /**
+     * Callback method invoked when this callback is succeeded
+     * <em>after</em> a first call to {@link #tryComplete()}.
+     */
+    public abstract void resume();
+
+    /**
+     * Callback method invoked when this callback is failed
+     * <em>after</em> a first call to {@link #tryComplete()}.
+     */
+    public abstract void abort(Throwable failure);
+
+    /**
+     * Tries to complete this callback; driver code should call
+     * this method once <em>after</em> the asynchronous operation
+     * to detect whether the asynchronous operation has already
+     * completed or not.
+     *
+     * @return whether the attempt to complete was successful.
+     */
+    public boolean tryComplete()
+    {
+        return completed.compareAndSet(false, true);
+    }
+}