Implement onRequestSent for Netty provider, close AsyncHttpClient#434

Author: Stephane Landelle

api/src/main/java/org/asynchttpclient/AsyncHandlerExtensions.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2010-2012 Sonatype, Inc. All rights reserved.
+ *
+ * This program is licensed to you under the Apache License Version 2.0,
+ * and you may not use this file except in compliance with the Apache License Version 2.0.
+ * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the Apache License Version 2.0 is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
+ */
+package org.asynchttpclient;
+
+/**
+ * This interface hosts new low level callback methods on {@link AsyncHandler}.
+ * For now, those methods are in a dedicated interface in order not to break the existing API,
+ * but could be merged into one of the existing ones in AHC 2.
+ * 
+ * More additional hooks might come, such as:
+ * <ul>
+ *   <li>onRetry()</li>
+ *   <li>onConnected()</li>
+ *   <li>onConnectionClosed()</li>
+ *   <li>onBytesSent(long numberOfBytes)</li>
+ *   <li>onBytesReceived(long numberOfBytes)</li>
+ * </ul>
+ */
+public interface AsyncHandlerExtensions {
+
+    /**
+     * Notify the callback when a request is being written on the wire.
+     * If the original request causes multiple requests to be sent, for example, because of authorization or retry,
+     * it will be notified multiple times.
+     * Currently only supported by the Netty provider.
+     */
+    void onRequestSent();
+}

providers/netty/src/main/java/org/asynchttpclient/providers/netty/request/NettyRequestSender.java

@@ -45,6 +45,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.asynchttpclient.AsyncHandler;
+import org.asynchttpclient.AsyncHandlerExtensions;
 import org.asynchttpclient.AsyncHttpClientConfig;
 import org.asynchttpclient.Body;
 import org.asynchttpclient.BodyGenerator;
@@ -501,6 +502,9 @@ public final <T> void writeRequest(final Channel channel, final AsyncHttpClientC
             // FIXME That doesn't just leave to true, the set is always done? and what's the point of not having a is/get?
             if (future.getAndSetWriteHeaders(true)) {
                 try {
+                    if (future.getAsyncHandler() instanceof AsyncHandlerExtensions) {
+                        AsyncHandlerExtensions.class.cast(future.getAsyncHandler()).onRequestSent();
+                    }
                     channel.writeAndFlush(nettyRequest, channel.newProgressivePromise()).addListener(new ProgressListener(config, true, future.getAsyncHandler(), future));
                 } catch (Throwable cause) {
                     // FIXME why not notify?