DefaultChannelHandlerInvoker write leak

Motivation:
DefaultChannelHandlerInvoker.invokeWrite calls a utility method validatePromise which may throw if the arguments are not valid. If this method throws then the message will not be released.

Modifications:
- If an exception is thrown the message should be released

Result:
No more leak in DefaultChannelHandlerInvoker.invokeWrite

transport/src/main/java/io/netty/channel/DefaultChannelHandlerInvoker.java

@@ -328,10 +328,14 @@ public class DefaultChannelHandlerInvoker implements ChannelHandlerInvoker {
         if (msg == null) {
             throw new NullPointerException("msg");
         }
-        if (!validatePromise(ctx, promise, true)) {
-            // promise cancelled
+        try {
+            if (!validatePromise(ctx, promise, true)) {
+                ReferenceCountUtil.release(msg);
+                return;
+            }
+        } catch (RuntimeException e) {
             ReferenceCountUtil.release(msg);
-            return;
+            throw e;
         }
 
         if (executor.inEventLoop()) {

transport/src/test/java/io/netty/channel/DefaultChannelHandlerInvokerTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2016 The Netty Project
+ *
+ * The Netty Project licenses this file to you 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 io.netty.channel;
+
+import io.netty.util.ReferenceCounted;
+import io.netty.util.concurrent.ImmediateEventExecutor;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class DefaultChannelHandlerInvokerTest {
+    @Mock
+    private ReferenceCounted msg;
+    @Mock
+    private ChannelHandlerContext ctx;
+    @Mock
+    private ChannelPromise promise;
+
+    @Before
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void writeWithInvalidPromiseStillReleasesMessage() {
+        when(promise.isDone()).thenReturn(true);
+        DefaultChannelHandlerInvoker invoker = new DefaultChannelHandlerInvoker(ImmediateEventExecutor.INSTANCE);
+        invoker.invokeWrite(ctx, msg, promise);
+        verify(msg).release();
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void writeWithNullPromiseStillReleasesMessage() {
+        when(promise.isDone()).thenReturn(true);
+        DefaultChannelHandlerInvoker invoker = new DefaultChannelHandlerInvoker(ImmediateEventExecutor.INSTANCE);
+        invoker.invokeWrite(ctx, msg, null);
+        verify(msg).release();
+    }
+}