From 73d1f3fe02982fa243f8afe55ab0ea92057690c4 Mon Sep 17 00:00:00 2001
From: Trustin Lee <trustin@gmail.com>
Date: Tue, 2 Aug 2011 09:33:27 +0900
Subject: [PATCH] NETTY-384 Another deadlock in ChunkedWriteHandler

ChunkedWriteHandler.discard() do not issue write requests to trigger exceptionCaught events and to notify write futures anymore.  Instead, it triggers exceptionCaught events and notifies write futures by itself.  Therefore, no write lock is involved during discard(), avoiding the reported dead lock.

However, this is a temporary solution, and eventually Netty must introduce more robust event thread model.
---
 .../handler/stream/ChunkedWriteHandler.java   | 49 +++++++++++--------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/src/main/java/org/jboss/netty/handler/stream/ChunkedWriteHandler.java b/src/main/java/org/jboss/netty/handler/stream/ChunkedWriteHandler.java
index 10a10f481e..466f0d94a7 100644
--- a/src/main/java/org/jboss/netty/handler/stream/ChunkedWriteHandler.java
+++ b/src/main/java/org/jboss/netty/handler/stream/ChunkedWriteHandler.java
@@ -17,6 +17,7 @@ package org.jboss.netty.handler.stream;
 
 import static org.jboss.netty.channel.Channels.*;
 
+import java.nio.channels.ClosedChannelException;
 import java.util.Queue;
 
 import org.jboss.netty.buffer.ChannelBuffers;
@@ -150,32 +151,40 @@ public class ChunkedWriteHandler implements ChannelUpstreamHandler, ChannelDowns
         ctx.sendUpstream(e);
     }
 
-    private synchronized void discard(ChannelHandlerContext ctx) {
-        for (;;) {
-            if (currentEvent == null) {
-                currentEvent = queue.poll();
-            }
+    private void discard(ChannelHandlerContext ctx) {
+        ClosedChannelException cause = null;
+        boolean fireExceptionCaught = false;
+        synchronized (this) {
+            for (;;) {
+                if (currentEvent == null) {
+                    currentEvent = queue.poll();
+                }
 
-            if (currentEvent == null) {
-                break;
-            }
+                if (currentEvent == null) {
+                    break;
+                }
 
-            MessageEvent currentEvent = this.currentEvent;
-            this.currentEvent = null;
+                MessageEvent currentEvent = this.currentEvent;
+                this.currentEvent = null;
 
-            Object m = currentEvent.getMessage();
-            if (m instanceof ChunkedInput) {
-                closeInput((ChunkedInput) m);
+                Object m = currentEvent.getMessage();
+                if (m instanceof ChunkedInput) {
+                    closeInput((ChunkedInput) m);
+                }
 
                 // Trigger a ClosedChannelException
-                Channels.write(
-                        ctx, currentEvent.getFuture(), ChannelBuffers.EMPTY_BUFFER,
-                        currentEvent.getRemoteAddress());
-            } else {
-                // Trigger a ClosedChannelException
-                ctx.sendDownstream(currentEvent);
+                if (cause == null) {
+                    cause = new ClosedChannelException();
+                }
+                currentEvent.getFuture().setFailure(cause);
+                fireExceptionCaught = true;
+
+                currentEvent = null;
             }
-            currentEvent = null;
+        }
+
+        if (fireExceptionCaught) {
+            Channels.fireExceptionCaught(currentEvent.getChannel(), cause);
         }
     }