From 5a844d0bd69267b469d12773eaab666b5294b9a5 Mon Sep 17 00:00:00 2001
From: Norman Maurer <nmaurer@redhat.com>
Date: Wed, 23 Oct 2013 13:55:53 +0200
Subject: [PATCH] [#1812] Rework ByteToMessageDecoder.channelRead(..) method to
 allow for inlining

---
 .../handler/codec/ByteToMessageDecoder.java   | 82 +++++++++----------
 1 file changed, 38 insertions(+), 44 deletions(-)

diff --git a/codec/src/main/java/io/netty/handler/codec/ByteToMessageDecoder.java b/codec/src/main/java/io/netty/handler/codec/ByteToMessageDecoder.java
index 5ce3350871..a40bdb196c 100644
--- a/codec/src/main/java/io/netty/handler/codec/ByteToMessageDecoder.java
+++ b/codec/src/main/java/io/netty/handler/codec/ByteToMessageDecoder.java
@@ -49,6 +49,7 @@ public abstract class ByteToMessageDecoder extends ChannelInboundHandlerAdapter
     ByteBuf cumulation;
     private boolean singleDecode;
     private boolean decodeWasNull;
+    private boolean first;
 
     protected ByteToMessageDecoder() {
         if (getClass().isAnnotationPresent(Sharable.class)) {
@@ -121,64 +122,57 @@ public abstract class ByteToMessageDecoder extends ChannelInboundHandlerAdapter
 
     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
-        RecyclableArrayList out = RecyclableArrayList.newInstance();
-        try {
-            if (msg instanceof ByteBuf) {
+        if (msg instanceof ByteBuf) {
+            RecyclableArrayList out = RecyclableArrayList.newInstance();
+            try {
                 ByteBuf data = (ByteBuf) msg;
-                if (cumulation == null) {
+                first = cumulation == null;
+                if (first) {
                     cumulation = data;
-                    try {
-                        callDecode(ctx, cumulation, out);
-                    } finally {
-                        if (cumulation != null && !cumulation.isReadable()) {
-                            cumulation.release();
-                            cumulation = null;
-                        }
-                    }
                 } else {
-                    try {
-                        if (cumulation.writerIndex() > cumulation.maxCapacity() - data.readableBytes()) {
-                            ByteBuf oldCumulation = cumulation;
-                            cumulation = ctx.alloc().buffer(oldCumulation.readableBytes() + data.readableBytes());
-                            cumulation.writeBytes(oldCumulation);
-                            oldCumulation.release();
-                        }
-                        cumulation.writeBytes(data);
-                        callDecode(ctx, cumulation, out);
-                    } finally {
-                        if (cumulation != null) {
-                            if (!cumulation.isReadable()) {
-                                cumulation.release();
-                                cumulation = null;
-                            } else {
-                                cumulation.discardSomeReadBytes();
-                            }
-                        }
-                        data.release();
+                    if (cumulation.writerIndex() > cumulation.maxCapacity() - data.readableBytes()) {
+                        expandCumulation(ctx, data.readableBytes());
                     }
+                    cumulation.writeBytes(data);
+                    data.release();
                 }
-            } else {
-                out.add(msg);
-            }
-        } catch (DecoderException e) {
-            throw e;
-        } catch (Throwable t) {
-            throw new DecoderException(t);
-        } finally {
-            int size = out.size();
-            if (size == 0) {
-                decodeWasNull = true;
-            } else {
+                callDecode(ctx, cumulation, out);
+            } catch (DecoderException e) {
+                throw e;
+            } catch (Throwable t) {
+                throw new DecoderException(t);
+            } finally {
+                if (cumulation != null && !cumulation.isReadable()) {
+                    cumulation.release();
+                    cumulation = null;
+                }
+                int size = out.size();
+                decodeWasNull = size == 0;
+
                 for (int i = 0; i < size; i ++) {
                     ctx.fireChannelRead(out.get(i));
                 }
+                out.recycle();
             }
-            out.recycle();
+        } else {
+            ctx.fireChannelRead(msg);
         }
     }
 
+    private void expandCumulation(ChannelHandlerContext ctx, int readable) {
+        ByteBuf oldCumulation = cumulation;
+        cumulation = ctx.alloc().buffer(oldCumulation.readableBytes() + readable);
+        cumulation.writeBytes(oldCumulation);
+        oldCumulation.release();
+    }
+
     @Override
     public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
+        if (cumulation != null && !first) {
+            // discard some bytes if possible to make more room in the
+            // buffer
+            cumulation.discardSomeReadBytes();
+        }
         if (decodeWasNull) {
             decodeWasNull = false;
             if (!ctx.channel().config().isAutoRead()) {