From 4059c9f3549753119576a287492dd70ae4742988 Mon Sep 17 00:00:00 2001
From: Norman Maurer <nmaurer@redhat.com>
Date: Wed, 13 Aug 2014 11:06:03 +0200
Subject: [PATCH] [#2761] ChannelOutboundBuffer can cause data-corruption
 because of caching ByteBuffers

Motivation:

We cache the ByteBuffers in ChannelOutboundBuffer.nioBuffers() for the Entries in the ChannelOutboundBuffer to reduce some overhead. The problem is this can lead to data-corruption if an incomplete write happens and next time we try to do a non-gathering write.

To fix this we should remove the caching which does not help a lot anyway and just make the code buggy.

Modifications:

Remove the caching of ByteBuffers.

Result:

No more data-corruption.
---
 .../netty/channel/ChannelOutboundBuffer.java  | 28 ++-----------------
 1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java b/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
index cdfeb7aaf7..b74e1793f3 100644
--- a/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
+++ b/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
@@ -352,31 +352,17 @@ public final class ChannelOutboundBuffer {
 
                 if (readableBytes > 0) {
                     nioBufferSize += readableBytes;
-                    int count = entry.count;
-                    if (count == -1) {
-                        //noinspection ConstantValueVariableUse
-                        entry.count = count =  buf.nioBufferCount();
-                    }
+                    int count = buf.nioBufferCount();
                     int neededSpace = nioBufferCount + count;
                     if (neededSpace > nioBuffers.length) {
                         nioBuffers = expandNioBufferArray(nioBuffers, neededSpace, nioBufferCount);
                         NIO_BUFFERS.set(threadLocalMap, nioBuffers);
                     }
                     if (count == 1) {
-                        ByteBuffer nioBuf = entry.buf;
-                        if (nioBuf == null) {
-                            // cache ByteBuffer as it may need to create a new ByteBuffer instance if its a
-                            // derived buffer
-                            entry.buf = nioBuf = buf.internalNioBuffer(readerIndex, readableBytes);
-                        }
+                        ByteBuffer nioBuf = buf.internalNioBuffer(readerIndex, readableBytes);
                         nioBuffers[nioBufferCount ++] = nioBuf;
                     } else {
-                        ByteBuffer[] nioBufs = entry.bufs;
-                        if (nioBufs == null) {
-                            // cached ByteBuffers as they may be expensive to create in terms
-                            // of Object allocation
-                            entry.bufs = nioBufs = buf.nioBuffers();
-                        }
+                        ByteBuffer[] nioBufs = buf.nioBuffers(readerIndex, readableBytes);
                         nioBufferCount = fillBufferArray(nioBufs, nioBuffers, nioBufferCount);
                     }
                 }
@@ -586,13 +572,10 @@ public final class ChannelOutboundBuffer {
         private final Handle handle;
         Entry next;
         Object msg;
-        ByteBuffer[] bufs;
-        ByteBuffer buf;
         ChannelPromise promise;
         long progress;
         long total;
         int pendingSize;
-        int count = -1;
         boolean cancelled;
 
         private Entry(Handle handle) {
@@ -620,8 +603,6 @@ public final class ChannelOutboundBuffer {
                 pendingSize = 0;
                 total = 0;
                 progress = 0;
-                bufs = null;
-                buf = null;
                 return pSize;
             }
             return 0;
@@ -629,14 +610,11 @@ public final class ChannelOutboundBuffer {
 
         void recycle() {
             next = null;
-            bufs = null;
-            buf = null;
             msg = null;
             promise = null;
             progress = 0;
             total = 0;
             pendingSize = 0;
-            count = -1;
             cancelled = false;
             RECYCLER.recycle(this, handle);
         }