From 572b6a8f196ad619859ab0a4bd391a7c405d5f2a Mon Sep 17 00:00:00 2001
From: Nizar Mankulangara <nizarcbd@gmail.com>
Date: Mon, 9 Sep 2019 00:47:23 -0700
Subject: [PATCH]     SimpleChannelPool POOL_KEY attribute name is easy to get
 conflict from user code (#9542) (#9548)

Motivation:

    It is noticed that SimpleChannelPool's POOL_KEY attribute name channelPool is easy to get conflict with user code and throws an exception 'channelPool' is already in use. Being a generic framework - it would be great if we can name the attribute something unique - may be use UUID for the name since the name is not required later.

    Modifications:

    This change make sure that the POOL_KEY used inside SimpleChannelPool is unique by appending the object hashcode in the name.

    Result:

    No unwanted channel attribute name conflict with user code.
---
 .../io/netty/channel/pool/SimpleChannelPool.java  | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java b/transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java
index fe711fbfb2..74a6d410c4 100644
--- a/transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java
+++ b/transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java
@@ -39,7 +39,8 @@ import static io.netty.util.internal.ObjectUtil.*;
  *
  */
 public class SimpleChannelPool implements ChannelPool {
-    private static final AttributeKey<SimpleChannelPool> POOL_KEY = AttributeKey.newInstance("channelPool");
+    private final AttributeKey<SimpleChannelPool> poolKey = AttributeKey.newInstance("channelPool." +
+        System.identityHashCode(this));
     private final Deque<Channel> deque = PlatformDependent.newConcurrentDeque();
     private final ChannelPoolHandler handler;
     private final ChannelHealthChecker healthCheck;
@@ -171,7 +172,7 @@ public class SimpleChannelPool implements ChannelPool {
             if (ch == null) {
                 // No Channel left in the pool bootstrap a new Channel
                 Bootstrap bs = bootstrap.clone();
-                bs.attr(POOL_KEY, this);
+                bs.attr(poolKey, this);
                 ChannelFuture f = connectChannel(bs);
                 if (f.isDone()) {
                     notifyConnect(f, promise);
@@ -237,7 +238,7 @@ public class SimpleChannelPool implements ChannelPool {
         if (future.isSuccess()) {
             if (future.getNow()) {
                 try {
-                    ch.attr(POOL_KEY).set(this);
+                    ch.attr(poolKey).set(this);
                     handler.channelAcquired(ch);
                     promise.setSuccess(ch);
                 } catch (Throwable cause) {
@@ -293,7 +294,7 @@ public class SimpleChannelPool implements ChannelPool {
     private void doReleaseChannel(Channel channel, Promise<Void> promise) {
         assert channel.eventLoop().inEventLoop();
         // Remove the POOL_KEY attribute from the Channel and check if it was acquired from this pool, if not fail.
-        if (channel.attr(POOL_KEY).getAndSet(null) != this) {
+        if (channel.attr(poolKey).getAndSet(null) != this) {
             closeAndFail(channel,
                          // Better include a stacktrace here as this is an user error.
                          new IllegalArgumentException(
@@ -357,12 +358,12 @@ public class SimpleChannelPool implements ChannelPool {
         }
     }
 
-    private static void closeChannel(Channel channel) {
-        channel.attr(POOL_KEY).getAndSet(null);
+    private void closeChannel(Channel channel) {
+        channel.attr(poolKey).getAndSet(null);
         channel.close();
     }
 
-    private static void closeAndFail(Channel channel, Throwable cause, Promise<?> promise) {
+    private void closeAndFail(Channel channel, Throwable cause, Promise<?> promise) {
         closeChannel(channel);
         promise.tryFailure(cause);
     }