From 2c99fc0f1290c65685c5036fdc9884921823ad7d Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Sat, 22 Jun 2019 07:27:04 +0200
Subject: [PATCH] Recycle RecyclableArrayDeque as fast as possible in
 FlowControlHandler (#9263)

Motivation:

FlowControlHandler does use a recyclable ArrayDeque internally but only recycles it when the channel is closed. We should better recycle it once it is empty.

Modifications:

Recycle the deque as fast as possible

Result:

Less RecyclableArrayDeque instances.
---
 .../io/netty/handler/flow/FlowControlHandler.java     | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/handler/src/main/java/io/netty/handler/flow/FlowControlHandler.java b/handler/src/main/java/io/netty/handler/flow/FlowControlHandler.java
index 576227c172..7ad723222c 100644
--- a/handler/src/main/java/io/netty/handler/flow/FlowControlHandler.java
+++ b/handler/src/main/java/io/netty/handler/flow/FlowControlHandler.java
@@ -88,7 +88,7 @@ public class FlowControlHandler extends ChannelDuplexHandler {
      * testing, debugging and inspection purposes and it is not Thread safe!
      */
     boolean isQueueEmpty() {
-        return queue.isEmpty();
+        return queue == null || queue.isEmpty();
     }
 
     /**
@@ -190,8 +190,13 @@ public class FlowControlHandler extends ChannelDuplexHandler {
             // We're firing a completion event every time one (or more)
             // messages were consumed and the queue ended up being drained
             // to an empty state.
-            if (queue.isEmpty() && consumed > 0) {
-                ctx.fireChannelReadComplete();
+            if (queue.isEmpty()) {
+                queue.recycle();
+                queue = null;
+
+                if (consumed > 0) {
+                    ctx.fireChannelReadComplete();
+                }
             }
 
             return consumed;