From e3337c3fcaf9bddbe89acec285b2786b9ffd2f47 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Thu, 30 Nov 2023 16:42:08 +0100
Subject: [PATCH] StreamTracker should better extend ArrayDeque to reduce
 memory copies

Motivation:

StreamTracker did extend ArrayList which is not optimal as we always remove from index 0 and so cause memory copies.

Modifications:

Let StreamTracker extend ArrayDeque so removals dont cause memory copies all the time

Result:

Less memory copies
---
 .../java/io/netty/incubator/codec/http3/QpackEncoder.java   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/java/io/netty/incubator/codec/http3/QpackEncoder.java b/src/main/java/io/netty/incubator/codec/http3/QpackEncoder.java
index 2b4d5cb..835fc7f 100644
--- a/src/main/java/io/netty/incubator/codec/http3/QpackEncoder.java
+++ b/src/main/java/io/netty/incubator/codec/http3/QpackEncoder.java
@@ -21,7 +21,7 @@
 import io.netty.util.ReferenceCountUtil;
 import io.netty.util.collection.LongObjectHashMap;
 
-import java.util.ArrayList;
+import java.util.ArrayDeque;
 import java.util.Map;
 
 import static io.netty.incubator.codec.http3.Http3CodecUtils.closeOnFailure;
@@ -495,13 +495,13 @@ private boolean mayNotBlockStream() {
         return blockedStreams >= maxBlockedStreams - 1;
     }
 
-    private static final class StreamTracker extends ArrayList<Integer> {
+    private static final class StreamTracker extends ArrayDeque<Integer> {
         StreamTracker() {
             super(1); // we will mostly have a single header block in a stream.
         }
 
         int takeNextInsertCount() {
-            return isEmpty() ? -1 : remove(0);
+            return isEmpty() ? -1 : poll();
         }
     }
 }