From bccf4a63dce2a51cdad679a7dc4c6a2aba149f3f Mon Sep 17 00:00:00 2001
From: Sudarsan Reddy <sreddy@cloudflare.com>
Date: Fri, 8 Oct 2021 13:48:20 +0100
Subject: [PATCH] UN-5213: Increase MaxStreams value for QUIC transport

The default max streams value of 100 is rather small when subject to
high load in terms of connecting QUIC with streams faster than it can
create new ones. This high value allows for more throughput.
---
 connection/connection.go |  2 ++
 connection/http2.go      |  3 +--
 origin/tunnel.go         | 10 +++++-----
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/connection/connection.go b/connection/connection.go
index f061672c..2a57229f 100644
--- a/connection/connection.go
+++ b/connection/connection.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"math"
 	"net/http"
 	"strconv"
 	"strings"
@@ -19,6 +20,7 @@ const (
 	lbProbeUserAgentPrefix = "Mozilla/5.0 (compatible; Cloudflare-Traffic-Manager/1.0; +https://www.cloudflare.com/traffic-manager/;"
 	LogFieldConnIndex      = "connIndex"
 	MaxGracePeriod         = time.Minute * 3
+	MaxConcurrentStreams   = math.MaxUint32
 )
 
 var switchingProtocolText = fmt.Sprintf("%d %s", http.StatusSwitchingProtocols, http.StatusText(http.StatusSwitchingProtocols))
diff --git a/connection/http2.go b/connection/http2.go
index 2e869890..cfe65f78 100644
--- a/connection/http2.go
+++ b/connection/http2.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"math"
 	"net"
 	"net/http"
 	"runtime/debug"
@@ -60,7 +59,7 @@ func NewHTTP2Connection(
 	return &HTTP2Connection{
 		conn: conn,
 		server: &http2.Server{
-			MaxConcurrentStreams: math.MaxUint32,
+			MaxConcurrentStreams: MaxConcurrentStreams,
 		},
 		config:               config,
 		connOptions:          connOptions,
diff --git a/origin/tunnel.go b/origin/tunnel.go
index 798c821c..190be47d 100644
--- a/origin/tunnel.go
+++ b/origin/tunnel.go
@@ -358,7 +358,6 @@ func serveTunnel(
 			config,
 			connOptions,
 			controlStream,
-			connectedFuse,
 			reconnectCh,
 			gracefulShutdownC)
 
@@ -509,15 +508,16 @@ func ServeQUIC(
 	config *TunnelConfig,
 	connOptions *tunnelpogs.ConnectionOptions,
 	controlStreamHandler connection.ControlStreamHandler,
-	connectedFuse connection.ConnectedFuse,
 	reconnectCh chan ReconnectSignal,
 	gracefulShutdownC <-chan struct{},
 ) (err error, recoverable bool) {
 	tlsConfig := config.EdgeTLSConfigs[connection.QUIC]
 	quicConfig := &quic.Config{
-		HandshakeIdleTimeout: quicHandshakeIdleTimeout,
-		MaxIdleTimeout:       quicMaxIdleTimeout,
-		KeepAlive:            true,
+		HandshakeIdleTimeout:  quicHandshakeIdleTimeout,
+		MaxIdleTimeout:        quicMaxIdleTimeout,
+		MaxIncomingStreams:    connection.MaxConcurrentStreams,
+		MaxIncomingUniStreams: connection.MaxConcurrentStreams,
+		KeepAlive:             true,
 	}
 	for {
 		select {