From d465a8510ed1cd11a4c40d4565ae33e4b3f07f0e Mon Sep 17 00:00:00 2001
From: Andrew Creskey <acreskey@mozilla.com>
Date: Thu, 7 Sep 2023 18:51:47 +0000
Subject: [PATCH] Bug 1851908 - Add a preference to specify neqo's congestion
 control algorithm r=necko-reviewers,kershaw

We want to experiment with NewReno so expose this via pref.

Differential Revision: https://phabricator.services.mozilla.com/D187602
---
 modules/libpref/init/StaticPrefList.yaml |  9 +++++++++
 netwerk/socket/neqo_glue/src/lib.rs      | 18 ++++++++++++++----
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index b2252f564b9b..9cd72bdc442a 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -12417,6 +12417,15 @@
   value: false
   mirror: always
 
+# The congestion control algorithm with which to configure neqo.
+# 0 => NewReno
+# 1 => Cubic
+- name: network.http.http3.cc_algorithm
+  type: RelaxedAtomicUint32
+  value: 1
+  mirror: always
+  rust: true
+
 # When true, a http request will be upgraded to https when HTTPS RR is
 # available.
 - name: network.dns.upgrade_with_https_rr
diff --git a/netwerk/socket/neqo_glue/src/lib.rs b/netwerk/socket/neqo_glue/src/lib.rs
index 02568e69fc91..a159cbdb4f28 100644
--- a/netwerk/socket/neqo_glue/src/lib.rs
+++ b/netwerk/socket/neqo_glue/src/lib.rs
@@ -124,10 +124,20 @@ impl NeqoHttp3Conn {
         } else {
             vec![quic_version]
         };
+
+        let cc_algorithm = match static_prefs::pref!("network.http.http3.cc_algorithm") {
+            0 => CongestionControlAlgorithm::NewReno,
+            1 => CongestionControlAlgorithm::Cubic,
+            _ => {
+                // Unknown preferences; default to Cubic
+                CongestionControlAlgorithm::Cubic
+            }
+        };
+
         #[allow(unused_mut)]
         let mut params = ConnectionParameters::default()
             .versions(quic_version, version_list)
-            .cc_algorithm(CongestionControlAlgorithm::Cubic)
+            .cc_algorithm(cc_algorithm)
             .max_data(max_data)
             .max_stream_data(StreamType::BiDi, false, max_stream_data)
             .grease(static_prefs::pref!("security.tls.grease_http3_enable"));
@@ -1338,9 +1348,9 @@ pub extern "C" fn neqo_http3conn_webtransport_set_sendorder(
 ) -> nsresult {
     match conn
         .conn
-	.webtransport_set_sendorder(StreamId::from(stream_id), sendorder)
+        .webtransport_set_sendorder(StreamId::from(stream_id), sendorder)
     {
-	Ok(()) => NS_OK,
-	Err(_) => NS_ERROR_UNEXPECTED,
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_UNEXPECTED,
     }
 }