From d2729193c72fd01621bd2a55d64135f86a8674a5 Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Fri, 27 Aug 2021 21:11:03 +0900
Subject: [PATCH] nghttpx: Add --frontend-http3-max-concurrent-streams option

---
 gennghttpxfun.py            |  1 +
 src/shrpx.cc                | 13 +++++++++++++
 src/shrpx_config.cc         | 10 ++++++++++
 src/shrpx_config.h          |  4 ++++
 src/shrpx_http3_upstream.cc |  3 ++-
 5 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/gennghttpxfun.py b/gennghttpxfun.py
index be2c8390..c2156cb9 100755
--- a/gennghttpxfun.py
+++ b/gennghttpxfun.py
@@ -187,6 +187,7 @@ OPTIONS = [
     "frontend-http3-connection-window-size",
     "frontend-http3-max-window-size",
     "frontend-http3-max-connection-window-size",
+    "frontend-http3-max-concurrent-streams",
 ]
 
 LOGVARS = [
diff --git a/src/shrpx.cc b/src/shrpx.cc
index e2733a6c..79d8da73 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -1568,6 +1568,7 @@ void fill_default_config(Config *config) {
   {
     auto &upstreamconf = http3conf.upstream;
 
+    upstreamconf.max_concurrent_streams = 100;
     upstreamconf.window_size = 256_k;
     upstreamconf.connection_window_size = 1_m;
     upstreamconf.max_window_size = 6_m;
@@ -2939,6 +2940,11 @@ QUIC:
               Default: )"
       << util::utos_unit(config->http3.upstream.max_connection_window_size)
       << R"(
+  --frontend-http3-max-concurrent-streams=<N>
+              Set the maximum number of  the concurrent streams in one
+              frontend HTTP/3 connection.
+              Default: )"
+      << config->http3.upstream.max_concurrent_streams << R"(
 )";
 #endif // ENABLE_HTTP3
 
@@ -3658,6 +3664,8 @@ int main(int argc, char **argv) {
          &flag, 177},
         {SHRPX_OPT_FRONTEND_HTTP3_MAX_CONNECTION_WINDOW_SIZE.c_str(),
          required_argument, &flag, 178},
+        {SHRPX_OPT_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS.c_str(),
+         required_argument, &flag, 179},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -4509,6 +4517,11 @@ int main(int argc, char **argv) {
             SHRPX_OPT_FRONTEND_HTTP3_MAX_CONNECTION_WINDOW_SIZE,
             StringRef{optarg});
         break;
+      case 179:
+        // --frontend-http3-max-concurrent-streams
+        cmdcfgs.emplace_back(SHRPX_OPT_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS,
+                             StringRef{optarg});
+        break;
       default:
         break;
       }
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 3fb61021..fa24b8d0 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -2600,6 +2600,9 @@ int option_lookup_token(const char *name, size_t namelen) {
       if (util::strieq_l("frontend-http2-max-concurrent-stream", name, 36)) {
         return SHRPX_OPTID_FRONTEND_HTTP2_MAX_CONCURRENT_STREAMS;
       }
+      if (util::strieq_l("frontend-http3-max-concurrent-stream", name, 36)) {
+        return SHRPX_OPTID_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS;
+      }
       break;
     }
     break;
@@ -3954,6 +3957,13 @@ int parse_config(Config *config, int optid, const StringRef &opt,
 #endif // ENABLE_HTTP3
 
     return 0;
+  case SHRPX_OPTID_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS:
+#ifdef ENABLE_HTTP3
+    return parse_uint(&config->http3.upstream.max_concurrent_streams, opt,
+                      optarg);
+#else  // !ENABLE_HTTP3
+    return 0;
+#endif // !ENABLE_HTTP3
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";
 
diff --git a/src/shrpx_config.h b/src/shrpx_config.h
index 08b903f8..6dc61592 100644
--- a/src/shrpx_config.h
+++ b/src/shrpx_config.h
@@ -381,6 +381,8 @@ constexpr auto SHRPX_OPT_FRONTEND_HTTP3_MAX_WINDOW_SIZE =
     StringRef::from_lit("frontend-http3-max-window-size");
 constexpr auto SHRPX_OPT_FRONTEND_HTTP3_MAX_CONNECTION_WINDOW_SIZE =
     StringRef::from_lit("frontend-http3-max-connection-window-size");
+constexpr auto SHRPX_OPT_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS =
+    StringRef::from_lit("frontend-http3-max-concurrent-streams");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -753,6 +755,7 @@ struct QUICConfig {
 
 struct Http3Config {
   struct {
+    size_t max_concurrent_streams;
     int32_t window_size;
     int32_t connection_window_size;
     int32_t max_window_size;
@@ -1188,6 +1191,7 @@ enum {
   SHRPX_OPTID_FRONTEND_HTTP2_WINDOW_BITS,
   SHRPX_OPTID_FRONTEND_HTTP2_WINDOW_SIZE,
   SHRPX_OPTID_FRONTEND_HTTP3_CONNECTION_WINDOW_SIZE,
+  SHRPX_OPTID_FRONTEND_HTTP3_MAX_CONCURRENT_STREAMS,
   SHRPX_OPTID_FRONTEND_HTTP3_MAX_CONNECTION_WINDOW_SIZE,
   SHRPX_OPTID_FRONTEND_HTTP3_MAX_WINDOW_SIZE,
   SHRPX_OPTID_FRONTEND_HTTP3_READ_TIMEOUT,
diff --git a/src/shrpx_http3_upstream.cc b/src/shrpx_http3_upstream.cc
index d5c649cd..60d979ff 100644
--- a/src/shrpx_http3_upstream.cc
+++ b/src/shrpx_http3_upstream.cc
@@ -513,7 +513,8 @@ int Http3Upstream::init(const UpstreamAddr *faddr, const Address &remote_addr,
 
   ngtcp2_transport_params params;
   ngtcp2_transport_params_default(&params);
-  params.initial_max_streams_bidi = 100;
+  params.initial_max_streams_bidi = http3conf.upstream.max_concurrent_streams;
+  // The minimum number of unidirectional streams required for HTTP/3.
   params.initial_max_streams_uni = 3;
   params.initial_max_data = http3conf.upstream.connection_window_size;
   params.initial_max_stream_data_bidi_remote = http3conf.upstream.window_size;