From 13cd9cd3c03e7ad1aca2e3b2dd75e630401b5ff1 Mon Sep 17 00:00:00 2001
From: William Yang <mscame@gmail.com>
Date: Wed, 22 May 2024 10:57:21 +0200
Subject: [PATCH 1/2] tmp: hardcode lb mode 1

---
 c_src/quicer_nif.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/c_src/quicer_nif.c b/c_src/quicer_nif.c
index 1a9a1239..63e396c1 100644
--- a/c_src/quicer_nif.c
+++ b/c_src/quicer_nif.c
@@ -1179,6 +1179,8 @@ openLib(ErlNifEnv *env, __unused_parm__ int argc, const ERL_NIF_TERM argv[])
   TP_NIF_3(success, 0, 2);
 
   res = SUCCESS(ATOM_TRUE);
+  uint16_t lb_mode = 1;
+  MsQuic->SetParam(NULL, QUIC_PARAM_GLOBAL_LOAD_BALACING_MODE, sizeof(uint16_t), &lb_mode);
 
   if (enif_get_string(env, lttngLib, lttngPath, PATH_MAX, ERL_NIF_LATIN1))
     {

From 2aca923f5caa850c382c5f767f7da1ac79e81de7 Mon Sep 17 00:00:00 2001
From: William Yang <mscame@gmail.com>
Date: Wed, 22 May 2024 15:28:39 +0200
Subject: [PATCH 2/2] feat: lb-mode

---
 c_src/quicer_nif.c | 23 +++++++++++++++++------
 src/quicer.app.src |  2 +-
 src/quicer_nif.erl |  5 ++++-
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/c_src/quicer_nif.c b/c_src/quicer_nif.c
index 63e396c1..91eec7a2 100644
--- a/c_src/quicer_nif.c
+++ b/c_src/quicer_nif.c
@@ -1148,14 +1148,14 @@ on_unload(__unused_parm__ ErlNifEnv *env, __unused_parm__ void *priv_data)
 }
 
 static ERL_NIF_TERM
-openLib(ErlNifEnv *env, __unused_parm__ int argc, const ERL_NIF_TERM argv[])
+openLib(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 {
-  assert(1 == argc);
+  CXPLAT_FRE_ASSERT(argc == 1);
   TP_NIF_3(enter, 0, 1);
   QUIC_STATUS status = QUIC_STATUS_SUCCESS;
   ERL_NIF_TERM res = ATOM_FALSE;
-  ERL_NIF_TERM lttngLib = argv[0];
   char lttngPath[PATH_MAX] = { 0 };
+  unsigned int lb_mode = 0;
 
   pthread_mutex_lock(&MsQuicLock);
   if (MsQuic)
@@ -1179,10 +1179,21 @@ openLib(ErlNifEnv *env, __unused_parm__ int argc, const ERL_NIF_TERM argv[])
   TP_NIF_3(success, 0, 2);
 
   res = SUCCESS(ATOM_TRUE);
-  uint16_t lb_mode = 1;
-  MsQuic->SetParam(NULL, QUIC_PARAM_GLOBAL_LOAD_BALACING_MODE, sizeof(uint16_t), &lb_mode);
 
-  if (enif_get_string(env, lttngLib, lttngPath, PATH_MAX, ERL_NIF_LATIN1))
+  ERL_NIF_TERM eterm = ATOM_UNDEFINED;
+
+  if (enif_get_map_value(
+          env, argv[0], ATOM_QUIC_PARAM_GLOBAL_LOAD_BALACING_MODE, &eterm)
+      && enif_get_uint(env, eterm, &lb_mode))
+    {
+      MsQuic->SetParam(NULL,
+                       QUIC_PARAM_GLOBAL_LOAD_BALACING_MODE,
+                       sizeof(uint16_t),
+                       (uint16_t *)&lb_mode);
+    }
+
+  if (enif_get_map_value(env, argv[0], ATOM_TRACE, &eterm)
+      && enif_get_string(env, eterm, lttngPath, PATH_MAX, ERL_NIF_LATIN1))
     {
       // loading lttng lib is optional, ok to fail
       if (dlopen(lttngPath, (unsigned)RTLD_NOW | (unsigned)RTLD_GLOBAL))
diff --git a/src/quicer.app.src b/src/quicer.app.src
index 83a7940b..0611c81d 100644
--- a/src/quicer.app.src
+++ b/src/quicer.app.src
@@ -7,7 +7,7 @@
         stdlib
     ]},
     {mod, {quicer_app, []}},
-    {env, []},
+    {env, [{lb_mode, 0}]},
     {modules, [
         quicer,
         quicer_app,
diff --git a/src/quicer_nif.erl b/src/quicer_nif.erl
index 2b03d3f7..4bb0ca03 100644
--- a/src/quicer_nif.erl
+++ b/src/quicer_nif.erl
@@ -153,7 +153,10 @@ open_lib() ->
             {error, _} ->
                 priv_dir()
         end,
-    open_lib(LibFile).
+    open_lib(#{
+        load_balacing_mode => application:get_env(quicer, lb_mode, 0),
+        trace => LibFile
+    }).
 
 open_lib(_LttngLib) ->
     erlang:nif_error(nif_library_not_loaded).