From 0e885f1ff15e2b246308451801e686e85eeffd55 Mon Sep 17 00:00:00 2001
From: Andrew Noyes <andrew@weaselab.dev>
Date: Wed, 20 Aug 2025 11:36:02 -0400
Subject: [PATCH] Perfetto tracing in load tester

---
 CMakeLists.txt        |  4 +++-
 tools/load_tester.cpp | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 12330e1..11ebc48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,8 @@ set(CMAKE_CXX_FLAGS_DEBUG "-g -O0 -Wall -Wextra")
 set(CMAKE_CXX_FLAGS_RELEASE
     "-g -O3 -Wall -Wextra -DNDEBUG -fno-omit-frame-pointer")
 
+add_subdirectory(third_party)
+
 find_package(Threads REQUIRED)
 
 include(FetchContent)
@@ -202,7 +204,7 @@ target_include_directories(debug_arena PRIVATE src)
 
 # Load tester
 add_executable(load_tester tools/load_tester.cpp)
-target_link_libraries(load_tester Threads::Threads llhttp_static)
+target_link_libraries(load_tester Threads::Threads llhttp_static perfetto)
 
 add_test(NAME arena_allocator_tests COMMAND test_arena_allocator)
 add_test(NAME commit_request_tests COMMAND test_commit_request)
diff --git a/tools/load_tester.cpp b/tools/load_tester.cpp
index 22c9734..2e0aa8e 100644
--- a/tools/load_tester.cpp
+++ b/tools/load_tester.cpp
@@ -27,6 +27,21 @@
 #define __has_feature(x) 0
 #endif
 
+#define ENABLE_PERFETTO 1
+
+#if ENABLE_PERFETTO
+#include <perfetto.h>
+#else
+#define PERFETTO_DEFINE_CATEGORIES(...)
+#define PERFETTO_TRACK_EVENT_STATIC_STORAGE(...)
+#define TRACE_EVENT(...)
+#endif
+
+PERFETTO_DEFINE_CATEGORIES(
+    perfetto::Category("network").SetDescription("Network"));
+
+PERFETTO_TRACK_EVENT_STATIC_STORAGE();
+
 namespace {
 
 double now() {
@@ -249,6 +264,8 @@ struct Connection {
       request = request.substr(w, request.size() - w);
       if (request.empty()) {
         ++requestsSent;
+        TRACE_EVENT("network", "send request",
+                    perfetto::Flow::Global(currentRequestId));
         if (requestsSent == g_config.requests_per_connection) {
           return true;
         }
@@ -290,6 +307,8 @@ private:
   }
 
   int on_message_complete() {
+    TRACE_EVENT("network", "receive response",
+                perfetto::Flow::Global(responseId));
     responseId = 0;
     ++responsesReceived;
     initRequest();
@@ -455,6 +474,13 @@ void parse_args(int argc, char *argv[]) {
 }
 
 int main(int argc, char *argv[]) {
+#if ENABLE_PERFETTO
+  perfetto::TracingInitArgs args;
+  args.backends |= perfetto::kSystemBackend;
+  perfetto::Tracing::Initialize(args);
+  perfetto::TrackEvent::Register();
+#endif
+
   parse_args(argc, argv);
 
   // Print configuration