config: add a mutex for config

We want to wait to render before config has been fully loaded.
Otherwise this can sometimes cause a crash when we access config
options while they are being assigned.

src/overlay.cpp

@@ -666,6 +666,8 @@ void horizontal_separator(struct overlay_params& params) {
 
 void render_imgui(swapchain_stats& data, struct overlay_params& params, ImVec2& window_size, bool is_vulkan)
 {
+   std::unique_lock<std::mutex> lock(config_mtx);
+   config_cv.wait(lock, []{ return config_ready; });
    // data.engine = EngineTypes::GAMESCOPE;
    HUDElements.sw_stats = &data; HUDElements.params = &params;
    HUDElements.is_vulkan = is_vulkan;

src/overlay_params.cpp

@@ -41,6 +41,9 @@
 #include "fps_metrics.h"
 
 std::unique_ptr<fpsMetrics> fpsmetrics;
+std::mutex config_mtx;
+std::condition_variable config_cv;
+bool config_ready = false;
 
 #if __cplusplus >= 201703L
 
@@ -1001,6 +1004,12 @@ parse_overlay_config(struct overlay_params *params,
 #endif
    if (HUDElements.net)
       HUDElements.net->should_reset = true;
+
+   {
+      std::lock_guard<std::mutex> lock(config_mtx);
+      config_ready = true;
+      config_cv.notify_one();
+   }
 }
 
 bool parse_preset_config(int preset, struct overlay_params *params){

src/overlay_params.h

@@ -6,6 +6,8 @@
 #include <vector>
 #include <unordered_map>
 #include <cstdint>
+#include <condition_variable>
+#include <mutex>
 
 #ifdef __cplusplus
 extern "C" {
@@ -330,9 +332,11 @@ void parse_overlay_config(struct overlay_params *params,
 void presets(int preset, struct overlay_params *params, bool inherit=false);
 bool parse_preset_config(int preset, struct overlay_params *params);
 void add_to_options(struct overlay_params *params, std::string option, std::string value);
-
 #ifdef __cplusplus
 }
 #endif
+extern std::mutex config_mtx;
+extern std::condition_variable config_cv;
+extern bool config_ready;
 
 #endif /* MANGOHUD_OVERLAY_PARAMS_H */