Merge branch 'light-debugger-crash-fix' into 'main'

[REMIX-2785] Fix crashes related to light manager threading

See merge request lightspeedrtx/dxvk-remix-nv!1602

Author: MarkEHenderson

src/dxvk/rtx_render/rtx_light_manager.cpp

@@ -96,7 +96,24 @@ namespace dxvk {
   }
 
   void LightManager::clear() {
+    if (!m_lightDebugUILock.owns_lock()) {
+      m_lightDebugUILock.lock();
+    }
     m_lights.clear();
+    m_linearizedLights.clear();
+    m_lightDebugUILock.unlock();
+  }
+
+  void LightManager::clearFromUIThread() {
+    // This needs to wait for `m_lightDebugUILock` to be unlocked, so it doesn't
+    // cause crashes.
+    std::lock_guard<std::mutex> lock(m_lightUIMutex);
+    m_lights.clear();
+    m_linearizedLights.clear();
+
+    // Note: Fallback light reset here so that changes to its settings will take effect, does not need to be part
+    // of usual light clearing logic though.
+    m_fallbackLight.reset();
   }
 
   void LightManager::garbageCollectionInternal() {
@@ -126,6 +143,9 @@ namespace dxvk {
   }
 
   void LightManager::garbageCollection(RtCamera& camera) {
+    if (!m_lightDebugUILock.owns_lock()) {
+      m_lightDebugUILock.lock();
+    }
     if (RtxOptions::AntiCulling::isLightAntiCullingEnabled()) {
       cFrustum& cameraLightAntiCullingFrustum = camera.getLightAntiCullingFrustum();
       for (auto& [lightHash, rtLight] : getLightTable()) {
@@ -162,6 +182,7 @@ namespace dxvk {
     }
 
     garbageCollectionInternal();
+    m_lightDebugUILock.unlock();
   }
 
   void LightManager::dynamicLightMatching() {
@@ -316,7 +337,7 @@ namespace dxvk {
     // can be processed like all other lights without complex logic at the cost of potentially more computational
     // cost, but it might actually work out in favor of performance since unordered map traversal done redundantly
     // may be more expensive than simple vector traversal on the linearized list.
-
+    
     m_linearizedLights.clear();
 
     if (m_fallbackLight) {
@@ -333,7 +354,7 @@ namespace dxvk {
       auto found = m_externalLights.find(handle);
       if (found != m_externalLights.end()) {
         m_linearizedLights.emplace_back(&found->second);
-      }
+     }
     }
 
     // Count the active light of each type
@@ -569,6 +590,11 @@ namespace dxvk {
   }
 
   RtLight* LightManager::addLight(const RtLight& rtLight, const RtLightAntiCullingType antiCullingType, const XXH64_hash_t lightToReplace) {
+    if (!m_lightDebugUILock.owns_lock()) {
+      // As addLight can actually erase old lights, we need to lock the mutex starting from the first call each frame.
+      m_lightDebugUILock.lock();
+    }
+
     // This light is "off". This includes negative valued lights which in D3D games originally would act as subtractive lighting.
     const Vector3 originalRadiance = rtLight.getRadiance();
     if (originalRadiance.x < 0 || originalRadiance.y < 0 || originalRadiance.z < 0

src/dxvk/rtx_render/rtx_light_manager.h

@@ -78,6 +78,7 @@ struct LightManager : public CommonDeviceObject {
   const DomeLightArgs& getDomeLightArgs() const { return m_gpuDomeLightArgs; }
 
   void clear();
+  void clearFromUIThread();
 
   void garbageCollection(RtCamera& camera);
 
@@ -124,6 +125,10 @@ struct LightManager : public CommonDeviceObject {
   std::vector<unsigned char> m_lightsGPUData{};
   std::vector<uint16_t> m_lightMappingData{};
 
+  // Mutex to prevent the debugging UI from accessing the light data after it's been deleted.
+  mutable std::mutex m_lightUIMutex;
+  std::unique_lock<std::mutex> m_lightDebugUILock = std::unique_lock<std::mutex>(m_lightUIMutex, std::defer_lock);
+
   bool getActiveDomeLight(DomeLight& lightOut);
 
   void garbageCollectionInternal();

src/dxvk/rtx_render/rtx_light_manager_gui.cpp

@@ -180,11 +180,7 @@ namespace dxvk {
 
     // Clear the lights and fallback light if the settings are dirty to recreate the lights on the next frame.
     if (lightSettingsDirty) {
-      clear();
-
-      // Note: Fallback light reset here so that changes to its settings will take effect, does not need to be part
-      // of usual light clearing logic though.
-      m_fallbackLight.reset();
+      clearFromUIThread();
     }
   }
 
@@ -424,6 +420,7 @@ namespace dxvk {
     ImGui::SetNextWindowSize(viewport->Size);
     ImGui::PushStyleColor(ImGuiCol_WindowBg, ImVec4(0.f, 0.f, 0.f, 0.0f));
     if (ImGui::Begin("Light Debug View", nullptr, ImGuiWindowFlags_NoNav | ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoSavedSettings)) {
+      std::lock_guard<std::mutex> lock(m_lightUIMutex);
       ImDrawList* drawList = ImGui::GetWindowDrawList();
       drawList->PushClipRectFullScreen();
       const RtCamera& camera = device()->getCommon()->getSceneManager().getCamera();