Switch to using a work scheduler instead of a stack lock for state up…

…dates
project-chip · Feb 16, 2023 · b59312a · b59312a
1 parent 7a9f3b2
commit b59312a
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Showing 2 changed files with 27 additions and 4 deletions.
diff --git a/examples/common/imgui_ui/ui.cpp b/examples/common/imgui_ui/ui.cpp
@@ -25,6 +25,7 @@
 #include <lib/support/logging/CHIPLogging.h>
 
 #include <atomic>
+#include <thread>
 
 namespace example {
 namespace Ui {
@@ -60,7 +61,7 @@ void UiInit(SDL_GLContext * gl_context, SDL_Window ** window)
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
     SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
     SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
-    SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
+    SDL_WindowFlags window_flags = (SDL_WindowFlags) (SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     *window     = SDL_CreateWindow("Light UI", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
     *gl_context = SDL_GL_CreateContext(*window);
     SDL_GL_MakeCurrent(*window, *gl_context);
@@ -189,10 +190,26 @@ void ImguiUi::Render()
     }
 }
 
+void ImguiUi::ChipLoopUpdateCallback(intptr_t self)
+{
+    ImguiUi * _this = reinterpret_cast<ImguiUi *>(self);
+    _this->ChipLoopStateUpdate();
+    sem_post(&_this->mChipLoopWaitSemaphore); // notify complete
+}
+
 void ImguiUi::UpdateState()
 {
-    chip::DeviceLayer::StackLock lock;
-    ChipLoopStateUpdate();
+    chip::DeviceLayer::PlatformMgr().ScheduleWork(&ChipLoopUpdateCallback, reinterpret_cast<intptr_t>(this));
+    // ensure update is done when existing
+    if (sem_trywait(&mChipLoopWaitSemaphore) != 0)
+    {
+        if (!gUiRunning.load())
+        {
+            // UI should stop, no need to wait, probably chip main loop is stopped
+            return;
+        }
+        std::this_thread::yield();
+    }
 }
 
 } // namespace Ui

diff --git a/examples/common/imgui_ui/ui.h b/examples/common/imgui_ui/ui.h
@@ -19,6 +19,8 @@
 #include <AppMain.h>
 #include <imgui_ui/windows/window.h>
 
+#include <semaphore.h>
+
 #include <list>
 #include <memory>
 
@@ -33,7 +35,8 @@ namespace Ui {
 class ImguiUi : public AppMainLoopImplementation
 {
 public:
-    virtual ~ImguiUi() = default;
+    ImguiUi() { sem_init(&mChipLoopWaitSemaphore, 0 /* shared */, 0); }
+    virtual ~ImguiUi() { sem_destroy(&mChipLoopWaitSemaphore); }
 
     void AddWindow(std::unique_ptr<Window> window) { mWindows.push_back(std::move(window)); }
 
@@ -52,7 +55,10 @@ class ImguiUi : public AppMainLoopImplementation
     // to CHIP API calls)
     void ChipLoopStateUpdate();
 
+    sem_t mChipLoopWaitSemaphore;
     std::list<std::unique_ptr<Window>> mWindows;
+
+    static void ChipLoopUpdateCallback(intptr_t self);
 };
 
 } // namespace Ui