后台服务协程化

web_server/app/Web_Plot_Session.cpp

@@ -25,20 +25,21 @@ struct Web_Plot_Session::Impl {
         scene = std::move(*built_scene);
         scene->activate_view();
     }
+    std::optional<Web_Response> encode_frame() {
+        std::string pixels;
+        scene->with_frame([&](Image_View image) {
+            pixels = encode_pixel_frame(image, ++sequence);
+        });
+        if (pixels.empty()) return std::nullopt;
+        return Web_Response{Web_Response_Type::Pixels, std::move(pixels)};
+    }
     std::optional<Web_Response> handle(const Web_Event& event) {
         return std::visit([this](const auto& value) -> std::optional<Web_Response> {
             using T = std::decay_t<decltype(value)>;
             if constexpr (std::same_as<T, Frame_Request>) {
                 const auto result = scene->render_frame();
-                if (!result || scene->wait_for_render() != Scene_Render_Result::none)
-                    return std::nullopt;
-                std::string pixels;
-                scene->with_frame([&](Image_View image) {
-                    pixels = encode_pixel_frame(image, ++sequence);
-                });
-                if (pixels.empty()) return std::nullopt;
-                return Web_Response{Web_Response_Type::Pixels,
-                                    std::move(pixels)};
+                if (!result || scene->wait_for_render() != Scene_Render_Result::none) return std::nullopt;
+                return encode_frame();
             } else if constexpr (std::same_as<T, Viewport_Resize>) {
                 viewport = value.size;
                 rebuild();
@@ -48,10 +49,37 @@ struct Web_Plot_Session::Impl {
             return std::nullopt;
         }, event);
     }
+    void async_handle(const Web_Event& event, Web_Response_Completion completion) {
+        if (!std::holds_alternative<Frame_Request>(event)) {
+            completion({handle(event), {}});
+            return;
+        }
+        const auto result = scene->render_frame(
+            [this, completion](Scene_Render_Result render_result, std::exception_ptr exception) mutable {
+                if (exception) {
+                    completion({{}, std::move(exception)});
+                    return;
+                }
+                if (render_result != Scene_Render_Result::none) {
+                    completion({});
+                    return;
+                }
+                try {
+                    completion({encode_frame(), {}});
+                }
+                catch (...) {
+                    completion({{}, std::current_exception()});
+                }
+            });
+        if (!result || *result != Plot_Render_Status::rendered) completion({});
+    }
 };
 Web_Plot_Session::Web_Plot_Session() : impl_(std::make_unique<Impl>()) {}
 Web_Plot_Session::~Web_Plot_Session() = default;
 std::optional<Web_Response> Web_Plot_Session::handle(const Web_Event& event) {
     return impl_->handle(event);
 }
+void Web_Plot_Session::async_handle(const Web_Event& event, Web_Response_Completion completion) {
+    impl_->async_handle(event, std::move(completion));
+}
 } // namespace renderive::web