From 7ac72d23d88c86a31deaeada5b390ea508474077 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Mon, 29 Jan 2024 16:19:39 +0100
Subject: [PATCH] Make `frame.info.cpu_usage` take more into account

---
 crates/eframe/src/epi.rs                     | 5 ++++-
 crates/eframe/src/native/epi_integration.rs  | 6 +++---
 crates/eframe/src/native/glow_integration.rs | 8 +++++---
 crates/eframe/src/native/wgpu_integration.rs | 8 ++++----
 4 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/crates/eframe/src/epi.rs b/crates/eframe/src/epi.rs
index d34b1aecae50..9a20a757e6d9 100644
--- a/crates/eframe/src/epi.rs
+++ b/crates/eframe/src/epi.rs
@@ -757,7 +757,10 @@ pub struct IntegrationInfo {
     /// `None` means "don't know".
     pub system_theme: Option<Theme>,
 
-    /// Seconds of cpu usage (in seconds) of UI code on the previous frame.
+    /// Seconds of cpu usage (in seconds) on the previous frame.
+    ///
+    /// This includes [`App::update`] as well as rendering (except for vsync waiting).
+    ///
     /// `None` if this is the first frame.
     pub cpu_usage: Option<f32>,
 }
diff --git a/crates/eframe/src/native/epi_integration.rs b/crates/eframe/src/native/epi_integration.rs
index e91278a39e80..e00e3b23a274 100644
--- a/crates/eframe/src/native/epi_integration.rs
+++ b/crates/eframe/src/native/epi_integration.rs
@@ -258,9 +258,9 @@ impl EpiIntegration {
         egui_winit.on_window_event(window, event)
     }
 
-    pub fn pre_update(&mut self) {
+    pub fn start_frame_timer(&mut self) {
         self.frame_start = Instant::now();
-        self.app_icon_setter.update();
+        self.app_icon_setter.update(); // TODO(emilk): this is probably not the right place for this call
     }
 
     /// Run user code - this can create immediate viewports, so hold no locks over this!
@@ -304,7 +304,7 @@ impl EpiIntegration {
         std::mem::take(&mut self.pending_full_output)
     }
 
-    pub fn post_update(&mut self) {
+    pub fn end_frame_timer(&mut self) {
         let frame_time = self.frame_start.elapsed().as_secs_f64() as f32;
         self.frame.info.cpu_usage = Some(frame_time);
     }
diff --git a/crates/eframe/src/native/glow_integration.rs b/crates/eframe/src/native/glow_integration.rs
index ea193ee87528..c21158a823b0 100644
--- a/crates/eframe/src/native/glow_integration.rs
+++ b/crates/eframe/src/native/glow_integration.rs
@@ -493,6 +493,8 @@ impl GlowWinitRunning {
         #[cfg(feature = "puffin")]
         puffin::GlobalProfiler::lock().new_frame();
 
+        self.integration.start_frame_timer();
+
         {
             let glutin = self.glutin.borrow();
             let viewport = &glutin.viewports[&viewport_id];
@@ -522,8 +524,6 @@ impl GlowWinitRunning {
             let mut raw_input = egui_winit.take_egui_input(window);
             let viewport_ui_cb = viewport.viewport_ui_cb.clone();
 
-            self.integration.pre_update();
-
             raw_input.time = Some(self.integration.beginning.elapsed().as_secs_f64());
             raw_input.viewports = glutin
                 .viewports
@@ -604,7 +604,6 @@ impl GlowWinitRunning {
         let gl_surface = viewport.gl_surface.as_ref().unwrap();
         let egui_winit = viewport.egui_winit.as_mut().unwrap();
 
-        integration.post_update();
         egui_winit.handle_platform_output(window, platform_output);
 
         let clipped_primitives = integration.egui_ctx.tessellate(shapes, pixels_per_point);
@@ -640,7 +639,10 @@ impl GlowWinitRunning {
             integration.post_rendering(window);
         }
 
+        integration.end_frame_timer(); // Must be called before vsync.
+
         {
+            // vsync
             crate::profile_scope!("swap_buffers");
             if let Err(err) = gl_surface.swap_buffers(
                 current_gl_context
diff --git a/crates/eframe/src/native/wgpu_integration.rs b/crates/eframe/src/native/wgpu_integration.rs
index 56847b92124b..d53362886652 100644
--- a/crates/eframe/src/native/wgpu_integration.rs
+++ b/crates/eframe/src/native/wgpu_integration.rs
@@ -528,6 +528,8 @@ impl WgpuWinitRunning {
             shared,
         } = self;
 
+        integration.start_frame_timer();
+
         let (viewport_ui_cb, raw_input) = {
             crate::profile_scope!("Prepare");
             let mut shared_lock = shared.borrow_mut();
@@ -584,8 +586,6 @@ impl WgpuWinitRunning {
             let egui_winit = egui_winit.as_mut().unwrap();
             let mut raw_input = egui_winit.take_egui_input(window);
 
-            integration.pre_update();
-
             raw_input.time = Some(integration.beginning.elapsed().as_secs_f64());
             raw_input.viewports = viewports
                 .iter()
@@ -628,8 +628,6 @@ impl WgpuWinitRunning {
             return EventResult::Wait;
         };
 
-        integration.post_update();
-
         let FullOutput {
             platform_output,
             textures_delta,
@@ -643,6 +641,8 @@ impl WgpuWinitRunning {
         {
             let clipped_primitives = egui_ctx.tessellate(shapes, pixels_per_point);
 
+            integration.end_frame_timer(); // TODO(emilk): include everything in rendering except for vsync
+
             let screenshot_requested = std::mem::take(&mut viewport.screenshot_requested);
             let screenshot = painter.paint_and_update_textures(
                 viewport_id,