Add perfetto tracing events to fonts (#33436)

* trace fonts

Co-authored-by: Delan Azabani <dazabani@igalia.com>
Signed-off-by: atbrakhi <atbrakhi@igalia.com>

* review fix

Co-authored-by: Delan Azabani <dazabani@igalia.com>
Signed-off-by: atbrakhi <atbrakhi@igalia.com>

---------

Signed-off-by: atbrakhi <atbrakhi@igalia.com>
Co-authored-by: Delan Azabani <dazabani@igalia.com>

Cargo.lock

@@ -1914,6 +1914,7 @@ dependencies = [
  "smallvec",
  "style",
  "surfman",
+ "tracing",
  "truetype",
  "unicode-bidi",
  "unicode-properties",

components/fonts/Cargo.toml

@@ -41,6 +41,7 @@ servo_url = { path = "../url" }
 smallvec = { workspace = true, features = ["union"] }
 surfman = { workspace = true }
 style = { workspace = true }
+tracing = { workspace = true }
 unicode-bidi = { workspace = true, features = ["with_serde"] }
 unicode-properties = { workspace = true }
 unicode-script = { workspace = true }

components/fonts/font_cache_thread.rs

@@ -23,6 +23,7 @@ use style::values::computed::font::{
 };
 use style::values::computed::{FontStretch, FontWeight};
 use style::values::specified::FontStretch as SpecifiedFontStretch;
+use tracing::{span, Level};
 use webrender_api::{FontInstanceFlags, FontInstanceKey, FontKey};
 use webrender_traits::WebRenderFontApi;
 
@@ -102,12 +103,19 @@ struct FontCache {
 }
 
 impl FontCache {
+    #[tracing::instrument(skip(self), fields(servo_profiling = true))]
     fn run(&mut self) {
         loop {
             let msg = self.port.recv().unwrap();
 
             match msg {
                 Command::GetFontTemplates(descriptor_to_match, font_family, result) => {
+                    let span = span!(
+                        Level::TRACE,
+                        "Command::GetFontTemplates",
+                        servo_profiling = true
+                    );
+                    let _span = span.enter();
                     let templates =
                         self.find_font_templates(descriptor_to_match.as_ref(), &font_family);
                     debug!("Found templates for descriptor {descriptor_to_match:?}: ");
@@ -141,6 +149,12 @@ impl FontCache {
                             .font_data
                             .entry(identifier)
                             .or_insert_with(|| font_template.data());
+                        let span = span!(
+                            Level::TRACE,
+                            "GetFontTemplates send",
+                            servo_profiling = true
+                        );
+                        let _span = span.enter();
                         let _ = bytes_sender.send(data);
                     }
                 },
@@ -186,6 +200,7 @@ impl FontCache {
         });
     }
 
+    #[tracing::instrument(skip(self), fields(servo_profiling = true))]
     fn find_font_templates(
         &mut self,
         descriptor_to_match: Option<&FontDescriptor>,

components/servo/lib.rs

@@ -89,6 +89,7 @@ use surfman::platform::generic::multi::context::NativeContext as LinuxNativeCont
 use surfman::{GLApi, GLVersion};
 #[cfg(all(target_os = "linux", not(target_env = "ohos")))]
 use surfman::{NativeConnection, NativeContext};
+use tracing::{span, Level};
 use webgpu::swapchain::WGPUImageMap;
 use webrender::{RenderApiSender, ShaderPrecacheFlags, UploadMethod, ONE_TIME_USAGE_HINT};
 use webrender_api::{
@@ -1105,6 +1106,7 @@ impl WebRenderFontApi for WebRenderFontApiCompositorProxy {
         receiver.recv().unwrap()
     }
 
+    #[tracing::instrument(skip(self), fields(servo_profiling = true))]
     fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey {
         let (sender, receiver) = unbounded();
         let (bytes_sender, bytes_receiver) =
@@ -1113,7 +1115,11 @@ impl WebRenderFontApi for WebRenderFontApiCompositorProxy {
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
                 FontToCompositorMsg::AddFont(sender, index, bytes_receiver),
             )));
-        let _ = bytes_sender.send(&data);
+        {
+            let span = span!(Level::TRACE, "add_font send", servo_profiling = true);
+            let _span = span.enter();
+            let _ = bytes_sender.send(&data);
+        }
         receiver.recv().unwrap()
     }