add usefull information to trace

src/lib.rs

@@ -10,7 +10,7 @@ mod perfetto {
 
 use perfetto::DebugAnnotation;
 use prost::Message;
-use tracing::{field::Visit, span, Dispatch, Level, Subscriber};
+use tracing::{field::Visit, span, Dispatch, Level, Metadata, Subscriber};
 
 pub fn install_perfetto_subscriber() {
     let subscriber = PerfettoSubscriber::new();
@@ -49,6 +49,31 @@ struct DebugAnnotationVisitor {
 }
 
 impl DebugAnnotationVisitor {
+    fn new_with_metadata(metadata: &'static Metadata<'static>) -> Self {
+        Self {
+            data: vec![
+                DebugAnnotation {
+                    name_field: Some(perfetto::debug_annotation::NameField::Name(String::from(
+                        "module_path",
+                    ))),
+                    value: metadata
+                        .module_path()
+                        .map(|m| perfetto::debug_annotation::Value::StringValue(m.to_owned())),
+                },
+                DebugAnnotation {
+                    name_field: Some(perfetto::debug_annotation::NameField::Name(String::from(
+                        "location",
+                    ))),
+                    value: Some(perfetto::debug_annotation::Value::StringValue(format!(
+                        "{}: {}",
+                        metadata.file().unwrap_or(""),
+                        metadata.line().unwrap_or(0)
+                    ))),
+                },
+            ],
+        }
+    }
+
     fn new() -> Self {
         Self { data: Vec::new() }
     }
@@ -188,7 +213,7 @@ impl Subscriber for PerfettoSubscriber {
             .id_counter
             .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
 
-        let mut debug_annotations = DebugAnnotationVisitor::new();
+        let mut debug_annotations = DebugAnnotationVisitor::new_with_metadata(span.metadata());
         span.record(&mut debug_annotations);
 
         let mut inner = self.inner.lock().unwrap();
@@ -205,6 +230,16 @@ impl Subscriber for PerfettoSubscriber {
 
     fn record(&self, span: &span::Id, values: &span::Record<'_>) {
         // println!("record {:?} {:?}", span, values);
+        let mut debug_annotations = DebugAnnotationVisitor::new();
+        values.record(&mut debug_annotations);
+
+        let mut inner = self.inner.lock().unwrap();
+        inner
+            .spans
+            .get_mut(&span.into_u64())
+            .unwrap()
+            .debug_annotations
+            .append(&mut debug_annotations.data);
     }
 
     fn record_follows_from(&self, span: &span::Id, follows: &span::Id) {
@@ -217,7 +252,7 @@ impl Subscriber for PerfettoSubscriber {
             let time = self.start_time.elapsed().as_nanos() as u64;
             let mut inner = self.inner.lock().unwrap();
 
-            let mut debug_annotations = DebugAnnotationVisitor::new();
+            let mut debug_annotations = DebugAnnotationVisitor::new_with_metadata(event.metadata());
             event.record(&mut debug_annotations);
 
             inner.buffer.push(perfetto::TracePacket {