debug_annotations: Add support for fully suppressing an event via a field

crates/layer/src/debug_annotations.rs

@@ -10,10 +10,12 @@ use tracing_perfetto_sdk_schema::track_event;
 use tracing_perfetto_sdk_sys::ffi;
 
 const COUNTER_FIELD_PREFIX: &str = "counter.";
+const SUPPRESS_EVENT_FIELD: &str = "perfetto.suppress_event";
 
 #[derive(Default)]
 pub struct FFIDebugAnnotations {
     counters: Vec<Counter>,
+    suppress_event: bool,
     strings: Vec<ffi::DebugStringAnnotation>,
     bools: Vec<ffi::DebugBoolAnnotation>,
     ints: Vec<ffi::DebugIntAnnotation>,
@@ -23,6 +25,7 @@ pub struct FFIDebugAnnotations {
 #[derive(Clone, Debug, Default, PartialEq)]
 pub struct ProtoDebugAnnotations {
     counters: Vec<Counter>,
+    suppress_event: bool,
     annotations: Vec<schema::DebugAnnotation>,
 }
 
@@ -48,6 +51,10 @@ impl FFIDebugAnnotations {
             doubles: self.doubles.as_slice(),
         }
     }
+
+    pub fn suppress_event(&self) -> bool {
+        self.suppress_event
+    }
 }
 
 impl field::Visit for FFIDebugAnnotations {
@@ -104,10 +111,14 @@ impl field::Visit for FFIDebugAnnotations {
     }
 
     fn record_bool(&mut self, field: &field::Field, value: bool) {
-        self.bools.push(ffi::DebugBoolAnnotation {
-            key: field.name(),
-            value,
-        });
+        if field.name() == SUPPRESS_EVENT_FIELD {
+            self.suppress_event = value;
+        } else {
+            self.bools.push(ffi::DebugBoolAnnotation {
+                key: field.name(),
+                value,
+            });
+        }
     }
 
     fn record_str(&mut self, field: &field::Field, value: &str) {
@@ -141,6 +152,10 @@ impl ProtoDebugAnnotations {
         mem::take(&mut self.counters)
     }
 
+    pub fn suppress_event(&self) -> bool {
+        self.suppress_event
+    }
+
     fn name_field(field: &field::Field) -> Option<debug_annotation::NameField> {
         Some(debug_annotation::NameField::Name(field.name().to_string()))
     }
@@ -206,11 +221,15 @@ impl field::Visit for ProtoDebugAnnotations {
     }
 
     fn record_bool(&mut self, field: &field::Field, value: bool) {
-        self.annotations.push(schema::DebugAnnotation {
-            name_field: Self::name_field(field),
-            value: Some(debug_annotation::Value::BoolValue(value)),
-            ..Default::default()
-        });
+        if field.name() == SUPPRESS_EVENT_FIELD {
+            self.suppress_event = value;
+        } else {
+            self.annotations.push(schema::DebugAnnotation {
+                name_field: Self::name_field(field),
+                value: Some(debug_annotation::Value::BoolValue(value)),
+                ..Default::default()
+            });
+        }
     }
 
     fn record_str(&mut self, field: &field::Field, value: &str) {

crates/layer/src/lib.rs

@@ -91,6 +91,16 @@
 //! **NOTE**: at the time of writing, counters are only implemented by the
 //! [`NativeLayer`].
 //!
+//! ## Suppressing events
+//!
+//! Sometimes, you want to log a tracing event but have it be suppressed in the
+//! Perfetto trace in particular. You can set the `perfetto.suppress_event =
+//! true` field for that to happen:
+//!
+//! ```no_run
+//! tracing::info!(perfetto.suppress_event=true, "won't be included in the Perfetto trace");
+//! ```
+//!
 //! ## Controlling output destinations
 //!
 //! For [`NativeLayer`], traces can be written to anything that implements the

crates/layer/src/native_layer.rs

@@ -775,8 +775,10 @@ where
         event.record(&mut debug_annotations);
         self.report_counters(meta, debug_annotations.take_counters());
 
-        let (track_uuid, sequence_id, _) = self.pick_trace_track_sequence();
-        self.report_event(meta, debug_annotations, track_uuid, sequence_id);
+        if !debug_annotations.suppress_event() {
+            let (track_uuid, sequence_id, _) = self.pick_trace_track_sequence();
+            self.report_event(meta, debug_annotations, track_uuid, sequence_id);
+        }
     }
 
     fn on_enter(&self, id: &span::Id, ctx: layer::Context<'_, S>) {

crates/layer/src/sdk_layer.rs

@@ -267,15 +267,17 @@ where
         let mut debug_annotations = debug_annotations::FFIDebugAnnotations::default();
         event.record(&mut debug_annotations);
 
-        let meta = event.metadata();
-        let (track_uuid, _) = self.pick_trace_track();
-        ffi::trace_track_event_instant(
-            track_uuid.as_raw(),
-            meta.name(),
-            meta.file().unwrap_or_default(),
-            meta.line().unwrap_or_default(),
-            &debug_annotations.as_ffi(),
-        );
+        if !debug_annotations.suppress_event() {
+            let meta = event.metadata();
+            let (track_uuid, _) = self.pick_trace_track();
+            ffi::trace_track_event_instant(
+                track_uuid.as_raw(),
+                meta.name(),
+                meta.file().unwrap_or_default(),
+                meta.line().unwrap_or_default(),
+                &debug_annotations.as_ffi(),
+            );
+        }
     }
 
     fn on_enter(&self, id: &span::Id, ctx: layer::Context<'_, S>) {