Bug 1932617 - Move test_get_num_recorded_errors to a trait and use trait objects r=TravisLong

This reduces the size of the generated function (with huge match statements) significantly.
On a local (optimized) Linux build `event_test_get_error` went from 260573 byte to 46245.

`event_test_get_value_wrapper` from 49506 to 45559.

This is based on a change in the Glean SDK.

Differential Revision: https://phabricator.services.mozilla.com/D266375

Author: badboy

toolkit/components/glean/api/src/ffi/macros.rs

@@ -199,6 +199,12 @@ macro_rules! test_get_errors {
             glean::ErrorType::InvalidOverflow,
         ];
         let mut error_str = None;
+        // Only `events` use this trait right now
+        // Ignoring the unused import simplifies the macro right now.
+        // This might change in the future.
+        #[allow(unused_imports)]
+        use crate::private::TestGetNumErrors;
+
         for &error_type in error_types.iter() {
             let num_errors = $metric.test_get_num_recorded_errors(error_type);
             if num_errors > 0 {

toolkit/components/glean/api/src/private/event.rs

@@ -165,6 +165,18 @@ impl<K: 'static + ExtraKeys + Send + Sync + Clone> EventMetric<K> {
     }
 }
 
+impl<K> crate::private::TestGetNumErrors for EventMetric<K> {
+    fn test_get_num_recorded_errors(&self, error_type: glean::ErrorType) -> i32 {
+        match self {
+            EventMetric::Parent { inner, .. } => inner.test_get_num_recorded_errors(error_type),
+            EventMetric::Child(c) => panic!(
+                "Cannot get the number of recorded errors for {:?} in non-main process!",
+                c.id
+            ),
+        }
+    }
+}
+
 #[inherent]
 impl<K: 'static + ExtraKeys + Send + Sync + Clone> Event for EventMetric<K> {
     type Extra = K;
@@ -199,16 +211,6 @@ impl<K: 'static + ExtraKeys + Send + Sync + Clone> Event for EventMetric<K> {
             }
         }
     }
-
-    pub fn test_get_num_recorded_errors(&self, error: glean::ErrorType) -> i32 {
-        match self {
-            EventMetric::Parent { inner, .. } => inner.test_get_num_recorded_errors(error),
-            EventMetric::Child(meta) => panic!(
-                "Cannot get the number of recorded errors for {:?} in non-main process!",
-                meta.id
-            ),
-        }
-    }
 }
 
 #[inherent]

toolkit/components/glean/api/src/private/mod.rs

@@ -677,6 +677,21 @@ fn truncate_string_for_marker_to_length(mut input: String, byte_length: usize) -
     input
 }
 
+pub trait TestGetNumErrors {
+    /// **Exported for test purposes.**
+    ///
+    /// Gets the number of recorded errors for the given metric and error type.
+    ///
+    /// # Arguments
+    ///
+    /// * `error` - The type of error
+    ///
+    /// # Returns
+    ///
+    /// The number of errors reported.
+    fn test_get_num_recorded_errors(&self, error_type: glean::ErrorType) -> i32;
+}
+
 #[cfg(test)]
 mod truncation_tests {
     use crate::private::truncate_string_for_marker;

toolkit/components/glean/build_scripts/glean_parser_ext/templates/rust.jinja2

@@ -432,12 +432,14 @@ pub(crate) mod __glean_metric_maps {
     ///
     /// Panics if no event by the given metric ID could be found.
     pub(crate) fn event_test_get_value_wrapper(metric_id: u32, ping_name: Option<String>) -> Option<Vec<RecordedEvent>> {
-        match metric_id {
+        let event = match metric_id {
 {% for metric_id, event in events_by_id.items() %}
-           {{metric_id}} => super::{{event}}.test_get_value(ping_name),
+           {{metric_id}} => &*super::{{event}} as &dyn ::glean::TestGetValue<Output=Vec<RecordedEvent>>,
 {% endfor %}
            _ => panic!("No event for metric id {}", metric_id),
-        }
+        };
+
+        return event.test_get_value(ping_name);
     }
 
     /// Check the provided event for errors.
@@ -458,11 +460,15 @@ pub(crate) mod __glean_metric_maps {
     #[allow(unused_variables)]
     pub(crate) fn event_test_get_error(metric_id: u32) -> Option<String> {
         #[cfg(feature = "with_gecko")]
-        match metric_id {
+        {
+            let event = match metric_id {
 {% for metric_id, event in events_by_id.items() %}
-           {{metric_id}} => test_get_errors!(super::{{event}}),
+               {{metric_id}} => &*super::{{event}} as &dyn crate::private::TestGetNumErrors,
 {% endfor %}
-           _ => panic!("No event for metric id {}", metric_id),
+               _ => panic!("No event for metric id {}", metric_id),
+            };
+
+            return test_get_errors!(event);
         }
 
         #[cfg(not(feature = "with_gecko"))]

toolkit/components/glean/tests/pytest/metrics_test_output

@@ -1863,13 +1863,15 @@ pub(crate) mod __glean_metric_maps {
     ///
     /// Panics if no event by the given metric ID could be found.
     pub(crate) fn event_test_get_value_wrapper(metric_id: u32, ping_name: Option<String>) -> Option<Vec<RecordedEvent>> {
-        match metric_id {
-           21 => super::test_nested::event_metric.test_get_value(ping_name),
-           22 => super::test_nested::event_metric_with_extra.test_get_value(ping_name),
-           49 => super::test2_nested::event_metric.test_get_value(ping_name),
-           50 => super::test2_nested::event_metric_with_extra.test_get_value(ping_name),
+        let event = match metric_id {
+           21 => &*super::test_nested::event_metric as &dyn ::glean::TestGetValue<Output=Vec<RecordedEvent>>,
+           22 => &*super::test_nested::event_metric_with_extra as &dyn ::glean::TestGetValue<Output=Vec<RecordedEvent>>,
+           49 => &*super::test2_nested::event_metric as &dyn ::glean::TestGetValue<Output=Vec<RecordedEvent>>,
+           50 => &*super::test2_nested::event_metric_with_extra as &dyn ::glean::TestGetValue<Output=Vec<RecordedEvent>>,
            _ => panic!("No event for metric id {}", metric_id),
-        }
+        };
+
+        return event.test_get_value(ping_name);
     }
 
     /// Check the provided event for errors.
@@ -1890,12 +1892,16 @@ pub(crate) mod __glean_metric_maps {
     #[allow(unused_variables)]
     pub(crate) fn event_test_get_error(metric_id: u32) -> Option<String> {
         #[cfg(feature = "with_gecko")]
-        match metric_id {
-           21 => test_get_errors!(super::test_nested::event_metric),
-           22 => test_get_errors!(super::test_nested::event_metric_with_extra),
-           49 => test_get_errors!(super::test2_nested::event_metric),
-           50 => test_get_errors!(super::test2_nested::event_metric_with_extra),
-           _ => panic!("No event for metric id {}", metric_id),
+        {
+            let event = match metric_id {
+               21 => &*super::test_nested::event_metric as &dyn crate::private::TestGetNumErrors,
+               22 => &*super::test_nested::event_metric_with_extra as &dyn crate::private::TestGetNumErrors,
+               49 => &*super::test2_nested::event_metric as &dyn crate::private::TestGetNumErrors,
+               50 => &*super::test2_nested::event_metric_with_extra as &dyn crate::private::TestGetNumErrors,
+               _ => panic!("No event for metric id {}", metric_id),
+            };
+
+            return test_get_errors!(event);
         }
 
         #[cfg(not(feature = "with_gecko"))]