feat(metrics): Add ability to compute metrics summary and attach it to events (#3769)

Author: iambriccardo

CHANGELOG.md

@@ -16,6 +16,9 @@
 - Ingest profiler_id in the profile context and in spans. ([#3714](https://github.com/getsentry/relay/pull/3714), [#3784](https://github.com/getsentry/relay/pull/3784))
 - Support extrapolation of metrics extracted from sampled data, as long as the sample rate is set in the DynamicSamplingContext. ([#3753](https://github.com/getsentry/relay/pull/3753))
 - Extract thread ID and name in spans. ([#3771](https://github.com/getsentry/relay/pull/3771))
+- Compute metrics summary on the extracted custom metrics. ([#3769](https://github.com/getsentry/relay/pull/3769))
+
+>>>>>>> master
 
 ## 24.6.0
 

relay-dynamic-config/src/global.rs

@@ -214,6 +214,14 @@ pub struct Options {
     )]
     pub span_extraction_sample_rate: Option<f32>,
 
+    /// Overall sampling of metrics summaries computation.
+    #[serde(
+        rename = "relay.compute-metrics-summaries.sample-rate",
+        deserialize_with = "default_on_error",
+        skip_serializing_if = "is_default"
+    )]
+    pub compute_metrics_summaries_sample_rate: Option<f32>,
+
     /// The maximum duplication factor used to extrapolate distribution metrics from sampled data.
     ///
     /// This applies as long as Relay duplicates distribution values to extrapolate. The default is

relay-event-schema/src/protocol/metrics_summary.rs

@@ -40,3 +40,13 @@ pub struct MetricSummary {
     /// Tags of the metric.
     pub tags: Annotated<Object<String>>,
 }
+
+impl MetricSummary {
+    /// Merges another [`MetricSummary`] in this [`MetricsSummary`].
+    pub fn merge(&mut self, other: MetricSummary) {
+        self.min.merge(other.min, |l, r| *l = l.min(r));
+        self.max.merge(other.max, |l, r| *l = l.max(r));
+        self.sum.merge(other.sum, |l, r| *l += r);
+        self.count.merge(other.count, |l, r| *l += r);
+    }
+}

relay-protocol/src/annotated.rs

@@ -190,6 +190,15 @@ impl<T> Annotated<T> {
     {
         self.value_mut().get_or_insert_with(f)
     }
+
+    /// Merges the supplied [`Annotated`] in the left [`Annotated`].
+    pub fn merge(&mut self, other: Annotated<T>, block: impl FnOnce(&mut T, T)) {
+        match (self.value_mut(), other.into_value()) {
+            (Some(left), Some(right)) => block(left, right),
+            (None, Some(right)) => self.set_value(Some(right)),
+            _ => {}
+        }
+    }
 }
 
 impl<T> Annotated<T>