Refactor how durations are measured

src/util/Cargo.toml

@@ -42,3 +42,5 @@ hyper = "0.14"
 
 kube = { version = "0.62", features = ["runtime", "derive"] }
 k8s-openapi = { version = "0.13", features = ["v1_22"] }
+
+opentelemetry = "0.17"

src/util/lib.rs

@@ -8,6 +8,7 @@ pub mod config;
 pub mod crdt;
 pub mod data;
 pub mod error;
+pub mod metrics;
 pub mod persister;
 pub mod time;
 pub mod token_bucket;

src/util/metrics.rs

@@ -0,0 +1,35 @@
+use std::time::SystemTime;
+
+use futures::{future::BoxFuture, Future, FutureExt};
+
+use opentelemetry::{KeyValue, metrics::*};
+
+pub trait RecordDuration<'a>: 'a {
+	type Output;
+
+	fn record_duration(self, r: &'a ValueRecorder<f64>, attributes: &'a [KeyValue]) -> BoxFuture<'a, Self::Output>;
+	fn bound_record_duration(self, r: &'a BoundValueRecorder<f64>) -> BoxFuture<'a, Self::Output>;
+}
+
+impl<'a, T, O> RecordDuration<'a> for T
+where T: Future<Output=O> + Send + 'a {
+	type Output = O;
+
+	fn record_duration(self, r: &'a ValueRecorder<f64>, attributes: &'a [KeyValue]) -> BoxFuture<'a, Self::Output> {
+		async move {
+			let request_start = SystemTime::now();
+			let res = self.await;
+			r.record(request_start.elapsed().map_or(0.0, |d| d.as_secs_f64()), attributes);
+			res
+		}.boxed()
+	}
+
+	fn bound_record_duration(self, r: &'a BoundValueRecorder<f64>) -> BoxFuture<'a, Self::Output> {
+		async move {
+			let request_start = SystemTime::now();
+			let res = self.await;
+			r.record(request_start.elapsed().map_or(0.0, |d| d.as_secs_f64()));
+			res
+		}.boxed()
+	}
+}