1 files changed, 35 insertions, 0 deletions
diff --git a/src/util/metrics.rs b/src/util/metrics.rs
new file mode 100644
index 00000000..b3b1fc3c
--- /dev/null
+++ b/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()
+	}
+}