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use std::time::Instant;
use libopentelemetry::{
global,
metrics::{Counter, Unit, ValueRecorder},
Key,
};
use crate::{Endpoint, IntoResponse, Middleware, Request, Response};
const METHOD_KEY: Key = Key::from_static_str("request_method");
const PATH_KEY: Key = Key::from_static_str("request_path");
const STATUS_KEY: Key = Key::from_static_str("response_status_code");
#[cfg_attr(docsrs, doc(cfg(feature = "opentelemetry")))]
pub struct OpenTelemetryMetrics {
request_count: Counter<u64>,
error_count: Counter<u64>,
duration: ValueRecorder<f64>,
}
impl Default for OpenTelemetryMetrics {
fn default() -> Self {
Self::new()
}
}
impl OpenTelemetryMetrics {
pub fn new() -> Self {
let meter = global::meter("poem");
Self {
request_count: meter
.u64_counter("poem_requests_count")
.with_description("total request count (since start of service)")
.init(),
error_count: meter
.u64_counter("poem_errors_count")
.with_description("failed request count (since start of service)")
.init(),
duration: meter
.f64_value_recorder("poem_request_duration_ms")
.with_unit(Unit::new("milliseconds"))
.with_description(
"request duration histogram (in milliseconds, since start of service)",
)
.init(),
}
}
}
impl<E: Endpoint> Middleware<E> for OpenTelemetryMetrics {
type Output = OpenTelemetryMetricsEndpoint<E>;
fn transform(&self, ep: E) -> Self::Output {
OpenTelemetryMetricsEndpoint {
request_count: self.request_count.clone(),
error_count: self.error_count.clone(),
duration: self.duration.clone(),
inner: ep,
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "opentelemetry")))]
pub struct OpenTelemetryMetricsEndpoint<E> {
request_count: Counter<u64>,
error_count: Counter<u64>,
duration: ValueRecorder<f64>,
inner: E,
}
#[async_trait::async_trait]
impl<E: Endpoint> Endpoint for OpenTelemetryMetricsEndpoint<E> {
type Output = Response;
async fn call(&self, req: Request) -> Self::Output {
let mut labels = Vec::with_capacity(3);
labels.push(METHOD_KEY.string(req.method().to_string()));
labels.push(PATH_KEY.string(req.uri().path().to_string()));
let s = Instant::now();
let resp = self.inner.call(req).await.into_response();
let elapsed = s.elapsed();
labels.push(STATUS_KEY.i64(resp.status().as_u16() as i64));
if resp.status().is_server_error() {
self.error_count.add(1, &labels)
}
self.request_count.add(1, &labels);
self.duration
.record(elapsed.as_secs_f64() / 1000.0, &labels);
resp
}
}