System Initiative
Officialby systeminit
tower.rs•8.28 kB
pub use web_socket_trace::WebSocketTraceLayer;
mod limit_requests {
use std::{
future::Future,
pin::Pin,
sync::{
Arc,
atomic::{
AtomicU32,
Ordering,
},
},
task::{
Context,
Poll,
},
};
use pin_project_lite::pin_project;
use telemetry::prelude::*;
use tokio::sync::mpsc;
use tower::{
Layer,
Service,
};
use crate::ShutdownSource;
#[derive(Clone, Debug)]
pub struct LimitRequestLayer {
remaining: Arc<Option<AtomicU32>>,
shutdown_tx: mpsc::Sender<ShutdownSource>,
}
impl LimitRequestLayer {
#[allow(dead_code)]
pub fn new(
remaining: Arc<Option<AtomicU32>>,
shutdown_tx: mpsc::Sender<ShutdownSource>,
) -> Self {
Self {
remaining,
shutdown_tx,
}
}
}
impl<S> Layer<S> for LimitRequestLayer {
type Service = LimitRequest<S>;
fn layer(&self, inner: S) -> Self::Service {
LimitRequest::new(inner, self.remaining.clone(), self.shutdown_tx.clone())
}
}
#[derive(Clone, Debug)]
pub struct LimitRequest<T> {
inner: T,
remaining: Arc<Option<AtomicU32>>,
shutdown_tx: mpsc::Sender<ShutdownSource>,
}
impl<T> LimitRequest<T> {
pub fn new(
inner: T,
remaining: Arc<Option<AtomicU32>>,
shutdown_tx: mpsc::Sender<ShutdownSource>,
) -> Self {
Self {
inner,
remaining,
shutdown_tx,
}
}
}
impl<S, Request> Service<Request> for LimitRequest<S>
where
S: Service<Request>,
S::Error: Sync,
{
type Response = S::Response;
type Error = S::Error;
type Future = ResponseFuture<S::Future>;
fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.inner.poll_ready(cx)
}
fn call(&mut self, request: Request) -> Self::Future {
let shutdown_tx = match (*self.remaining).as_ref() {
// If we're limiting requests, then decrement by one and if we're at zero, pass
// along a shutdown tx handle to the future. Otherwise, the future doesn't get a
// shutdown handle.
Some(remaining) => {
let mut updated = remaining.load(Ordering::Relaxed);
updated = updated.saturating_sub(1);
remaining.store(updated, Ordering::Relaxed);
debug!("requests remaining: {}", updated);
if updated > 0 {
None
} else {
Some(self.shutdown_tx.clone())
}
}
// If we're not limiting requests, then pass `None`
None => None,
};
let response = self.inner.call(request);
ResponseFuture::new(response, shutdown_tx)
}
}
pin_project! {
#[derive(Debug)]
pub struct ResponseFuture<T> {
#[pin]
response: T,
shutdown_tx: Option<mpsc::Sender<ShutdownSource>>,
}
}
impl<T> ResponseFuture<T> {
fn new(response: T, shutdown_tx: Option<mpsc::Sender<ShutdownSource>>) -> Self {
Self {
response,
shutdown_tx,
}
}
}
impl<F, T, E> Future for ResponseFuture<F>
where
F: Future<Output = Result<T, E>>,
{
type Output = Result<T, E>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let this = self.project();
match this.response.poll(cx) {
Poll::Ready(value) => {
if let Some(tx) = this.shutdown_tx {
let tx = tx.clone();
tokio::spawn(async move {
trace!("sending shutdown to limit request shutdown receiver");
if tx.send(ShutdownSource::LimitRequest).await.is_err() {
trace!(
"the limit request shutdown receiver has already been dropped"
);
}
});
}
Poll::Ready(value)
}
Poll::Pending => Poll::Pending,
}
}
}
}
mod web_socket_trace {
use std::{
future::Future,
pin::Pin,
task::{
Context,
Poll,
},
};
use axum::{
body::Body,
extract::MatchedPath,
http::Request,
response::Response,
};
use pin_project_lite::pin_project;
use telemetry::prelude::*;
use telemetry_http::{
ParentSpan,
propagation,
};
use tower::{
Layer,
Service,
};
// Vendored and modified from futures_core::task::poll::ready
macro_rules! ready {
($e:expr_2021 $(,)?) => {
match $e {
::std::task::Poll::Ready(t) => t,
::std::task::Poll::Pending => return ::std::task::Poll::Pending,
}
};
}
#[derive(Clone, Debug)]
pub struct WebSocketTraceLayer;
impl WebSocketTraceLayer {
pub fn new() -> Self {
Self
}
}
impl<S> Layer<S> for WebSocketTraceLayer {
type Service = WebSocketTrace<S>;
fn layer(&self, inner: S) -> Self::Service {
WebSocketTrace::new(inner)
}
}
#[derive(Clone, Debug)]
pub struct WebSocketTrace<S> {
inner: S,
}
impl<S> WebSocketTrace<S> {
pub fn new(inner: S) -> Self {
Self { inner }
}
}
impl<S> Service<Request<Body>> for WebSocketTrace<S>
where
S: Service<Request<Body>, Response = Response> + Send + 'static,
S::Future: Send + 'static,
{
type Response = S::Response;
type Error = S::Error;
type Future = ResponseFuture<S::Future>;
fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.inner.poll_ready(cx)
}
fn call(&mut self, mut req: Request<Body>) -> Self::Future {
let span = span_from_request(&req);
req.extensions_mut().insert(ParentSpan::new(span.clone()));
let response = {
let _guard = span.enter();
self.inner.call(req)
};
ResponseFuture { inner: response }
}
}
pin_project! {
#[derive(Debug)]
pub struct ResponseFuture<S> {
#[pin]
inner: S,
}
}
impl<F, T, E> Future for ResponseFuture<F>
where
F: Future<Output = Result<T, E>>,
{
type Output = Result<T, E>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let this = self.project();
let result = ready!(this.inner.poll(cx));
Poll::Ready(result)
}
}
fn span_from_request(req: &Request<Body>) -> Span {
let span = span!(
Level::INFO,
"GET websocket",
otel.kind = SpanKind::Server.as_str(),
otel.name = Empty,
otel.status_code = Empty,
otel.status_message = Empty,
);
let method = req.method().as_str();
let matched_path = req.extensions().get::<MatchedPath>().map(|mp| mp.as_str());
span.record(
"otel.name",
match matched_path {
Some(path) => format!("WS {method} {path}"),
None => format!("WS {method}"),
},
);
// Extract OpenTelemetry parent span metadata from the request headers (if it exists) and
// associate it with this request span
propagation::parent_span_from_headers(&span, req.headers());
span
}
}
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