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use std::{
borrow::Cow,
ops::Not,
pin::Pin,
task::{Context, Poll},
time::Duration,
};
use bytes::Bytes;
use futures_util::{
future::{Fuse, FusedFuture},
Future, FutureExt, StreamExt,
};
use prost::Message;
use tower::{Layer, Service};
use crate::{
body::Body,
client::{
prelude::ClientError,
transport::{SocketRequestMarker, TransportError},
},
common::extensions::Extensions,
proto::{Error as HrpcError, HrpcErrorIdentifier, RetryInfo},
request::{self, BoxRequest},
};
type CloneExtensionsFn = fn(&Extensions, &mut Extensions);
#[derive(Clone)]
pub struct BackoffLayer {
clone_exts: CloneExtensionsFn,
max_retries: usize,
}
impl Default for BackoffLayer {
fn default() -> Self {
Self {
clone_exts: |_, _| {},
max_retries: 5,
}
}
}
impl BackoffLayer {
pub fn clone_extensions_fn(mut self, f: CloneExtensionsFn) -> Self {
self.clone_exts = f;
self
}
pub fn max_retries(mut self, num: usize) -> Self {
self.max_retries = num;
self
}
}
impl<S> Layer<S> for BackoffLayer {
type Service = Backoff<S>;
fn layer(&self, inner: S) -> Self::Service {
Backoff {
inner,
clone_exts: self.clone_exts,
max_retries: self.max_retries,
}
}
}
#[derive(Clone)]
pub struct Backoff<S> {
inner: S,
clone_exts: CloneExtensionsFn,
max_retries: usize,
}
impl<S> Backoff<S> {
pub fn new(inner: S) -> Self {
Self {
inner,
clone_exts: |_, _| {},
max_retries: 5,
}
}
pub fn clone_extensions_fn(mut self, f: CloneExtensionsFn) -> Self {
self.clone_exts = f;
self
}
pub fn max_retries(mut self, num: usize) -> Self {
self.max_retries = num;
self
}
}
impl<S, Err> Service<BoxRequest> for Backoff<S>
where
S: Service<BoxRequest, Error = TransportError<Err>> + Clone,
{
type Response = S::Response;
type Error = S::Error;
type Future = BackoffFuture<Err, S>;
fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
Service::poll_ready(&mut self.inner, cx)
}
fn call(&mut self, req: BoxRequest) -> Self::Future {
BackoffFuture::new(self.inner.clone(), self.clone_exts, req, self.max_retries)
}
}
struct RequestFactory {
body: Bytes,
extensions: Extensions,
endpoint: Cow<'static, str>,
clone_exts: CloneExtensionsFn,
}
impl RequestFactory {
fn from_req(req: BoxRequest, clone_exts: CloneExtensionsFn) -> Result<Self, BoxRequest> {
let request::Parts {
mut body,
endpoint,
extensions,
} = req.into();
let maybe_body = body
.next()
.now_or_never()
.flatten()
.transpose()
.ok()
.flatten();
let body = match maybe_body {
Some(b) => b,
None => {
return Err(BoxRequest::from(request::Parts {
body,
endpoint,
extensions,
}));
}
};
Ok(Self {
clone_exts,
body,
endpoint,
extensions,
})
}
fn make_req(&self) -> BoxRequest {
let mut extensions = Extensions::new();
(self.clone_exts)(&self.extensions, &mut extensions);
if let Some(marker) = self.extensions.get::<SocketRequestMarker>().cloned() {
extensions.insert(marker);
}
let parts = request::Parts {
body: Body::full(self.body.clone()),
endpoint: self.endpoint.clone(),
extensions,
};
BoxRequest::from(parts)
}
}
pin_project_lite::pin_project! {
pub struct BackoffFuture<Err, S: Service<BoxRequest, Error = TransportError<Err>>> {
maybe_request_factory: Result<RequestFactory, BoxRequest>,
service: S,
max_retries: usize,
retried: usize,
req_fut: Option<Pin<Box<Fuse<S::Future>>>>,
wait: Option<Pin<Box<Sleep>>>,
}
}
impl<Err, S: Service<BoxRequest, Error = TransportError<Err>>> BackoffFuture<Err, S> {
fn new(
service: S,
clone_exts_fn: CloneExtensionsFn,
request: BoxRequest,
max_retries: usize,
) -> Self {
Self {
max_retries,
retried: 0,
req_fut: None,
maybe_request_factory: RequestFactory::from_req(request, clone_exts_fn),
service,
wait: None,
}
}
}
impl<Err, S: Service<BoxRequest, Error = TransportError<Err>>> Future for BackoffFuture<Err, S> {
type Output = <<S as Service<BoxRequest>>::Future as Future>::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let mut this = self.project();
if let Some(req_fut) = this.req_fut.as_mut().map(|pin| pin.as_mut()) {
if req_fut.is_terminated().not() {
let resp = futures_util::ready!(req_fut.poll(cx));
let mut scheduled = false;
if let (
true,
Err(TransportError::GenericClient(ClientError::EndpointError {
hrpc_error,
..
})),
) = ((this.retried < this.max_retries), &resp)
{
if HrpcErrorIdentifier::ResourceExhausted.compare(&hrpc_error.identifier) {
let retry_after = RetryInfo::decode(hrpc_error.details.clone())
.map_or(3, |info| info.retry_after);
let retry_after =
(0..this.retried.saturating_sub(1)).fold(retry_after, |r, _| r * 2);
tracing::error!(
retry_count = %this.retried,
"request rate limited, scheduling for retry in {} seconds",
retry_after,
);
*this.wait = Some(Box::pin(sleep(Duration::from_secs(retry_after.into()))));
scheduled = true;
}
}
if scheduled.not() {
return Poll::Ready(resp);
}
}
}
if let Some(sleep) = this.wait.as_mut().map(|pin| pin.as_mut()) {
futures_util::ready!(Sleeper::poll(sleep, cx));
}
match &this.maybe_request_factory {
Ok(request_factory) => {
let req = request_factory.make_req();
*this.req_fut = Some(Box::pin(Service::call(&mut this.service, req).fuse()));
*this.retried += 1;
tracing::debug!(retry_count = %this.retried, "retrying request");
cx.waker().wake_by_ref();
Poll::Pending
},
Err(req) => {
Poll::Ready(Err(TransportError::GenericClient(ClientError::EndpointError {
endpoint: Cow::Owned(req.endpoint().to_string()),
hrpc_error: HrpcError::default()
.with_message("can't do request because no body was immediately available; this might be a bug in the backoff layer")
.with_identifier("hrpcrs.client.backoff-no-immediate-body"),
})))
}
}
}
}
trait Sleeper {
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()>;
}
use sleeper::*;
#[cfg(all(feature = "http_hyper_client", not(target_arch = "wasm32")))]
mod sleeper {
use super::*;
pub(super) use ::tokio::time::Sleep;
pub(super) fn sleep(duration: Duration) -> Sleep {
::tokio::time::sleep(duration)
}
impl Sleeper for Sleep {
fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> std::task::Poll<()> {
Future::poll(self, cx)
}
}
}
#[cfg(all(feature = "http_wasm_client", target_arch = "wasm32"))]
mod sleeper {
use super::*;
use gloo_timers::future::TimeoutFuture;
pub(super) fn sleep(duration: Duration) -> Sleep {
Sleep {
inner: gloo_timers::future::sleep(duration),
}
}
pin_project_lite::pin_project! {
pub(super) struct Sleep {
#[pin]
inner: TimeoutFuture,
}
}
unsafe impl Send for Sleep {}
impl Sleeper for Sleep {
fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> std::task::Poll<()> {
let this = self.project();
Future::poll(this.inner, cx)
}
}
}