2019-03-01 15:25:21 -08:00
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//! Future types
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2019-04-08 20:11:09 -07:00
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use crate::error::{self, Error};
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2019-09-10 08:39:51 -07:00
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use futures_core::ready;
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use pin_project::{pin_project, project};
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use std::{
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future::Future,
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pin::Pin,
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task::{Context, Poll},
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};
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2019-03-01 15:25:21 -08:00
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use tower_service::Service;
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/// Filtered response future
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2019-09-10 08:39:51 -07:00
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#[pin_project]
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2019-03-01 15:25:21 -08:00
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#[derive(Debug)]
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pub struct ResponseFuture<T, S, Request>
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where
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S: Service<Request>,
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{
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2019-09-10 08:39:51 -07:00
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#[pin]
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2019-03-01 15:25:21 -08:00
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/// Response future state
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state: State<Request, S::Future>,
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2019-09-10 08:39:51 -07:00
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#[pin]
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2019-03-01 15:25:21 -08:00
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/// Predicate future
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check: T,
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/// Inner service
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service: S,
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}
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2019-09-10 08:39:51 -07:00
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#[pin_project]
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2019-03-01 15:25:21 -08:00
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#[derive(Debug)]
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enum State<Request, U> {
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Check(Option<Request>),
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WaitResponse(#[pin] U),
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2019-03-01 15:25:21 -08:00
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}
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2019-09-10 08:39:51 -07:00
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impl<F, T, S, Request> ResponseFuture<F, S, Request>
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2019-03-01 15:25:21 -08:00
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where
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2019-09-10 08:39:51 -07:00
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F: Future<Output = Result<T, Error>>,
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2019-03-01 15:25:21 -08:00
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S: Service<Request>,
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S::Error: Into<error::Source>,
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{
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pub(crate) fn new(request: Request, check: F, service: S) -> Self {
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ResponseFuture {
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state: State::Check(Some(request)),
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check,
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service,
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}
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}
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}
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2019-09-10 08:39:51 -07:00
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impl<F, T, S, Request> Future for ResponseFuture<F, S, Request>
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2019-03-01 15:25:21 -08:00
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where
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2019-09-10 08:39:51 -07:00
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F: Future<Output = Result<T, Error>>,
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2019-03-01 15:25:21 -08:00
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S: Service<Request>,
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S::Error: Into<error::Source>,
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{
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type Output = Result<S::Response, Error>;
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2019-09-10 08:39:51 -07:00
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#[project]
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fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let mut this = self.project();
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loop {
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#[project]
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match this.state.project() {
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State::Check(request) => {
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let request = request
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.take()
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.expect("we either give it back or leave State::Check once we take");
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2019-03-01 15:25:21 -08:00
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// Poll predicate
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match this.check.as_mut().poll(cx)? {
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Poll::Ready(_) => {
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let response = this.service.call(request);
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this.state.set(State::WaitResponse(response));
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}
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Poll::Pending => {
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this.state.set(State::Check(Some(request)));
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return Poll::Pending;
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}
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}
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}
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State::WaitResponse(response) => {
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return Poll::Ready(ready!(response.poll(cx)).map_err(Error::inner));
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}
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}
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}
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}
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}
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