64 lines
1.4 KiB
Rust
64 lines
1.4 KiB
Rust
//! Future types
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use std::fmt;
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use std::future::Future;
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use std::pin::Pin;
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use std::task::{Context, Poll};
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use futures_core::ready;
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use pin_project::pin_project;
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use super::error::Overloaded;
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/// Future for the `LoadShed` service.
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#[pin_project]
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pub struct ResponseFuture<F> {
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#[pin]
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state: ResponseState<F>,
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}
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#[pin_project(project = ResponseStateProj)]
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enum ResponseState<F> {
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Called(#[pin] F),
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Overloaded,
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}
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impl<F> ResponseFuture<F> {
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pub(crate) fn called(fut: F) -> Self {
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ResponseFuture {
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state: ResponseState::Called(fut),
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}
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}
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pub(crate) fn overloaded() -> Self {
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ResponseFuture {
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state: ResponseState::Overloaded,
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}
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}
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}
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impl<F, T, E> Future for ResponseFuture<F>
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where
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F: Future<Output = Result<T, E>>,
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E: Into<crate::BoxError>,
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{
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type Output = Result<T, crate::BoxError>;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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match self.project().state.project() {
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ResponseStateProj::Called(fut) => Poll::Ready(ready!(fut.poll(cx)).map_err(Into::into)),
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ResponseStateProj::Overloaded => Poll::Ready(Err(Overloaded::new().into())),
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}
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}
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}
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impl<F> fmt::Debug for ResponseFuture<F>
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where
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// bounds for future-proofing...
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F: fmt::Debug,
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.write_str("ResponseFuture")
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}
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}
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