84 lines
2.7 KiB
Rust
84 lines
2.7 KiB
Rust
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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use futures::{
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channel::{mpsc, oneshot},
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future, ready,
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};
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use tower::Service;
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use crate::protocol::internal::{Request, Response};
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use super::{ErrorSlot, SharedPeerError};
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/// The "client" duplex half of a peer connection.
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pub struct Client {
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pub(super) span: tracing::Span,
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pub(super) server_tx: mpsc::Sender<ClientRequest>,
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pub(super) error_slot: ErrorSlot,
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}
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/// A message from the `peer::Client` to the `peer::Server`, containing both a
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/// request and a return message channel. The reason the return channel is
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/// included is because `peer::Client::call` returns a future that may be moved
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/// around before it resolves, so the future must have ownership of the channel
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/// on which it receives the response.
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#[derive(Debug)]
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pub(super) struct ClientRequest(
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pub(super) Request,
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pub(super) oneshot::Sender<Result<Response, SharedPeerError>>,
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);
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impl Service<Request> for Client {
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type Response = Response;
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type Error = SharedPeerError;
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type Future =
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Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static>>;
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fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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if ready!(self.server_tx.poll_ready(cx)).is_err() {
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Poll::Ready(Err(self
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.error_slot
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.try_get_error()
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.expect("failed servers must set their error slot")))
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} else {
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Poll::Ready(Ok(()))
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}
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}
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fn call(&mut self, req: Request) -> Self::Future {
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use futures::future::FutureExt;
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use tracing_futures::Instrument;
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let (tx, rx) = oneshot::channel();
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match self.server_tx.try_send(ClientRequest(req, tx)) {
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Err(e) => {
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if e.is_disconnected() {
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future::ready(Err(self
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.error_slot
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.try_get_error()
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.expect("failed servers must set their error slot")))
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.instrument(self.span.clone())
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.boxed()
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} else {
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// sending fails when there's not enough
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// channel space, but we called poll_ready
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panic!("called call without poll_ready");
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}
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}
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Ok(()) => {
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// The receiver end of the oneshot is itself a future.
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rx.map(|oneshot_recv_result| {
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oneshot_recv_result
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.expect("ClientRequest oneshot sender must not be dropped before send")
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})
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.instrument(self.span.clone())
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.boxed()
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}
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}
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}
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}
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