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Simplify Future for RequestDispatch #554

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Simplify Future for RequestDispatch #554

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32 changes: 5 additions & 27 deletions tarpc/src/client.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,6 @@ use futures::{prelude::*, ready, stream::Fuse, task::*};
use in_flight_requests::InFlightRequests;
use pin_project::pin_project;
use std::{
any::Any,
convert::TryFrom,
fmt,
pin::Pin,
Expand Down Expand Up @@ -269,7 +268,6 @@ where
transport: transport.fuse(),
in_flight_requests: InFlightRequests::default(),
pending_requests,
terminal_error: None,
},
}
}
Expand All @@ -291,11 +289,6 @@ pub struct RequestDispatch<Req, Resp, C> {
in_flight_requests: InFlightRequests<Result<Resp, RpcError>>,
/// Configures limits to prevent unlimited resource usage.
config: Config,
/// Produces errors that can be sent in response to any unprocessed requests at the time
/// RequestDispatch is dropped. Correctness note: this field should only be populated by
/// RequestDispatch::poll, which relies on downcasting the Any to a concrete error type
/// determined within the poll function.
terminal_error: Option<ChannelError<dyn Any + Send + Sync + 'static>>,
}

impl<Req, Resp, C> RequestDispatch<Req, Resp, C>
Expand Down Expand Up @@ -353,12 +346,6 @@ where
self.as_mut().project().pending_requests
}

fn terminal_error_mut<'a>(
self: &'a mut Pin<&mut Self>,
) -> &'a mut Option<ChannelError<dyn Any + Send + Sync + 'static>> {
self.as_mut().project().terminal_error
}

fn pump_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
Expand Down Expand Up @@ -659,20 +646,13 @@ where
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), ChannelError<C::Error>>> {
loop {
if let Some(e) = self.terminal_error_mut() {
let result = ready!(self.run(cx));
match result {
Ok(()) => Poll::Ready(Ok(())),
Err(e) => {
tracing::debug!("RpcError::Channel");
let e: ChannelError<C::Error> = e
.clone()
.downcast()
.expect("Invariant: ChannelError must store a C::Error");
ready!(self.shut_down_with_terminal_error(cx, e.clone().upcast_error()));
return Poll::Ready(Err(e));
}
let result = ready!(self.run(cx));
match result {
Ok(()) => return Poll::Ready(Ok(())),
Err(e) => *self.terminal_error_mut() = Some(e.upcast_any()),
Poll::Ready(Err(e))
}
}
}
Expand Down Expand Up @@ -986,7 +966,6 @@ mod tests {
canceled_requests,
in_flight_requests: InFlightRequests::default(),
config: Config::default(),
terminal_error: None,
});
let channel = Channel {
to_dispatch,
Expand Down Expand Up @@ -1082,7 +1061,6 @@ mod tests {
canceled_requests,
in_flight_requests: InFlightRequests::default(),
config: Config::default(),
terminal_error: None,
};

let channel = Channel {
Expand Down
40 changes: 1 addition & 39 deletions tarpc/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -250,7 +250,7 @@ pub(crate) mod util;

pub use crate::transport::sealed::Transport;

use std::{any::Any, error::Error, io, sync::Arc, time::Instant};
use std::{error::Error, io, sync::Arc, time::Instant};

/// A message from a client to a server.
#[derive(Debug)]
Expand Down Expand Up @@ -445,44 +445,6 @@ where
}
}

impl<E> ChannelError<E>
where
E: Send + Sync + 'static,
{
/// Converts the ChannelError's source error type to a dyn Any. This is useful in type-erased
/// contexts, for example, storing a ChannelError in a non-generic type like
/// [`client::RpcError`].
fn upcast_any(self) -> ChannelError<dyn Any + Send + Sync + 'static> {
use ChannelError::*;
match self {
Read(e) => Read(e),
Ready(e) => Ready(e),
Write(e) => Write(e),
Flush(e) => Flush(e),
Close(e) => Close(e),
}
}
}

impl ChannelError<dyn Any + Send + Sync + 'static> {
/// Converts the ChannelError's source error type to a concrete type. This is useful in
/// type-erased contexts, for example, storing a ChannelError in a non-generic type like
/// [`Client::RpcError`].
fn downcast<E>(self) -> Result<ChannelError<E>, Self>
where
E: Any + Send + Sync,
{
use ChannelError::*;
match self {
Read(e) => e.downcast::<E>().map(Read).map_err(Read),
Ready(e) => e.downcast::<E>().map(Ready).map_err(Ready),
Write(e) => e.downcast::<E>().map(Write).map_err(Write),
Flush(e) => e.downcast::<E>().map(Flush).map_err(Flush),
Close(e) => e.downcast::<E>().map(Close).map_err(Close),
}
}
}

impl ServerError {
/// Returns a new server error with `kind` and `detail`.
pub fn new(kind: io::ErrorKind, detail: String) -> ServerError {
Expand Down