112 lines
3.4 KiB
Rust
112 lines
3.4 KiB
Rust
use core::fmt::{Debug, Formatter, Result as FmtResult};
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use core::pin::Pin;
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use futures_core::task::{Context, Poll};
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use futures_sink::Sink;
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use pin_project_lite::pin_project;
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pin_project! {
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/// Sink that clones incoming items and forwards them to two sinks at the same time.
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///
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/// Backpressure from any downstream sink propagates up, which means that this sink
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/// can only process items as fast as its _slowest_ downstream sink.
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#[must_use = "sinks do nothing unless polled"]
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pub struct Fanout<Si1, Si2> {
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#[pin]
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sink1: Si1,
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#[pin]
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sink2: Si2
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}
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}
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impl<Si1, Si2> Fanout<Si1, Si2> {
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pub(super) fn new(sink1: Si1, sink2: Si2) -> Self {
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Self { sink1, sink2 }
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}
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/// Get a shared reference to the inner sinks.
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pub fn get_ref(&self) -> (&Si1, &Si2) {
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(&self.sink1, &self.sink2)
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}
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/// Get a mutable reference to the inner sinks.
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pub fn get_mut(&mut self) -> (&mut Si1, &mut Si2) {
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(&mut self.sink1, &mut self.sink2)
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}
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/// Get a pinned mutable reference to the inner sinks.
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pub fn get_pin_mut(self: Pin<&mut Self>) -> (Pin<&mut Si1>, Pin<&mut Si2>) {
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let this = self.project();
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(this.sink1, this.sink2)
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}
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/// Consumes this combinator, returning the underlying sinks.
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///
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/// Note that this may discard intermediate state of this combinator,
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/// so care should be taken to avoid losing resources when this is called.
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pub fn into_inner(self) -> (Si1, Si2) {
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(self.sink1, self.sink2)
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}
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}
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impl<Si1: Debug, Si2: Debug> Debug for Fanout<Si1, Si2> {
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fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
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f.debug_struct("Fanout").field("sink1", &self.sink1).field("sink2", &self.sink2).finish()
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}
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}
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impl<Si1, Si2, Item> Sink<Item> for Fanout<Si1, Si2>
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where
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Si1: Sink<Item>,
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Item: Clone,
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Si2: Sink<Item, Error = Si1::Error>,
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{
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type Error = Si1::Error;
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fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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let this = self.project();
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let sink1_ready = this.sink1.poll_ready(cx)?.is_ready();
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let sink2_ready = this.sink2.poll_ready(cx)?.is_ready();
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let ready = sink1_ready && sink2_ready;
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if ready {
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Poll::Ready(Ok(()))
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} else {
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Poll::Pending
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}
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}
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fn start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> {
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let this = self.project();
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this.sink1.start_send(item.clone())?;
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this.sink2.start_send(item)?;
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Ok(())
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}
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fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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let this = self.project();
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let sink1_ready = this.sink1.poll_flush(cx)?.is_ready();
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let sink2_ready = this.sink2.poll_flush(cx)?.is_ready();
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let ready = sink1_ready && sink2_ready;
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if ready {
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Poll::Ready(Ok(()))
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} else {
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Poll::Pending
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}
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}
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fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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let this = self.project();
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let sink1_ready = this.sink1.poll_close(cx)?.is_ready();
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let sink2_ready = this.sink2.poll_close(cx)?.is_ready();
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let ready = sink1_ready && sink2_ready;
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if ready {
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Poll::Ready(Ok(()))
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} else {
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Poll::Pending
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}
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}
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}
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