-
Notifications
You must be signed in to change notification settings - Fork 620
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Add TryStreamExt::try_buffered (#2245)
- Loading branch information
Showing
4 changed files
with
172 additions
and
3 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,89 @@ | ||
use crate::stream::{Fuse, FuturesOrdered, StreamExt, IntoStream}; | ||
use crate::future::{IntoFuture, TryFutureExt}; | ||
use futures_core::future::TryFuture; | ||
use futures_core::stream::{Stream, TryStream}; | ||
use futures_core::task::{Context, Poll}; | ||
#[cfg(feature = "sink")] | ||
use futures_sink::Sink; | ||
use pin_project::pin_project; | ||
use core::pin::Pin; | ||
|
||
/// Stream for the [`try_buffered`](super::TryStreamExt::try_buffered) method. | ||
#[pin_project] | ||
#[derive(Debug)] | ||
#[must_use = "streams do nothing unless polled"] | ||
pub struct TryBuffered<St> | ||
where | ||
St: TryStream, | ||
St::Ok: TryFuture, | ||
{ | ||
#[pin] | ||
stream: Fuse<IntoStream<St>>, | ||
in_progress_queue: FuturesOrdered<IntoFuture<St::Ok>>, | ||
max: usize, | ||
} | ||
|
||
impl<St> TryBuffered<St> | ||
where | ||
St: TryStream, | ||
St::Ok: TryFuture, | ||
{ | ||
pub(super) fn new(stream: St, n: usize) -> TryBuffered<St> { | ||
TryBuffered { | ||
stream: IntoStream::new(stream).fuse(), | ||
in_progress_queue: FuturesOrdered::new(), | ||
max: n, | ||
} | ||
} | ||
|
||
delegate_access_inner!(stream, St, (. .)); | ||
} | ||
|
||
impl<St> Stream for TryBuffered<St> | ||
where | ||
St: TryStream, | ||
St::Ok: TryFuture<Error = St::Error>, | ||
{ | ||
type Item = Result<<St::Ok as TryFuture>::Ok, St::Error>; | ||
|
||
fn poll_next( | ||
self: Pin<&mut Self>, | ||
cx: &mut Context<'_>, | ||
) -> Poll<Option<Self::Item>> { | ||
let mut this = self.project(); | ||
|
||
// First up, try to spawn off as many futures as possible by filling up | ||
// our queue of futures. Propagate errors from the stream immediately. | ||
while this.in_progress_queue.len() < *this.max { | ||
match this.stream.as_mut().poll_next(cx)? { | ||
Poll::Ready(Some(fut)) => this.in_progress_queue.push(fut.into_future()), | ||
Poll::Ready(None) | Poll::Pending => break, | ||
} | ||
} | ||
|
||
// Attempt to pull the next value from the in_progress_queue | ||
match this.in_progress_queue.poll_next_unpin(cx) { | ||
x @ Poll::Pending | x @ Poll::Ready(Some(_)) => return x, | ||
Poll::Ready(None) => {} | ||
} | ||
|
||
// If more values are still coming from the stream, we're not done yet | ||
if this.stream.is_done() { | ||
Poll::Ready(None) | ||
} else { | ||
Poll::Pending | ||
} | ||
} | ||
} | ||
|
||
// Forwarding impl of Sink from the underlying stream | ||
#[cfg(feature = "sink")] | ||
impl<S, Item, E> Sink<Item> for TryBuffered<S> | ||
where | ||
S: TryStream + Sink<Item, Error = E>, | ||
S::Ok: TryFuture<Error = E>, | ||
{ | ||
type Error = E; | ||
|
||
delegate_sink!(stream, Item); | ||
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters