| use crate::stream::{Fuse, FuturesUnordered, StreamExt}; |
| use crate::try_future::{IntoFuture, TryFutureExt}; |
| use crate::try_stream::IntoStream; |
| use futures_core::future::TryFuture; |
| use futures_core::stream::{Stream, TryStream}; |
| use futures_core::task::{Context, Poll}; |
| use futures_sink::Sink; |
| use pin_utils::{unsafe_pinned, unsafe_unpinned}; |
| use core::pin::Pin; |
| |
| /// Stream for the |
| /// [`try_buffer_unordered`](super::TryStreamExt::try_buffer_unordered) method. |
| #[derive(Debug)] |
| #[must_use = "streams do nothing unless polled"] |
| pub struct TryBufferUnordered<St> |
| where St: TryStream |
| { |
| stream: Fuse<IntoStream<St>>, |
| in_progress_queue: FuturesUnordered<IntoFuture<St::Ok>>, |
| max: usize, |
| } |
| |
| impl<St> Unpin for TryBufferUnordered<St> |
| where St: TryStream + Unpin |
| {} |
| |
| impl<St> TryBufferUnordered<St> |
| where St: TryStream, |
| St::Ok: TryFuture, |
| { |
| unsafe_pinned!(stream: Fuse<IntoStream<St>>); |
| unsafe_unpinned!(in_progress_queue: FuturesUnordered<IntoFuture<St::Ok>>); |
| |
| pub(super) fn new(stream: St, n: usize) -> Self { |
| TryBufferUnordered { |
| stream: IntoStream::new(stream).fuse(), |
| in_progress_queue: FuturesUnordered::new(), |
| max: n, |
| } |
| } |
| |
| /// Acquires a reference to the underlying stream that this combinator is |
| /// pulling from. |
| pub fn get_ref(&self) -> &St { |
| self.stream.get_ref().get_ref() |
| } |
| |
| /// Acquires a mutable reference to the underlying stream that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| pub fn get_mut(&mut self) -> &mut St { |
| self.stream.get_mut().get_mut() |
| } |
| |
| /// Acquires a pinned mutable reference to the underlying stream that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| pub fn get_pin_mut<'a>(self: Pin<&'a mut Self>) -> Pin<&'a mut St> { |
| self.stream().get_pin_mut().get_pin_mut() |
| } |
| |
| /// Consumes this combinator, returning the underlying stream. |
| /// |
| /// Note that this may discard intermediate state of this combinator, so |
| /// care should be taken to avoid losing resources when this is called. |
| pub fn into_inner(self) -> St { |
| self.stream.into_inner().into_inner() |
| } |
| } |
| |
| impl<St> Stream for TryBufferUnordered<St> |
| where St: TryStream, |
| St::Ok: TryFuture<Error = St::Error>, |
| { |
| type Item = Result<<St::Ok as TryFuture>::Ok, St::Error>; |
| |
| fn poll_next( |
| mut self: Pin<&mut Self>, |
| cx: &mut Context<'_>, |
| ) -> Poll<Option<Self::Item>> { |
| // First up, try to spawn off as many futures as possible by filling up |
| // our slab of futures. Propagate errors from the stream immediately. |
| while self.in_progress_queue.len() < self.max { |
| match self.as_mut().stream().poll_next(cx) { |
| Poll::Ready(Some(Ok(fut))) => self.as_mut().in_progress_queue().push(fut.into_future()), |
| Poll::Ready(Some(Err(e))) => return Poll::Ready(Some(Err(e))), |
| Poll::Ready(None) | Poll::Pending => break, |
| } |
| } |
| |
| // Attempt to pull the next value from the in_progress_queue |
| match Pin::new(self.as_mut().in_progress_queue()).poll_next(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 self.stream.is_done() { |
| Poll::Ready(None) |
| } else { |
| Poll::Pending |
| } |
| } |
| } |
| |
| // Forwarding impl of Sink from the underlying stream |
| impl<S, Item> Sink<Item> for TryBufferUnordered<S> |
| where S: TryStream + Sink<Item>, |
| S::Ok: TryFuture<Error = S::Error>, |
| { |
| type SinkError = S::SinkError; |
| |
| delegate_sink!(stream, Item); |
| } |