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use crate::stream_ext::Fuse;
use crate::Stream;
use tokio::time::{sleep, Sleep};
use core::future::Future;
use core::pin::Pin;
use core::task::{Context, Poll};
use pin_project_lite::pin_project;
use std::time::Duration;
pin_project! {
/// Stream returned by the [`chunks_timeout`](super::StreamExt::chunks_timeout) method.
#[must_use = "streams do nothing unless polled"]
#[derive(Debug)]
pub struct ChunksTimeout<S: Stream> {
#[pin]
stream: Fuse<S>,
#[pin]
deadline: Option<Sleep>,
duration: Duration,
items: Vec<S::Item>,
cap: usize, // https://github.com/rust-lang/futures-rs/issues/1475
}
}
impl<S: Stream> ChunksTimeout<S> {
pub(super) fn new(stream: S, max_size: usize, duration: Duration) -> Self {
ChunksTimeout {
stream: Fuse::new(stream),
deadline: None,
duration,
items: Vec::with_capacity(max_size),
cap: max_size,
}
}
}
impl<S: Stream> Stream for ChunksTimeout<S> {
type Item = Vec<S::Item>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut me = self.as_mut().project();
loop {
match me.stream.as_mut().poll_next(cx) {
Poll::Pending => break,
Poll::Ready(Some(item)) => {
if me.items.is_empty() {
me.deadline.set(Some(sleep(*me.duration)));
me.items.reserve_exact(*me.cap);
}
me.items.push(item);
if me.items.len() >= *me.cap {
return Poll::Ready(Some(std::mem::take(me.items)));
}
}
Poll::Ready(None) => {
// Returning Some here is only correct because we fuse the inner stream.
let last = if me.items.is_empty() {
None
} else {
Some(std::mem::take(me.items))
};
return Poll::Ready(last);
}
}
}
if !me.items.is_empty() {
if let Some(deadline) = me.deadline.as_pin_mut() {
ready!(deadline.poll(cx));
}
return Poll::Ready(Some(std::mem::take(me.items)));
}
Poll::Pending
}
fn size_hint(&self) -> (usize, Option<usize>) {
let chunk_len = if self.items.is_empty() { 0 } else { 1 };
let (lower, upper) = self.stream.size_hint();
let lower = (lower / self.cap).saturating_add(chunk_len);
let upper = upper.and_then(|x| x.checked_add(chunk_len));
(lower, upper)
}
}
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