255 lines
7.5 KiB
Rust
255 lines
7.5 KiB
Rust
//! An unbounded set of streams
|
|
|
|
use core::fmt::{self, Debug};
|
|
use core::iter::FromIterator;
|
|
use core::pin::Pin;
|
|
|
|
use futures_core::ready;
|
|
use futures_core::stream::{FusedStream, Stream};
|
|
use futures_core::task::{Context, Poll};
|
|
|
|
use pin_project_lite::pin_project;
|
|
|
|
use super::assert_stream;
|
|
use crate::stream::{futures_unordered, FuturesUnordered, StreamExt, StreamFuture};
|
|
|
|
pin_project! {
|
|
/// An unbounded set of streams
|
|
///
|
|
/// This "combinator" provides the ability to maintain a set of streams
|
|
/// and drive them all to completion.
|
|
///
|
|
/// Streams are pushed into this set and their realized values are
|
|
/// yielded as they become ready. Streams will only be polled when they
|
|
/// generate notifications. This allows to coordinate a large number of streams.
|
|
///
|
|
/// Note that you can create a ready-made `SelectAll` via the
|
|
/// `select_all` function in the `stream` module, or you can start with an
|
|
/// empty set with the `SelectAll::new` constructor.
|
|
#[must_use = "streams do nothing unless polled"]
|
|
pub struct SelectAll<St> {
|
|
#[pin]
|
|
inner: FuturesUnordered<StreamFuture<St>>,
|
|
}
|
|
}
|
|
|
|
impl<St: Debug> Debug for SelectAll<St> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
write!(f, "SelectAll {{ ... }}")
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> SelectAll<St> {
|
|
/// Constructs a new, empty `SelectAll`
|
|
///
|
|
/// The returned `SelectAll` does not contain any streams and, in this
|
|
/// state, `SelectAll::poll` will return `Poll::Ready(None)`.
|
|
pub fn new() -> Self {
|
|
Self { inner: FuturesUnordered::new() }
|
|
}
|
|
|
|
/// Returns the number of streams contained in the set.
|
|
///
|
|
/// This represents the total number of in-flight streams.
|
|
pub fn len(&self) -> usize {
|
|
self.inner.len()
|
|
}
|
|
|
|
/// Returns `true` if the set contains no streams
|
|
pub fn is_empty(&self) -> bool {
|
|
self.inner.is_empty()
|
|
}
|
|
|
|
/// Push a stream into the set.
|
|
///
|
|
/// This function submits the given stream to the set for managing. This
|
|
/// function will not call `poll` on the submitted stream. The caller must
|
|
/// ensure that `SelectAll::poll` is called in order to receive task
|
|
/// notifications.
|
|
pub fn push(&mut self, stream: St) {
|
|
self.inner.push(stream.into_future());
|
|
}
|
|
|
|
/// Returns an iterator that allows inspecting each stream in the set.
|
|
pub fn iter(&self) -> Iter<'_, St> {
|
|
Iter(self.inner.iter())
|
|
}
|
|
|
|
/// Returns an iterator that allows modifying each stream in the set.
|
|
pub fn iter_mut(&mut self) -> IterMut<'_, St> {
|
|
IterMut(self.inner.iter_mut())
|
|
}
|
|
|
|
/// Clears the set, removing all streams.
|
|
pub fn clear(&mut self) {
|
|
self.inner.clear()
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> Default for SelectAll<St> {
|
|
fn default() -> Self {
|
|
Self::new()
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> Stream for SelectAll<St> {
|
|
type Item = St::Item;
|
|
|
|
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
|
|
loop {
|
|
match ready!(self.inner.poll_next_unpin(cx)) {
|
|
Some((Some(item), remaining)) => {
|
|
self.push(remaining);
|
|
return Poll::Ready(Some(item));
|
|
}
|
|
Some((None, _)) => {
|
|
// `FuturesUnordered` thinks it isn't terminated
|
|
// because it yielded a Some.
|
|
// We do not return, but poll `FuturesUnordered`
|
|
// in the next loop iteration.
|
|
}
|
|
None => return Poll::Ready(None),
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> FusedStream for SelectAll<St> {
|
|
fn is_terminated(&self) -> bool {
|
|
self.inner.is_terminated()
|
|
}
|
|
}
|
|
|
|
/// Convert a list of streams into a `Stream` of results from the streams.
|
|
///
|
|
/// This essentially takes a list of streams (e.g. a vector, an iterator, etc.)
|
|
/// and bundles them together into a single stream.
|
|
/// The stream will yield items as they become available on the underlying
|
|
/// streams internally, in the order they become available.
|
|
///
|
|
/// Note that the returned set can also be used to dynamically push more
|
|
/// streams into the set as they become available.
|
|
///
|
|
/// This function is only available when the `std` or `alloc` feature of this
|
|
/// library is activated, and it is activated by default.
|
|
pub fn select_all<I>(streams: I) -> SelectAll<I::Item>
|
|
where
|
|
I: IntoIterator,
|
|
I::Item: Stream + Unpin,
|
|
{
|
|
let mut set = SelectAll::new();
|
|
|
|
for stream in streams {
|
|
set.push(stream);
|
|
}
|
|
|
|
assert_stream::<<I::Item as Stream>::Item, _>(set)
|
|
}
|
|
|
|
impl<St: Stream + Unpin> FromIterator<St> for SelectAll<St> {
|
|
fn from_iter<T: IntoIterator<Item = St>>(iter: T) -> Self {
|
|
select_all(iter)
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> Extend<St> for SelectAll<St> {
|
|
fn extend<T: IntoIterator<Item = St>>(&mut self, iter: T) {
|
|
for st in iter {
|
|
self.push(st)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> IntoIterator for SelectAll<St> {
|
|
type Item = St;
|
|
type IntoIter = IntoIter<St>;
|
|
|
|
fn into_iter(self) -> Self::IntoIter {
|
|
IntoIter(self.inner.into_iter())
|
|
}
|
|
}
|
|
|
|
impl<'a, St: Stream + Unpin> IntoIterator for &'a SelectAll<St> {
|
|
type Item = &'a St;
|
|
type IntoIter = Iter<'a, St>;
|
|
|
|
fn into_iter(self) -> Self::IntoIter {
|
|
self.iter()
|
|
}
|
|
}
|
|
|
|
impl<'a, St: Stream + Unpin> IntoIterator for &'a mut SelectAll<St> {
|
|
type Item = &'a mut St;
|
|
type IntoIter = IterMut<'a, St>;
|
|
|
|
fn into_iter(self) -> Self::IntoIter {
|
|
self.iter_mut()
|
|
}
|
|
}
|
|
|
|
/// Immutable iterator over all streams in the unordered set.
|
|
#[derive(Debug)]
|
|
pub struct Iter<'a, St: Unpin>(futures_unordered::Iter<'a, StreamFuture<St>>);
|
|
|
|
/// Mutable iterator over all streams in the unordered set.
|
|
#[derive(Debug)]
|
|
pub struct IterMut<'a, St: Unpin>(futures_unordered::IterMut<'a, StreamFuture<St>>);
|
|
|
|
/// Owned iterator over all streams in the unordered set.
|
|
#[derive(Debug)]
|
|
pub struct IntoIter<St: Unpin>(futures_unordered::IntoIter<StreamFuture<St>>);
|
|
|
|
impl<'a, St: Stream + Unpin> Iterator for Iter<'a, St> {
|
|
type Item = &'a St;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
let st = self.0.next()?;
|
|
let next = st.get_ref();
|
|
// This should always be true because FuturesUnordered removes completed futures.
|
|
debug_assert!(next.is_some());
|
|
next
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.0.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> ExactSizeIterator for Iter<'_, St> {}
|
|
|
|
impl<'a, St: Stream + Unpin> Iterator for IterMut<'a, St> {
|
|
type Item = &'a mut St;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
let st = self.0.next()?;
|
|
let next = st.get_mut();
|
|
// This should always be true because FuturesUnordered removes completed futures.
|
|
debug_assert!(next.is_some());
|
|
next
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.0.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> ExactSizeIterator for IterMut<'_, St> {}
|
|
|
|
impl<St: Stream + Unpin> Iterator for IntoIter<St> {
|
|
type Item = St;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
let st = self.0.next()?;
|
|
let next = st.into_inner();
|
|
// This should always be true because FuturesUnordered removes completed futures.
|
|
debug_assert!(next.is_some());
|
|
next
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.0.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<St: Stream + Unpin> ExactSizeIterator for IntoIter<St> {}
|