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use crate::FuturesOrderedBounded;
use crate::FuturesUnorderedBounded;
use core::future::Future;
use futures_core::Stream;
mod for_each;
mod ordered;
mod unordered;
pub use for_each::ForEachConcurrent;
pub use ordered::BufferedOrdered;
pub use unordered::BufferUnordered;
impl<T: ?Sized + Stream> BufferedStreamExt for T {}
/// An extension trait for `Stream`s that provides a variety of convenient
/// combinator functions.
pub trait BufferedStreamExt: Stream {
/// An adaptor for creating a buffered list of pending futures.
///
/// If this stream's item can be converted into a future, then this adaptor
/// will buffer up to at most `n` futures and then return the outputs in the
/// same order as the underlying stream. No more than `n` futures will be
/// buffered at any point in time, and less than `n` may also be buffered
/// depending on the state of each future.
///
/// The returned stream will be a stream of each future's output.
fn buffered_ordered(self, n: usize) -> BufferedOrdered<Self>
where
Self::Item: Future,
Self: Sized,
{
BufferedOrdered {
stream: Some(self),
in_progress_queue: FuturesOrderedBounded::new(n),
}
}
/// An adaptor for creating a buffered list of pending futures (unordered).
///
/// If this stream's item can be converted into a future, then this adaptor
/// will buffer up to `n` futures and then return the outputs in the order
/// in which they complete. No more than `n` futures will be buffered at
/// any point in time, and less than `n` may also be buffered depending on
/// the state of each future.
///
/// The returned stream will be a stream of each future's output.
///
/// # Examples
///
/// ```
/// # futures::executor::block_on(async {
/// use futures::channel::oneshot;
/// use futures::stream::{self, StreamExt};
/// use futures_buffered::BufferedStreamExt;
///
/// let (send_one, recv_one) = oneshot::channel();
/// let (send_two, recv_two) = oneshot::channel();
///
/// let stream_of_futures = stream::iter(vec![recv_one, recv_two]);
/// let mut buffered = stream_of_futures.buffered_unordered(10);
///
/// send_two.send(2i32)?;
/// assert_eq!(buffered.next().await, Some(Ok(2i32)));
///
/// send_one.send(1i32)?;
/// assert_eq!(buffered.next().await, Some(Ok(1i32)));
///
/// assert_eq!(buffered.next().await, None);
/// # Ok::<(), i32>(()) }).unwrap();
/// ```
///
/// See [`BufferUnordered`] for performance details
fn buffered_unordered(self, n: usize) -> BufferUnordered<Self>
where
Self::Item: Future,
Self: Sized,
{
BufferUnordered {
stream: Some(self),
in_progress_queue: FuturesUnorderedBounded::new(n),
}
}
/// Runs this stream to completion, executing the provided asynchronous
/// closure for each element on the stream concurrently as elements become
/// available.
///
/// This is similar to [`StreamExt::for_each`](futures_util::StreamExt::for_each), but the futures
/// produced by the closure are run concurrently (but not in parallel--
/// this combinator does not introduce any threads).
///
/// The closure provided will be called for each item this stream produces,
/// yielding a future. That future will then be executed to completion
/// concurrently with the other futures produced by the closure.
///
/// The first argument is an optional limit on the number of concurrent
/// futures. If this limit is not `None`, no more than `limit` futures
/// will be run concurrently. The `limit` argument is of type
/// `Into<Option<usize>>`, and so can be provided as either `None`,
/// `Some(10)`, or just `10`. Note: a limit of zero is interpreted as
/// no limit at all, and will have the same result as passing in `None`.
///
/// This method is only available when the `std` or `alloc` feature of this
/// library is activated, and it is activated by default.
///
/// # Examples
///
/// ```
/// # futures::executor::block_on(async {
/// use futures::channel::oneshot;
/// use futures::stream::{self, StreamExt};
///
/// let (tx1, rx1) = oneshot::channel();
/// let (tx2, rx2) = oneshot::channel();
/// let (tx3, rx3) = oneshot::channel();
///
/// let fut = stream::iter(vec![rx1, rx2, rx3]).for_each_concurrent(
/// /* limit */ 2,
/// |rx| async move {
/// rx.await.unwrap();
/// }
/// );
/// tx1.send(()).unwrap();
/// tx2.send(()).unwrap();
/// tx3.send(()).unwrap();
/// fut.await;
/// # })
/// ```
fn for_each_concurrent<Fut, F>(self, limit: usize, f: F) -> ForEachConcurrent<Self, Fut, F>
where
F: FnMut(Self::Item) -> Fut,
Fut: Future<Output = ()>,
Self: Sized,
{
ForEachConcurrent::new(self, limit, f)
}
}