Struct vortex_io::SizeLimitedStream

pub struct SizeLimitedStream<Fut> { /* private fields */ }

A [Stream] that can work on several simultaneous requests, capping the amount of memory it uses at any given point.

It is meant to serve as a buffer between a producer and consumer of IO requests, with built-in backpressure that prevents the producer from materializing more than a specified maximum amount of memory.

This crate internally makes use of tokio’s [Semaphore], and thus is only available with the tokio feature enabled.

Implementations

impl<Fut> SizeLimitedStream<Fut>

pub fn new(max_bytes: usize) -> Self

pub fn bytes_available(&self) -> usize

impl<Fut> SizeLimitedStream<Fut>

where Fut: Future,

pub async fn push(&self, fut: Fut, bytes: usize)

Push a future into the queue after reserving bytes of capacity.

This call may need to wait until there is sufficient capacity available in the stream to begin work on this future.

pub fn try_push(&self, fut: Fut, bytes: usize) -> Result<(), Fut>

Synchronous push method. This method will attempt to push if there is enough capacity to begin work on the future immediately.

If there is not enough capacity, the original future is returned to the caller.

Trait Implementations

impl<Fut> Stream for SizeLimitedStream<Fut>

where Fut: Future,

type Item = <Fut as Future>::Output

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

impl<'pin, Fut> Unpin for SizeLimitedStream<Fut>

where PinnedFieldsOf<__SizeLimitedStream<'pin, Fut>>: Unpin,