Struct StreamUnobtrusivePeeker

pub(crate) struct StreamUnobtrusivePeeker<S>
where
    S: Stream,
{
    buffered: Option<<S as Stream>::Item>,
    poll_waker: Option<Waker>,
    inner: Option<S>,
}

Wraps Stream and provides \[poll_]peek and unobtrusive_peek

unobtrusive_peek is callable in sync contexts, outside the reading task.

Like [futures::stream::Peekable], this has an async peek method, and poll_peek, for use from the task that is also reading (via the Stream impl). But, that type doesn’t have unobtrusive_peek.

One way to conceptualise this is that StreamUnobtrusivePeeker is dual-ported: the two sets of APIs, while provided on the same type, are typically called from different contexts.

Fields

buffered: Option<<S as Stream>::Item>

poll_waker: Option<Waker>

inner: Option<S>

Implementations

impl<S> StreamUnobtrusivePeeker<S>

where S: Stream,

pub fn new(inner: S) -> StreamUnobtrusivePeeker<S>

Create a new StreamUnobtrusivePeeker from a Stream

impl<S> StreamUnobtrusivePeeker<S>

where S: Stream,

pub fn peek( self: Pin<&mut StreamUnobtrusivePeeker<S>>, ) -> PeekFuture<'_, StreamUnobtrusivePeeker<S>>

Wait for an item to be ready, and then inspect it

Equivalent to [futures::stream::Peekable::peek].

Tasks, waking, and calling context

This should be called by the task that is reading from the stream. If it is called by another task, the reading task would miss notifications.

pub fn as_raw_inner_pin_mut<'s>( self: Pin<&'s mut StreamUnobtrusivePeeker<S>>, ) -> Option<Pin<&'s mut S>>

Obtain a raw reference to the inner stream

Correctness!

This method must be used with care! Whatever you do mustn’t interfere with polling and peeking. Careless use can result in wrong behaviour including deadlocks.

Trait Implementations

impl<S> Debug for StreamUnobtrusivePeeker<S>

where S: Debug + Stream, <S as Stream>::Item: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<S> FusedStream for StreamUnobtrusivePeeker<S>

where S: Stream,

fn is_terminated(&self) -> bool

Returns true if the stream should no longer be polled.

impl<S> PeekableStream for StreamUnobtrusivePeeker<S>

where S: Stream,

fn poll_peek<'s>( self: Pin<&'s mut StreamUnobtrusivePeeker<S>>, cx: &mut Context<'_>, ) -> Poll<Option<&'s <S as Stream>::Item>>

Poll for an item to be ready, and then inspect it.

fn poll_peek_mut<'s>( self: Pin<&'s mut StreamUnobtrusivePeeker<S>>, cx: &mut Context<'_>, ) -> Poll<Option<&'s mut <S as Stream>::Item>>

Poll for an item to be ready, and then inspect it.

impl<S> Stream for StreamUnobtrusivePeeker<S>

where S: Stream,

type Item = <S as Stream>::Item

Values yielded by the stream.

fn poll_next( self: Pin<&mut StreamUnobtrusivePeeker<S>>, cx: &mut Context<'_>, ) -> Poll<Option<<StreamUnobtrusivePeeker<S> as Stream>::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<S> UnobtrusivePeekableStream for StreamUnobtrusivePeeker<S>

where S: Stream,

fn unobtrusive_peek_mut<'s>( self: Pin<&'s mut StreamUnobtrusivePeeker<S>>, ) -> Option<&'s mut <S as Stream>::Item>

Peek at the next available value, while not losing a previously registered waker.

fn unobtrusive_peek(self: Pin<&mut Self>) -> Option<&Self::Item>

Peek at the next available value, while not losing a previously registered waker.

impl<'pin, S> Unpin for StreamUnobtrusivePeeker<S>

where S: Stream, <PinnedFieldsOfHelperStruct<__StreamUnobtrusivePeeker<'pin, S>> as PinnedFieldsOfHelperTrait>::Actual: Unpin,