Struct tokio_util::sync::PollSemaphore

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pub struct PollSemaphore { /* private fields */ }
Expand description

A wrapper around Semaphore that provides a poll_acquire method.

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impl PollSemaphore

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pub fn new(semaphore: Arc<Semaphore>) -> Self

Create a new PollSemaphore.

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pub fn close(&self)

Closes the semaphore.

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pub fn clone_inner(&self) -> Arc<Semaphore>

Obtain a clone of the inner semaphore.

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pub fn into_inner(self) -> Arc<Semaphore>

Get back the inner semaphore.

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pub fn poll_acquire( &mut self, cx: &mut Context<'_>, ) -> Poll<Option<OwnedSemaphorePermit>>

Poll to acquire a permit from the semaphore.

This can return the following values:

  • Poll::Pending if a permit is not currently available.
  • Poll::Ready(Some(permit)) if a permit was acquired.
  • Poll::Ready(None) if the semaphore has been closed.

When this method returns Poll::Pending, the current task is scheduled to receive a wakeup when a permit becomes available, or when the semaphore is closed. Note that on multiple calls to poll_acquire, only the Waker from the Context passed to the most recent call is scheduled to receive a wakeup.

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pub fn poll_acquire_many( &mut self, cx: &mut Context<'_>, permits: u32, ) -> Poll<Option<OwnedSemaphorePermit>>

Poll to acquire many permits from the semaphore.

This can return the following values:

  • Poll::Pending if a permit is not currently available.
  • Poll::Ready(Some(permit)) if a permit was acquired.
  • Poll::Ready(None) if the semaphore has been closed.

When this method returns Poll::Pending, the current task is scheduled to receive a wakeup when the permits become available, or when the semaphore is closed. Note that on multiple calls to poll_acquire, only the Waker from the Context passed to the most recent call is scheduled to receive a wakeup.

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pub fn available_permits(&self) -> usize

Returns the current number of available permits.

This is equivalent to the Semaphore::available_permits method on the tokio::sync::Semaphore type.

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pub fn add_permits(&self, n: usize)

Adds n new permits to the semaphore.

The maximum number of permits is Semaphore::MAX_PERMITS, and this function will panic if the limit is exceeded.

This is equivalent to the Semaphore::add_permits method on the tokio::sync::Semaphore type.

Trait Implementations§

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impl AsRef<Semaphore> for PollSemaphore

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fn as_ref(&self) -> &Semaphore

Converts this type into a shared reference of the (usually inferred) input type.
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impl Clone for PollSemaphore

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fn clone(&self) -> PollSemaphore

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for PollSemaphore

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

Formats the value using the given formatter. Read more
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impl Stream for PollSemaphore

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type Item = OwnedSemaphorePermit

Values yielded by the stream.
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fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<OwnedSemaphorePermit>>

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

Returns the bounds on the remaining length of the stream. Read more

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> StreamExt for T
where T: Stream + ?Sized,

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fn next(&mut self) -> Next<'_, Self>
where Self: Unpin,

Creates a future that resolves to the next item in the stream. Read more
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fn into_future(self) -> StreamFuture<Self>
where Self: Sized + Unpin,

Converts this stream into a future of (next_item, tail_of_stream). If the stream terminates, then the next item is None. Read more
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fn map<T, F>(self, f: F) -> Map<Self, F>
where F: FnMut(Self::Item) -> T, Self: Sized,

Maps this stream’s items to a different type, returning a new stream of the resulting type. Read more
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fn enumerate(self) -> Enumerate<Self>
where Self: Sized,

Creates a stream which gives the current iteration count as well as the next value. Read more
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fn filter<Fut, F>(self, f: F) -> Filter<Self, Fut, F>
where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Filters the values produced by this stream according to the provided asynchronous predicate. Read more
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fn filter_map<Fut, T, F>(self, f: F) -> FilterMap<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = Option<T>>, Self: Sized,

Filters the values produced by this stream while simultaneously mapping them to a different type according to the provided asynchronous closure. Read more
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fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future, Self: Sized,

Computes from this stream’s items new items of a different type using an asynchronous closure. Read more
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fn collect<C>(self) -> Collect<Self, C>
where C: Default + Extend<Self::Item>, Self: Sized,

Transforms a stream into a collection, returning a future representing the result of that computation. Read more
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fn unzip<A, B, FromA, FromB>(self) -> Unzip<Self, FromA, FromB>
where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Sized + Stream<Item = (A, B)>,

Converts a stream of pairs into a future, which resolves to pair of containers. Read more
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fn concat(self) -> Concat<Self>
where Self: Sized, Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator + Default,

Concatenate all items of a stream into a single extendable destination, returning a future representing the end result. Read more
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fn count(self) -> Count<Self>
where Self: Sized,

Drives the stream to completion, counting the number of items. Read more
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fn cycle(self) -> Cycle<Self>
where Self: Sized + Clone,

Repeats a stream endlessly. Read more
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fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F>
where F: FnMut(T, Self::Item) -> Fut, Fut: Future<Output = T>, Self: Sized,

Execute an accumulating asynchronous computation over a stream, collecting all the values into one final result. Read more
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fn any<Fut, F>(self, f: F) -> Any<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Execute predicate over asynchronous stream, and return true if any element in stream satisfied a predicate. Read more
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fn all<Fut, F>(self, f: F) -> All<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Execute predicate over asynchronous stream, and return true if all element in stream satisfied a predicate. Read more
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fn flatten(self) -> Flatten<Self>
where Self::Item: Stream, Self: Sized,

Flattens a stream of streams into just one continuous stream. Read more
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fn flatten_unordered( self, limit: impl Into<Option<usize>>, ) -> FlattenUnorderedWithFlowController<Self, ()>
where Self::Item: Stream + Unpin, Self: Sized,

Flattens a stream of streams into just one continuous stream. Polls inner streams produced by the base stream concurrently. Read more
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fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
where F: FnMut(Self::Item) -> U, U: Stream, Self: Sized,

Maps a stream like StreamExt::map but flattens nested Streams. Read more
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fn flat_map_unordered<U, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> FlatMapUnordered<Self, U, F>
where U: Stream + Unpin, F: FnMut(Self::Item) -> U, Self: Sized,

Maps a stream like StreamExt::map but flattens nested Streams and polls them concurrently, yielding items in any order, as they made available. Read more
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fn scan<S, B, Fut, F>(self, initial_state: S, f: F) -> Scan<Self, S, Fut, F>
where F: FnMut(&mut S, Self::Item) -> Fut, Fut: Future<Output = Option<B>>, Self: Sized,

Combinator similar to StreamExt::fold that holds internal state and produces a new stream. Read more
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fn skip_while<Fut, F>(self, f: F) -> SkipWhile<Self, Fut, F>
where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Skip elements on this stream while the provided asynchronous predicate resolves to true. Read more
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fn take_while<Fut, F>(self, f: F) -> TakeWhile<Self, Fut, F>
where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Take elements from this stream while the provided asynchronous predicate resolves to true. Read more
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fn take_until<Fut>(self, fut: Fut) -> TakeUntil<Self, Fut>
where Fut: Future, Self: Sized,

Take elements from this stream until the provided future resolves. Read more
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fn for_each<Fut, F>(self, f: F) -> ForEach<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = ()>, Self: Sized,

Runs this stream to completion, executing the provided asynchronous closure for each element on the stream. Read more
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fn for_each_concurrent<Fut, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> ForEachConcurrent<Self, Fut, F>
where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = ()>, Self: Sized,

Runs this stream to completion, executing the provided asynchronous closure for each element on the stream concurrently as elements become available. Read more
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fn take(self, n: usize) -> Take<Self>
where Self: Sized,

Creates a new stream of at most n items of the underlying stream. Read more
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fn skip(self, n: usize) -> Skip<Self>
where Self: Sized,

Creates a new stream which skips n items of the underlying stream. Read more
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fn fuse(self) -> Fuse<Self>
where Self: Sized,

Fuse a stream such that poll_next will never again be called once it has finished. This method can be used to turn any Stream into a FusedStream. Read more
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fn by_ref(&mut self) -> &mut Self

Borrows a stream, rather than consuming it. Read more
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fn catch_unwind(self) -> CatchUnwind<Self>
where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the stream. Read more
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fn boxed<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + Send + 'a>>
where Self: Sized + Send + 'a,

Wrap the stream in a Box, pinning it. Read more
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fn boxed_local<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + 'a>>
where Self: Sized + 'a,

Wrap the stream in a Box, pinning it. Read more
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fn buffered(self, n: usize) -> Buffered<Self>
where Self::Item: Future, Self: Sized,

An adaptor for creating a buffered list of pending futures. Read more
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fn buffer_unordered(self, n: usize) -> BufferUnordered<Self>
where Self::Item: Future, Self: Sized,

An adaptor for creating a buffered list of pending futures (unordered). Read more
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fn zip<St>(self, other: St) -> Zip<Self, St>
where St: Stream, Self: Sized,

An adapter for zipping two streams together. Read more
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fn chain<St>(self, other: St) -> Chain<Self, St>
where St: Stream<Item = Self::Item>, Self: Sized,

Adapter for chaining two streams. Read more
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fn peekable(self) -> Peekable<Self>
where Self: Sized,

Creates a new stream which exposes a peek method. Read more
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fn chunks(self, capacity: usize) -> Chunks<Self>
where Self: Sized,

An adaptor for chunking up items of the stream inside a vector. Read more
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fn ready_chunks(self, capacity: usize) -> ReadyChunks<Self>
where Self: Sized,

An adaptor for chunking up ready items of the stream inside a vector. Read more
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fn inspect<F>(self, f: F) -> Inspect<Self, F>
where F: FnMut(&Self::Item), Self: Sized,

Do something with each item of this stream, afterwards passing it on. Read more
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fn left_stream<B>(self) -> Either<Self, B>
where B: Stream<Item = Self::Item>, Self: Sized,

Wrap this stream in an Either stream, making it the left-hand variant of that Either. Read more
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fn right_stream<B>(self) -> Either<B, Self>
where B: Stream<Item = Self::Item>, Self: Sized,

Wrap this stream in an Either stream, making it the right-hand variant of that Either. Read more
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fn poll_next_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>
where Self: Unpin,

A convenience method for calling Stream::poll_next on Unpin stream types.
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fn select_next_some(&mut self) -> SelectNextSome<'_, Self>
where Self: Unpin + FusedStream,

Returns a Future that resolves when the next item in this stream is ready. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more