[][src]Struct futures::stream::FuturesOrdered

#[must_use = "streams do nothing unless polled"]
pub struct FuturesOrdered<T> where
    T: Future
{ /* fields omitted */ }

An unbounded queue of futures.

This "combinator" is similar to FuturesUnordered, but it imposes an order on top of the set of futures. While futures in the set will race to completion in parallel, results will only be returned in the order their originating futures were added to the queue.

Futures are pushed into this queue and their realized values are yielded in order. This structure is optimized to manage a large number of futures. Futures managed by FuturesOrdered will only be polled when they generate notifications. This reduces the required amount of work needed to coordinate large numbers of futures.

When a FuturesOrdered is first created, it does not contain any futures. Calling poll in this state will result in Ok(Async::Ready(None)) to be returned. Futures are submitted to the queue using push; however, the future will not be polled at this point. FuturesOrdered will only poll managed futures when FuturesOrdered::poll is called. As such, it is important to call poll after pushing new futures.

If FuturesOrdered::poll returns Ok(Async::Ready(None)) this means that the queue is currently not managing any futures. A future may be submitted to the queue at a later time. At that point, a call to FuturesOrdered::poll will either return the future's resolved value or Ok(Async::NotReady) if the future has not yet completed. When multiple futures are submitted to the queue, FuturesOrdered::poll will return Ok(Async::NotReady) until the first future completes, even if some of the later futures have already completed.

Note that you can create a ready-made FuturesOrdered via the futures_ordered function in the stream module, or you can start with an empty queue with the FuturesOrdered::new constructor.

Methods

impl<T> FuturesOrdered<T> where
    T: Future
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pub fn new() -> FuturesOrdered<T>[src]

Constructs a new, empty FuturesOrdered

The returned FuturesOrdered does not contain any futures and, in this state, FuturesOrdered::poll will return Ok(Async::Ready(None)).

pub fn len(&self) -> usize[src]

Returns the number of futures contained in the queue.

This represents the total number of in-flight futures, both those currently processing and those that have completed but which are waiting for earlier futures to complete.

pub fn is_empty(&self) -> bool[src]

Returns true if the queue contains no futures

pub fn push(&mut self, future: T)[src]

Push a future into the queue.

This function submits the given future to the internal set for managing. This function will not call poll on the submitted future. The caller must ensure that FuturesOrdered::poll is called in order to receive task notifications.

Trait Implementations

impl<T> Stream for FuturesOrdered<T> where
    T: Future
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type Item = T::Item

The type of item this stream will yield on success.

type Error = T::Error

The type of error this stream may generate.

Important traits for Wait<S>
fn wait(self) -> Wait<Self> where
    Self: Sized
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Creates an iterator which blocks the current thread until each item of this stream is resolved. Read more

fn into_future(self) -> StreamFuture<Self> where
    Self: Sized
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Converts this stream into a Future. Read more

fn map<U, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> U,
    Self: Sized
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Converts a stream of type T to a stream of type U. Read more

fn map_err<U, F>(self, f: F) -> MapErr<Self, F> where
    F: FnMut(Self::Error) -> U,
    Self: Sized
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Converts a stream of error type T to a stream of error type U. Read more

fn filter<F>(self, f: F) -> Filter<Self, F> where
    F: FnMut(&Self::Item) -> bool,
    Self: Sized
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Filters the values produced by this stream according to the provided predicate. Read more

fn filter_map<F, B>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>,
    Self: Sized
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Filters the values produced by this stream while simultaneously mapping them to a different type. Read more

fn then<F, U>(self, f: F) -> Then<Self, F, U> where
    F: FnMut(Result<Self::Item, Self::Error>) -> U,
    U: IntoFuture,
    Self: Sized
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Chain on a computation for when a value is ready, passing the resulting item to the provided closure f. Read more

fn and_then<F, U>(self, f: F) -> AndThen<Self, F, U> where
    F: FnMut(Self::Item) -> U,
    U: IntoFuture<Error = Self::Error>,
    Self: Sized
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Chain on a computation for when a value is ready, passing the successful results to the provided closure f. Read more

fn or_else<F, U>(self, f: F) -> OrElse<Self, F, U> where
    F: FnMut(Self::Error) -> U,
    U: IntoFuture<Item = Self::Item>,
    Self: Sized
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Chain on a computation for when an error happens, passing the erroneous result to the provided closure f. Read more

fn collect(self) -> Collect<Self> where
    Self: Sized
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Collect all of the values of this stream into a vector, returning a future representing the result of that computation. Read more

fn concat2(self) -> Concat2<Self> where
    Self: Sized,
    Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator + Default
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Concatenate all results of a stream into a single extendable destination, returning a future representing the end result. Read more

fn concat(self) -> Concat<Self> where
    Self: Sized,
    Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator
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Deprecated since 0.1.14:

please use Stream::concat2 instead

Concatenate all results of a stream into a single extendable destination, returning a future representing the end result. Read more

fn fold<F, T, Fut>(self, init: T, f: F) -> Fold<Self, F, Fut, T> where
    F: FnMut(T, Self::Item) -> Fut,
    Fut: IntoFuture<Item = T>,
    Self::Error: From<Fut::Error>,
    Self: Sized
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Execute an accumulating computation over a stream, collecting all the values into one final result. Read more

fn flatten(self) -> Flatten<Self> where
    Self::Item: Stream,
    <Self::Item as Stream>::Error: From<Self::Error>,
    Self: Sized
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Flattens a stream of streams into just one continuous stream. Read more

fn skip_while<P, R>(self, pred: P) -> SkipWhile<Self, P, R> where
    P: FnMut(&Self::Item) -> R,
    R: IntoFuture<Item = bool, Error = Self::Error>,
    Self: Sized
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Skip elements on this stream while the predicate provided resolves to true. Read more

fn take_while<P, R>(self, pred: P) -> TakeWhile<Self, P, R> where
    P: FnMut(&Self::Item) -> R,
    R: IntoFuture<Item = bool, Error = Self::Error>,
    Self: Sized
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Take elements from this stream while the predicate provided resolves to true. Read more

fn for_each<F, U>(self, f: F) -> ForEach<Self, F, U> where
    F: FnMut(Self::Item) -> U,
    U: IntoFuture<Item = (), Error = Self::Error>,
    Self: Sized
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Runs this stream to completion, executing the provided closure for each element on the stream. Read more

fn from_err<E: From<Self::Error>>(self) -> FromErr<Self, E> where
    Self: Sized
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Map this stream's error to any error implementing From for this stream's Error, returning a new stream. Read more

fn take(self, amt: u64) -> Take<Self> where
    Self: Sized
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Creates a new stream of at most amt items of the underlying stream. Read more

fn skip(self, amt: u64) -> Skip<Self> where
    Self: Sized
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Creates a new stream which skips amt items of the underlying stream. Read more

fn fuse(self) -> Fuse<Self> where
    Self: Sized
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Fuse a stream such that poll will never again be called once it has finished. Read more

fn by_ref(&mut self) -> &mut Self where
    Self: Sized
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Borrows a stream, rather than consuming it. Read more

fn catch_unwind(self) -> CatchUnwind<Self> where
    Self: Sized + UnwindSafe
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Catches unwinding panics while polling the stream. Read more

fn buffered(self, amt: usize) -> Buffered<Self> where
    Self::Item: IntoFuture<Error = Self::Error>,
    Self: Sized
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An adaptor for creating a buffered list of pending futures. Read more

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

fn merge<S>(self, other: S) -> Merge<Self, S> where
    S: Stream<Error = Self::Error>,
    Self: Sized
[src]

Deprecated:

functionality provided by select now

An adapter for merging the output of two streams. Read more

fn zip<S>(self, other: S) -> Zip<Self, S> where
    S: Stream<Error = Self::Error>,
    Self: Sized
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An adapter for zipping two streams together. Read more

fn chain<S>(self, other: S) -> Chain<Self, S> where
    S: Stream<Item = Self::Item, Error = Self::Error>,
    Self: Sized
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Adapter for chaining two stream. Read more

fn peekable(self) -> Peekable<Self> where
    Self: Sized
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Creates a new stream which exposes a peek method. Read more

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

fn select<S>(self, other: S) -> Select<Self, S> where
    S: Stream<Item = Self::Item, Error = Self::Error>,
    Self: Sized
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Creates a stream that selects the next element from either this stream or the provided one, whichever is ready first. Read more

fn forward<S>(self, sink: S) -> Forward<Self, S> where
    S: Sink<SinkItem = Self::Item>,
    Self::Error: From<S::SinkError>,
    Self: Sized
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A future that completes after the given stream has been fully processed into the sink, including flushing. Read more

fn split(self) -> (SplitSink<Self>, SplitStream<Self>) where
    Self: Sink + Sized
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Splits this Stream + Sink object into separate Stream and Sink objects. Read more

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item),
    Self: Sized
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Do something with each item of this stream, afterwards passing it on. Read more

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> where
    F: FnMut(&Self::Error),
    Self: Sized
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Do something with the error of this stream, afterwards passing it on. Read more

impl<T: Debug> Debug for FuturesOrdered<T> where
    T: Future
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impl<F: Future> FromIterator<F> for FuturesOrdered<F>[src]

impl<T> Default for FuturesOrdered<T> where
    T: Future
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Auto Trait Implementations

impl<T> Send for FuturesOrdered<T> where
    T: Send,
    <T as Future>::Item: Send

impl<T> Sync for FuturesOrdered<T> where
    T: Sync,
    <T as Future>::Item: Sync

Blanket Implementations

impl<T> From<T> for T[src]

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.

impl<T, U> Into<U> for T where
    U: From<T>, 
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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.

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