Struct futures_util::stream::FuturesUnordered

#[must_use = "streams do nothing unless polled"]
pub struct FuturesUnordered<Fut> { /* fields omitted */ }

A set of futures which may complete in any order.

This structure is optimized to manage a large number of futures. Futures managed by FuturesUnordered will only be polled when they generate wake-up notifications. This reduces the required amount of work needed to poll large numbers of futures.

FuturesUnordered can be filled by collecting an iterator of futures into a FuturesUnordered, or by pushing futures onto an existing FuturesUnordered. When new futures are added, poll_next must be called in order to begin receiving wake-ups for new futures.

Note that you can create a ready-made FuturesUnordered via the collect method, or you can start with an empty set with the FuturesUnordered::new constructor.

This type is only available when the std or alloc feature of this library is activated, and it is activated by default.

Methods

impl<Fut: Future> FuturesUnordered<Fut>

pub fn new() -> FuturesUnordered<Fut>

Constructs a new, empty FuturesUnordered.

The returned FuturesUnordered does not contain any futures. In this state, FuturesUnordered::poll_next will return Poll::Ready(None).

impl<Fut> FuturesUnordered<Fut>

pub fn len(&self) -> usize

Returns the number of futures contained in the set.

This represents the total number of in-flight futures.

pub fn is_empty(&self) -> bool

Returns true if the set contains no futures.

pub fn push(&self, future: Fut)

Push a future into the set.

This method adds the given future to the set. This method will not call poll on the submitted future. The caller must ensure that FuturesUnordered::poll_next is called in order to receive wake-up notifications for the given future.

Important traits for Iter<'a, Fut>

impl<'a, Fut: Unpin> Iterator for Iter<'a, Fut> type Item = &'a Fut;

pub fn iter(&self) -> Iter<Fut> where
    Fut: Unpin, 

Returns an iterator that allows inspecting each future in the set.

Important traits for IterMut<'a, Fut>

impl<'a, Fut: Unpin> Iterator for IterMut<'a, Fut> type Item = &'a mut Fut;

pub fn iter_mut(&mut self) -> IterMut<Fut> where
    Fut: Unpin, 

Returns an iterator that allows modifying each future in the set.

Important traits for IterPinMut<'a, Fut>

impl<'a, Fut> Iterator for IterPinMut<'a, Fut> type Item = Pin<&'a mut Fut>;

pub fn iter_pin_mut(self: Pin<&mut Self>) -> IterPinMut<Fut>

Returns an iterator that allows modifying each future in the set.

Trait Implementations

impl<Fut: Send> Send for FuturesUnordered<Fut>

impl<Fut: Sync> Sync for FuturesUnordered<Fut>

impl<Fut> Unpin for FuturesUnordered<Fut>

impl<Fut> Drop for FuturesUnordered<Fut>

fn drop(&mut self)

Executes the destructor for this type.

impl<Fut: Future> Default for FuturesUnordered<Fut>

fn default() -> FuturesUnordered<Fut>

Returns the "default value" for a type.

impl<Fut> Debug for FuturesUnordered<Fut>

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

Formats the value using the given formatter.

impl<Fut: Future> FromIterator<Fut> for FuturesUnordered<Fut>

fn from_iter<I>(iter: I) -> Self where
    I: IntoIterator<Item = Fut>, 

Creates a value from an iterator.

impl<Fut: Future> Stream for FuturesUnordered<Fut>

type Item = Fut::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<Fut: Future> FusedStream for FuturesUnordered<Fut>

fn is_terminated(&self) -> bool

Returns true if the stream should no longer be polled.

impl<'_> Spawn for FuturesUnordered<FutureObj<'_, ()>>

fn spawn_obj(
    &self,
    future_obj: FutureObj<'static, ()>
) -> Result<(), SpawnError>

Spawns a future that will be run to completion.

fn status(&self) -> Result<(), SpawnError>

Determines whether the executor is able to spawn new tasks.

impl<'_> LocalSpawn for FuturesUnordered<LocalFutureObj<'_, ()>>

fn spawn_local_obj(
    &self,
    future_obj: LocalFutureObj<'static, ()>
) -> Result<(), SpawnError>

Spawns a future that will be run to completion.

fn status_local(&self) -> Result<(), SpawnError>

Determines whether the executor is able to spawn new tasks.