pub struct FuturesOrdered<T> where
    T: Future
{ /* private fields */ }
Expand description

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.

Implementations

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)).

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.

Returns true if the queue contains no futures

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

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Creates a value from an iterator. Read more

The type of item this stream will yield on success.

The type of error this stream may generate.

Attempt to pull out the next value of this stream, returning None if the stream is finished. Read more

Creates an iterator which blocks the current thread until each item of this stream is resolved. Read more

Converts this stream into a Future. Read more

Converts a stream of type T to a stream of type U. Read more

Converts a stream of error type T to a stream of error type U. Read more

Filters the values produced by this stream according to the provided predicate. Read more

Filters the values produced by this stream while simultaneously mapping them to a different type. Read more

Chain on a computation for when a value is ready, passing the resulting item to the provided closure f. Read more

Chain on a computation for when a value is ready, passing the successful results to the provided closure f. Read more

Chain on a computation for when an error happens, passing the erroneous result to the provided closure f. Read more

Collect all of the values of this stream into a vector, returning a future representing the result of that computation. Read more

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

👎 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

Execute an accumulating computation over a stream, collecting all the values into one final result. Read more

Flattens a stream of streams into just one continuous stream. Read more

Skip elements on this stream while the predicate provided resolves to true. Read more

Take elements from this stream while the predicate provided resolves to true. Read more

Runs this stream to completion, executing the provided closure for each element on the stream. Read more

Map this stream’s error to any error implementing From for this stream’s Error, returning a new stream. Read more

Creates a new stream of at most amt items of the underlying stream. Read more

Creates a new stream which skips amt items of the underlying stream. Read more

Fuse a stream such that poll will never again be called once it has finished. Read more

Borrows a stream, rather than consuming it. Read more

Catches unwinding panics while polling the stream. Read more

An adaptor for creating a buffered list of pending futures. Read more

An adaptor for creating a buffered list of pending futures (unordered). Read more

👎 Deprecated:

functionality provided by select now

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

An adapter for zipping two streams together. Read more

Adapter for chaining two stream. Read more

Creates a new stream which exposes a peek method. Read more

An adaptor for chunking up items of the stream inside a vector. Read more

Creates a stream that selects the next element from either this stream or the provided one, whichever is ready first. Read more

A future that completes after the given stream has been fully processed into the sink, including flushing. Read more

Splits this Stream + Sink object into separate Stream and Sink objects. Read more

Do something with each item of this stream, afterwards passing it on. Read more

Do something with the error of this stream, afterwards passing it on. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.