Trait futures_util::sink::SinkExt [−][src]
An extension trait for Sink
s that provides a variety of convenient
combinator functions.
Provided methods
fn with<U, Fut, F, E>(self, f: F) -> With<Self, Item, U, Fut, F> where
F: FnMut(U) -> Fut,
Fut: Future<Output = Result<Item, E>>,
E: From<Self::Error>,
Self: Sized,
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F: FnMut(U) -> Fut,
Fut: Future<Output = Result<Item, E>>,
E: From<Self::Error>,
Self: Sized,
Composes a function in front of the sink.
This adapter produces a new sink that passes each value through the
given function f
before sending it to self
.
To process each value, f
produces a future, which is then polled to
completion before passing its result down to the underlying sink. If the
future produces an error, that error is returned by the new sink.
Note that this function consumes the given sink, returning a wrapped
version, much like Iterator::map
.
fn with_flat_map<U, St, F>(self, f: F) -> WithFlatMap<Self, Item, U, St, F> where
F: FnMut(U) -> St,
St: Stream<Item = Result<Item, Self::Error>>,
Self: Sized,
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F: FnMut(U) -> St,
St: Stream<Item = Result<Item, Self::Error>>,
Self: Sized,
Composes a function in front of the sink.
This adapter produces a new sink that passes each value through the
given function f
before sending it to self
.
To process each value, f
produces a stream, of which each value
is passed to the underlying sink. A new value will not be accepted until
the stream has been drained
Note that this function consumes the given sink, returning a wrapped
version, much like Iterator::flat_map
.
Examples
use futures::channel::mpsc; use futures::sink::SinkExt; use futures::stream::{self, StreamExt}; let (tx, rx) = mpsc::channel(5); let mut tx = tx.with_flat_map(|x| { stream::iter(vec![Ok(42); x]) }); tx.send(5).await.unwrap(); drop(tx); let received: Vec<i32> = rx.collect().await; assert_eq!(received, vec![42, 42, 42, 42, 42]);
fn sink_map_err<E, F>(self, f: F) -> SinkMapErr<Self, F> where
F: FnOnce(Self::Error) -> E,
Self: Sized,
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F: FnOnce(Self::Error) -> E,
Self: Sized,
Transforms the error returned by the sink.
fn sink_err_into<E>(self) -> SinkErrInto<Self, Item, E> where
Self: Sized,
Self::Error: Into<E>,
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Self: Sized,
Self::Error: Into<E>,
Map this sink’s error to a different error type using the Into
trait.
If wanting to map errors of a Sink + Stream
, use .sink_err_into().err_into()
.
fn buffer(self, capacity: usize) -> Buffer<Self, Item> where
Self: Sized,
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Self: Sized,
Adds a fixed-size buffer to the current sink.
The resulting sink will buffer up to capacity
items when the
underlying sink is unwilling to accept additional items. Calling flush
on the buffered sink will attempt to both empty the buffer and complete
processing on the underlying sink.
Note that this function consumes the given sink, returning a wrapped
version, much like Iterator::map
.
This method is only available when the std
or alloc
feature of this
library is activated, and it is activated by default.
fn close(&mut self) -> Close<'_, Self, Item>ⓘ where
Self: Unpin,
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Self: Unpin,
Close the sink.
fn fanout<Si>(self, other: Si) -> Fanout<Self, Si> where
Self: Sized,
Item: Clone,
Si: Sink<Item, Error = Self::Error>,
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Self: Sized,
Item: Clone,
Si: Sink<Item, Error = Self::Error>,
Fanout items to multiple sinks.
This adapter clones each incoming item and forwards it to both this as well as the other sink at the same time.
fn flush(&mut self) -> Flush<'_, Self, Item>ⓘ where
Self: Unpin,
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Self: Unpin,
Flush the sink, processing all pending items.
This adapter is intended to be used when you want to stop sending to the sink until all current requests are processed.
fn send(&mut self, item: Item) -> Send<'_, Self, Item>ⓘ where
Self: Unpin,
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Self: Unpin,
A future that completes after the given item has been fully processed into the sink, including flushing.
Note that, because of the flushing requirement, it is usually better
to batch together items to send via feed
or send_all
,
rather than flushing between each item.
fn feed(&mut self, item: Item) -> Feed<'_, Self, Item>ⓘ where
Self: Unpin,
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Self: Unpin,
A future that completes after the given item has been received by the sink.
Unlike send
, the returned future does not flush the sink.
It is the caller’s responsibility to ensure all pending items
are processed, which can be done via flush
or close
.
fn send_all<'a, St: ?Sized>(
&'a mut self,
stream: &'a mut St
) -> SendAll<'a, Self, St>ⓘ where
St: TryStream<Ok = Item, Error = Self::Error> + Stream + Unpin,
Self: Unpin,
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&'a mut self,
stream: &'a mut St
) -> SendAll<'a, Self, St>ⓘ where
St: TryStream<Ok = Item, Error = Self::Error> + Stream + Unpin,
Self: Unpin,
A future that completes after the given stream has been fully processed into the sink, including flushing.
This future will drive the stream to keep producing items until it is exhausted, sending each item to the sink. It will complete once both the stream is exhausted, the sink has received all items, and the sink has been flushed. Note that the sink is not closed.
Doing sink.send_all(stream)
is roughly equivalent to
stream.forward(sink)
. The returned future will exhaust all items from
stream
and send them to self
.
fn left_sink<Si2>(self) -> Either<Self, Si2>ⓘ where
Si2: Sink<Item, Error = Self::Error>,
Self: Sized,
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Si2: Sink<Item, Error = Self::Error>,
Self: Sized,
Wrap this sink in an Either
sink, making it the left-hand variant
of that Either
.
This can be used in combination with the right_sink
method to write if
statements that evaluate to different streams in different branches.
fn right_sink<Si1>(self) -> Either<Si1, Self>ⓘ where
Si1: Sink<Item, Error = Self::Error>,
Self: Sized,
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Si1: Sink<Item, Error = Self::Error>,
Self: Sized,
Wrap this stream in an Either
stream, making it the right-hand variant
of that Either
.
This can be used in combination with the left_sink
method to write if
statements that evaluate to different streams in different branches.
fn poll_ready_unpin(
&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
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&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
A convenience method for calling Sink::poll_ready
on Unpin
sink types.
fn start_send_unpin(&mut self, item: Item) -> Result<(), Self::Error> where
Self: Unpin,
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Self: Unpin,
A convenience method for calling Sink::start_send
on Unpin
sink types.
fn poll_flush_unpin(
&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
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&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
A convenience method for calling Sink::poll_flush
on Unpin
sink types.
fn poll_close_unpin(
&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
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&mut self,
cx: &mut Context<'_>
) -> Poll<Result<(), Self::Error>> where
Self: Unpin,
A convenience method for calling Sink::poll_close
on Unpin
sink types.