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//! Conversion to the `Stream` type from iterators.
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
use crate::dataflow::channels::Message;
use crate::dataflow::operators::generic::operator::source;
use crate::dataflow::operators::CapabilitySet;
use crate::dataflow::{Scope, Stream};
use crate::progress::Timestamp;
use crate::Data;
/// Converts to a timely `Stream`.
pub trait ToStream<T: Timestamp, D: Data> {
/// Converts to a timely `Stream`.
///
/// # Examples
///
/// ```
/// use timely::dataflow::operators::{ToStream, Capture};
/// use timely::dataflow::operators::capture::Extract;
///
/// let (data1, data2) = timely::example(|scope| {
/// let data1 = (0..3).to_stream(scope).capture();
/// let data2 = vec![0,1,2].to_stream(scope).capture();
/// (data1, data2)
/// });
///
/// assert_eq!(data1.extract(), data2.extract());
/// ```
fn to_stream<S: Scope<Timestamp=T>>(self, scope: &mut S) -> Stream<S, D>;
}
impl<T: Timestamp, I: IntoIterator+'static> ToStream<T, I::Item> for I where I::Item: Data {
fn to_stream<S: Scope<Timestamp=T>>(self, scope: &mut S) -> Stream<S, I::Item> {
source(scope, "ToStream", |capability, info| {
// Acquire an activator, so that the operator can rescheduled itself.
let activator = scope.activator_for(&info.address[..]);
let mut iterator = self.into_iter().fuse();
let mut capability = Some(capability);
move |output| {
if let Some(element) = iterator.next() {
let mut session = output.session(capability.as_ref().unwrap());
session.give(element);
for element in iterator.by_ref().take((256 * Message::<T, I::Item>::default_length()) - 1) {
session.give(element);
}
activator.activate();
}
else {
capability = None;
}
}
})
}
}
/// Data and progress events of the native stream.
pub enum Event<F: IntoIterator, D> {
/// Indicates that timestamps have advanced to frontier F
Progress(F),
/// Indicates that event D happened at time T
Message(F::Item, D),
}
/// Converts to a timely `Stream`.
pub trait ToStreamAsync<T: Timestamp, D: Data> {
/// Converts a [native `Stream`](futures_util::stream::Stream) of [`Event`s](Event) into a [timely
/// `Stream`](crate::dataflow::Stream).
///
/// # Examples
///
/// ```
/// use futures_util::stream;
///
/// use timely::dataflow::operators::{Capture, Event, ToStream, ToStreamAsync};
/// use timely::dataflow::operators::capture::Extract;
///
/// let native_stream = stream::iter(vec![
/// Event::Message(0, 0),
/// Event::Message(0, 1),
/// Event::Message(0, 2),
/// Event::Progress(Some(0)),
/// ]);
///
/// let native_stream = Box::pin(native_stream);
///
/// let (data1, data2) = timely::example(|scope| {
/// let data1 = native_stream.to_stream(scope).capture();
/// let data2 = vec![0,1,2].to_stream(scope).capture();
///
/// (data1, data2)
/// });
///
/// assert_eq!(data1.extract(), data2.extract());
/// ```
fn to_stream<S: Scope<Timestamp = T>>(self: Pin<Box<Self>>, scope: &S) -> Stream<S, D>;
}
impl<T, D, F, I> ToStreamAsync<T, D> for I
where
D: Data,
T: Timestamp,
F: IntoIterator<Item = T>,
I: futures_util::stream::Stream<Item = Event<F, D>> + ?Sized + 'static,
{
fn to_stream<S: Scope<Timestamp = T>>(mut self: Pin<Box<Self>>, scope: &S) -> Stream<S, D> {
source(scope, "ToStreamAsync", move |capability, info| {
let activator = Arc::new(scope.sync_activator_for(&info.address[..]));
let mut cap_set = CapabilitySet::from_elem(capability);
move |output| {
let waker = futures_util::task::waker_ref(&activator);
let mut context = Context::from_waker(&waker);
// Consume all the ready items of the source_stream and issue them to the operator
while let Poll::Ready(item) = self.as_mut().poll_next(&mut context) {
match item {
Some(Event::Progress(time)) => {
cap_set.downgrade(time);
}
Some(Event::Message(time, data)) => {
output.session(&cap_set.delayed(&time)).give(data);
}
None => {
cap_set.downgrade(&[]);
break;
}
}
}
}
})
}
}