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//! Extension methods for `Stream` based on record-by-record transformation.
use crate::Container;
use crate::progress::Timestamp;
use crate::dataflow::Stream;
use crate::dataflow::channels::pact::Pipeline;
use crate::dataflow::operators::generic::operator::Operator;
/// Extension trait for reclocking a stream.
pub trait Reclock<'scope, T: Timestamp> {
/// Delays records until an input is observed on the `clock` input.
///
/// The source stream is buffered until a record is seen on the clock input,
/// at which point a notification is requested and all data with time less
/// or equal to the clock time are sent. This method does not ensure that all
/// workers receive the same clock records, which can be accomplished with
/// `broadcast`.
///
/// # Examples
///
/// ```
/// use timely::dataflow::operators::{ToStream, Reclock, Capture};
/// use timely::dataflow::operators::vec::{Delay, Map};
/// use timely::dataflow::operators::capture::Extract;
///
/// let captured = timely::example(|scope| {
///
/// // produce data 0..10 at times 0..10.
/// let data = (0..10).to_stream(scope)
/// .delay(|x,t| *x);
///
/// // product clock ticks at three times.
/// let clock = vec![3, 5, 8].into_iter()
/// .to_stream(scope)
/// .delay(|x,t| *x)
/// .map(|_| ());
///
/// // reclock the data.
/// data.reclock(clock)
/// .capture()
/// });
///
/// let extracted = captured.extract();
/// assert_eq!(extracted.len(), 3);
/// assert_eq!(extracted[0], (3, vec![0,1,2,3]));
/// assert_eq!(extracted[1], (5, vec![4,5]));
/// assert_eq!(extracted[2], (8, vec![6,7,8]));
/// ```
fn reclock<TC: Container>(self, clock: Stream<'scope, T, TC>) -> Self;
}
impl<'scope, T: Timestamp, C: Container> Reclock<'scope, T> for Stream<'scope, T, C> {
fn reclock<TC: Container>(self, clock: Stream<'scope, T, TC>) -> Self {
let mut stash = vec![];
self.binary_notify(clock, Pipeline, Pipeline, "Reclock", vec![], move |input1, input2, output, notificator| {
// stash each data input with its timestamp.
input1.for_each_time(|cap, data| {
for data in data {
stash.push((cap.time().clone(), std::mem::take(data)));
}
});
// request notification at time, to flush stash.
input2.for_each_time(|time, _data| {
notificator.notify_at(time.retain(output.output_index()));
});
// each time with complete stash can be flushed.
notificator.for_each(|cap,_,_| {
let mut session = output.session(&cap);
for &mut (ref t, ref mut data) in &mut stash {
if t.less_equal(cap.time()) {
session.give_container(data);
}
}
stash.retain(|x| !x.0.less_equal(cap.time()));
});
})
}
}