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//! Extension trait and implementation for observing and action on streamed data.
use crate::Data;
use crate::dataflow::channels::pact::Pipeline;
use crate::dataflow::{Stream, Scope};
use crate::dataflow::operators::generic::Operator;
/// Methods to inspect records and batches of records on a stream.
pub trait Inspect<G: Scope, D: Data> {
/// Runs a supplied closure on each observed data element.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Map, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn inspect(&self, mut func: impl FnMut(&D)+'static) -> Stream<G, D> {
self.inspect_batch(move |_, data| {
for datum in data.iter() { func(datum); }
})
}
/// Runs a supplied closure on each observed data element and associated time.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Map, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .inspect_time(|t, x| println!("seen at: {:?}\t{:?}", t, x));
/// });
/// ```
fn inspect_time(&self, mut func: impl FnMut(&G::Timestamp, &D)+'static) -> Stream<G, D> {
self.inspect_batch(move |time, data| {
for datum in data.iter() {
func(&time, &datum);
}
})
}
/// Runs a supplied closure on each observed data batch (time and data slice).
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Map, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .inspect_batch(|t,xs| println!("seen at: {:?}\t{:?} records", t, xs.len()));
/// });
/// ```
fn inspect_batch(&self, func: impl FnMut(&G::Timestamp, &[D])+'static) -> Stream<G, D>;
}
impl<G: Scope, D: Data> Inspect<G, D> for Stream<G, D> {
fn inspect_batch(&self, mut func: impl FnMut(&G::Timestamp, &[D])+'static) -> Stream<G, D> {
let mut vector = Vec::new();
self.unary(Pipeline, "InspectBatch", move |_,_| move |input, output| {
input.for_each(|time, data| {
data.swap(&mut vector);
func(&time, &vector[..]);
output.session(&time).give_vec(&mut vector);
});
})
}
}