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//! Extension trait and implementation for observing and action on streamed data.
use crate::Container;
use crate::progress::Timestamp;
use crate::dataflow::channels::pact::Pipeline;
use crate::dataflow::Stream;
use crate::dataflow::operators::generic::Operator;
/// Methods to inspect records and batches of records on a stream.
pub trait Inspect<T: Timestamp, C>: InspectCore<T, C> + Sized
where
for<'a> &'a C: IntoIterator,
{
/// Runs a supplied closure on each observed data element.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .container::<Vec<_>>()
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn inspect<F>(self, mut func: F) -> Self
where
F: for<'a> FnMut(<&'a C as IntoIterator>::Item) + 'static,
{
self.inspect_batch(move |_, data| {
for datum in data.into_iter() { func(datum); }
})
}
/// Runs a supplied closure on each observed data element and associated time.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .container::<Vec<_>>()
/// .inspect_time(|t, x| println!("seen at: {:?}\t{:?}", t, x));
/// });
/// ```
fn inspect_time<F>(self, mut func: F) -> Self
where
F: for<'a> FnMut(&T, <&'a C as IntoIterator>::Item) + 'static,
{
self.inspect_batch(move |time, data| {
for datum in data.into_iter() {
func(time, datum);
}
})
}
/// Runs a supplied closure on each observed data batch (time and data slice).
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .container::<Vec<_>>()
/// .inspect_batch(|t,xs| println!("seen at: {:?}\t{:?} records", t, xs.len()));
/// });
/// ```
fn inspect_batch(self, mut func: impl FnMut(&T, &C)+'static) -> Self {
self.inspect_core(move |event| {
if let Ok((time, data)) = event {
func(time, data);
}
})
}
/// Runs a supplied closure on each observed data batch, and each frontier advancement.
///
/// Rust's `Result` type is used to distinguish the events, with `Ok` for time and data,
/// and `Err` for frontiers. Frontiers are only presented when they change.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .container::<Vec<_>>()
/// .inspect_core(|event| {
/// match event {
/// Ok((time, data)) => println!("seen at: {:?}\t{:?} records", time, data.len()),
/// Err(frontier) => println!("frontier advanced to {:?}", frontier),
/// }
/// });
/// });
/// ```
fn inspect_core<F>(self, func: F) -> Self where F: FnMut(Result<(&T, &C), &[T]>)+'static;
}
impl<T: Timestamp, C: Container> Inspect<T, C> for Stream<'_, T, C>
where
for<'a> &'a C: IntoIterator,
{
fn inspect_core<F>(self, func: F) -> Self where F: FnMut(Result<(&T, &C), &[T]>) + 'static {
self.inspect_container(func)
}
}
/// Inspect containers
pub trait InspectCore<T: Timestamp, C> {
/// Runs a supplied closure on each observed container, and each frontier advancement.
///
/// Rust's `Result` type is used to distinguish the events, with `Ok` for time and data,
/// and `Err` for frontiers. Frontiers are only presented when they change.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, InspectCore};
///
/// timely::example(|scope| {
/// (0..10).to_stream(scope)
/// .container::<Vec<_>>()
/// .inspect_container(|event| {
/// match event {
/// Ok((time, data)) => println!("seen at: {:?}\t{:?} records", time, data.len()),
/// Err(frontier) => println!("frontier advanced to {:?}", frontier),
/// }
/// });
/// });
/// ```
fn inspect_container<F>(self, func: F) -> Self where F: FnMut(Result<(&T, &C), &[T]>)+'static;
}
impl<T: Timestamp, C: Container> InspectCore<T, C> for Stream<'_, T, C> {
fn inspect_container<F>(self, mut func: F) -> Self
where F: FnMut(Result<(&T, &C), &[T]>)+'static
{
let mut frontier = crate::progress::Antichain::from_elem(T::minimum());
self.unary_frontier(Pipeline, "InspectBatch", move |_,_| move |(input, chain), output| {
if chain.frontier() != frontier.borrow() {
frontier.clear();
frontier.extend(chain.frontier().iter().cloned());
func(Err(frontier.elements()));
}
input.for_each_time(|time, data| {
let mut session = output.session(&time);
for data in data {
func(Ok((&time, &*data)));
session.give_container(data);
}
});
})
}
}