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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
//! Types to build async operators with general shapes.
use std::cell::{Cell, RefCell};
use std::collections::VecDeque;
use std::future::Future;
use std::pin::Pin;
use std::rc::Rc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::task::{ready, Context, Poll, Waker};
use futures_util::task::ArcWake;
use futures_util::Stream;
use timely::communication::{Pull, Push};
use timely::container::columnation::Columnation;
use timely::container::{CapacityContainerBuilder, ContainerBuilder, PushInto};
use timely::dataflow::channels::pact::ParallelizationContract;
use timely::dataflow::channels::pushers::Tee;
use timely::dataflow::channels::Bundle;
use timely::dataflow::operators::generic::builder_rc::OperatorBuilder as OperatorBuilderRc;
use timely::dataflow::operators::generic::{
InputHandleCore, OperatorInfo, OutputHandleCore, OutputWrapper,
};
use timely::dataflow::operators::{Capability, CapabilitySet, InputCapability};
use timely::dataflow::{Scope, StreamCore};
use timely::progress::{Antichain, Timestamp};
use timely::scheduling::{Activator, SyncActivator};
use timely::Message;
use timely::{Container, PartialOrder};
use crate::containers::stack::{AccountedStackBuilder, StackWrapper};
/// Builds async operators with generic shape.
pub struct OperatorBuilder<G: Scope> {
builder: OperatorBuilderRc<G>,
/// The activator for this operator
activator: Activator,
/// The waker set up to activate this timely operator when woken
operator_waker: Arc<TimelyWaker>,
/// The currently known upper frontier of each of the input handles.
input_frontiers: Vec<Antichain<G::Timestamp>>,
/// Input queues for each of the declared inputs of the operator.
input_queues: Vec<Box<dyn InputQueue<G::Timestamp>>>,
/// Holds type erased closures that flush an output handle when called. These handles will be
/// automatically drained when the operator is scheduled after the logic future has been polled
output_flushes: Vec<Box<dyn FnMut()>>,
/// A handle to check whether all workers have pressed the shutdown button.
shutdown_handle: ButtonHandle,
/// A button to coordinate shutdown of this operator among workers.
shutdown_button: Button,
}
/// A helper trait abstracting over an input handle. It facilitates keeping around type erased
/// handles for each of the operator inputs.
trait InputQueue<T: Timestamp> {
/// Accepts all available input into local queues.
fn accept_input(&mut self);
/// Drains all available input and empties the local queue.
fn drain_input(&mut self);
/// Registers a frontier notification to be delivered.
fn notify_progress(&mut self, upper: Antichain<T>);
}
impl<T, D, C, P> InputQueue<T> for InputHandleQueue<T, D, C, P>
where
T: Timestamp,
D: Container,
C: InputConnection<T> + 'static,
P: Pull<Bundle<T, D>> + 'static,
{
fn accept_input(&mut self) {
let mut queue = self.queue.borrow_mut();
let mut new_data = false;
while let Some((cap, data)) = self.handle.next() {
new_data = true;
let cap = self.connection.accept(cap);
queue.push_back(Event::Data(cap, std::mem::take(data)));
}
if new_data {
if let Some(waker) = self.waker.take() {
waker.wake();
}
}
}
fn drain_input(&mut self) {
self.queue.borrow_mut().clear();
self.handle.for_each(|_, _| {});
}
fn notify_progress(&mut self, upper: Antichain<T>) {
let mut queue = self.queue.borrow_mut();
// It's beneficial to consolidate two consecutive progress statements into one if the
// operator hasn't seen the previous progress yet. This also avoids accumulation of
// progress statements in the queue if the operator only conditionally checks this input.
match queue.back_mut() {
Some(&mut Event::Progress(ref mut prev_upper)) => *prev_upper = upper,
_ => queue.push_back(Event::Progress(upper)),
}
if let Some(waker) = self.waker.take() {
waker.wake();
}
}
}
struct InputHandleQueue<
T: Timestamp,
D: Container,
C: InputConnection<T>,
P: Pull<Bundle<T, D>> + 'static,
> {
queue: Rc<RefCell<VecDeque<Event<T, C::Capability, D>>>>,
waker: Rc<Cell<Option<Waker>>>,
connection: C,
handle: InputHandleCore<T, D, P>,
}
/// An async Waker that activates a specific operator when woken and marks the task as ready
struct TimelyWaker {
activator: SyncActivator,
active: AtomicBool,
task_ready: AtomicBool,
}
impl ArcWake for TimelyWaker {
fn wake_by_ref(arc_self: &Arc<Self>) {
arc_self.task_ready.store(true, Ordering::SeqCst);
// Only activate the timely operator if it's not already active to avoid an infinite loop
if !arc_self.active.load(Ordering::SeqCst) {
// We don't have any guarantees about how long the Waker will be held for and so we
// must be prepared for the receiving end to have hung up when we finally do get woken.
// This can happen if by the time the waker is called the receiving timely worker has
// been shutdown. For this reason we ignore the activation error.
let _ = arc_self.activator.activate();
}
}
}
/// Async handle to an operator's input stream
pub struct AsyncInputHandle<T: Timestamp, D: Container, C: InputConnection<T>> {
queue: Rc<RefCell<VecDeque<Event<T, C::Capability, D>>>>,
waker: Rc<Cell<Option<Waker>>>,
/// Whether this handle has finished producing data
done: bool,
}
impl<T: Timestamp, D: Container, C: InputConnection<T>> AsyncInputHandle<T, D, C> {
pub fn next_sync(&mut self) -> Option<Event<T, C::Capability, D>> {
let mut queue = self.queue.borrow_mut();
match queue.pop_front()? {
Event::Data(cap, data) => Some(Event::Data(cap, data)),
Event::Progress(frontier) => {
self.done = frontier.is_empty();
Some(Event::Progress(frontier))
}
}
}
/// Waits for the handle to have data. After this function returns it is guaranteed that at
/// least one call to `next_sync` will be `Some(_)`.
pub async fn ready(&self) {
std::future::poll_fn(|cx| self.poll_ready(cx)).await
}
fn poll_ready(&self, cx: &Context<'_>) -> Poll<()> {
if self.queue.borrow().is_empty() {
self.waker.set(Some(cx.waker().clone()));
Poll::Pending
} else {
Poll::Ready(())
}
}
}
impl<T: Timestamp, D: Container, C: InputConnection<T>> Stream for AsyncInputHandle<T, D, C> {
type Item = Event<T, C::Capability, D>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
if self.done {
return Poll::Ready(None);
}
ready!(self.poll_ready(cx));
Poll::Ready(self.next_sync())
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.queue.borrow().len(), None)
}
}
/// An event of an input stream
#[derive(Debug)]
pub enum Event<T: Timestamp, C, D> {
/// A data event
Data(C, D),
/// A progress event
Progress(Antichain<T>),
}
pub struct AsyncOutputHandle<
T: Timestamp,
CB: ContainerBuilder,
P: Push<Bundle<T, CB::Container>> + 'static,
> {
// The field order is important here as the handle is borrowing from the wrapper. See also the
// safety argument in the constructor
handle: Rc<RefCell<OutputHandleCore<'static, T, CB, P>>>,
wrapper: Rc<Pin<Box<OutputWrapper<T, CB, P>>>>,
index: usize,
}
impl<T, C, P> AsyncOutputHandle<T, CapacityContainerBuilder<C>, P>
where
T: Timestamp,
C: Container,
P: Push<Bundle<T, C>> + 'static,
{
#[inline]
pub fn give_container(&self, cap: &Capability<T>, container: &mut C) {
let mut handle = self.handle.borrow_mut();
handle.session_with_builder(cap).give_container(container);
}
}
impl<T, CB, P> AsyncOutputHandle<T, CB, P>
where
T: Timestamp,
CB: ContainerBuilder,
P: Push<Bundle<T, CB::Container>> + 'static,
{
fn new(wrapper: OutputWrapper<T, CB, P>, index: usize) -> Self {
let mut wrapper = Rc::new(Box::pin(wrapper));
// SAFETY:
// get_unchecked_mut is safe because we are not moving the wrapper
//
// transmute is safe because:
// * We're erasing the lifetime but we guarantee through field order that the handle will
// be dropped before the wrapper, thus manually enforcing the lifetime.
// * We never touch wrapper again after this point
let handle = unsafe {
let handle = Rc::get_mut(&mut wrapper)
.unwrap()
.as_mut()
.get_unchecked_mut()
.activate();
std::mem::transmute::<OutputHandleCore<'_, T, CB, P>, OutputHandleCore<'static, T, CB, P>>(
handle,
)
};
Self {
wrapper,
handle: Rc::new(RefCell::new(handle)),
index,
}
}
fn cease(&self) {
self.handle.borrow_mut().cease()
}
}
impl<T, C, P> AsyncOutputHandle<T, CapacityContainerBuilder<C>, P>
where
T: Timestamp,
C: Container,
P: Push<Bundle<T, C>> + 'static,
{
pub fn give<D>(&self, cap: &Capability<T>, data: D)
where
CapacityContainerBuilder<C>: PushInto<D>,
{
let mut handle = self.handle.borrow_mut();
handle.session_with_builder(cap).give(data);
}
}
impl<T, D, P>
AsyncOutputHandle<T, AccountedStackBuilder<CapacityContainerBuilder<StackWrapper<D>>>, P>
where
D: timely::Data + Columnation,
T: Timestamp,
P: Push<Bundle<T, StackWrapper<D>>>,
{
pub const MAX_OUTSTANDING_BYTES: usize = 128 * 1024 * 1024;
/// Provides one record at the time specified by the capability. This method will automatically
/// yield back to timely after [Self::MAX_OUTSTANDING_BYTES] have been produced.
pub async fn give_fueled<D2>(&self, cap: &Capability<T>, data: D2)
where
StackWrapper<D>: PushInto<D2>,
{
let should_yield = {
let mut handle = self.handle.borrow_mut();
let mut session = handle.session_with_builder(cap);
session.push_into(data);
let should_yield = session.builder().bytes.get() > Self::MAX_OUTSTANDING_BYTES;
if should_yield {
session.builder().bytes.set(0);
}
should_yield
};
if should_yield {
tokio::task::yield_now().await;
}
}
}
impl<T: Timestamp, CB: ContainerBuilder, P: Push<Bundle<T, CB::Container>> + 'static> Clone
for AsyncOutputHandle<T, CB, P>
{
fn clone(&self) -> Self {
Self {
handle: Rc::clone(&self.handle),
wrapper: Rc::clone(&self.wrapper),
index: self.index,
}
}
}
/// A trait describing the connection behavior between an input of an operator and zero or more of
/// its outputs.
pub trait InputConnection<T: Timestamp> {
/// The capability type associated with this connection behavior.
type Capability;
/// Generates a summary description of the connection behavior given the number of outputs.
fn describe(&self, outputs: usize) -> Vec<Antichain<T::Summary>>;
/// Accepts an input capability.
fn accept(&self, input_cap: InputCapability<T>) -> Self::Capability;
}
/// A marker type representing a disconnected input.
pub struct Disconnected;
impl<T: Timestamp> InputConnection<T> for Disconnected {
type Capability = T;
fn describe(&self, outputs: usize) -> Vec<Antichain<T::Summary>> {
vec![Antichain::new(); outputs]
}
fn accept(&self, input_cap: InputCapability<T>) -> Self::Capability {
input_cap.time().clone()
}
}
/// A marker type representing an input connected to exactly one output.
pub struct ConnectedToOne(usize);
impl<T: Timestamp> InputConnection<T> for ConnectedToOne {
type Capability = Capability<T>;
fn describe(&self, outputs: usize) -> Vec<Antichain<T::Summary>> {
let mut summary = vec![Antichain::new(); outputs];
summary[self.0] = Antichain::from_elem(T::Summary::default());
summary
}
fn accept(&self, input_cap: InputCapability<T>) -> Self::Capability {
input_cap.retain_for_output(self.0)
}
}
/// A marker type representing an input connected to many outputs.
pub struct ConnectedToMany<const N: usize>([usize; N]);
impl<const N: usize, T: Timestamp> InputConnection<T> for ConnectedToMany<N> {
type Capability = [Capability<T>; N];
fn describe(&self, outputs: usize) -> Vec<Antichain<T::Summary>> {
let mut summary = vec![Antichain::new(); outputs];
for output in self.0 {
summary[output] = Antichain::from_elem(T::Summary::default());
}
summary
}
fn accept(&self, input_cap: InputCapability<T>) -> Self::Capability {
self.0
.map(|output| input_cap.delayed_for_output(input_cap.time(), output))
}
}
/// A helper trait abstracting over an output handle. It facilitates passing type erased
/// output handles during operator construction.
/// It is not meant to be implemented by users.
pub trait OutputIndex {
/// The output index of this handle.
fn index(&self) -> usize;
}
impl<T: Timestamp, CB: ContainerBuilder> OutputIndex
for AsyncOutputHandle<T, CB, Tee<T, CB::Container>>
{
fn index(&self) -> usize {
self.index
}
}
impl<G: Scope> OperatorBuilder<G> {
/// Allocates a new generic async operator builder from its containing scope.
pub fn new(name: String, mut scope: G) -> Self {
let builder = OperatorBuilderRc::new(name, scope.clone());
let info = builder.operator_info();
let activator = scope.activator_for(Rc::clone(&info.address));
let sync_activator = scope.sync_activator_for(info.address.to_vec());
let operator_waker = TimelyWaker {
activator: sync_activator,
active: AtomicBool::new(false),
task_ready: AtomicBool::new(true),
};
let (shutdown_handle, shutdown_button) = button(&mut scope, info.address);
OperatorBuilder {
builder,
activator,
operator_waker: Arc::new(operator_waker),
input_frontiers: Default::default(),
input_queues: Default::default(),
output_flushes: Default::default(),
shutdown_handle,
shutdown_button,
}
}
/// Adds a new input that is connected to the specified output, returning the async input handle to use.
pub fn new_input_for<D: Container, P>(
&mut self,
stream: &StreamCore<G, D>,
pact: P,
output: &dyn OutputIndex,
) -> AsyncInputHandle<G::Timestamp, D, ConnectedToOne>
where
P: ParallelizationContract<G::Timestamp, D>,
{
let index = output.index();
assert!(index < self.builder.shape().outputs());
self.new_input_connection(stream, pact, ConnectedToOne(index))
}
/// Adds a new input that is connected to the specified outputs, returning the async input handle to use.
pub fn new_input_for_many<const N: usize, D: Container, P>(
&mut self,
stream: &StreamCore<G, D>,
pact: P,
outputs: [&dyn OutputIndex; N],
) -> AsyncInputHandle<G::Timestamp, D, ConnectedToMany<N>>
where
P: ParallelizationContract<G::Timestamp, D>,
{
let indices = outputs.map(|output| output.index());
for index in indices {
assert!(index < self.builder.shape().outputs());
}
self.new_input_connection(stream, pact, ConnectedToMany(indices))
}
/// Adds a new input that is not connected to any output, returning the async input handle to use.
pub fn new_disconnected_input<D: Container, P>(
&mut self,
stream: &StreamCore<G, D>,
pact: P,
) -> AsyncInputHandle<G::Timestamp, D, Disconnected>
where
P: ParallelizationContract<G::Timestamp, D>,
{
self.new_input_connection(stream, pact, Disconnected)
}
/// Adds a new input with connection information, returning the async input handle to use.
pub fn new_input_connection<D: Container, P, C>(
&mut self,
stream: &StreamCore<G, D>,
pact: P,
connection: C,
) -> AsyncInputHandle<G::Timestamp, D, C>
where
P: ParallelizationContract<G::Timestamp, D>,
C: InputConnection<G::Timestamp> + 'static,
{
self.input_frontiers
.push(Antichain::from_elem(G::Timestamp::minimum()));
let outputs = self.builder.shape().outputs();
let handle = self
.builder
.new_input_connection(stream, pact, connection.describe(outputs));
let waker = Default::default();
let queue = Default::default();
let input_queue = InputHandleQueue {
queue: Rc::clone(&queue),
waker: Rc::clone(&waker),
connection,
handle,
};
self.input_queues.push(Box::new(input_queue));
AsyncInputHandle {
queue,
waker,
done: false,
}
}
/// Adds a new output, returning the output handle and stream.
pub fn new_output<CB: ContainerBuilder>(
&mut self,
) -> (
AsyncOutputHandle<G::Timestamp, CB, Tee<G::Timestamp, CB::Container>>,
StreamCore<G, CB::Container>,
) {
let index = self.builder.shape().outputs();
let connection = vec![Antichain::new(); self.builder.shape().inputs()];
let (wrapper, stream) = self.builder.new_output_connection(connection);
let handle = AsyncOutputHandle::new(wrapper, index);
let flush_handle = handle.clone();
self.output_flushes
.push(Box::new(move || flush_handle.cease()));
(handle, stream)
}
/// Creates an operator implementation from supplied logic constructor. It returns a shutdown
/// button that when pressed it will cause the logic future to be dropped and input handles to
/// be drained. The button can be converted into a token by using
/// [`Button::press_on_drop`]
pub fn build<B, L>(self, constructor: B) -> Button
where
B: FnOnce(Vec<Capability<G::Timestamp>>) -> L,
L: Future + 'static,
{
let operator_waker = self.operator_waker;
let mut input_frontiers = self.input_frontiers;
let mut input_queues = self.input_queues;
let mut output_flushes = self.output_flushes;
let mut shutdown_handle = self.shutdown_handle;
self.builder.build_reschedule(move |caps| {
let mut logic_fut = Some(Box::pin(constructor(caps)));
move |new_frontiers| {
operator_waker.active.store(true, Ordering::SeqCst);
for (i, queue) in input_queues.iter_mut().enumerate() {
// First, discover if there are any frontier notifications
let cur = &mut input_frontiers[i];
let new = new_frontiers[i].frontier();
if PartialOrder::less_than(&cur.borrow(), &new) {
queue.notify_progress(new.to_owned());
*cur = new.to_owned();
}
// Then accept all input into local queues. This step registers the received
// messages with progress tracking.
queue.accept_input();
}
operator_waker.active.store(false, Ordering::SeqCst);
// If our worker pressed the button we stop scheduling the logic future and/or
// draining the input handles to stop producing data and frontier updates
// downstream.
if shutdown_handle.local_pressed() {
// When all workers press their buttons we drop the logic future and start
// draining the input handles.
if shutdown_handle.all_pressed() {
logic_fut = None;
for queue in input_queues.iter_mut() {
queue.drain_input();
}
false
} else {
true
}
} else {
// Schedule the logic future if any of the wakers above marked the task as ready
if let Some(fut) = logic_fut.as_mut() {
if operator_waker.task_ready.load(Ordering::SeqCst) {
let waker = futures_util::task::waker_ref(&operator_waker);
let mut cx = Context::from_waker(&waker);
operator_waker.task_ready.store(false, Ordering::SeqCst);
if Pin::new(fut).poll(&mut cx).is_ready() {
// We're done with logic so deallocate the task
logic_fut = None;
}
// Flush all the outputs before exiting
for flush in output_flushes.iter_mut() {
(flush)();
}
}
}
// The timely operator needs to be kept alive if the task is pending
if logic_fut.is_some() {
true
} else {
// Othewise we should keep draining all inputs
for queue in input_queues.iter_mut() {
queue.drain_input();
}
false
}
}
}
});
self.shutdown_button
}
/// Creates a fallible operator implementation from supplied logic constructor. If the `Future`
/// resolves to an error it will be emitted in the returned error stream and then the operator
/// will wait indefinitely until the shutdown button is pressed.
///
/// # Capability handling
///
/// Unlike [`OperatorBuilder::build`], this method does not give owned capabilities to the
/// constructor. All initial capabilities are wrapped in a `CapabilitySet` and a mutable
/// reference to them is given instead. This is done to avoid storing owned capabilities in the
/// state of the logic future which would make using the `?` operator unsafe, since the
/// frontiers would incorrectly advance, potentially causing incorrect actions downstream.
///
/// ```ignore
/// builder.build_fallible(|caps| Box::pin(async move {
/// // Assert that we have the number of capabilities we expect
/// // `cap` will be a `&mut Option<Capability<T>>`:
/// let [cap_set]: &mut [_; 1] = caps.try_into().unwrap();
///
/// // Using cap to send data:
/// output.give(&cap_set[0], 42);
///
/// // Using cap_set to downgrade it:
/// cap_set.downgrade([]);
///
/// // Explicitly dropping the capability:
/// // Simply running `drop(cap_set)` will only drop the reference and not the capability set itself!
/// *cap_set = CapabilitySet::new();
///
/// // !! BIG WARNING !!:
/// // It is tempting to `take` the capability out of the set for convenience. This will
/// // move the capability into the future state, tying its lifetime to it, which will get
/// // dropped when an error is hit, causing incorrect progress statements.
/// let cap = cap_set.delayed(&Timestamp::minimum());
/// *cap_set = CapabilitySet::new(); // DO NOT DO THIS
/// }));
/// ```
pub fn build_fallible<E: 'static, F>(
mut self,
constructor: F,
) -> (Button, StreamCore<G, Vec<Rc<E>>>)
where
F: for<'a> FnOnce(
&'a mut [CapabilitySet<G::Timestamp>],
) -> Pin<Box<dyn Future<Output = Result<(), E>> + 'a>>
+ 'static,
{
// Create a new completely disconnected output
let (error_output, error_stream) = self.new_output();
let button = self.build(|mut caps| async move {
let error_cap = caps.pop().unwrap();
let mut caps = caps
.into_iter()
.map(CapabilitySet::from_elem)
.collect::<Vec<_>>();
if let Err(err) = constructor(&mut *caps).await {
error_output.give(&error_cap, Rc::new(err));
drop(error_cap);
// IMPORTANT: wedge this operator until the button is pressed. Returning would drop
// the capabilities and could produce incorrect progress statements.
std::future::pending().await
}
});
(button, error_stream)
}
/// Creates operator info for the operator.
pub fn operator_info(&self) -> OperatorInfo {
self.builder.operator_info()
}
/// Returns the activator for the operator.
pub fn activator(&self) -> &Activator {
&self.activator
}
}
/// Creates a new coordinated button the worker configuration described by `scope`.
pub fn button<G: Scope>(scope: &mut G, addr: Rc<[usize]>) -> (ButtonHandle, Button) {
let index = scope.new_identifier();
let (pushers, puller) = scope.allocate(index, addr);
let local_pressed = Rc::new(Cell::new(false));
let handle = ButtonHandle {
buttons_remaining: scope.peers(),
local_pressed: Rc::clone(&local_pressed),
puller,
};
let token = Button {
pushers,
local_pressed,
};
(handle, token)
}
/// A button that can be used to coordinate an action after all workers have pressed it.
pub struct ButtonHandle {
/// The number of buttons still unpressed among workers.
buttons_remaining: usize,
/// A flag indicating whether this worker has pressed its button.
local_pressed: Rc<Cell<bool>>,
puller: Box<dyn Pull<Message<bool>>>,
}
impl ButtonHandle {
/// Returns whether this worker has pressed its button.
pub fn local_pressed(&self) -> bool {
self.local_pressed.get()
}
/// Returns whether all workers have pressed their buttons.
pub fn all_pressed(&mut self) -> bool {
while self.puller.recv().is_some() {
self.buttons_remaining -= 1;
}
self.buttons_remaining == 0
}
}
pub struct Button {
pushers: Vec<Box<dyn Push<Message<bool>>>>,
local_pressed: Rc<Cell<bool>>,
}
impl Button {
/// Presses the button. It is safe to call this function multiple times.
pub fn press(&mut self) {
for mut pusher in self.pushers.drain(..) {
pusher.send(Message::from_typed(true));
pusher.done();
}
self.local_pressed.set(true);
}
/// Converts this button into a deadman's switch that will automatically press the button when
/// dropped.
pub fn press_on_drop(self) -> PressOnDropButton {
PressOnDropButton(self)
}
}
pub struct PressOnDropButton(Button);
impl Drop for PressOnDropButton {
fn drop(&mut self) {
self.0.press();
}
}
#[cfg(test)]
mod test {
use futures_util::StreamExt;
use timely::dataflow::channels::pact::Pipeline;
use timely::dataflow::operators::capture::Extract;
use timely::dataflow::operators::{Capture, ToStream};
use timely::WorkerConfig;
use super::*;
#[mz_ore::test]
fn async_operator() {
let capture = timely::example(|scope| {
let input = (0..10).to_stream(scope);
let mut op = OperatorBuilder::new("async_passthru".to_string(), input.scope());
let (output, output_stream) = op.new_output();
let mut input_handle = op.new_input_for(&input, Pipeline, &output);
op.build(move |_capabilities| async move {
tokio::task::yield_now().await;
while let Some(event) = input_handle.next().await {
match event {
Event::Data(cap, data) => {
for item in data.iter().copied() {
tokio::task::yield_now().await;
output.give(&cap, item);
}
}
Event::Progress(_frontier) => {}
}
}
});
output_stream.capture()
});
let extracted = capture.extract();
assert_eq!(extracted, vec![(0, vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9])]);
}
#[mz_ore::test]
fn gh_18837() {
let (builders, other) = timely::CommunicationConfig::Process(2).try_build().unwrap();
timely::execute::execute_from(builders, other, WorkerConfig::default(), |worker| {
let index = worker.index();
let tokens = worker.dataflow::<u64, _, _>(move |scope| {
let mut producer = OperatorBuilder::new("producer".to_string(), scope.clone());
let (_output, output_stream) =
producer.new_output::<CapacityContainerBuilder<Vec<usize>>>();
let producer_button = producer.build(move |mut capabilities| async move {
let mut cap = capabilities.pop().unwrap();
if index != 0 {
return;
}
// Worker 0 downgrades to 1 and keeps the capability around forever
cap.downgrade(&1);
std::future::pending().await
});
let mut consumer = OperatorBuilder::new("consumer".to_string(), scope.clone());
let mut input_handle = consumer.new_disconnected_input(&output_stream, Pipeline);
let consumer_button = consumer.build(move |_| async move {
while let Some(event) = input_handle.next().await {
if let Event::Progress(frontier) = event {
// We should never observe a frontier greater than [1]
assert!(frontier.less_equal(&1));
}
}
});
(
producer_button.press_on_drop(),
consumer_button.press_on_drop(),
)
});
// Run dataflow until only worker 0 holds the frontier to [1]
for _ in 0..100 {
worker.step();
}
// Then drop the tokens of worker 0
if index == 0 {
drop(tokens)
}
// And step the dataflow some more to ensure consumers don't observe frontiers advancing.
for _ in 0..100 {
worker.step();
}
})
.expect("timely panicked");
}
}