partway towards commands

I got very confused and started mucking about with "spawn" when in fact all I needed was the "inline" extension type in orcx that allows the interpreter to expose custom constants.

orchid-async-utils/src/debug.rs

@@ -0,0 +1,185 @@
+//! Note that these utilities are safe and simple in order to facilitate
+//! debugging without adding more points of failure, but they're not efficient;
+//! they may perform heap allocations, I/O and other expensive operations, or
+//! even block the thread altogether waiting for input whenever they receive
+//! control
+
+use std::cell::RefCell;
+use std::fmt::Display;
+use std::pin::pin;
+use std::rc::Rc;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::task::{Context, Poll, Wake, Waker};
+use std::thread::panicking;
+
+use futures::Stream;
+use itertools::Itertools;
+use task_local::task_local;
+
+struct OnPollWaker<F: Fn() + 'static>(Waker, F);
+impl<F: Fn() + 'static> Wake for OnPollWaker<F> {
+	fn wake(self: Arc<Self>) {
+		(self.1)();
+		self.0.wake_by_ref()
+	}
+}
+
+/// Attach a callback to the [Future] protocol for testing and debugging.
+pub async fn on_wake<F: Future>(
+	f: F,
+	wake: impl Fn() + Clone + Send + Sync + 'static,
+) -> F::Output {
+	let mut f = pin!(f);
+	futures::future::poll_fn(|cx| {
+		let waker = Arc::new(OnPollWaker(cx.waker().clone(), wake.clone())).into();
+		f.as_mut().poll(&mut Context::from_waker(&waker))
+	})
+	.await
+}
+
+/// Respond to [Future::poll] with a callback. For maximum flexibility and state
+/// control, your callback receives the actual poll job as a callback function.
+/// Failure to call this function will result in an immediate panic.
+pub async fn wrap_poll<Fut: Future>(
+	f: Fut,
+	mut cb: impl FnMut(Box<dyn FnOnce() -> bool + '_>),
+) -> Fut::Output {
+	let mut f = pin!(f);
+	futures::future::poll_fn(|cx| {
+		let poll = RefCell::new(None);
+		cb(Box::new(|| {
+			let poll1 = f.as_mut().poll(cx);
+			let ret = poll1.is_ready();
+			*poll.borrow_mut() = Some(poll1);
+			ret
+		}));
+		poll.into_inner().expect("Callback to on_poll failed to call its argument")
+	})
+	.await
+}
+
+/// Respond to [Stream::poll_next] with a callback. The semantics of the
+/// callback are identical to that in [wrap_poll]
+pub fn wrap_poll_next<'a, S: Stream + 'a>(
+	s: S,
+	mut cb: impl FnMut(Box<dyn FnOnce() -> bool + '_>) + 'a,
+) -> impl Stream<Item = S::Item> + 'a {
+	let mut s = Box::pin(s);
+	futures::stream::poll_fn(move |cx| {
+		let poll = RefCell::new(None);
+		cb(Box::new(|| {
+			let poll1 = s.as_mut().poll_next(cx);
+			let ret = poll1.is_ready();
+			*poll.borrow_mut() = Some(poll1);
+			ret
+		}));
+		poll.into_inner().expect("Callback to on_poll failed to call its argument")
+	})
+}
+
+/// Attach a callback to the [Stream] protocol for testing and debugging.
+pub fn on_stream_wake<'a, S: Stream + 'a>(
+	s: S,
+	wake: impl Fn() + Clone + Send + Sync + 'static,
+) -> impl Stream<Item = S::Item> {
+	let mut s = Box::pin(s);
+	futures::stream::poll_fn(move |cx| {
+		let waker = Arc::new(OnPollWaker(cx.waker().clone(), wake.clone())).into();
+		s.as_mut().poll_next(&mut Context::from_waker(&waker))
+	})
+}
+
+task_local! {
+	static LABEL_STATE: Vec<Rc<String>>
+}
+
+/// Add a label to the "label stack" for the duration of a future that helps you
+/// efficiently visualize important aspects of the call stack during logging
+pub async fn with_label<Fut: Future>(label: &str, f: Fut) -> Fut::Output {
+	let mut new_lbl = LABEL_STATE.try_with(|lbl| lbl.clone()).unwrap_or_default();
+	new_lbl.push(Rc::new(label.to_string()));
+	LABEL_STATE.scope(new_lbl, f).await
+}
+
+/// Allows to print the label stack
+pub fn label() -> impl Display + Clone + Send + Sync + 'static {
+	LABEL_STATE.try_with(|lbl| lbl.iter().join("/")).unwrap_or("".to_string())
+}
+
+/// Displays the label stack when printed
+pub struct Label;
+impl Display for Label {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}", label()) }
+}
+
+/// Attaches generic eprintln handlers to a future
+pub async fn eprint_events<Fut: Future>(note: &str, f: Fut) -> Fut::Output {
+	let label = label();
+	let note1 = note.to_string();
+	on_wake(
+		wrap_poll(f, |cb| {
+			eprintln!("{Label} polling {note}");
+			eprintln!("{Label} polled {note} (ready? {})", cb())
+		}),
+		move || eprintln!("{label} woke {note1}"),
+	)
+	.await
+}
+
+/// Attaches generic eprintln handlers to a stream
+pub fn eprint_stream_events<'a, S: Stream + 'a>(
+	note: &'a str,
+	s: S,
+) -> impl Stream<Item = S::Item> + 'a {
+	let label = label();
+	let note1 = note.to_string();
+	on_stream_wake(
+		wrap_poll_next(s, move |cb| {
+			eprintln!("{Label} polling {note}");
+			eprintln!("{Label} polled {note} (ready? {})", cb())
+		}),
+		move || eprintln!("{label} woke {note1}"),
+	)
+}
+
+struct SpinWaker(AtomicBool);
+impl Wake for SpinWaker {
+	fn wake(self: Arc<Self>) { self.0.store(true, Ordering::Relaxed); }
+}
+
+/// A dumb executor that keeps synchronously re-running the future as long as it
+/// keeps synchronously waking itself. This is useful for deterministic tests
+/// that don't contain side effects or threading.
+///
+/// # Panics
+///
+/// If the future doesn't wake itself and doesn't settle.
+pub fn spin_on<Fut: Future>(f: Fut) -> Fut::Output {
+	let repeat = Arc::new(SpinWaker(AtomicBool::new(false)));
+	let mut f = pin!(f);
+	let waker = repeat.clone().into();
+	let mut cx = Context::from_waker(&waker);
+	loop {
+		match f.as_mut().poll(&mut cx) {
+			Poll::Ready(t) => break t,
+			Poll::Pending if repeat.0.swap(false, Ordering::Relaxed) => (),
+			Poll::Pending => panic!("The future did not exit and did not call its waker."),
+		}
+	}
+}
+
+/// Create an object that will panic if dropped. [PanicOnDrop::defuse] must be
+/// called once the particular constraint preventing a drop has passed
+pub fn assert_no_drop(msg: &'static str) -> PanicOnDrop { PanicOnDrop(true, msg) }
+
+/// This object will panic if dropped. Call [Self::defuse] when dropping is safe
+/// again
+pub struct PanicOnDrop(bool, &'static str);
+impl PanicOnDrop {
+	/// Allow dropping the object without causing a panic
+	pub fn defuse(mut self) { self.0 = false; }
+}
+impl Drop for PanicOnDrop {
+	fn drop(&mut self) { assert!(panicking() || !self.0, "{}", self.1) }
+}