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refactor: drop futures_util dependency
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wyfo committed Dec 3, 2023
1 parent 75eaaff commit d48c8e9
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Showing 3 changed files with 27 additions and 23 deletions.
3 changes: 0 additions & 3 deletions Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,6 @@ unindent = { version = "0.2.1", optional = true }
# support crate for multiple-pymethods feature
inventory = { version = "0.3.0", optional = true }

# coroutine implementation
futures-util = "0.3"

# crate integrations that can be added using the eponymous features
anyhow = { version = "1.0", optional = true }
chrono = { version = "0.4.25", default-features = false, optional = true }
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33 changes: 18 additions & 15 deletions src/coroutine.rs
Original file line number Diff line number Diff line change
@@ -1,21 +1,19 @@
//! Python coroutine implementation, used notably when wrapping `async fn`
//! with `#[pyfunction]`/`#[pymethods]`.
use std::task::Waker;
use std::{
any::Any,
future::Future,
panic,
pin::Pin,
sync::Arc,
task::{Context, Poll},
};

use futures_util::FutureExt;
use pyo3_macros::{pyclass, pymethods};

use crate::{
coroutine::waker::AsyncioWaker,
exceptions::{PyAttributeError, PyRuntimeError, PyStopIteration},
panic::PanicException,
pyclass::IterNextOutput,
types::{PyIterator, PyString},
IntoPy, Py, PyAny, PyErr, PyObject, PyResult, Python,
Expand All @@ -25,19 +23,18 @@ pub(crate) mod cancel;
mod waker;

use crate::coroutine::cancel::ThrowCallback;
use crate::panic::PanicException;
pub use cancel::CancelHandle;

const COROUTINE_REUSED_ERROR: &str = "cannot reuse already awaited coroutine";

type FutureOutput = Result<PyResult<PyObject>, Box<dyn Any + Send>>;

/// Python coroutine wrapping a [`Future`].
#[pyclass(crate = "crate")]
pub struct Coroutine {
name: Option<Py<PyString>>,
qualname_prefix: Option<&'static str>,
throw_callback: Option<ThrowCallback>,
future: Option<Pin<Box<dyn Future<Output = FutureOutput> + Send>>>,
future: Option<Pin<Box<dyn Future<Output = PyResult<PyObject>> + Send>>>,
waker: Option<Arc<AsyncioWaker>>,
}

Expand Down Expand Up @@ -68,7 +65,7 @@ impl Coroutine {
name,
qualname_prefix,
throw_callback,
future: Some(Box::pin(panic::AssertUnwindSafe(wrap).catch_unwind())),
future: Some(Box::pin(wrap)),
waker: None,
}
}
Expand Down Expand Up @@ -98,22 +95,28 @@ impl Coroutine {
} else {
self.waker = Some(Arc::new(AsyncioWaker::new()));
}
let waker = futures_util::task::waker(self.waker.clone().unwrap());
let waker = Waker::from(self.waker.clone().unwrap());
// poll the Rust future and forward its results if ready
if let Poll::Ready(res) = future_rs.as_mut().poll(&mut Context::from_waker(&waker)) {
self.close();
return match res {
Ok(res) => Ok(IterNextOutput::Return(res?)),
Err(err) => Err(PanicException::from_panic_payload(err)),
};
// polling is UnwindSafe because the future is dropped in case of panic
let poll = || future_rs.as_mut().poll(&mut Context::from_waker(&waker));
match panic::catch_unwind(panic::AssertUnwindSafe(poll)) {
Ok(Poll::Ready(res)) => {
self.close();
return Ok(IterNextOutput::Return(res?));
}
Err(err) => {
self.close();
return Err(PanicException::from_panic_payload(err));
}
_ => {}
}
// otherwise, initialize the waker `asyncio.Future`
if let Some(future) = self.waker.as_ref().unwrap().initialize_future(py)? {
// `asyncio.Future` must be awaited; fortunately, it implements `__iter__ = __await__`
// and will yield itself if its result has not been set in polling above
if let Some(future) = PyIterator::from_object(future).unwrap().next() {
// future has not been leaked into Python for now, and Rust code can only call
// `set_result(None)` in `ArcWake` implementation, so it's safe to unwrap
// `set_result(None)` in `Wake` implementation, so it's safe to unwrap
return Ok(IterNextOutput::Yield(future.unwrap().into()));
}
}
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14 changes: 9 additions & 5 deletions src/coroutine/waker.rs
Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
use crate::sync::GILOnceCell;
use crate::types::PyCFunction;
use crate::{intern, wrap_pyfunction, Py, PyAny, PyObject, PyResult, Python};
use futures_util::task::ArcWake;
use pyo3_macros::pyfunction;
use std::sync::Arc;
use std::task::Wake;

/// Lazy `asyncio.Future` wrapper, implementing [`ArcWake`] by calling `Future.set_result`.
/// Lazy `asyncio.Future` wrapper, implementing [`Wake`] by calling `Future.set_result`.
///
/// asyncio future is let uninitialized until [`initialize_future`][1] is called.
/// If [`wake`][2] is called before future initialization (during Rust future polling),
Expand All @@ -31,10 +31,14 @@ impl AsyncioWaker {
}
}

impl ArcWake for AsyncioWaker {
fn wake_by_ref(arc_self: &Arc<Self>) {
impl Wake for AsyncioWaker {
fn wake(self: Arc<Self>) {
self.wake_by_ref()
}

fn wake_by_ref(self: &Arc<Self>) {
Python::with_gil(|gil| {
if let Some(loop_and_future) = arc_self.0.get_or_init(gil, || None) {
if let Some(loop_and_future) = self.0.get_or_init(gil, || None) {
loop_and_future
.set_result(gil)
.expect("unexpected error in coroutine waker");
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