From 3fe6d224e3837867dfbcdca3064573a89bc5bbe6 Mon Sep 17 00:00:00 2001
From: cschen <cschen@codemp.dev>
Date: Sat, 17 Aug 2024 01:12:35 +0200
Subject: [PATCH] feat(python): summon black magic to allow possible release of
 the GIL between .awaits plus nice static runtime singleton
 fetcher/instantiator

---
 src/ffi/python/controllers.rs | 18 +++++++++---------
 src/ffi/python/mod.rs         | 29 +++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/src/ffi/python/controllers.rs b/src/ffi/python/controllers.rs
index 359c9de..fadab5c 100644
--- a/src/ffi/python/controllers.rs
+++ b/src/ffi/python/controllers.rs
@@ -16,22 +16,22 @@ impl CursorController {
 			buffer: path,
 			user: None,
 		};
-		self.send(pos).await
+		super::AllowThreads(self.send(pos)).await
 	}
 
 	#[pyo3(name = "try_recv")]
 	async fn pytry_recv(&self) -> crate::Result<Option<Cursor>> {
-		self.try_recv().await
+		super::AllowThreads(self.try_recv()).await
 	}
 
 	#[pyo3(name = "recv")]
 	async fn pyrecv(&self) -> crate::Result<Cursor> {
-		self.recv().await
+		super::AllowThreads(self.recv()).await
 	}
 
 	#[pyo3(name = "poll")]
 	async fn pypoll(&self) -> crate::Result<()> {
-		self.poll().await
+		super::AllowThreads(self.poll()).await
 	}
 
 	#[pyo3(name = "stop")]
@@ -45,7 +45,7 @@ impl CursorController {
 impl BufferController {
 	#[pyo3(name = "content")]
 	async fn pycontent(&self) -> crate::Result<String> {
-		self.content().await
+		super::AllowThreads(Box::pin(self.content())).await
 	}
 
 	#[pyo3(name = "send")]
@@ -56,22 +56,22 @@ impl BufferController {
 			content: txt,
 			hash: None,
 		};
-		self.send(op).await
+		super::AllowThreads(self.send(op)).await
 	}
 
 	#[pyo3(name = "try_recv")]
 	async fn pytry_recv(&self) -> crate::Result<Option<TextChange>> {
-		self.try_recv().await
+		super::AllowThreads(self.try_recv()).await
 	}
 
 	#[pyo3(name = "recv")]
 	async fn pyrecv(&self) -> crate::Result<TextChange> {
-		self.recv().await
+		super::AllowThreads(self.recv()).await
 	}
 
 	#[pyo3(name = "poll")]
 	async fn pypoll(&self) -> crate::Result<()> {
-		self.poll().await
+		super::AllowThreads(self.poll()).await
 	}
 }
 
diff --git a/src/ffi/python/mod.rs b/src/ffi/python/mod.rs
index a455b4f..a1c30ef 100644
--- a/src/ffi/python/mod.rs
+++ b/src/ffi/python/mod.rs
@@ -3,6 +3,11 @@ pub mod controllers;
 pub mod workspace;
 
 use std::sync::Arc;
+use std::{
+	future::Future,
+	pin::{pin, Pin},
+	task::{Context, Poll},
+};
 
 use crate::{
 	api::{Cursor, TextChange},
@@ -14,6 +19,30 @@ use pyo3::exceptions::{PyConnectionError, PyRuntimeError, PySystemError};
 use pyo3::prelude::*;
 use tokio::sync::{mpsc, Mutex};
 
+fn tokio() -> &'static tokio::runtime::Runtime {
+	use std::sync::OnceLock;
+	static RT: OnceLock<tokio::runtime::Runtime> = OnceLock::new();
+	RT.get_or_init(|| tokio::runtime::Runtime::new().unwrap())
+}
+
+// workaround to allow the GIL to be released across awaits
+struct AllowThreads<F>(F);
+
+impl<F> Future for AllowThreads<F>
+where
+	F: Future + Unpin + Send,
+	F::Output: Send,
+{
+	type Output = F::Output;
+
+	fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+		let waker = cx.waker();
+		Python::with_gil(|gil| {
+			gil.allow_threads(|| pin!(&mut self.0).poll(&mut Context::from_waker(waker)))
+		})
+	}
+}
+
 impl From<crate::Error> for PyErr {
 	fn from(value: crate::Error) -> Self {
 		match value {