From db5c2ee37eebb89b4bfb9637729b1685ddb82ce5 Mon Sep 17 00:00:00 2001
From: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Date: Mon, 2 Dec 2024 20:10:20 +0000
Subject: [PATCH] toolchains: Run listing tasks on background thread (#21414)

Potentially fixes #21404

This is a speculative fix, as while I was trying to repro this issue
I've noticed that introducing artificial delays in ToolchainLister::list
could impact apps responsiveness. These delays were essentially there to
stimulate PET taking a while to find venvs.

Release Notes:

- Improved app responsiveness in environments with multiple Python
virtual environments
---
 crates/language/src/toolchain.rs      |  2 +-
 crates/languages/src/python.rs        |  2 +-
 crates/project/src/toolchain_store.rs | 14 ++++++++------
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/crates/language/src/toolchain.rs b/crates/language/src/toolchain.rs
index cd9a3bc4032b0d..3fc1ac4514834c 100644
--- a/crates/language/src/toolchain.rs
+++ b/crates/language/src/toolchain.rs
@@ -22,7 +22,7 @@ pub struct Toolchain {
     pub language_name: LanguageName,
 }
 
-#[async_trait(?Send)]
+#[async_trait]
 pub trait ToolchainLister: Send + Sync {
     async fn list(
         &self,
diff --git a/crates/languages/src/python.rs b/crates/languages/src/python.rs
index de4bf2f2c2ec2c..abc56946786dec 100644
--- a/crates/languages/src/python.rs
+++ b/crates/languages/src/python.rs
@@ -526,7 +526,7 @@ fn env_priority(kind: Option<PythonEnvironmentKind>) -> usize {
     }
 }
 
-#[async_trait(?Send)]
+#[async_trait]
 impl ToolchainLister for PythonToolchainProvider {
     async fn list(
         &self,
diff --git a/crates/project/src/toolchain_store.rs b/crates/project/src/toolchain_store.rs
index c601ff8f12c86e..cd5f10617839cb 100644
--- a/crates/project/src/toolchain_store.rs
+++ b/crates/project/src/toolchain_store.rs
@@ -308,12 +308,14 @@ impl LocalToolchainStore {
                 })
                 .ok()?
                 .await;
-            let language = registry.language_for_name(&language_name.0).await.ok()?;
-            let toolchains = language
-                .toolchain_lister()?
-                .list(root.to_path_buf(), project_env)
-                .await;
-            Some(toolchains)
+
+            cx.background_executor()
+                .spawn(async move {
+                    let language = registry.language_for_name(&language_name.0).await.ok()?;
+                    let toolchains = language.toolchain_lister()?;
+                    Some(toolchains.list(root.to_path_buf(), project_env).await)
+                })
+                .await
         })
     }
     pub(crate) fn active_toolchain(