perf(vfs): list directories off the main thread (#973)

`fs_read_dir` was a synchronous Tauri command, so every directory listing ran on the main thread. On a slow file system such as a network share (`\\wsl.localhost\...`), each stat while expanding the project tree stalled the whole UI. The listing now runs on the blocking pool, as the other disk-heavy commands do, both for the desktop command and over RPC.

Refs #916.

Co-authored-by: ntbang0901 <[email protected]>

crates/ide-host/src/ops/fs.rs

@@ -73,24 +73,28 @@ pub async fn copy_merge(
 /// Files of a deleted folder snapshotted in Local History.
 const DELETE_SNAPSHOT_LIMIT: usize = 2000;
 
-pub fn read_dir(host: &Host, window: &str, path: PathBuf) -> IdeResult<Vec<FileEntry>> {
-    let excludes = host
-        .project(window)
-        .map(|p| {
-            let globs = p.exclude_globs();
-            // `read_dir` matches relative to the enclosing repository: re-anchor
-            // project-root patterns (`/build`) when the project is a repo subfolder.
-            let repo = p.root.ancestors().find(|d| d.join(".git").exists());
-            match repo.and_then(|r| p.root.strip_prefix(r).ok()).filter(|rel| !rel.as_os_str().is_empty()) {
-                Some(rel) => {
-                    let rel = rel.to_string_lossy().replace('\\', "/");
-                    globs.into_iter().map(|g| if g.starts_with('/') { format!("/{rel}{g}") } else { g }).collect()
+/// Runs on the blocking pool: on a network share (`\\wsl.localhost`) every stat is slow.
+pub async fn read_dir(host: &Host, window: &str, path: PathBuf) -> IdeResult<Vec<FileEntry>> {
+    let project = host.project(window);
+    host.blocking(move || {
+        let excludes = project
+            .map(|p| {
+                let globs = p.exclude_globs();
+                // `read_dir` matches relative to the enclosing repository: re-anchor
+                // project-root patterns (`/build`) when the project is a repo subfolder.
+                let repo = p.root.ancestors().find(|d| d.join(".git").exists());
+                match repo.and_then(|r| p.root.strip_prefix(r).ok()).filter(|rel| !rel.as_os_str().is_empty()) {
+                    Some(rel) => {
+                        let rel = rel.to_string_lossy().replace('\\', "/");
+                        globs.into_iter().map(|g| if g.starts_with('/') { format!("/{rel}{g}") } else { g }).collect()
+                    }
+                    None => globs,
                 }
-                None => globs,
-            }
-        })
-        .unwrap_or_default();
-    ide_vfs::read_dir(&path, &excludes)
+            })
+            .unwrap_or_default();
+        ide_vfs::read_dir(&path, &excludes)
+    })
+    .await
 }
 
 /// Creates an empty file; inside a project, honours the EditorConfig

crates/ide-host/src/rpc.rs

@@ -178,7 +178,7 @@ impl Dispatcher {
             Ok(())
         })
         .add("cancel_task", |c| async move { Ok(ide_core::task::cancel(c.arg::<TaskId>("id")?)) })
-        .add("fs_read_dir", |c| async move { ops::fs::read_dir(&c.host, &c.window, c.arg("path")?) })
+        .add("fs_read_dir", |c| async move { ops::fs::read_dir(&c.host, &c.window, c.arg("path")?).await })
         .add("fs_entry_kind", |c| async move { ops::fs::entry_kind(&c.host, c.arg("path")?).await })
         .add("fs_create_file", |c| async move { ops::fs::create_file(&c.host, &c.window, c.arg("path")?) })
         .add("fs_create_file_bytes", |c| async move {

src-tauri/src/commands/fs.rs

@@ -39,8 +39,8 @@ pub async fn fs_copy_merge(
 
 #[tauri::command]
 #[specta::specta]
-pub fn fs_read_dir(window: Window, state: State<'_, AppState>, path: PathBuf) -> IdeResult<Vec<FileEntry>> {
-    fs::read_dir(&state.host, window.label(), path)
+pub async fn fs_read_dir(window: Window, state: State<'_, AppState>, path: PathBuf) -> IdeResult<Vec<FileEntry>> {
+    fs::read_dir(&state.host, window.label(), path).await
 }
 
 /// Creates an empty file; inside a project, honours the EditorConfig