Request a UI redraw on Drop of an Injector

This fixes the changed files picker when used against a clean worktree
for example. Without it the running indicator does not disappear. It
also simplifies the dynamic query handler's implementation so that it
doesn't need to request a redraw explicitly.

Co-authored-by: Pascal Kuthe <pascalkuthe@pm.me>

helix-event/src/lib.rs

@@ -34,7 +34,9 @@
 use anyhow::Result;
 pub use cancel::{cancelable_future, cancelation, CancelRx, CancelTx};
 pub use debounce::{send_blocking, AsyncHook};
-pub use redraw::{lock_frame, redraw_requested, request_redraw, start_frame, RenderLockGuard};
+pub use redraw::{
+    lock_frame, redraw_requested, request_redraw, start_frame, RenderLockGuard, RequestRedrawOnDrop,
+};
 pub use registry::Event;
 
 mod cancel;

helix-event/src/redraw.rs

@@ -51,3 +51,12 @@ pub fn start_frame() {
 pub fn lock_frame() -> RenderLockGuard {
     RENDER_LOCK.read()
 }
+
+/// A zero sized type that requests a redraw via [request_redraw] when the type [Drop]s.
+pub struct RequestRedrawOnDrop;
+
+impl Drop for RequestRedrawOnDrop {
+    fn drop(&mut self) {
+        request_redraw();
+    }
+}

helix-term/src/ui/picker.rs

@@ -153,6 +153,12 @@ pub struct Injector<T, D> {
     editor_data: Arc<D>,
     version: usize,
     picker_version: Arc<AtomicUsize>,
+    /// A marker that requests a redraw when the injector drops.
+    /// This marker causes the "running" indicator to disappear when a background job
+    /// providing items is finished and drops. This could be wrapped in an [Arc] to ensure
+    /// that the redraw is only requested when all Injectors drop for a Picker (which removes
+    /// the "running" indicator) but the redraw handle is debounced so this is unnecessary.
+    _redraw: helix_event::RequestRedrawOnDrop,
 }
 
 impl<I, D> Clone for Injector<I, D> {
@@ -163,6 +169,7 @@ impl<I, D> Clone for Injector<I, D> {
             editor_data: self.editor_data.clone(),
             version: self.version,
             picker_version: self.picker_version.clone(),
+            _redraw: helix_event::RequestRedrawOnDrop,
         }
     }
 }
@@ -284,6 +291,7 @@ impl<T: 'static + Send + Sync, D: 'static + Send + Sync> Picker<T, D> {
             editor_data: Arc::new(editor_data),
             version: 0,
             picker_version: Arc::new(AtomicUsize::new(0)),
+            _redraw: helix_event::RequestRedrawOnDrop,
         };
         (matcher, streamer)
     }
@@ -386,6 +394,7 @@ impl<T: 'static + Send + Sync, D: 'static + Send + Sync> Picker<T, D> {
             editor_data: self.editor_data.clone(),
             version: self.version.load(atomic::Ordering::Relaxed),
             picker_version: self.version.clone(),
+            _redraw: helix_event::RequestRedrawOnDrop,
         }
     }
 

helix-term/src/ui/picker/handlers.rs

@@ -174,11 +174,8 @@ impl<T: 'static + Send + Sync, D: 'static + Send + Sync> AsyncHook for DynamicQu
                 if let Err(err) = get_options.await {
                     log::info!("Dynamic request failed: {err}");
                 }
-                // The picker's shows its running indicator when there are any active
+                // NOTE: the Drop implementation of Injector will request a redraw when the
-                // injectors. When we're done injecting new options, drop the injector
+                // injector falls out of scope here, clearing the "running" indicator.
-                // and request a redraw to remove the running indicator.
-                drop(injector);
-                helix_event::request_redraw();
             });
         })
     }