Switch from Arc/RwLock to Rc/RefCell for CodeContextMenu (zed-industr…

…ies#22035)

`CodeContextMenu` is always accessed on one thread, so only `Rc`s and
`Rc<RefCell<_>>` are needed. There should be tiny performance benefits
from this. The main benefit of this is that when seeing code accessing a
`RwLock` it would be reasonable to wonder whether it will block. The
only potential downside is the potential for panics due to overlapping
borrows of the RefCells. I think this is an acceptable risk because most
errors of this nature will be local or will be caught by clippy via the
check for holding a RefCell reference over an `await`.

Release Notes:

- N/A

crates/assistant/src/inline_assistant.rs

@@ -47,6 +47,7 @@ use std::{
     iter, mem,
     ops::{Range, RangeInclusive},
     pin::Pin,
+    rc::Rc,
     sync::Arc,
     task::{self, Poll},
     time::{Duration, Instant},
@@ -174,7 +175,7 @@ impl InlineAssistant {
         if let Some(editor) = item.act_as::<Editor>(cx) {
             editor.update(cx, |editor, cx| {
                 editor.push_code_action_provider(
-                    Arc::new(AssistantCodeActionProvider {
+                    Rc::new(AssistantCodeActionProvider {
                         editor: cx.view().downgrade(),
                         workspace: workspace.downgrade(),
                     }),

crates/assistant/src/slash_command.rs

@@ -7,11 +7,13 @@ use editor::{CompletionProvider, Editor};
 use fuzzy::{match_strings, StringMatchCandidate};
 use gpui::{AppContext, Model, Task, ViewContext, WeakView, WindowContext};
 use language::{Anchor, Buffer, CodeLabel, Documentation, HighlightId, LanguageServerId, ToPoint};
-use parking_lot::{Mutex, RwLock};
+use parking_lot::Mutex;
 use project::CompletionIntent;
 use rope::Point;
 use std::{
+    cell::RefCell,
     ops::Range,
+    rc::Rc,
     sync::{
         atomic::{AtomicBool, Ordering::SeqCst},
         Arc,
@@ -322,7 +324,7 @@ impl CompletionProvider for SlashCommandCompletionProvider {
         &self,
         _: Model<Buffer>,
         _: Vec<usize>,
-        _: Arc<RwLock<Box<[project::Completion]>>>,
+        _: Rc<RefCell<Box<[project::Completion]>>>,
         _: &mut ViewContext<Editor>,
     ) -> Task<Result<bool>> {
         Task::ready(Ok(true))

crates/assistant2/src/inline_assistant.rs

@@ -45,6 +45,7 @@ use std::{
     iter, mem,
     ops::{Range, RangeInclusive},
     pin::Pin,
+    rc::Rc,
     sync::Arc,
     task::{self, Poll},
     time::Instant,
@@ -178,7 +179,7 @@ impl InlineAssistant {
         if let Some(editor) = item.act_as::<Editor>(cx) {
             editor.update(cx, |editor, cx| {
                 editor.push_code_action_provider(
-                    Arc::new(AssistantCodeActionProvider {
+                    Rc::new(AssistantCodeActionProvider {
                         editor: cx.view().downgrade(),
                         workspace: workspace.downgrade(),
                     }),

crates/collab_ui/Cargo.toml

@@ -44,7 +44,6 @@ gpui.workspace = true
 language.workspace = true
 menu.workspace = true
 notifications.workspace = true
-parking_lot.workspace = true
 picker.workspace = true
 project.workspace = true
 release_channel.workspace = true

crates/collab_ui/src/chat_panel/message_editor.rs

@@ -12,10 +12,15 @@ use language::{
     language_settings::SoftWrap, Anchor, Buffer, BufferSnapshot, CodeLabel, LanguageRegistry,
     LanguageServerId, ToOffset,
 };
-use parking_lot::RwLock;
 use project::{search::SearchQuery, Completion};
 use settings::Settings;
-use std::{ops::Range, sync::Arc, sync::LazyLock, time::Duration};
+use std::{
+    cell::RefCell,
+    ops::Range,
+    rc::Rc,
+    sync::{Arc, LazyLock},
+    time::Duration,
+};
 use theme::ThemeSettings;
 use ui::{prelude::*, TextSize};
 
@@ -68,7 +73,7 @@ impl CompletionProvider for MessageEditorCompletionProvider {
         &self,
         _buffer: Model<Buffer>,
         _completion_indices: Vec<usize>,
-        _completions: Arc<RwLock<Box<[Completion]>>>,
+        _completions: Rc<RefCell<Box<[Completion]>>>,
         _cx: &mut ViewContext<Editor>,
     ) -> Task<anyhow::Result<bool>> {
         Task::ready(Ok(false))

crates/editor/src/code_context_menus.rs

@@ -1,4 +1,5 @@
-use std::{cell::Cell, cmp::Reverse, ops::Range, sync::Arc};
+use std::cell::RefCell;
+use std::{cell::Cell, cmp::Reverse, ops::Range, rc::Rc};
 
 use fuzzy::{StringMatch, StringMatchCandidate};
 use gpui::{
@@ -11,7 +12,6 @@ use language::{CodeLabel, Documentation};
 use lsp::LanguageServerId;
 use multi_buffer::{Anchor, ExcerptId};
 use ordered_float::OrderedFloat;
-use parking_lot::RwLock;
 use project::{CodeAction, Completion, TaskSourceKind};
 use task::ResolvedTask;
 use ui::{
@@ -137,9 +137,9 @@ pub struct CompletionsMenu {
     sort_completions: bool,
     pub initial_position: Anchor,
     pub buffer: Model<Buffer>,
-    pub completions: Arc<RwLock<Box<[Completion]>>>,
-    match_candidates: Arc<[StringMatchCandidate]>,
-    pub matches: Arc<[StringMatch]>,
+    pub completions: Rc<RefCell<Box<[Completion]>>>,
+    match_candidates: Rc<[StringMatchCandidate]>,
+    pub matches: Rc<[StringMatch]>,
     pub selected_item: usize,
     scroll_handle: UniformListScrollHandle,
     resolve_completions: bool,
@@ -169,7 +169,7 @@ impl CompletionsMenu {
             initial_position,
             buffer,
             show_completion_documentation,
-            completions: Arc::new(RwLock::new(completions)),
+            completions: RefCell::new(completions).into(),
             match_candidates,
             matches: Vec::new().into(),
             selected_item: 0,
@@ -223,7 +223,7 @@ impl CompletionsMenu {
             sort_completions,
             initial_position: selection.start,
             buffer,
-            completions: Arc::new(RwLock::new(completions)),
+            completions: RefCell::new(completions).into(),
             match_candidates,
             matches,
             selected_item: 0,
@@ -329,13 +329,13 @@ impl CompletionsMenu {
         workspace: Option<WeakView<Workspace>>,
         cx: &mut ViewContext<Editor>,
     ) -> AnyElement {
+        let completions = self.completions.borrow_mut();
         let show_completion_documentation = self.show_completion_documentation;
         let widest_completion_ix = self
             .matches
             .iter()
             .enumerate()
             .max_by_key(|(_, mat)| {
-                let completions = self.completions.read();
                 let completion = &completions[mat.candidate_id];
                 let documentation = &completion.documentation;
 
@@ -350,14 +350,12 @@ impl CompletionsMenu {
             })
             .map(|(ix, _)| ix);
 
-        let completions = self.completions.clone();
-        let matches = self.matches.clone();
         let selected_item = self.selected_item;
         let style = style.clone();
 
         let multiline_docs = if show_completion_documentation {
             let mat = &self.matches[selected_item];
-            match &self.completions.read()[mat.candidate_id].documentation {
+            match &completions[mat.candidate_id].documentation {
                 Some(Documentation::MultiLinePlainText(text)) => {
                     Some(div().child(SharedString::from(text.clone())))
                 }
@@ -401,13 +399,16 @@ impl CompletionsMenu {
                 .occlude()
         });
 
+        drop(completions);
+        let completions = self.completions.clone();
+        let matches = self.matches.clone();
         let list = uniform_list(
             cx.view().clone(),
             "completions",
             matches.len(),
             move |_editor, range, cx| {
                 let start_ix = range.start;
-                let completions_guard = completions.read();
+                let completions_guard = completions.borrow_mut();
 
                 matches[range]
                     .iter()
@@ -548,7 +549,7 @@ impl CompletionsMenu {
             }
         }
 
-        let completions = self.completions.read();
+        let completions = self.completions.borrow_mut();
         if self.sort_completions {
             matches.sort_unstable_by_key(|mat| {
                 // We do want to strike a balance here between what the language server tells us
@@ -611,13 +612,13 @@ impl CompletionsMenu {
 pub struct AvailableCodeAction {
     pub excerpt_id: ExcerptId,
     pub action: CodeAction,
-    pub provider: Arc<dyn CodeActionProvider>,
+    pub provider: Rc<dyn CodeActionProvider>,
 }
 
 #[derive(Clone)]
 pub struct CodeActionContents {
-    pub tasks: Option<Arc<ResolvedTasks>>,
-    pub actions: Option<Arc<[AvailableCodeAction]>>,
+    pub tasks: Option<Rc<ResolvedTasks>>,
+    pub actions: Option<Rc<[AvailableCodeAction]>>,
 }
 
 impl CodeActionContents {
@@ -702,7 +703,7 @@ pub enum CodeActionsItem {
     CodeAction {
         excerpt_id: ExcerptId,
         action: CodeAction,
-        provider: Arc<dyn CodeActionProvider>,
+        provider: Rc<dyn CodeActionProvider>,
     },
 }