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changeset 3798:3d3199d56787

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lsp: Resolve completion item asynchronously on idle-timeout (#4781) d7d0d5ffb79b6f2e09c6ab8af6e112c41e6f73e8 resolves completion items on the idle-timeout event. The `Completion::resolve_completion_item` function blocks on the LSP request though, which blocks the compositor and in turn blocks the event loop. So until the language server returns the resolved completion item, Helix is unable to respond to keypresses or other LSP messages. This is typically ok since the resolution request is fast but for some language servers this can be problematic, and ideally we shouldn't be blocking like this anyways. When receiving a `completionItem/resolve` request, the Volar server sends a `workspace/configuration` request to Helix and blocks itself on the response, leading to a deadlock. Eventually the resolve request times out within Helix but Helix is locked up and unresponsive in that window. This change resolves the completion item without blocking the compositor.
author Michael Davis <mcarsondavis@gmail.com>
date Fri, 18 Nov 2022 12:27:46 -0600
parents a521acb1486e
children 439b63371513
files helix-lsp/src/client.rs helix-term/src/ui/completion.rs helix-term/src/ui/menu.rs
diffstat 3 files changed, 52 insertions(+), 14 deletions(-) [+]
line wrap: on
line diff
--- a/helix-lsp/src/client.rs	Fri Nov 18 14:36:40 2022 +0000
+++ b/helix-lsp/src/client.rs	Fri Nov 18 12:27:46 2022 -0600
@@ -650,12 +650,11 @@
         self.call::<lsp::request::Completion>(params)
     }
 
-    pub async fn resolve_completion_item(
+    pub fn resolve_completion_item(
         &self,
         completion_item: lsp::CompletionItem,
-    ) -> Result<lsp::CompletionItem> {
-        self.request::<lsp::request::ResolveCompletionItem>(completion_item)
-            .await
+    ) -> impl Future<Output = Result<Value>> {
+        self.call::<lsp::request::ResolveCompletionItem>(completion_item)
     }
 
     pub fn text_document_signature_help(
--- a/helix-term/src/ui/completion.rs	Fri Nov 18 14:36:40 2022 +0000
+++ b/helix-term/src/ui/completion.rs	Fri Nov 18 12:27:46 2022 -0600
@@ -257,7 +257,7 @@
         let future = language_server.resolve_completion_item(completion_item);
         let response = helix_lsp::block_on(future);
         match response {
-            Ok(completion_item) => Some(completion_item),
+            Ok(value) => serde_json::from_value(value).ok(),
             Err(err) => {
                 log::error!("execute LSP command: {}", err);
                 None
@@ -304,6 +304,12 @@
         self.popup.contents().is_empty()
     }
 
+    fn replace_item(&mut self, old_item: lsp::CompletionItem, new_item: lsp::CompletionItem) {
+        self.popup.contents_mut().replace_option(old_item, new_item);
+    }
+
+    /// Asynchronously requests that the currently selection completion item is
+    /// resolved through LSP `completionItem/resolve`.
     pub fn ensure_item_resolved(&mut self, cx: &mut commands::Context) -> bool {
         // > If computing full completion items is expensive, servers can additionally provide a
         // > handler for the completion item resolve request. ...
@@ -313,16 +319,38 @@
         // > 'completionItem/resolve' request is sent with the selected completion item as a parameter.
         // > The returned completion item should have the documentation property filled in.
         // https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_completion
-        match self.popup.contents_mut().selection_mut() {
-            Some(item) if item.documentation.is_none() => {
-                let doc = doc!(cx.editor);
-                if let Some(resolved_item) = Self::resolve_completion_item(doc, item.clone()) {
-                    *item = resolved_item;
+        let current_item = match self.popup.contents().selection() {
+            Some(item) if item.documentation.is_none() => item.clone(),
+            _ => return false,
+        };
+
+        let language_server = match doc!(cx.editor).language_server() {
+            Some(language_server) => language_server,
+            None => return false,
+        };
+
+        // This method should not block the compositor so we handle the response asynchronously.
+        let future = language_server.resolve_completion_item(current_item.clone());
+
+        cx.callback(
+            future,
+            move |_editor, compositor, response: Option<lsp::CompletionItem>| {
+                let resolved_item = match response {
+                    Some(item) => item,
+                    None => return,
+                };
+
+                if let Some(completion) = &mut compositor
+                    .find::<crate::ui::EditorView>()
+                    .unwrap()
+                    .completion
+                {
+                    completion.replace_item(current_item, resolved_item);
                 }
-                true
-            }
-            _ => false,
-        }
+            },
+        );
+
+        true
     }
 }
 
--- a/helix-term/src/ui/menu.rs	Fri Nov 18 14:36:40 2022 +0000
+++ b/helix-term/src/ui/menu.rs	Fri Nov 18 12:27:46 2022 -0600
@@ -224,6 +224,17 @@
     }
 }
 
+impl<T: Item + PartialEq> Menu<T> {
+    pub fn replace_option(&mut self, old_option: T, new_option: T) {
+        for option in &mut self.options {
+            if old_option == *option {
+                *option = new_option;
+                break;
+            }
+        }
+    }
+}
+
 use super::PromptEvent as MenuEvent;
 
 impl<T: Item + 'static> Component for Menu<T> {