language: Only block the foreground on buffer reparsing when necessary (#43888)

Gist is we only need to block the foreground thread for reparsing if
immediate language changes are useful to the user. That is usually only
the case when they edit the buffer

Release Notes:

- Improved performance of large project searches and project diffs

Co-authored by: David Kleingeld <david@zed.dev>

crates/project/src/buffer_store.rs

@@ -684,8 +684,9 @@ impl LocalBufferStore {
         cx: &mut Context<BufferStore>,
     ) -> Task<Result<Entity<Buffer>>> {
         cx.spawn(async move |buffer_store, cx| {
-            let buffer =
-                cx.new(|cx| Buffer::local("", cx).with_language(language::PLAIN_TEXT.clone(), cx))?;
+            let buffer = cx.new(|cx| {
+                Buffer::local("", cx).with_language_immediate(language::PLAIN_TEXT.clone(), cx)
+            })?;
             buffer_store.update(cx, |buffer_store, cx| {
                 buffer_store.add_buffer(buffer.clone(), cx).log_err();
                 if !project_searchable {
@@ -1591,8 +1592,10 @@ impl BufferStore {
         cx: &mut Context<Self>,
     ) -> Entity<Buffer> {
         let buffer = cx.new(|cx| {
-            Buffer::local(text, cx)
-                .with_language(language.unwrap_or_else(|| language::PLAIN_TEXT.clone()), cx)
+            Buffer::local(text, cx).with_language_immediate(
+                language.unwrap_or_else(|| language::PLAIN_TEXT.clone()),
+                cx,
+            )
         });
 
         self.add_buffer(buffer.clone(), cx).log_err();

crates/project/src/git_store.rs

@@ -3885,7 +3885,7 @@ impl Repository {
                         let git_commit_language =
                             language_registry.language_for_name("Git Commit").await?;
                         buffer.update(&mut cx, |buffer, cx| {
-                            buffer.set_language(Some(git_commit_language), cx);
+                            buffer.set_language_immediate(Some(git_commit_language), cx);
                         })?;
                     }
                     this.update(&mut cx, |this, _| {
@@ -3912,7 +3912,7 @@ impl Repository {
             if let Some(language_registry) = language_registry {
                 let git_commit_language = language_registry.language_for_name("Git Commit").await?;
                 buffer.update(cx, |buffer, cx| {
-                    buffer.set_language(Some(git_commit_language), cx);
+                    buffer.set_language_immediate(Some(git_commit_language), cx);
                 })?;
             }
 

crates/project/src/lsp_store.rs

@@ -4353,7 +4353,7 @@ impl LspStore {
                         }
 
                         for buffer in buffers_with_unknown_injections {
-                            buffer.update(cx, |buffer, cx| buffer.reparse(cx));
+                            buffer.update(cx, |buffer, cx| buffer.reparse(cx, false));
                         }
                     })
                     .ok();