Fix progress token is already registered crash

After we started reporting progress when running cargo check during
loading, it is possible to crash the client with two identical progress
tokens.

This points to a deeper issue: we might be running several cargo checks
concurrently, which doesn't make sense.

This commit linearizes all workspace fetches, making sure no updates are
lost.

As an additional touch, it also normalizes progress & result reporting,
to make sure they stand in sync.

1 files changed, 10 insertions, 6 deletions

diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 22ee96775..51fb2eb74 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -11,7 +11,6 @@ use ide::{Canceled, FileId};
 use ide_db::base_db::VfsPath;
 use lsp_server::{Connection, Notification, Request, Response};
 use lsp_types::notification::Notification as _;
-use project_model::ProjectWorkspace;
 use vfs::ChangeKind;
 
 use crate::{
@@ -62,7 +61,6 @@ enum Event {
 pub(crate) enum Task {
     Response(Response),
     Diagnostics(Vec<(FileId, Vec<lsp_types::Diagnostic>)>),
-    Workspaces(Vec<anyhow::Result<ProjectWorkspace>>),
     PrimeCaches(PrimeCachesProgress),
     FetchWorkspace(ProjectWorkspaceProgress),
 }
@@ -143,7 +141,8 @@ impl GlobalState {
             |_, _| (),
         );
 
-        self.fetch_workspaces();
+        self.fetch_workspaces_request();
+        self.fetch_workspaces_if_needed();
 
         while let Some(event) = self.next_event(&inbox) {
             if let Event::Lsp(lsp_server::Message::Notification(not)) = &event {
@@ -204,7 +203,6 @@ impl GlobalState {
                                 self.diagnostics.set_native_diagnostics(file_id, diagnostics)
                             }
                         }
-                        Task::Workspaces(workspaces) => self.switch_workspaces(workspaces),
                         Task::PrimeCaches(progress) => match progress {
                             PrimeCachesProgress::Started => prime_caches_progress.push(progress),
                             PrimeCachesProgress::StartedOnCrate { .. } => {
@@ -224,7 +222,11 @@ impl GlobalState {
                                 ProjectWorkspaceProgress::Report(msg) => {
                                     (Progress::Report, Some(msg))
                                 }
-                                ProjectWorkspaceProgress::End => (Progress::End, None),
+                                ProjectWorkspaceProgress::End(workspaces) => {
+                                    self.fetch_workspaces_completed();
+                                    self.switch_workspaces(workspaces);
+                                    (Progress::End, None)
+                                }
                             };
                             self.report_progress("fetching", state, msg, None);
                         }
@@ -403,6 +405,8 @@ impl GlobalState {
             }
         }
 
+        self.fetch_workspaces_if_needed();
+
         let loop_duration = loop_start.elapsed();
         if loop_duration > Duration::from_millis(100) {
             log::warn!("overly long loop turn: {:?}", loop_duration);
@@ -440,7 +444,7 @@ impl GlobalState {
         }
 
         RequestDispatcher { req: Some(req), global_state: self }
-            .on_sync::<lsp_ext::ReloadWorkspace>(|s, ()| Ok(s.fetch_workspaces()))?
+            .on_sync::<lsp_ext::ReloadWorkspace>(|s, ()| Ok(s.fetch_workspaces_request()))?
             .on_sync::<lsp_ext::JoinLines>(|s, p| handlers::handle_join_lines(s.snapshot(), p))?
             .on_sync::<lsp_ext::OnEnter>(|s, p| handlers::handle_on_enter(s.snapshot(), p))?
             .on_sync::<lsp_types::request::Shutdown>(|s, ()| {