crates/rust-analyzer/src/main_loop.rs

   1 //! The main loop of `rust-analyzer` responsible for dispatching LSP
   2 //! requests/replies and notifications back to the client.
   3 use std::{
   4     env, fmt,
   5     time::{Duration, Instant},
   6 };
   7
   8 use crossbeam_channel::{select, Receiver};
   9 use ide::PrimeCachesProgress;
  10 use ide::{Canceled, FileId};
  11 use ide_db::base_db::VfsPath;
  12 use lsp_server::{Connection, Notification, Request, Response};
  13 use lsp_types::notification::Notification as _;
  14 use project_model::ProjectWorkspace;
  15 use vfs::ChangeKind;
  16
  17 use crate::{
  18     config::Config,
  19     dispatch::{NotificationDispatcher, RequestDispatcher},
  20     document::DocumentData,
  21     from_proto,
  22     global_state::{file_id_to_url, url_to_file_id, GlobalState, Status},
  23     handlers, lsp_ext,
  24     lsp_utils::{apply_document_changes, is_canceled, notification_is, Progress},
  25     Result,
  26 };
  27
  28 pub fn main_loop(config: Config, connection: Connection) -> Result<()> {
  29     log::info!("initial config: {:#?}", config);
  30
  31     // Windows scheduler implements priority boosts: if thread waits for an
  32     // event (like a condvar), and event fires, priority of the thread is
  33     // temporary bumped. This optimization backfires in our case: each time the
  34     // `main_loop` schedules a task to run on a threadpool, the worker threads
  35     // gets a higher priority, and (on a machine with fewer cores) displaces the
  36     // main loop! We work-around this by marking the main loop as a
  37     // higher-priority thread.
  38     //
  39     // https://docs.microsoft.com/en-us/windows/win32/procthread/scheduling-priorities
  40     // https://docs.microsoft.com/en-us/windows/win32/procthread/priority-boosts
  41     // https://github.com/rust-analyzer/rust-analyzer/issues/2835
  42     #[cfg(windows)]
  43     unsafe {
  44         use winapi::um::processthreadsapi::*;
  45         let thread = GetCurrentThread();
  46         let thread_priority_above_normal = 1;
  47         SetThreadPriority(thread, thread_priority_above_normal);
  48     }
  49
  50     GlobalState::new(connection.sender, config).run(connection.receiver)
  51 }
  52
  53 enum Event {
  54     Lsp(lsp_server::Message),
  55     Task(Task),
  56     Vfs(vfs::loader::Message),
  57     Flycheck(flycheck::Message),
  58 }
  59
  60 #[derive(Debug)]
  61 pub(crate) enum Task {
  62     Response(Response),
  63     Diagnostics(Vec<(FileId, Vec<lsp_types::Diagnostic>)>),
  64     Workspaces(Vec<anyhow::Result<ProjectWorkspace>>),
  65     PrimeCaches(PrimeCachesProgress),
  66 }
  67
  68 impl fmt::Debug for Event {
  69     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  70         let debug_verbose_not = |not: &Notification, f: &mut fmt::Formatter| {
  71             f.debug_struct("Notification").field("method", &not.method).finish()
  72         };
  73
  74         match self {
  75             Event::Lsp(lsp_server::Message::Notification(not)) => {
  76                 if notification_is::<lsp_types::notification::DidOpenTextDocument>(not)
  77                     || notification_is::<lsp_types::notification::DidChangeTextDocument>(not)
  78                 {
  79                     return debug_verbose_not(not, f);
  80                 }
  81             }
  82             Event::Task(Task::Response(resp)) => {
  83                 return f
  84                     .debug_struct("Response")
  85                     .field("id", &resp.id)
  86                     .field("error", &resp.error)
  87                     .finish();
  88             }
  89             _ => (),
  90         }
  91         match self {
  92             Event::Lsp(it) => fmt::Debug::fmt(it, f),
  93             Event::Task(it) => fmt::Debug::fmt(it, f),
  94             Event::Vfs(it) => fmt::Debug::fmt(it, f),
  95             Event::Flycheck(it) => fmt::Debug::fmt(it, f),
  96         }
  97     }
  98 }
  99
 100 impl GlobalState {
 101     fn run(mut self, inbox: Receiver<lsp_server::Message>) -> Result<()> {
 102         if self.config.linked_projects.is_empty() && self.config.notifications.cargo_toml_not_found
 103         {
 104             self.show_message(
 105                 lsp_types::MessageType::Error,
 106                 "rust-analyzer failed to discover workspace".to_string(),
 107             );
 108         };
 109
 110         let save_registration_options = lsp_types::TextDocumentSaveRegistrationOptions {
 111             include_text: Some(false),
 112             text_document_registration_options: lsp_types::TextDocumentRegistrationOptions {
 113                 document_selector: Some(vec![
 114                     lsp_types::DocumentFilter {
 115                         language: None,
 116                         scheme: None,
 117                         pattern: Some("**/*.rs".into()),
 118                     },
 119                     lsp_types::DocumentFilter {
 120                         language: None,
 121                         scheme: None,
 122                         pattern: Some("**/Cargo.toml".into()),
 123                     },
 124                     lsp_types::DocumentFilter {
 125                         language: None,
 126                         scheme: None,
 127                         pattern: Some("**/Cargo.lock".into()),
 128                     },
 129                 ]),
 130             },
 131         };
 132
 133         let registration = lsp_types::Registration {
 134             id: "textDocument/didSave".to_string(),
 135             method: "textDocument/didSave".to_string(),
 136             register_options: Some(serde_json::to_value(save_registration_options).unwrap()),
 137         };
 138         self.send_request::<lsp_types::request::RegisterCapability>(
 139             lsp_types::RegistrationParams { registrations: vec![registration] },
 140             |_, _| (),
 141         );
 142
 143         self.fetch_workspaces();
 144
 145         while let Some(event) = self.next_event(&inbox) {
 146             if let Event::Lsp(lsp_server::Message::Notification(not)) = &event {
 147                 if not.method == lsp_types::notification::Exit::METHOD {
 148                     return Ok(());
 149                 }
 150             }
 151             self.handle_event(event)?
 152         }
 153
 154         Err("client exited without proper shutdown sequence")?
 155     }
 156
 157     fn next_event(&self, inbox: &Receiver<lsp_server::Message>) -> Option<Event> {
 158         select! {
 159             recv(inbox) -> msg =>
 160                 msg.ok().map(Event::Lsp),
 161
 162             recv(self.task_pool.receiver) -> task =>
 163                 Some(Event::Task(task.unwrap())),
 164
 165             recv(self.loader.receiver) -> task =>
 166                 Some(Event::Vfs(task.unwrap())),
 167
 168             recv(self.flycheck_receiver) -> task =>
 169                 Some(Event::Flycheck(task.unwrap())),
 170         }
 171     }
 172
 173     fn handle_event(&mut self, event: Event) -> Result<()> {
 174         let loop_start = Instant::now();
 175         // NOTE: don't count blocking select! call as a loop-turn time
 176         let _p = profile::span("GlobalState::handle_event");
 177
 178         log::info!("handle_event({:?})", event);
 179         let task_queue_len = self.task_pool.handle.len();
 180         if task_queue_len > 0 {
 181             log::info!("task queue len: {}", task_queue_len);
 182         }
 183
 184         let prev_status = self.status;
 185         match event {
 186             Event::Lsp(msg) => match msg {
 187                 lsp_server::Message::Request(req) => self.on_request(loop_start, req)?,
 188                 lsp_server::Message::Notification(not) => {
 189                     self.on_notification(not)?;
 190                 }
 191                 lsp_server::Message::Response(resp) => self.complete_request(resp),
 192             },
 193             Event::Task(mut task) => {
 194                 let _p = profile::span("GlobalState::handle_event/task");
 195                 let mut prime_caches_progress = Vec::new();
 196                 loop {
 197                     match task {
 198                         Task::Response(response) => self.respond(response),
 199                         Task::Diagnostics(diagnostics_per_file) => {
 200                             for (file_id, diagnostics) in diagnostics_per_file {
 201                                 self.diagnostics.set_native_diagnostics(file_id, diagnostics)
 202                             }
 203                         }
 204                         Task::Workspaces(workspaces) => self.switch_workspaces(workspaces),
 205                         Task::PrimeCaches(progress) => match progress {
 206                             PrimeCachesProgress::Started => prime_caches_progress.push(progress),
 207                             PrimeCachesProgress::StartedOnCrate { .. } => {
 208                                 match prime_caches_progress.last_mut() {
 209                                     Some(last @ PrimeCachesProgress::StartedOnCrate { .. }) => {
 210                                         // Coalesce subsequent update events.
 211                                         *last = progress;
 212                                     }
 213                                     _ => prime_caches_progress.push(progress),
 214                                 }
 215                             }
 216                             PrimeCachesProgress::Finished => prime_caches_progress.push(progress),
 217                         },
 218                     }
 219                     // Coalesce multiple task events into one loop turn
 220                     task = match self.task_pool.receiver.try_recv() {
 221                         Ok(task) => task,
 222                         Err(_) => break,
 223                     };
 224                 }
 225
 226                 for progress in prime_caches_progress {
 227                     let (state, message, fraction);
 228                     match progress {
 229                         PrimeCachesProgress::Started => {
 230                             state = Progress::Begin;
 231                             message = None;
 232                             fraction = 0.0;
 233                         }
 234                         PrimeCachesProgress::StartedOnCrate { on_crate, n_done, n_total } => {
 235                             state = Progress::Report;
 236                             message = Some(format!("{}/{} ({})", n_done, n_total, on_crate));
 237                             fraction = Progress::fraction(n_done, n_total);
 238                         }
 239                         PrimeCachesProgress::Finished => {
 240                             state = Progress::End;
 241                             message = None;
 242                             fraction = 1.0;
 243                         }
 244                     };
 245
 246                     self.report_progress("indexing", state, message, Some(fraction));
 247                 }
 248             }
 249             Event::Vfs(mut task) => {
 250                 let _p = profile::span("GlobalState::handle_event/vfs");
 251                 loop {
 252                     match task {
 253                         vfs::loader::Message::Loaded { files } => {
 254                             let vfs = &mut self.vfs.write().0;
 255                             for (path, contents) in files {
 256                                 let path = VfsPath::from(path);
 257                                 if !self.mem_docs.contains_key(&path) {
 258                                     vfs.set_file_contents(path, contents)
 259                                 }
 260                             }
 261                         }
 262                         vfs::loader::Message::Progress { n_total, n_done } => {
 263                             if n_total == 0 {
 264                                 self.transition(Status::Invalid);
 265                             } else {
 266                                 let state = if n_done == 0 {
 267                                     self.transition(Status::Loading);
 268                                     Progress::Begin
 269                                 } else if n_done < n_total {
 270                                     Progress::Report
 271                                 } else {
 272                                     assert_eq!(n_done, n_total);
 273                                     self.transition(Status::Ready);
 274                                     Progress::End
 275                                 };
 276                                 self.report_progress(
 277                                     "roots scanned",
 278                                     state,
 279                                     Some(format!("{}/{}", n_done, n_total)),
 280                                     Some(Progress::fraction(n_done, n_total)),
 281                                 )
 282                             }
 283                         }
 284                     }
 285                     // Coalesce many VFS event into a single loop turn
 286                     task = match self.loader.receiver.try_recv() {
 287                         Ok(task) => task,
 288                         Err(_) => break,
 289                     }
 290                 }
 291             }
 292             Event::Flycheck(mut task) => {
 293                 let _p = profile::span("GlobalState::handle_event/flycheck");
 294                 loop {
 295                     match task {
 296                         flycheck::Message::AddDiagnostic { workspace_root, diagnostic } => {
 297                             let diagnostics =
 298                                 crate::diagnostics::to_proto::map_rust_diagnostic_to_lsp(
 299                                     &self.config.diagnostics_map,
 300                                     &diagnostic,
 301                                     &workspace_root,
 302                                 );
 303                             for diag in diagnostics {
 304                                 match url_to_file_id(&self.vfs.read().0, &diag.url) {
 305                                     Ok(file_id) => self.diagnostics.add_check_diagnostic(
 306                                         file_id,
 307                                         diag.diagnostic,
 308                                         diag.fixes,
 309                                     ),
 310                                     Err(err) => {
 311                                         log::error!(
 312                                             "File with cargo diagnostic not found in VFS: {}",
 313                                             err
 314                                         );
 315                                     }
 316                                 };
 317                             }
 318                         }
 319
 320                         flycheck::Message::Progress { id, progress } => {
 321                             let (state, message) = match progress {
 322                                 flycheck::Progress::DidStart => {
 323                                     self.diagnostics.clear_check();
 324                                     (Progress::Begin, None)
 325                                 }
 326                                 flycheck::Progress::DidCheckCrate(target) => {
 327                                     (Progress::Report, Some(target))
 328                                 }
 329                                 flycheck::Progress::DidCancel => (Progress::End, None),
 330                                 flycheck::Progress::DidFinish(result) => {
 331                                     if let Err(err) = result {
 332                                         log::error!("cargo check failed: {}", err)
 333                                     }
 334                                     (Progress::End, None)
 335                                 }
 336                             };
 337
 338                             // When we're running multiple flychecks, we have to include a disambiguator in
 339                             // the title, or the editor complains. Note that this is a user-facing string.
 340                             let title = if self.flycheck.len() == 1 {
 341                                 "cargo check".to_string()
 342                             } else {
 343                                 format!("cargo check (#{})", id + 1)
 344                             };
 345                             self.report_progress(&title, state, message, None);
 346                         }
 347                     }
 348                     // Coalesce many flycheck updates into a single loop turn
 349                     task = match self.flycheck_receiver.try_recv() {
 350                         Ok(task) => task,
 351                         Err(_) => break,
 352                     }
 353                 }
 354             }
 355         }
 356
 357         let state_changed = self.process_changes();
 358         if prev_status == Status::Loading && self.status == Status::Ready {
 359             for flycheck in &self.flycheck {
 360                 flycheck.update();
 361             }
 362         }
 363
 364         if self.status == Status::Ready && (state_changed || prev_status == Status::Loading) {
 365             self.update_file_notifications_on_threadpool();
 366
 367             // Refresh semantic tokens if the client supports it.
 368             if self.config.semantic_tokens_refresh {
 369                 self.semantic_tokens_cache.lock().clear();
 370                 self.send_request::<lsp_types::request::SemanticTokensRefesh>((), |_, _| ());
 371             }
 372         }
 373
 374         if let Some(diagnostic_changes) = self.diagnostics.take_changes() {
 375             for file_id in diagnostic_changes {
 376                 let url = file_id_to_url(&self.vfs.read().0, file_id);
 377                 let diagnostics = self.diagnostics.diagnostics_for(file_id).cloned().collect();
 378                 let version = from_proto::vfs_path(&url)
 379                     .map(|path| self.mem_docs.get(&path).map(|it| it.version))
 380                     .unwrap_or_default();
 381
 382                 self.send_notification::<lsp_types::notification::PublishDiagnostics>(
 383                     lsp_types::PublishDiagnosticsParams { uri: url, diagnostics, version },
 384                 );
 385             }
 386         }
 387
 388         let loop_duration = loop_start.elapsed();
 389         if loop_duration > Duration::from_millis(100) {
 390             log::warn!("overly long loop turn: {:?}", loop_duration);
 391             if env::var("RA_PROFILE").is_ok() {
 392                 self.show_message(
 393                     lsp_types::MessageType::Error,
 394                     format!("overly long loop turn: {:?}", loop_duration),
 395                 )
 396             }
 397         }
 398         Ok(())
 399     }
 400
 401     fn on_request(&mut self, request_received: Instant, req: Request) -> Result<()> {
 402         self.register_request(&req, request_received);
 403
 404         if self.shutdown_requested {
 405             self.respond(Response::new_err(
 406                 req.id,
 407                 lsp_server::ErrorCode::InvalidRequest as i32,
 408                 "Shutdown already requested.".to_owned(),
 409             ));
 410
 411             return Ok(());
 412         }
 413
 414         if self.status == Status::Loading && req.method != "shutdown" {
 415             self.respond(lsp_server::Response::new_err(
 416                 req.id,
 417                 // FIXME: i32 should impl From<ErrorCode> (from() guarantees lossless conversion)
 418                 lsp_server::ErrorCode::ContentModified as i32,
 419                 "Rust Analyzer is still loading...".to_owned(),
 420             ));
 421             return Ok(());
 422         }
 423
 424         RequestDispatcher { req: Some(req), global_state: self }
 425             .on_sync::<lsp_ext::ReloadWorkspace>(|s, ()| Ok(s.fetch_workspaces()))?
 426             .on_sync::<lsp_ext::JoinLines>(|s, p| handlers::handle_join_lines(s.snapshot(), p))?
 427             .on_sync::<lsp_ext::OnEnter>(|s, p| handlers::handle_on_enter(s.snapshot(), p))?
 428             .on_sync::<lsp_types::request::Shutdown>(|s, ()| {
 429                 s.shutdown_requested = true;
 430                 Ok(())
 431             })?
 432             .on_sync::<lsp_types::request::SelectionRangeRequest>(|s, p| {
 433                 handlers::handle_selection_range(s.snapshot(), p)
 434             })?
 435             .on_sync::<lsp_ext::MatchingBrace>(|s, p| {
 436                 handlers::handle_matching_brace(s.snapshot(), p)
 437             })?
 438             .on_sync::<lsp_ext::MemoryUsage>(|s, p| handlers::handle_memory_usage(s, p))?
 439             .on::<lsp_ext::AnalyzerStatus>(handlers::handle_analyzer_status)
 440             .on::<lsp_ext::SyntaxTree>(handlers::handle_syntax_tree)
 441             .on::<lsp_ext::ExpandMacro>(handlers::handle_expand_macro)
 442             .on::<lsp_ext::ParentModule>(handlers::handle_parent_module)
 443             .on::<lsp_ext::Runnables>(handlers::handle_runnables)
 444             .on::<lsp_ext::InlayHints>(handlers::handle_inlay_hints)
 445             .on::<lsp_ext::CodeActionRequest>(handlers::handle_code_action)
 446             .on::<lsp_ext::CodeActionResolveRequest>(handlers::handle_code_action_resolve)
 447             .on::<lsp_ext::HoverRequest>(handlers::handle_hover)
 448             .on::<lsp_ext::ExternalDocs>(handlers::handle_open_docs)
 449             .on::<lsp_ext::OpenCargoToml>(handlers::handle_open_cargo_toml)
 450             .on::<lsp_types::request::OnTypeFormatting>(handlers::handle_on_type_formatting)
 451             .on::<lsp_types::request::DocumentSymbolRequest>(handlers::handle_document_symbol)
 452             .on::<lsp_types::request::WorkspaceSymbol>(handlers::handle_workspace_symbol)
 453             .on::<lsp_types::request::GotoDefinition>(handlers::handle_goto_definition)
 454             .on::<lsp_types::request::GotoImplementation>(handlers::handle_goto_implementation)
 455             .on::<lsp_types::request::GotoTypeDefinition>(handlers::handle_goto_type_definition)
 456             .on::<lsp_types::request::Completion>(handlers::handle_completion)
 457             .on::<lsp_types::request::ResolveCompletionItem>(handlers::handle_resolve_completion)
 458             .on::<lsp_types::request::CodeLensRequest>(handlers::handle_code_lens)
 459             .on::<lsp_types::request::CodeLensResolve>(handlers::handle_code_lens_resolve)
 460             .on::<lsp_types::request::FoldingRangeRequest>(handlers::handle_folding_range)
 461             .on::<lsp_types::request::SignatureHelpRequest>(handlers::handle_signature_help)
 462             .on::<lsp_types::request::PrepareRenameRequest>(handlers::handle_prepare_rename)
 463             .on::<lsp_types::request::Rename>(handlers::handle_rename)
 464             .on::<lsp_types::request::References>(handlers::handle_references)
 465             .on::<lsp_types::request::Formatting>(handlers::handle_formatting)
 466             .on::<lsp_types::request::DocumentHighlightRequest>(handlers::handle_document_highlight)
 467             .on::<lsp_types::request::CallHierarchyPrepare>(handlers::handle_call_hierarchy_prepare)
 468             .on::<lsp_types::request::CallHierarchyIncomingCalls>(
 469                 handlers::handle_call_hierarchy_incoming,
 470             )
 471             .on::<lsp_types::request::CallHierarchyOutgoingCalls>(
 472                 handlers::handle_call_hierarchy_outgoing,
 473             )
 474             .on::<lsp_types::request::SemanticTokensFullRequest>(
 475                 handlers::handle_semantic_tokens_full,
 476             )
 477             .on::<lsp_types::request::SemanticTokensFullDeltaRequest>(
 478                 handlers::handle_semantic_tokens_full_delta,
 479             )
 480             .on::<lsp_types::request::SemanticTokensRangeRequest>(
 481                 handlers::handle_semantic_tokens_range,
 482             )
 483             .on::<lsp_ext::Ssr>(handlers::handle_ssr)
 484             .finish();
 485         Ok(())
 486     }
 487     fn on_notification(&mut self, not: Notification) -> Result<()> {
 488         NotificationDispatcher { not: Some(not), global_state: self }
 489             .on::<lsp_types::notification::Cancel>(|this, params| {
 490                 let id: lsp_server::RequestId = match params.id {
 491                     lsp_types::NumberOrString::Number(id) => id.into(),
 492                     lsp_types::NumberOrString::String(id) => id.into(),
 493                 };
 494                 this.cancel(id);
 495                 Ok(())
 496             })?
 497             .on::<lsp_types::notification::DidOpenTextDocument>(|this, params| {
 498                 if let Ok(path) = from_proto::vfs_path(&params.text_document.uri) {
 499                     if this
 500                         .mem_docs
 501                         .insert(path.clone(), DocumentData::new(params.text_document.version))
 502                         .is_some()
 503                     {
 504                         log::error!("duplicate DidOpenTextDocument: {}", path)
 505                     }
 506                     this.vfs
 507                         .write()
 508                         .0
 509                         .set_file_contents(path, Some(params.text_document.text.into_bytes()));
 510                     this.maybe_update_diagnostics();
 511                 }
 512                 Ok(())
 513             })?
 514             .on::<lsp_types::notification::DidChangeTextDocument>(|this, params| {
 515                 if let Ok(path) = from_proto::vfs_path(&params.text_document.uri) {
 516                     let doc = match this.mem_docs.get_mut(&path) {
 517                         Some(doc) => doc,
 518                         None => {
 519                             log::error!("expected DidChangeTextDocument: {}", path);
 520                             return Ok(());
 521                         }
 522                     };
 523                     let vfs = &mut this.vfs.write().0;
 524                     let file_id = vfs.file_id(&path).unwrap();
 525                     let mut text = String::from_utf8(vfs.file_contents(file_id).to_vec()).unwrap();
 526                     apply_document_changes(&mut text, params.content_changes);
 527
 528                     // The version passed in DidChangeTextDocument is the version after all edits are applied
 529                     // so we should apply it before the vfs is notified.
 530                     doc.version = params.text_document.version;
 531
 532                     vfs.set_file_contents(path.clone(), Some(text.into_bytes()));
 533                 }
 534                 Ok(())
 535             })?
 536             .on::<lsp_types::notification::DidCloseTextDocument>(|this, params| {
 537                 let mut version = None;
 538                 if let Ok(path) = from_proto::vfs_path(&params.text_document.uri) {
 539                     match this.mem_docs.remove(&path) {
 540                         Some(doc) => version = Some(doc.version),
 541                         None => log::error!("orphan DidCloseTextDocument: {}", path),
 542                     }
 543
 544                     this.semantic_tokens_cache.lock().remove(&params.text_document.uri);
 545
 546                     if let Some(path) = path.as_path() {
 547                         this.loader.handle.invalidate(path.to_path_buf());
 548                     }
 549                 }
 550
 551                 // Clear the diagnostics for the previously known version of the file.
 552                 // This prevents stale "cargo check" diagnostics if the file is
 553                 // closed, "cargo check" is run and then the file is reopened.
 554                 this.send_notification::<lsp_types::notification::PublishDiagnostics>(
 555                     lsp_types::PublishDiagnosticsParams {
 556                         uri: params.text_document.uri,
 557                         diagnostics: Vec::new(),
 558                         version,
 559                     },
 560                 );
 561                 Ok(())
 562             })?
 563             .on::<lsp_types::notification::DidSaveTextDocument>(|this, params| {
 564                 for flycheck in &this.flycheck {
 565                     flycheck.update();
 566                 }
 567                 if let Ok(abs_path) = from_proto::abs_path(&params.text_document.uri) {
 568                     this.maybe_refresh(&[(abs_path, ChangeKind::Modify)]);
 569                 }
 570                 Ok(())
 571             })?
 572             .on::<lsp_types::notification::DidChangeConfiguration>(|this, _params| {
 573                 // As stated in https://github.com/microsoft/language-server-protocol/issues/676,
 574                 // this notification's parameters should be ignored and the actual config queried separately.
 575                 this.send_request::<lsp_types::request::WorkspaceConfiguration>(
 576                     lsp_types::ConfigurationParams {
 577                         items: vec![lsp_types::ConfigurationItem {
 578                             scope_uri: None,
 579                             section: Some("rust-analyzer".to_string()),
 580                         }],
 581                     },
 582                     |this, resp| {
 583                         log::debug!("config update response: '{:?}", resp);
 584                         let Response { error, result, .. } = resp;
 585
 586                         match (error, result) {
 587                             (Some(err), _) => {
 588                                 log::error!("failed to fetch the server settings: {:?}", err)
 589                             }
 590                             (None, Some(mut configs)) => {
 591                                 if let Some(json) = configs.get_mut(0) {
 592                                     // Note that json can be null according to the spec if the client can't
 593                                     // provide a configuration. This is handled in Config::update below.
 594                                     let mut config = this.config.clone();
 595                                     config.update(json.take());
 596                                     this.update_configuration(config);
 597                                 }
 598                             }
 599                             (None, None) => log::error!(
 600                                 "received empty server settings response from the client"
 601                             ),
 602                         }
 603                     },
 604                 );
 605
 606                 return Ok(());
 607             })?
 608             .on::<lsp_types::notification::DidChangeWatchedFiles>(|this, params| {
 609                 for change in params.changes {
 610                     if let Ok(path) = from_proto::abs_path(&change.uri) {
 611                         this.loader.handle.invalidate(path);
 612                     }
 613                 }
 614                 Ok(())
 615             })?
 616             .finish();
 617         Ok(())
 618     }
 619     fn update_file_notifications_on_threadpool(&mut self) {
 620         self.maybe_update_diagnostics();
 621         self.task_pool.handle.spawn_with_sender({
 622             let snap = self.snapshot();
 623             move |sender| {
 624                 snap.analysis
 625                     .prime_caches(|progress| {
 626                         sender.send(Task::PrimeCaches(progress)).unwrap();
 627                     })
 628                     .unwrap_or_else(|_: Canceled| {
 629                         // Pretend that we're done, so that the progress bar is removed. Otherwise
 630                         // the editor may complain about it already existing.
 631                         sender.send(Task::PrimeCaches(PrimeCachesProgress::Finished)).unwrap()
 632                     });
 633             }
 634         });
 635     }
 636     fn maybe_update_diagnostics(&mut self) {
 637         let subscriptions = self
 638             .mem_docs
 639             .keys()
 640             .map(|path| self.vfs.read().0.file_id(&path).unwrap())
 641             .collect::<Vec<_>>();
 642
 643         log::trace!("updating notifications for {:?}", subscriptions);
 644         if self.config.publish_diagnostics {
 645             let snapshot = self.snapshot();
 646             let subscriptions = subscriptions.clone();
 647             self.task_pool.handle.spawn(move || {
 648                 let diagnostics = subscriptions
 649                     .into_iter()
 650                     .filter_map(|file_id| {
 651                         handlers::publish_diagnostics(&snapshot, file_id)
 652                             .map_err(|err| {
 653                                 if !is_canceled(&*err) {
 654                                     log::error!("failed to compute diagnostics: {:?}", err);
 655                                 }
 656                                 ()
 657                             })
 658                             .ok()
 659                             .map(|diags| (file_id, diags))
 660                     })
 661                     .collect::<Vec<_>>();
 662                 Task::Diagnostics(diagnostics)
 663             })
 664         }
 665     }
 666 }