Merge #6441

6441: Coalesce prime_caches updates r=matklad a=jonas-schievink

This reduces the number of progress bar updates we send to the client by collapsing subsequent updates into one. This doesn't work as well as I'd hoped (which is that we end up sending *no* updates, or only `start` and `end`, when the cache is already fresh), but it does reduce the number considerably: instead of ~720 updates on the rust-analyzer codebase, we now only send ~60.

It uses the same approach that is already in use for coalescing VFS events.

Hopefully this is enough to fix #6413.

Co-authored-by: Jonas Schievink <[email protected]>

Author: bors[bot]

crates/rust-analyzer/src/main_loop.rs

@@ -190,15 +190,35 @@ impl GlobalState {
                 }
                 lsp_server::Message::Response(resp) => self.complete_request(resp),
             },
-            Event::Task(task) => match task {
-                Task::Response(response) => self.respond(response),
-                Task::Diagnostics(diagnostics_per_file) => {
-                    for (file_id, diagnostics) in diagnostics_per_file {
-                        self.diagnostics.set_native_diagnostics(file_id, diagnostics)
+            Event::Task(mut task) => {
+                let _p = profile::span("GlobalState::handle_event/task");
+                let mut prime_caches_started = false;
+                let mut prime_caches_progress = None;
+                loop {
+                    match task {
+                        Task::Response(response) => self.respond(response),
+                        Task::Diagnostics(diagnostics_per_file) => {
+                            for (file_id, diagnostics) in diagnostics_per_file {
+                                self.diagnostics.set_native_diagnostics(file_id, diagnostics)
+                            }
+                        }
+                        Task::Workspaces(workspaces) => self.switch_workspaces(workspaces),
+                        Task::PrimeCaches(progress) => {
+                            if let PrimeCachesProgress::Started = progress {
+                                prime_caches_started = true;
+                            }
+
+                            prime_caches_progress = Some(progress);
+                        }
                     }
+                    // Coalesce multiple task events into one loop turn
+                    task = match self.task_pool.receiver.try_recv() {
+                        Ok(task) => task,
+                        Err(_) => break,
+                    };
                 }
-                Task::Workspaces(workspaces) => self.switch_workspaces(workspaces),
-                Task::PrimeCaches(progress) => {
+
+                if let Some(progress) = prime_caches_progress {
                     let (state, message, fraction);
                     match progress {
                         PrimeCachesProgress::Started => {
@@ -218,9 +238,14 @@ impl GlobalState {
                         }
                     };
 
-                    self.report_progress("indexing", state, message, Some(fraction));
+                    if state != Progress::Begin && prime_caches_started {
+                        // Progress indicator needs to be created first.
+                        self.report_progress("indexing", Progress::Begin, None, Some(0.0));
+                    }
+
+                    self.report_progress("indexing", state, message.clone(), Some(fraction));
                 }
-            },
+            }
             Event::Vfs(mut task) => {
                 let _p = profile::span("GlobalState::handle_event/vfs");
                 loop {