Assert we don't get out of order change messages from the client

And that we don't screw it up with race conditions or whatever internally

Author: nrc

src/actions/mod.rs

@@ -125,6 +125,8 @@ pub struct InitActionContext {
     // mutating actions can block until the data is ready.
     active_build_count: Arc<AtomicUsize>,
 
+    prev_changes: Arc<Mutex<HashMap<PathBuf, u64>>>,
+
     config: Arc<Mutex<Config>>,
     client_capabilities: Arc<lsp_data::ClientCapabilities>,
     /// Whether the server is performing cleanup (after having received
@@ -170,6 +172,7 @@ impl InitActionContext {
             current_project,
             previous_build_results: Arc::new(Mutex::new(HashMap::new())),
             build_queue,
+            prev_changes: Arc::new(Mutex::new(HashMap::new())),
             active_build_count: Arc::new(AtomicUsize::new(0)),
             client_capabilities: Arc::new(client_capabilities),
             shut_down: Arc::new(AtomicBool::new(false)),
@@ -268,6 +271,18 @@ impl InitActionContext {
         self.active_build_count.load(Ordering::SeqCst) == 0
     }
 
+    fn check_change_version(&self, file_path: &Path, version_num: u64) {
+        let mut prev_changes = self.prev_changes.lock().unwrap();
+        let file_path = file_path.to_owned();
+
+        if prev_changes.contains_key(&file_path) {
+            let prev_version = prev_changes[&file_path];
+            assert!(version_num > prev_version, "Out of order or duplicate change");
+        }
+
+        prev_changes.insert(file_path, version_num);
+    }
+
     fn convert_pos_to_span(&self, file_path: PathBuf, pos: Position) -> Span {
         trace!("convert_pos_to_span: {:?} {:?}", file_path, pos);
 

src/actions/notifications.rs

@@ -82,8 +82,15 @@ impl BlockingNotificationAction for DidChangeTextDocument {
             thread::current().id()
         );
 
+        if params.content_changes.is_empty() {
+            return Ok(());
+        }
+
         let ctx = ctx.inited();
         let file_path = parse_file_path!(&params.text_document.uri, "on_change")?;
+        let version_num = params.text_document.version.unwrap();
+
+        ctx.check_change_version(&file_path, version_num);
 
         let changes: Vec<Change> = params
             .content_changes
@@ -107,10 +114,8 @@ impl BlockingNotificationAction for DidChangeTextDocument {
         ctx.vfs
             .on_changes(&changes)
             .expect("error committing to VFS");
-        if !changes.is_empty() {
-            ctx.build_queue
-                .mark_file_dirty(file_path, params.text_document.version.unwrap())
-        }
+
+        ctx.build_queue.mark_file_dirty(file_path, version_num);
 
         if !ctx.config.lock().unwrap().build_on_save {
             ctx.build_current_project(BuildPriority::Normal, &out);