Fix a potential race between didChange and didOpen (#13209)

Author: Colengms

Diff for: Extension/src/LanguageServer/extension.ts

@@ -172,8 +172,13 @@ export async function activate(): Promise<void> {
         getCustomConfigProviders().forEach(provider => void client.onRegisterCustomConfigurationProvider(provider));
     });
 
-    disposables.push(vscode.workspace.onDidChangeConfiguration(onDidChangeSettings));
+    // These handlers for didChangeTextDocument and didOpenTextDocument are intentionally synchronous and are
+    // intended primarily to maintain openFileVersions with the most recent versions of files, as quickly as
+    // possible, without being delayed by awaits or queued behind other LSP messages, etc..
     disposables.push(vscode.workspace.onDidChangeTextDocument(onDidChangeTextDocument));
+    disposables.push(vscode.workspace.onDidOpenTextDocument(onDidOpenTextDocument));
+
+    disposables.push(vscode.workspace.onDidChangeConfiguration(onDidChangeSettings));
     disposables.push(vscode.window.onDidChangeTextEditorVisibleRanges((e) => clients.ActiveClient.enqueue(async () => onDidChangeTextEditorVisibleRanges(e))));
     disposables.push(vscode.window.onDidChangeActiveTextEditor((e) => clients.ActiveClient.enqueue(async () => onDidChangeActiveTextEditor(e))));
     ui.didChangeActiveEditor(); // Handle already active documents (for non-cpp files that we don't register didOpen).
@@ -303,6 +308,11 @@ function onDidChangeTextDocument(event: vscode.TextDocumentChangeEvent): void {
     me.onDidChangeTextDocument(event);
 }
 
+function onDidOpenTextDocument(document: vscode.TextDocument): void {
+    const me: Client = clients.getClientFor(document.uri);
+    me.onDidOpenTextDocument(document);
+}
+
 let noActiveEditorTimeout: NodeJS.Timeout | undefined;
 
 async function onDidChangeTextEditorVisibleRanges(event: vscode.TextEditorVisibleRangesChangeEvent): Promise<void> {

Diff for: Extension/src/LanguageServer/protocolFilter.ts

@@ -38,7 +38,6 @@ export function createProtocolFilter(): Middleware {
                         return;
                     }
                     // client.takeOwnership() will call client.TrackedDocuments.add() again, but that's ok. It's a Set.
-                    client.onDidOpenTextDocument(document);
                     client.takeOwnership(document);
                     void sendMessage(document);
                 }