From fae8e8e91bb31fdcebe9280bf99a41b365b7c01f Mon Sep 17 00:00:00 2001
From: Matt Bierner <matb@microsoft.com>
Date: Mon, 4 Jun 2018 18:37:30 -0700
Subject: [PATCH] Prevent multiple calls to listen

---
 .../src/features/bufferSyncSupport.ts                        | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/extensions/typescript-language-features/src/features/bufferSyncSupport.ts b/extensions/typescript-language-features/src/features/bufferSyncSupport.ts
index 8e46d7f4069..0e704f60a59 100644
--- a/extensions/typescript-language-features/src/features/bufferSyncSupport.ts
+++ b/extensions/typescript-language-features/src/features/bufferSyncSupport.ts
@@ -167,6 +167,7 @@ export default class BufferSyncSupport {
 	private readonly pendingDiagnostics = new Map<string, number>();
 	private readonly diagnosticDelayer: Delayer<any>;
 	private pendingGetErr: { request: Promise<any>, files: string[], token: CancellationTokenSource } | undefined;
+	private listening: boolean = false;
 
 	constructor(
 		client: ITypeScriptServiceClient,
@@ -187,6 +188,10 @@ export default class BufferSyncSupport {
 	public readonly onDelete = this._onDelete.event;
 
 	public listen(): void {
+		if (this.listening) {
+			return;
+		}
+		this.listening = true;
 		workspace.onDidOpenTextDocument(this.openTextDocument, this, this.disposables);
 		workspace.onDidCloseTextDocument(this.onDidCloseTextDocument, this, this.disposables);
 		workspace.onDidChangeTextDocument(this.onDidChangeTextDocument, this, this.disposables);
-- 
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