From 76e9ed75e6ae69108d7dbb5e16dd0677857ed085 Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Thu, 22 Jun 2023 11:48:38 -0700
Subject: [PATCH] blackhole listeners for disposed emitters to avoid strange
 state

---
 src/vs/base/common/event.ts                            | 10 ++++++++++
 .../userData/test/browser/fileUserDataProvider.test.ts |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/vs/base/common/event.ts b/src/vs/base/common/event.ts
index d5aac074a3eb5..c4f9b7282593d 100644
--- a/src/vs/base/common/event.ts
+++ b/src/vs/base/common/event.ts
@@ -848,8 +848,10 @@ class Stacktrace {
 	}
 }
 
+let id = 0;
 class UniqueContainer<T> {
 	stack?: Stacktrace;
+	public id = id++;
 	constructor(public readonly value: T) { }
 }
 const compactionThreshold = 2;
@@ -977,6 +979,11 @@ export class Emitter<T> {
 				return Disposable.None;
 			}
 
+			if (this._disposed) {
+				// todo: should we warn if a listener is added to a disposed emitter? This happens often
+				return Disposable.None;
+			}
+
 			if (thisArgs) {
 				callback = callback.bind(thisArgs);
 			}
@@ -1040,6 +1047,9 @@ export class Emitter<T> {
 
 		const index = listeners.indexOf(listener);
 		if (index === -1) {
+			console.log('disposed?', this._disposed);
+			console.log('size?', this._size);
+			console.log('arr?', JSON.stringify(this._listeners));
 			throw new Error('Attempted to dispose unknown listener');
 		}
 
diff --git a/src/vs/platform/userData/test/browser/fileUserDataProvider.test.ts b/src/vs/platform/userData/test/browser/fileUserDataProvider.test.ts
index b9b05469bde11..be1d5377a39a3 100644
--- a/src/vs/platform/userData/test/browser/fileUserDataProvider.test.ts
+++ b/src/vs/platform/userData/test/browser/fileUserDataProvider.test.ts
@@ -311,10 +311,10 @@ suite('FileUserDataProvider - Watching', () => {
 	const rootFileResource = joinPath(ROOT, 'User');
 	const rootUserDataResource = rootFileResource.with({ scheme: Schemas.vscodeUserData });
 
-	const fileEventEmitter: Emitter<readonly IFileChange[]> = new Emitter<readonly IFileChange[]>();
-	disposables.add(fileEventEmitter);
+	let fileEventEmitter: Emitter<readonly IFileChange[]>;
 
 	setup(() => {
+		fileEventEmitter = disposables.add(new Emitter<readonly IFileChange[]>());
 		testObject = disposables.add(new FileUserDataProvider(rootFileResource.scheme, new TestFileSystemProvider(fileEventEmitter.event), Schemas.vscodeUserData, new NullLogService()));
 	});