From 38aa43b66fc47723393a9ab065733ce808813047 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20M=C3=A4der?= <t.s.maeder@gmail.com>
Date: Fri, 3 Feb 2023 15:14:28 +0100
Subject: [PATCH 1/2] Don't repeatedly call Promise.race(). Fixes #12001
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The code was calling Promise.race() repeatedly while waiting for a file
to come into existence. This added a `PromiseReaction` object each time,
which never was collected

Contributed on behalf of STMicroelectronics

Signed-off-by: Thomas Mäder <t.s.maeder@gmail.com>
---
 .../nsfw-watcher/nsfw-filesystem-service.ts   | 33 +++++++++----------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts b/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
index e60b103f4e740..79cc13f49c27b 100644
--- a/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
+++ b/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
@@ -23,7 +23,7 @@ import {
     FileChangeType, FileSystemWatcherService, FileSystemWatcherServiceClient, WatchOptions
 } from '../../common/filesystem-watcher-protocol';
 import { FileChangeCollection } from '../file-change-collection';
-import { Deferred } from '@theia/core/lib/common/promise-util';
+import { Deferred, timeout } from '@theia/core/lib/common/promise-util';
 
 export interface NsfwWatcherOptions {
     ignored: IMinimatch[]
@@ -201,17 +201,21 @@ export class NsfwWatcher {
      * before running an NSFW watcher.
      */
     protected async start(): Promise<void> {
-        while (await this.orCancel(fsp.stat(this.fsPath).then(() => false, () => true))) {
-            await this.orCancel(new Promise(resolve => setTimeout(resolve, 500)));
+        while (!this.disposed && await fsp.stat(this.fsPath).then(() => false, () => true)) {
+            await timeout(500);
+        }
+        const watcher = await this.createNsfw();
+        if (this.disposed) {
+            return;
+        }
+
+        await watcher.start();
+        this.debug('STARTED', `disposed=${this.disposed}`);
+        // The watcher could be disposed while it was starting, make sure to check for this:
+        if (this.disposed) {
+            await this.stopNsfw(watcher);
+            return;
         }
-        const watcher = await this.orCancel(this.createNsfw());
-        await this.orCancel(watcher.start().then(() => {
-            this.debug('STARTED', `disposed=${this.disposed}`);
-            // The watcher could be disposed while it was starting, make sure to check for this:
-            if (this.disposed) {
-                this.stopNsfw(watcher);
-            }
-        }));
         this.nsfw = watcher;
     }
 
@@ -299,13 +303,6 @@ export class NsfwWatcher {
         });
     }
 
-    /**
-     * Wrap a promise to reject as soon as this handle gets disposed.
-     */
-    protected async orCancel<T>(promise: Promise<T>): Promise<T> {
-        return Promise.race<T>([this.deferredDisposalDeferred.promise, promise]);
-    }
-
     /**
      * When references hit zero, we'll schedule disposal for a bit later.
      *

From 9a8231d3f07ab56738da504e1e02f869cc8f4f74 Mon Sep 17 00:00:00 2001
From: Paul Marechal <paul.marechal@ericsson.com>
Date: Fri, 3 Feb 2023 17:06:53 -0500
Subject: [PATCH 2/2] throw upon cancellation

---
 .../nsfw-watcher/nsfw-filesystem-service.ts   | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts b/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
index 79cc13f49c27b..e5d5812e79ebc 100644
--- a/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
+++ b/packages/filesystem/src/node/nsfw-watcher/nsfw-filesystem-service.ts
@@ -196,25 +196,33 @@ export class NsfwWatcher {
         return this.refsPerClient.size > 0;
     }
 
+    /**
+     * @throws with {@link WatcherDisposal} if this instance is disposed.
+     */
+    protected assertNotDisposed(): void {
+        if (this.disposed) {
+            throw WatcherDisposal;
+        }
+    }
+
     /**
      * When starting a watcher, we'll first check and wait for the path to exists
      * before running an NSFW watcher.
      */
     protected async start(): Promise<void> {
-        while (!this.disposed && await fsp.stat(this.fsPath).then(() => false, () => true)) {
+        while (await fsp.stat(this.fsPath).then(() => false, () => true)) {
             await timeout(500);
+            this.assertNotDisposed();
         }
+        this.assertNotDisposed();
         const watcher = await this.createNsfw();
-        if (this.disposed) {
-            return;
-        }
-
+        this.assertNotDisposed();
         await watcher.start();
         this.debug('STARTED', `disposed=${this.disposed}`);
         // The watcher could be disposed while it was starting, make sure to check for this:
         if (this.disposed) {
             await this.stopNsfw(watcher);
-            return;
+            throw WatcherDisposal;
         }
         this.nsfw = watcher;
     }