use a proper AbortController instead of the home baked one

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

packages/backend-tasks/package.json

@@ -37,6 +37,7 @@
     "knex": "^0.95.1",
     "lodash": "^4.17.21",
     "luxon": "^2.0.2",
+    "node-abort-controller": "^3.0.1",
     "uuid": "^8.0.0",
     "winston": "^3.2.1",
     "zod": "^3.9.5"

packages/backend-tasks/src/tasks/CancelToken.ts

@@ -1,49 +0,0 @@
-/*
- * Copyright 2021 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-export class CancelToken {
-  #cancel: () => void;
-  #isCancelled: boolean;
-  #cancelPromise: Promise<void>;
-
-  static create(): CancelToken {
-    return new CancelToken();
-  }
-
-  private constructor() {
-    this.#isCancelled = false;
-
-    this.#cancel = () => {}; // Avoids a TS warning
-    this.#cancelPromise = new Promise(resolve => {
-      this.#cancel = () => {
-        this.#isCancelled = true;
-        resolve();
-      };
-    });
-  }
-
-  cancel(): void {
-    this.#cancel();
-  }
-
-  get isCancelled(): boolean {
-    return this.#isCancelled;
-  }
-
-  get promise(): Promise<void> {
-    return this.#cancelPromise;
-  }
-}

packages/backend-tasks/src/tasks/PluginTaskManagerJanitor.ts

@@ -16,9 +16,10 @@
 
 import { Knex } from 'knex';
 import { Duration } from 'luxon';
+import { AbortController, AbortSignal } from 'node-abort-controller';
 import { Logger } from 'winston';
 import { DbTasksRow, DB_TASKS_TABLE } from '../database/tables';
-import { CancelToken } from './CancelToken';
+import { sleep } from './util';
 
 /**
  * Makes sure to auto-expire and clean up things that time out or for other
@@ -28,7 +29,8 @@ export class PluginTaskManagerJanitor {
   private readonly knex: Knex;
   private readonly waitBetweenRuns: Duration;
   private readonly logger: Logger;
-  private readonly cancelToken: CancelToken;
+  private readonly abortController: AbortController;
+  private readonly abortSignal: AbortSignal;
 
   constructor(options: {
     knex: Knex;
@@ -38,23 +40,24 @@ export class PluginTaskManagerJanitor {
     this.knex = options.knex;
     this.waitBetweenRuns = options.waitBetweenRuns;
     this.logger = options.logger;
-    this.cancelToken = CancelToken.create();
+    this.abortController = new AbortController();
+    this.abortSignal = this.abortController.signal;
   }
 
   async start() {
-    while (!this.cancelToken.isCancelled) {
+    while (!this.abortSignal.aborted) {
       try {
         await this.runOnce();
       } catch (e) {
         this.logger.warn(`Error while performing janitorial tasks, ${e}`);
       }
 
-      await this.sleep(this.waitBetweenRuns);
+      await sleep(this.waitBetweenRuns, this.abortSignal);
     }
   }
 
   async stop() {
-    this.cancelToken.cancel();
+    this.abortController.abort();
   }
 
   private async runOnce() {
@@ -79,15 +82,4 @@ export class PluginTaskManagerJanitor {
       }
     }
   }
-
-  /**
-   * Sleeps for the given duration, but aborts sooner if the cancel token
-   * triggers.
-   */
-  private async sleep(duration: Duration) {
-    await Promise.race([
-      new Promise(resolve => setTimeout(resolve, duration.as('milliseconds'))),
-      this.cancelToken.promise,
-    ]);
-  }
 }

packages/backend-tasks/src/tasks/TaskWorker.ts

@@ -16,12 +16,12 @@
 
 import { Knex } from 'knex';
 import { Duration } from 'luxon';
+import { AbortController, AbortSignal } from 'node-abort-controller';
 import { v4 as uuid } from 'uuid';
 import { Logger } from 'winston';
 import { DbTasksRow, DB_TASKS_TABLE } from '../database/tables';
-import { CancelToken } from './CancelToken';
 import { TaskSettingsV1, taskSettingsV1Schema } from './types';
-import { nowPlus } from './util';
+import { nowPlus, sleep } from './util';
 
 const WORK_CHECK_FREQUENCY = Duration.fromObject({ seconds: 5 });
 
@@ -35,7 +35,8 @@ export class TaskWorker {
   private readonly fn: () => void | Promise<void>;
   private readonly knex: Knex;
   private readonly logger: Logger;
-  private readonly cancelToken: CancelToken;
+  private readonly abortController: AbortController;
+  private readonly abortSignal: AbortSignal;
 
   constructor(
     taskId: string,
@@ -47,7 +48,8 @@ export class TaskWorker {
     this.fn = fn;
     this.knex = knex;
     this.logger = logger;
-    this.cancelToken = CancelToken.create();
+    this.abortController = new AbortController();
+    this.abortSignal = this.abortController.signal;
   }
 
   async start(settings: TaskSettingsV1) {
@@ -63,13 +65,13 @@ export class TaskWorker {
 
     (async () => {
       try {
-        while (!this.cancelToken.isCancelled) {
+        while (!this.abortSignal.aborted) {
           const runResult = await this.runOnce();
           if (runResult.result === 'abort') {
             break;
           }
 
-          await this.sleep(WORK_CHECK_FREQUENCY);
+          await sleep(WORK_CHECK_FREQUENCY, this.abortSignal);
         }
         this.logger.info(`Task worker finished: ${this.taskId}`);
       } catch (e) {
@@ -79,7 +81,7 @@ export class TaskWorker {
   }
 
   stop() {
-    this.cancelToken.cancel();
+    this.abortController.abort();
   }
 
   /**
@@ -120,19 +122,6 @@ export class TaskWorker {
     return { result: 'completed' };
   }
 
-  /**
-   * Sleep for the given duration, but abort sooner if the cancel token
-   * triggers.
-   *
-   * @param duration - The amount of time to sleep, at most
-   */
-  private async sleep(duration: Duration): Promise<void> {
-    await Promise.race([
-      new Promise(resolve => setTimeout(resolve, duration.as('milliseconds'))),
-      this.cancelToken.promise,
-    ]);
-  }
-
   /**
    * Perform the initial store of the task info
    */

packages/backend-tasks/src/tasks/util.ts

@@ -17,6 +17,7 @@
 import { InputError } from '@backstage/errors';
 import { Knex } from 'knex';
 import { DateTime, Duration } from 'luxon';
+import { AbortSignal } from 'node-abort-controller';
 
 // Keep the IDs compatible with e.g. Prometheus
 export function validateId(id: string) {
@@ -43,3 +44,34 @@ export function nowPlus(duration: Duration | undefined, knex: Knex) {
     ? knex.raw(`datetime('now', ?)`, [`${seconds} seconds`])
     : knex.raw(`now() + interval '${seconds} seconds'`);
 }
+
+/**
+ * Sleep for the given duration, but return sooner if the abort signal
+ * triggers.
+ *
+ * @param duration - The amount of time to sleep, at most
+ * @param abortSignal - An optional abort signal that short circuits the wait
+ */
+export async function sleep(
+  duration: Duration,
+  abortSignal?: AbortSignal,
+): Promise<void> {
+  if (abortSignal?.aborted) {
+    return;
+  }
+
+  await new Promise<void>(resolve => {
+    let timeoutHandle: NodeJS.Timeout | undefined = undefined;
+
+    const done = () => {
+      if (timeoutHandle) {
+        clearTimeout(timeoutHandle);
+      }
+      abortSignal?.removeEventListener('abort', done);
+      resolve();
+    };
+
+    timeoutHandle = setTimeout(done, duration.as('milliseconds'));
+    abortSignal?.addEventListener('abort', done);
+  });
+}