src/utils/AsyncLock.ts

   1 // Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 import Queue from 'mnemonist/queue.js';
   4
   5 import { Constants } from './Constants.js';
   6
   7 export enum AsyncLockType {
   8   configuration = 'configuration',
   9   performance = 'performance',
  10 }
  11
  12 type ResolveType = (value: void | PromiseLike<void>) => void;
  13
  14 export class AsyncLock {
  15   private static readonly asyncLocks = new Map<AsyncLockType, AsyncLock>();
  16   private acquired: boolean;
  17   private readonly resolveQueue: Queue<ResolveType>;
  18
  19   private constructor() {
  20     this.acquired = false;
  21     this.resolveQueue = new Queue<ResolveType>();
  22   }
  23
  24   public static async runExclusive<T>(type: AsyncLockType, fn: () => T | Promise<T>): Promise<T> {
  25     return AsyncLock.acquire(type)
  26       .then(fn)
  27       .finally(() => {
  28         AsyncLock.release(type).catch(Constants.EMPTY_FUNCTION);
  29       });
  30   }
  31
  32   private static async acquire(type: AsyncLockType): Promise<void> {
  33     const asyncLock = AsyncLock.getAsyncLock(type);
  34     if (!asyncLock.acquired) {
  35       asyncLock.acquired = true;
  36       return;
  37     }
  38     return new Promise<void>((resolve) => {
  39       asyncLock.resolveQueue.enqueue(resolve);
  40     });
  41   }
  42
  43   private static async release(type: AsyncLockType): Promise<void> {
  44     const asyncLock = AsyncLock.getAsyncLock(type);
  45     if (asyncLock.resolveQueue.size === 0 && asyncLock.acquired) {
  46       asyncLock.acquired = false;
  47       return;
  48     }
  49     const queuedResolve = asyncLock.resolveQueue.dequeue()!;
  50     return new Promise<void>((resolve) => {
  51       queuedResolve();
  52       resolve();
  53     });
  54   }
  55
  56   private static getAsyncLock(type: AsyncLockType): AsyncLock {
  57     if (!AsyncLock.asyncLocks.has(type)) {
  58       AsyncLock.asyncLocks.set(type, new AsyncLock());
  59     }
  60     return AsyncLock.asyncLocks.get(type)!;
  61   }
  62 }