// Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
+import Queue from 'mnemonist/queue.js';
+
export enum AsyncLockType {
configuration = 'configuration',
performance = 'performance',
}
+type ResolveType = (value: void | PromiseLike<void>) => void;
+
export class AsyncLock {
- private static readonly instances = new Map<AsyncLockType, AsyncLock>();
+ private static readonly asyncLocks = new Map<AsyncLockType, AsyncLock>();
private acquired: boolean;
- private readonly resolveQueue: ((value: void | PromiseLike<void>) => void)[];
+ private readonly resolveQueue: Queue<ResolveType>;
- private constructor(private readonly type: AsyncLockType) {
+ private constructor() {
this.acquired = false;
- this.resolveQueue = [];
- }
-
- public static getInstance(type: AsyncLockType): AsyncLock {
- if (!AsyncLock.instances.has(type)) {
- AsyncLock.instances.set(type, new AsyncLock(type));
- }
- return AsyncLock.instances.get(type);
+ this.resolveQueue = new Queue<ResolveType>();
}
- public async acquire(): Promise<void> {
- if (!this.acquired) {
- this.acquired = true;
- } else {
- return new Promise((resolve) => {
- this.resolveQueue.push(resolve);
- });
+ public static async acquire(type: AsyncLockType): Promise<void> {
+ const asyncLock = AsyncLock.getAsyncLock(type);
+ if (!asyncLock.acquired) {
+ asyncLock.acquired = true;
+ return;
}
+ return new Promise<void>((resolve) => {
+ asyncLock.resolveQueue.enqueue(resolve);
+ });
}
- public async release(): Promise<void> {
- if (this.resolveQueue.length === 0 && this.acquired) {
- this.acquired = false;
+ public static async release(type: AsyncLockType): Promise<void> {
+ const asyncLock = AsyncLock.getAsyncLock(type);
+ if (asyncLock.resolveQueue.size === 0 && asyncLock.acquired) {
+ asyncLock.acquired = false;
return;
}
- const queuedResolve = this.resolveQueue.shift();
- return new Promise((resolve) => {
+ const queuedResolve = asyncLock.resolveQueue.dequeue()!;
+ return new Promise<void>((resolve) => {
queuedResolve();
resolve();
});
}
+
+ private static getAsyncLock(type: AsyncLockType): AsyncLock {
+ if (!AsyncLock.asyncLocks.has(type)) {
+ AsyncLock.asyncLocks.set(type, new AsyncLock());
+ }
+ return AsyncLock.asyncLocks.get(type)!;
+ }
}