Luna
45 lines
814 B
TypeScript
45 lines
814 B
TypeScript
export class Semaphore {
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private current = 0;
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private readonly waiting: Array<() => void> = [];
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constructor(private readonly limit: number) {}
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get active(): number {
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return this.current;
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}
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get queued(): number {
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return this.waiting.length;
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}
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async use<T>(task: () => Promise<T>): Promise<T> {
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await this.acquire();
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try {
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return await task();
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} finally {
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this.release();
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}
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}
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private async acquire(): Promise<void> {
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if (this.current < this.limit) {
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this.current += 1;
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return;
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}
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await new Promise<void>((resolve) => {
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this.waiting.push(() => {
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this.current += 1;
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resolve();
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});
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});
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}
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private release(): void {
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this.current -= 1;
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const next = this.waiting.shift();
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next?.();
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}
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}
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