async-queue.ts demo

async-queue.ts

type TCallback = (arg0?: any) => Promise<any>;

class AsyncQueue {
  private queue: (() => void)[] = [];
  private inProgress: boolean = false;
  private intervalId: Timeout;
  private interval: number = 1000;

  private start() {
    this.intervalId = setInterval(() => this.next(), this.interval);
  };

  private stop() {
    clearInterval(this.intervalId);
  };

  private next() {
    // if some request is still pending
    if (this.inProgress) return;
    // if the queue is empty
    if (!this.queue.length) {
      this.stop();
      return;
    }

    const [first, ...rest]: TCallback[] = this.queue;

    this.queue = rest || [];
    // disable any new request until the current is completed
    this.inProgress = true;
    first();
  };

  wrap(wrapped: TCallback) {
    return (...rest: any[]) => new Promise((resolve, reject) => {
      this.queue.push(() => {
        wrapped(...rest)
          .then(resolve, reject)
          .finally(() => {
            // unlock ability to run the next callback in the queue
            this.inProgress = false;
          });
      });

      if (!this.intervalId) {
        // activate polling if not active
        this.start();
      }
    });
  };
}

const asyncQueue = new AsyncQueue();

export const asyncFoo1 = asyncQueue.wrap(ASYNC_CALLBACK_1);
export const asyncFoo2 = asyncQueue.wrap(ASYNC_CALLBACK_2);
export const asyncFoo3 = asyncQueue.wrap(ASYNC_CALLBACK_3);