locking_in_javascript_3.cs

  loadWithPromiseLock = async (key: string): Promise<boolean> => {
    this.log(key + 'Calling loadWithPromiseLock');
    const random = Math.random();
    this.log(key + 'Random: ' + random);

    // Check if the data is already loaded
    if (this.promiseDataMap.has(key)) {
      this.log(key + 'Data is already loaded');
      return true;
    }

    // Check if there is already a loading promise for this key
    if (this.fallbackLoadingPromises.has(key)) {
      this.log(key + 'Data is already loading');
      return this.fallbackLoadingPromises.get(key)!;
    }

    // Create a new loading promise
    const loadingPromise = (async () => {
        this.log(key + '***START*** Loading data');
        await this.slowApiCall(key);

        this.promiseDataMap.set(key, 'data + ' + random);

        // Remove the loading promise from the map after completion
        this.fallbackLoadingPromises.delete(key);
        this.log(key + '***END*** Data loaded');
        return true;
    })();

    // Store the loading promise in the map
    this.fallbackLoadingPromises.set(key, loadingPromise);

    return loadingPromise;
  }