private checkConnectivity()

in src/shippers/elastic_v3/server/src/server_shipper.ts [195:238]
39 lines of code
6 McCabe index (conditional complexity)

  private checkConnectivity() {
    let backoff = 1 * MINUTE;
    merge(
      timer(0, 1 * MINUTE),
      // Also react to opt-in changes to avoid being stalled for 1 minute for the first connectivity check.
      // More details in: https://github.com/elastic/kibana/issues/135647
      this.isOptedIn$
    )
      .pipe(
        takeUntil(this.shutdown$),
        filter(() => this.isOptedIn$.value === true && this.firstTimeOffline !== null),
        // Using exhaustMap here because one request at a time is enough to check the connectivity.
        exhaustMap(async () => {
          const { ok } = await fetch(this.url, {
            method: 'OPTIONS',
          });

          if (!ok) {
            throw new Error(`Failed to connect to ${this.url}`);
          }

          this.firstTimeOffline = null;
          backoff = 1 * MINUTE;
        }),
        retryWhen((errors) =>
          errors.pipe(
            takeUntil(this.shutdown$),
            tap(() => {
              if (!this.firstTimeOffline) {
                this.firstTimeOffline = Date.now();
              } else if (Date.now() - this.firstTimeOffline > 24 * HOUR) {
                this.internalQueue.length = 0;
              }
              backoff = backoff * 2;
              if (backoff > 1 * HOUR) {
                backoff = 1 * HOUR;
              }
            }),
            delayWhen(() => timer(backoff))
          )
        )
      )
      .subscribe();
  }