async function tryFlush()

in src/autoscaler-common/counters-base.js [420:495]
45 lines of code
10 McCabe index (conditional complexity)

async function tryFlush() {
  // check for if we are initialised
  await pendingInit?.promise;

  if (!tryFlushEnabled || !EXPORTER_PARAMETERS[exporterMode].FLUSH_ENABLED) {
    // flushing disabled, do nothing!
    return;
  }

  // Avoid simultaneous flushing!
  if (flushInProgress) {
    return await flushInProgress.promise;
  }

  flushInProgress = PromiseWithResolvers.create();

  try {
    // If flushed recently, wait for the min interval to pass.
    const millisUntilNextForceFlush =
      lastForceFlushTime +
      EXPORTER_PARAMETERS[exporterMode].FLUSH_MIN_INTERVAL -
      Date.now();

    if (millisUntilNextForceFlush > 0) {
      // wait until we can force flush again!
      logger.debug('Counters.tryFlush() waiting until flushing again');
      await setTimeout(millisUntilNextForceFlush);
    }

    // OpenTelemetry's forceFlush() will always succeed, even if the backend
    // fails and reports an error...
    //
    // So we use the OpenTelemetry Global Error Handler installed above
    // to keep a count of the number of errors reported, and if an error
    // is reported during a flush, we wait a while and try again.
    // Not perfect, but the best we can do.
    //
    // To avoid end-users seeing these errors, we supress error messages
    // until the very last flush attempt.
    //
    // Note that if the OpenTelemetry metrics are exported to Google Cloud
    // Monitoring, the first time a counter is used, it will fail to be
    // exported and will need to be retried.
    let attempts = EXPORTER_PARAMETERS[exporterMode].FLUSH_MAX_ATTEMPTS;
    while (attempts > 0) {
      const oldOpenTelemetryErrorCount = openTelemetryErrorCount;

      // Suppress OTEL Diag error messages on all but the last flush attempt.
      DIAG_BUNYAN_LOGGER.suppressErrors = attempts > 1;
      await meterProvider.forceFlush();
      DIAG_BUNYAN_LOGGER.suppressErrors = false;

      lastForceFlushTime = Date.now();

      if (oldOpenTelemetryErrorCount === openTelemetryErrorCount) {
        // success!
        return;
      } else {
        logger.warn('Opentelemetry reported errors during flushing, retrying.');
      }
      await setTimeout(EXPORTER_PARAMETERS[exporterMode].FLUSH_MIN_INTERVAL);
      attempts--;
    }
    if (attempts <= 0) {
      logger.error(
        `Failed to flush counters after ${EXPORTER_PARAMETERS[exporterMode].FLUSH_MAX_ATTEMPTS} attempts - see OpenTelemetry logging`,
      );
    }
  } catch (err) {
    logger.error({err: err, message: `Error while flushing counters: ${err}`});
  } finally {
    // Release any waiters...
    flushInProgress.resolve(null);
    flushInProgress = null;
  }
}