public async Task <TimeSpan> UpdateServiceHelth()
{
// Read saved service providers from the DB
List <ServiceProvider> serviceProviders = await serviceProviderRepository.GetAll();
// Check network connectivity status
ServiceStatusResult updateResult = await networkService.CheckTcpConnection(serviceProviders);
// write new status to the DB
Task updateServiceProviderTask = serviceProviderRepository.Upsert(updateResult.ServiceProviders);
// send mail notifications
Task <TimeSpan> sendMailTask = SendNotifications(updateResult);
// DB update, email notification and polling freaquency read can happen asynchronusly
// Let the DB query run asynchronously while above two operations runs
Task <TimeSpan> pollingFreaquencyTask = serviceProviderRepository.GetMaximumPollingFreaquency();
// wait for DB update and notifications to complete
await updateServiceProviderTask;
TimeSpan minimumGracePeriod = await sendMailTask;
// wait for the query result. This should be already completed
TimeSpan pollingFreaquency = await pollingFreaquencyTask;
// Next update cycle will be initialized based on the minimum value between polling frequency and minimum grace period of failed services.
// From the NetworkService class correct polling frequency will be checked and skipped unnecessary network checks
TimeSpan nextUpdateFrequency = minimumGracePeriod < pollingFreaquency ? minimumGracePeriod : pollingFreaquency;
return(nextUpdateFrequency);
}