private Action GetProcessCustomerAction(Cashier cashier, CancellationToken token)
{
return(() =>
{
try
{
var customer = customersQueue.DequeueCustomer(); // blocking operation!
var rnd = new Random();
var processDurationInSeconds = rnd.Next(minCashierProcessingTime, maxCashierProcessingTime + 1);
cashier.ProcessCustomer(customer, processDurationInSeconds); // blocking operation!
logger.Info($"{cashier.Name} finished processing customer at: {customer.Finished}. Number of waiting customers: {customersQueue.GetCustomersCount()}");
}
catch (Exception e)
{
logger.Error($"Error in {cashier.Name} work: {e}");
}
finally
{
// I issue a new task instaed of just calling this Action recursively, beacuse it will cause
// the call stack to chain and eventually to cause an out of memory error.
// The child task is, by deafult, detached from its parent task and therefore will not chain a call stack.
if (!token.IsCancellationRequested)
{
taskFactory.StartNew(GetProcessCustomerAction(cashier, token), token);
}
else
{
logger.Info($"{cashier.Name} work was cancelled. Stopping.");
}
}
});
}
private void ProcessSingleCustomer()
{
var customer = customersQueue.DequeueCustomer(); // blocking operation
var rnd = new Random();
var processDurationInSeconds = rnd.Next(minCashierProcessingTime, maxCashierProcessingTime + 1);
taskFactory.StartNew(() =>
{
var cashier = new Cashier($"Cashier-{Thread.CurrentThread.ManagedThreadId}", sleepService);
try
{
cashier.ProcessCustomer(customer, processDurationInSeconds); // blocking operation!
logger.Info($"{cashier.Name} finished processing customer at: {customer.Finished}. Number of waiting customers: {customersQueue.GetCustomersCount()}");
}
catch (Exception e)
{
logger.Error($"Error in {cashier.Name} work: {e}");
}
finally
{
maxCashiersSemaphore.Release();
}
});
}