public void ResetDue <T>(T item)
where T : ISensorScanRateItem
{
if (!LastMeasurement.ContainsKey(item))
{
throw new InvalidOperationException("Sensor configuration item has not been registered earlier");
}
LastMeasurement[item].Restart();
}
public bool IsDue <T>(T item)
where T : ISensorScanRateItem
{
if (!LastMeasurement.ContainsKey(item))
{
throw new InvalidOperationException("Sensor configuration item has not been registered earlier");
}
var stopwatch = LastMeasurement[item];
return(stopwatch.Elapsed >= item.ScanRate);
}
private async Task Main(CancellationToken cancellationToken)
{
while (!cancellationToken.IsCancellationRequested)
{
try
{
if (IsConnected)
{
// collect due items
var dueItems = LastMeasurement
.Where(t => IsDue(t.Key))
.Select(t => t.Key)
.ToList();
if (dueItems.Any())
{
await OnIsDue(dueItems, cancellationToken);
}
else
{
// no items due
}
}
else
{
// do not request measurements while disconnected
// we have to delay in this situation at least for some
// time to avoid hot looping
Console.WriteLine($"Not connected, delaying new measurements for one second ..");
await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken);
}
// delay and wait for next cycle
var nextDueTimes = LastMeasurement
.Select(t => t.Key.ScanRate - t.Value.Elapsed)
.Distinct()
.OrderBy(t => t)
.ToList();
if (nextDueTimes.Count > 0)
{
var minDueTime = nextDueTimes.First();
// this delay is a smart guess observing that a Task.Delay() won't
// be accurate enough to accomodate a delay shorter than this interval.
// better avoid unnecessary delays if the smallest delay is shorter than this
// upon reaching this interval it is better to skip the delay and straight
// check if any item is due
var smallestPossibleDelay = TimeSpan.Zero;
if (minDueTime < smallestPossibleDelay)
{
// another item is already due, skip delay
}
else
{
await Task.Delay(minDueTime, cancellationToken);
}
}
else
{
await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken);
}
}
catch (TaskCanceledException)
{
// ignore
}
catch (Exception ex)
{
Console.WriteLine($"Measurement request generator caught exception and resumes operation: {ex}");
}
}
}