private async Task FetchMeasurementsAsync(DateTime Hour)
{
// Discard all old data.
hourData = new Dictionary <DateTime, List <Measurement> >();
// Determine where to stop.
var endHour = Hour.AddHours(PrefetchSize);
if (endHour > CacheEnd)
{
endHour = CacheEnd;
}
// Initialize the hour data cache.
for (DateTime i = Hour; i < endHour; i = i.AddHours(1))
{
hourData[i] = new List <Measurement>();
}
// Fetch raw data.
var measurements = await Database.GetRawMeasurementsAsync(SensorId, Hour, endHour);
// Insert data into cache.
foreach (var item in measurements)
{
var hour = MeasurementAggregation.Quantize(item.Time, TimeSpan.FromHours(1));
hourData[hour].Add(item);
}
}
private async Task <IEnumerable <Measurement> > GetMeasurementsAsync(FrozenPeriod Period)
{
const int MinutesPerHour = 60;
switch (Period.Compaction)
{
case CompactionLevel.DayAverages:
case CompactionLevel.HourAverages:
case CompactionLevel.Measurements:
// We'll re-create measurement data by replicating
// hour-average data.
var results = await GetHourAveragesAsync(
MeasurementAggregation.Quantize(Period.StartTime, TimeSpan.FromHours(1)),
(int)Math.Ceiling(Period.Duration.TotalHours));
return(ReplicateEach(results, Period.StartTime, Period.EndTime, TimeSpan.FromMinutes(1), MinutesPerHour).ToArray());
case CompactionLevel.None:
default:
// We can just fetch real measurements from the database.
return(await Database.GetRawMeasurementsAsync(SensorId, Period.StartTime, Period.EndTime));
}
}
private async Task <IEnumerable <Measurement> > GetHourAveragesAsync(FrozenPeriod Period)
{
const int HoursPerDay = 24;
switch (Period.Compaction)
{
case CompactionLevel.DayAverages:
case CompactionLevel.HourAverages:
// We'll re-create hour-average data by replicating
// day-average data.
var results = await GetDayAveragesAsync(
MeasurementAggregation.Quantize(Period.StartTime, TimeSpan.FromDays(1)),
(int)Math.Ceiling(Period.Duration.TotalDays));
return(ReplicateEach(results, Period.StartTime, Period.EndTime, TimeSpan.FromHours(1), HoursPerDay).ToArray());
case CompactionLevel.Measurements:
case CompactionLevel.None:
default:
// We can just fetch or create "real" hour-average data.
return(await GetRealHourAveragesAsync(Period.StartTime, (int)Period.Duration.TotalHours));
}
}
