/// <summary>
/// Gets densities for segments with size equal to <paramref name="segmentSize"/>
/// </summary>
/// <param name="buckets">Array of buckets</param>
/// <param name="start">Start timestamp of the event range we want to find. If null, then it is a first event time in the first bucket of the buckets array.</param>
/// <param name="segmentSize">Length/duration of one segment</param>
/// <param name="finalize">Flag indicating that density should be calculated for the last incomplete segment if there is one</param>
/// <param name="nextBatchStartTime">Next start time</param>
/// <returns></returns>
public static double[] GetDensities(ArraySegment <Bucket> bucketsArray, long?start, long segmentSize, bool finalize, out long nextBatchStartTime)
{
var buckets = bucketsArray.AsSpan();
if (buckets.Length < 1)
{
throw new ArgumentException("Empty array of buckets is not allowed");
}
if (!start.HasValue)
{
start = buckets[0].GetAbsoluteTimeForEvent(buckets[0].GetFirstEvent());
}
long end = buckets[buckets.Length - 1].GetAbsoluteTimeForEvent(buckets[buckets.Length - 1].GetLastEvent()) + 1;
ushort totalSegments = 0;
try
{
if (finalize)
{
totalSegments = checked ((ushort)Math.Ceiling((end - start.Value) / (double)segmentSize));
}
else
{
totalSegments = checked ((ushort)Math.Floor((end - start.Value) / (double)segmentSize));
}
}
catch (OverflowException)
{
throw new ArgumentException("Too small segment size for such a big range", nameof(segmentSize));
}
var densitiesBuf = new double[totalSegments];
DensityCalculator.CalculateDensities(
bucketsArray.AsMemory(),
new DensityCalculationRequest(start.Value, end, segmentSize),
densitiesBuf,
finalize,
out long processedRange
);
nextBatchStartTime = start.Value + processedRange;
return(densitiesBuf);
}
/// <summary>
/// Gets densities for segments with size equal to <paramref name="segmentSize"/>
/// </summary>
/// <param name="container">Bucket container</param>
/// <param name="start">Start time</param>
/// <param name="end">End time</param>
/// <param name="segmentSize">Length/duration of one segment</param>
/// <param name="targetBuffer">Targer buffer into which calculated densities are saved</param>
/// <returns></returns>
public static Span <double> GetDensities(BucketContainer container, long start, long end, long segmentSize, ref double[] targetBuffer)
{
if (end <= start)
{
throw new ArgumentException("Wrong interval. End timestamp must be greater than start timestamp.");
}
if (end - start < segmentSize)
{
throw new ArgumentException("Segment size is too big for this time interval", nameof(segmentSize));
}
var lastBucket = container.GetLastBucket();
var maxTime = lastBucket.GetAbsoluteTimeForEvent(lastBucket.GetLastEvent());
if (end > maxTime + 1)
{
end = maxTime + 1;
}
// Start time is out of range
if (end < start)
{
return(Span <double> .Empty);
}
ushort totalSegments = GetTotalSegments(start, end, segmentSize);
if (targetBuffer == null)
{
targetBuffer = new double[totalSegments];
}
else if (targetBuffer.Length < totalSegments)
{
throw new ArgumentException("Target buffer is too short", nameof(targetBuffer));
}
int processedSegmentsUsingHints = -1;
try
{
checked
{
container.DensityHintContainer?.TrySetDensitiesUsingHints(
start - container.FirstTimestamp,
end - container.FirstTimestamp,
segmentSize,
targetBuffer,
out processedSegmentsUsingHints
);
}
}
catch (OverflowException)
{
throw new InvalidOperationException("Too big range of events");
}
#if DEBUG
if (processedSegmentsUsingHints == 0 && segmentSize >= 10_000_000)
{
Debug.Fail("Density calculation is perfoming in unoptimized way. It can be eliminated by adjusting range and segment size to appropriate values.");
}
#endif
if (processedSegmentsUsingHints < 0)
{
processedSegmentsUsingHints = 0;
}
if (processedSegmentsUsingHints == totalSegments)
{
return(targetBuffer.AsSpan(0, totalSegments));
}
start += processedSegmentsUsingHints * segmentSize;
int uncalculatedDensitiesCount = totalSegments - processedSegmentsUsingHints;
var targetBufferCopy = targetBuffer;
Parallel.ForEach(GetPartitions(start, segmentSize, targetBuffer.AsSpan(processedSegmentsUsingHints, uncalculatedDensitiesCount)), (partition) =>
{
Span <double> batch = targetBufferCopy.AsSpan(processedSegmentsUsingHints, uncalculatedDensitiesCount)
.Slice(partition.leftBoundary, partition.batchLength);
DensityCalculator.CalculateDensities(
container.Buckets,
new DensityCalculationRequest(partition.start, partition.end, segmentSize),
batch,
true,
out long processedRange
);
});
return(targetBuffer.AsSpan(0, totalSegments));
}
