public static string ResolveToPartition(string partitionKey, int partitionCount)
{
if (string.IsNullOrWhiteSpace(partitionKey))
{
throw new ArgumentNullException(nameof(partitionKey));
}
if (partitionCount < 1 || partitionCount > DefaultLogicalPartitionCount)
{
throw new ArgumentOutOfRangeException(nameof(partitionCount), partitionCount, string.Format(CultureInfo.InvariantCulture, "Should be between {0} and {1}", 1, DefaultLogicalPartitionCount));
}
short logicalPartition = Math.Abs((short)(PerfectHash.HashToShort(partitionKey) % DefaultLogicalPartitionCount));
int shortRangeWidth = (int)Math.Floor((decimal)DefaultLogicalPartitionCount / (decimal)(partitionCount));
int remainingLogicalPartitions = DefaultLogicalPartitionCount - (partitionCount * shortRangeWidth);
int largeRangeWidth = shortRangeWidth + 1;
int largeRangesLogicalPartitions = largeRangeWidth * remainingLogicalPartitions;
int partitionIndex = logicalPartition < largeRangesLogicalPartitions
? logicalPartition / largeRangeWidth
: remainingLogicalPartitions + ((logicalPartition - largeRangesLogicalPartitions) / shortRangeWidth);
return(partitionIndex.ToString(NumberFormatInfo.InvariantInfo));
}
