public void test_probability_of_collisions_in_tag_produced_by_taking_3_lowest_bytes_from_hashcode_of_guid()
{
var dic = new Dictionary <Int32, Guid>();
var dup = new List <Int32>();
const int iterations = 1000000;
var duplicates = 0;
for (int i = 0; i < iterations; i++)
{
if (i % 100000 == 0)
{
Console.WriteLine(".");
}
var guid = Guid.NewGuid();
var tag = ProtobufSerializer.GenerateHierarchyTag(guid);
try
{
dic.Add(tag, guid);
}
catch (Exception ex)
{
var originalGuid = dic[tag];
duplicates++;
dup.Add(tag);
}
Assert.That(tag >= 0, Is.True, "Failed on comparing with 0 - {0}", tag);
Assert.That(tag <= 16777215, Is.True, "Failed on {0}", tag);
}
var percent = (double)duplicates / iterations;
Console.WriteLine("In {0} iterations, {1} duplicated tags. Percent {2}", iterations, duplicates, percent);
// testing ability to adjust by one:
var failes = 0;
foreach (var tag in dup)
{
try
{
dic.Add(tag + 1, Guid.Empty);
}
catch (Exception ex)
{
failes++;
}
}
//percent = (double)failes / iterations;
Console.WriteLine("In {0} duplicated tags, {1} can be easely fixed by +1.", dup.Count, dup.Count - failes);
}
public void should_be_in_valid_range()
{
for (int i = 0; i < 100000000; i++)
{
var guid = Guid.NewGuid();
var tag = ProtobufSerializer.GenerateHierarchyTag(guid);
Assert.That(tag >= 0, Is.True, "Should be greater or equal to 0, but was {0}", tag);
Assert.That(tag <= 16777215, Is.True, "Should be lower or equal to 16777215, but was {0}", tag);
}
}
public void hierarchy_tag_should_be_calculated_correctly()
{
Action <String, Int32> test = (guidText, tag) =>
{
var guid = Guid.Parse(guidText);
var calculatedTag = ProtobufSerializer.GenerateHierarchyTag(guid);
Assert.That(calculatedTag, Is.EqualTo(tag));
};
test("{66047c12-32c5-4842-8023-70d1658a836e}", 12661822);
test("{ea1dbd75-bf2b-4ed9-be6a-ce32c6b3e505}", 13175895);
test("{decde923-ff46-4c20-a6f6-ac7645e5325b}", 7625384);
test("{5c69c886-76ef-4458-8afb-dc7cc40501a2}", 7959428);
test("{628f6c9b-99bb-4bda-90e5-7b406ca0271a}", 13359269);
}