public async Task GuidQueryPartitioner_partitions_guids_fairly()
{
var totalNumberOfGuids = 1000;
var numberOfPartitions = 50;
var partitions = StreamQuery.Partition(
Guid.Empty,
Guid.Parse("ffffffff-ffff-ffff-ffff-ffffffffffff"))
.Among(numberOfPartitions);
var guids = Enumerable.Range(1, totalNumberOfGuids).Select(_ => Guid.NewGuid()).ToArray();
var partitioner = Stream.Partition<Guid, int, Guid>(
async (q, p) =>
guids.Where(g => new SqlGuid(g).CompareTo(new SqlGuid(p.LowerBoundExclusive)) > 0 &&
new SqlGuid(g).CompareTo(new SqlGuid(p.UpperBoundInclusive)) <= 0),
advanceCursor: (q, b) => q.Cursor.AdvanceTo(totalNumberOfGuids));
var aggregator = Aggregator.Create<Projection<HashSet<Guid>, int>, Guid>((p, b) =>
{
if (p.Value == null)
{
p.Value = new HashSet<Guid>();
}
foreach (var guid in b)
{
p.Value.Add(guid);
}
});
var store = new InMemoryProjectionStore<Projection<HashSet<Guid>, int>>();
await Task.WhenAll(partitions.Select(async partition =>
{
var stream = await partitioner.GetStream(partition);
var catchup = StreamCatchup.Create(stream, batchCount: int.MaxValue);
catchup.Subscribe(aggregator, store);
await catchup.RunSingleBatch();
await Task.Delay(500);
var projection = await store.Get(stream.Id);
Console.WriteLine(partition + ": " + projection.Value.Count);
}));
var approximateGuidsPerPartition = totalNumberOfGuids/numberOfPartitions;
var tolerance = (int) (totalNumberOfGuids*.12);
Console.WriteLine("\nMissing guids: ");
foreach (var guid in guids.Where(g => !store.Any(p => p.Value.Contains(g))))
{
Console.WriteLine(" " + guid);
}
store.Sum(p => p.Value.Count).Should().Be(totalNumberOfGuids);
store.ToList().ForEach(projection =>
{
projection.Value
.Count
.Should()
.BeInRange(approximateGuidsPerPartition - tolerance,
approximateGuidsPerPartition + tolerance);
});
}
