/// <summary>
/// Maps sharding ID to processor ID. This method is used to map process unqiue mutex id, or GDID to processor ID - which denotes a
/// set of actual executor hosts
/// </summary>
public int MapShardingKeyToProcessorID(string shardingKey)
{
var ids = ProcessorMap.Keys.ToArray();
if (ids.Length == 0)
{
throw new MetabaseException("TODO: MapShardingKeyToProcessorID(ProcessorMap is empty)");
}
var hash = ShardingUtils.StringToShardingID(shardingKey);
var idx = hash % (ulong)ids.Length;
return(ids[idx]);
}
public void RandomWebSafeStringToShardingIDTest()
{
var count = 1000000L;
var counters = new long[8];
for (var i = 0L; i < count; i++)
{
var shardID = ShardingUtils.StringToShardingID(ExternalRandomGenerator.Instance.NextRandomWebSafeString(4, 12));
counters[shardID % (ulong)counters.Length]++;
}
for (int i = 0, length = counters.Length; i < length; i++)
{
var percent = (counters[i] * 10000 / count) / 100.0;
Console.WriteLine("counter[{0}] = {1}; // {2}%".Args(i, counters[i], percent));
Aver.IsTrue(Math.Abs((100.0 / counters.Length) - percent) <= 1.0);
}
}
/// <summary>
/// Assigns a worker from the set for the supplied sharding key.
/// If key is null then a random member is assigned.
/// Returns null if there is no host available for assignment
/// </summary>
public virtual HostPair AssignHost(object shardingKey)
{
var hosts = m_Hosts;//thread-safe copy, as during execution another may swap
if (hosts == null || hosts.Length == 0)
{
return(new HostPair());
}
if (shardingKey == null)
{
shardingKey = App.Random.NextRandomInteger;
}
var idx = (uint)ShardingUtils.ObjectToShardingID(shardingKey) % hosts.Length;
var idx1 = -1L;
for (var c = 0; c < hosts.Length; c++)
{
var current = idx;
idx = (current + 1) % hosts.Length;
var host = hosts[current];
if (!host.LastDownTime.HasValue)
{
idx1 = current;
break;
}
}
var idx2 = -1L;
for (var c = 0; c < hosts.Length; c++)
{
var current = idx;
idx = (current + 1) % hosts.Length;
var host = hosts[current];
if (!host.LastDownTime.HasValue && current != idx1)
{
idx2 = current;
break;
}
}
return(new HostPair(idx1 >= 0 ? hosts[idx1].Section : null, idx2 >= 0 ? hosts[idx2].Section : null));
}
/// <summary>
/// Finds appropriate shard for key. See MDB.ShardingUtils
/// </summary>
public Shard GetShardForKey(byte[] key)
{
ulong subid = ShardingUtils.ObjectToShardingID(key);
return(Shards[subid % (ulong)Shards.Length]);
}
