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public class KetamaNodeLocator
{
private SortedList<long, string> ketamaNodes = new SortedList<long, string>();
private HashAlgorithm hashAlg;
private int numReps = 160;
public KetamaNodeLocator(List<string> nodes, int nodeCopies)
{
ketamaNodes = new SortedList<long, string>();
numReps = nodeCopies;
foreach (string node in nodes)
{
for (int i = 0; i < numReps / 4; i++)
{
byte[] digest = HashAlgorithm.computeMd5(node + i);
for (int h = 0; h < 4; h++)
{
long m = HashAlgorithm.hash(digest, h);
ketamaNodes[m] = node;
}
}
}
}
public string GetPrimary(string k)
{
byte[] digest = HashAlgorithm.computeMd5(k);
string rv = GetNodeForKey(HashAlgorithm.hash(digest, 0));
return rv;
}
string GetNodeForKey(long hash)
{
string rv;
long key = hash;
if (!ketamaNodes.ContainsKey(key))
{
var tailMap = from coll in ketamaNodes
where coll.Key > hash
select new { coll.Key };
if (tailMap == null || tailMap.Count() == 0)
key = ketamaNodes.FirstOrDefault().Key;
else
key = tailMap.FirstOrDefault().Key;
}
rv = ketamaNodes[key];
return rv;
}
}
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