// methods
/// <inheritdoc/>
public IEnumerable <ServerDescription> SelectServers(ClusterDescription cluster, IEnumerable <ServerDescription> servers)
{
var list = servers.ToList();
switch (list.Count)
{
case 0:
case 1:
return(list);
default:
{
// Follow the "Power of Two Choices" approach
// https://web.archive.org/web/20191212194243/https://www.nginx.com/blog/nginx-power-of-two-choices-load-balancing-algorithm/
var index1 = ThreadStaticRandom.Next(list.Count);
var index2 = (index1 + 1 + ThreadStaticRandom.Next(list.Count - 1)) % list.Count;
var endpoint1 = list[index1].EndPoint;
var endpoint2 = list[index2].EndPoint;
var server1 = _clusterableServers.First(s => EndPointHelper.Equals(s.Description.EndPoint, endpoint1));
var server2 = _clusterableServers.First(s => EndPointHelper.Equals(s.Description.EndPoint, endpoint2));
var selectedServer = server1.OutstandingOperationsCount < server2.OutstandingOperationsCount ? server1 : server2;
return(new[] { selectedServer.Description });
}
}
}
private PooledConnection ChooseAvailableConnection()
{
// if the pool is not full return null (so a new connection will be created)
if (_connections.Count < _settings.MaxConnections)
{
return(null);
}
// distribute load randomly among the connections
var index = ThreadStaticRandom.Next(_connections.Count);
return(_connections[index]);
}
// methods
/// <inheritdoc/>
public IEnumerable <ServerDescription> SelectServers(ClusterDescription cluster, IEnumerable <ServerDescription> servers)
{
var list = servers.ToList();
switch (list.Count)
{
case 0:
case 1:
return(list);
default:
var index = ThreadStaticRandom.Next(list.Count);
return(new[] { list[index] });
}
}
public Random() : this(ThreadStaticRandom.Next())
{
}