public string WhoseTaskIsIt(
RachisState state,
IDatabaseTask task,
Func <string> getLastResponsibleNode)
{
if (state == RachisState.Candidate || state == RachisState.Passive)
{
return(null);
}
var mentorNode = task.GetMentorNode();
if (mentorNode != null)
{
if (Members.Contains(mentorNode))
{
return(mentorNode);
}
}
var lastResponsibleNode = getLastResponsibleNode?.Invoke();
if (lastResponsibleNode != null)
{
return(lastResponsibleNode);
}
var topology = new List <string>(Members);
topology.AddRange(Promotables);
topology.AddRange(Rehabs);
topology.Sort();
if (topology.Count == 0)
{
return(null); // this is probably being deleted now, no one is able to run tasks
}
var key = task.GetTaskKey();
while (true)
{
var index = (int)Hashing.JumpConsistentHash.Calculate(key, topology.Count);
var entry = topology[index];
if (Members.Contains(entry))
{
return(entry);
}
topology.RemoveAt(index);
if (topology.Count == 0)
{
return(null); // all nodes in the topology are probably in rehab
}
// rehash so it will likely go to a different member in the cluster
key = Hashing.Mix(key);
}
}
public string WhoseTaskIsIt(
RachisState state,
IDatabaseTask task,
Func <string> getLastResponsibleNode)
{
if (state == RachisState.Candidate || state == RachisState.Passive)
{
return(null);
}
var mentorNode = task.GetMentorNode();
if (mentorNode != null)
{
if (Members.Contains(mentorNode))
{
return(mentorNode);
}
}
var lastResponsibleNode = getLastResponsibleNode?.Invoke();
if (lastResponsibleNode != null)
{
return(lastResponsibleNode);
}
var topology = new List <string>(Members);
topology.AddRange(Promotables);
topology.AddRange(Rehabs);
topology.Sort();
if (task.IsResourceIntensive() && Members.Count > 1)
{
// if resource intensive operation, we don't want to have it on the first node of the database topology
return(FindNodeForIntensiveOperation(task.GetTaskKey(), topology));
}
return(FindNode(task.GetTaskKey(), topology));
}
