internal Task ModifyTopology(Topology requested)
{
if (State != RaftEngineState.Leader)
{
throw new NotLeadingException("Cannot modify topology from a non leader node, current leader is: " +
(CurrentLeader ?? "no leader"));
}
var logEntry = PersistentState.GetLogEntry(CommitIndex);
if (logEntry == null)
{
throw new InvalidOperationException("No log entry for committed for index " + CommitIndex + ", this is probably a brand new cluster with no committed entries or a serious problem");
}
if (logEntry.Term != PersistentState.CurrentTerm)
{
throw new InvalidOperationException("Cannot modify the cluster topology when the committed index " + CommitIndex + " is in term " + logEntry.Term + " but the current term is " +
PersistentState.CurrentTerm + ". Wait until the leader finishes committing entries from the current term and try again");
}
var tcc = new TopologyChangeCommand
{
Completion = new TaskCompletionSource <object>(),
Requested = requested,
Previous = _currentTopology,
BufferCommand = false,
};
if (Interlocked.CompareExchange(ref _changingTopology, tcc.Completion.Task, null) != null)
{
throw new InvalidOperationException("Cannot change the cluster topology while another topology change is in progress");
}
try
{
if (_log.IsDebugEnabled)
{
_log.Debug("Topology change started on leader");
}
StartTopologyChange(tcc);
AppendCommand(tcc);
return(tcc.Completion.Task);
}
catch (Exception)
{
Interlocked.Exchange(ref _changingTopology, null);
throw;
}
}
