private ExecutingQueryInfo AddToCurrentlyRunningQueryList(string index, IndexQuery query, CancellationTokenSource externalTokenSource)
{
var set = WorkContext.CurrentlyRunningQueries.GetOrAdd(index, x => new ConcurrentSet <ExecutingQueryInfo>());
var queryStartTime = DateTime.UtcNow;
var queryId = WorkContext.GetNextQueryId();
var executingQueryInfo = new ExecutingQueryInfo(queryStartTime, query, queryId, externalTokenSource);
set.Add(executingQueryInfo);
return(executingQueryInfo);
}