Method waitUntilAllowStart

scope.go:163–199

(sleep time.Duration, deadline time.Time, labels prometheus.Labels)

}

func (s *scope) waitUntilAllowStart(sleep time.Duration, deadline time.Time, labels prometheus.Labels) error {
	for {
		err := s.inc()
		if err == nil {
			// The request is allowed to start.
			return nil
		}

		dLeft := time.Until(deadline)
		if dLeft <= 0 {
			// Give up: the request exceeded its wait time
			// in the queue :(
			return err
		}

		// The request has dLeft remaining time to wait in the queue.
		// Sleep for a bit and try starting it again.
		if sleep > dLeft {
			time.Sleep(dLeft)
		} else {
			time.Sleep(sleep)
		}
		var h *topology.Node
		// Choose new host, since the previous one may become obsolete
		// after sleeping.
		if s.sessionId == "" {
			h = s.cluster.getHost()
		} else {
			// if request has session_id, set same host
			h = s.cluster.getHostSticky(s.sessionId)
		}

		s.host = h
		s.labels["replica"] = h.ReplicaName()
		s.labels["cluster_node"] = h.Host()
	}
}

func (s *scope) calculateQueueDeadlineAndSleep() (time.Duration, time.Time) {
	d := s.maxQueueTime()