Function getNonExcludedInstance

pkg/querier/blocks_store_replicated_set.go:161–195

(set ring.ReplicationSet, exclude []string, balancingStrategy loadBalancingStrategy, zoneAwarenessEnabled bool, attemptedZones map[string]int)

}

func getNonExcludedInstance(set ring.ReplicationSet, exclude []string, balancingStrategy loadBalancingStrategy, zoneAwarenessEnabled bool, attemptedZones map[string]int) ring.InstanceDesc {
	if balancingStrategy == randomLoadBalancing {
		// Randomize the list of instances to not always query the same one.
		rand.Shuffle(len(set.Instances), func(i, j int) {
			set.Instances[i], set.Instances[j] = set.Instances[j], set.Instances[i]
		})
	}

	minAttempt := math.MaxInt
	numOfZone := set.GetNumOfZones()
	// There are still unattempted zones so we know min is 0.
	if len(attemptedZones) < numOfZone {
		minAttempt = 0
	} else {
		// Iterate over attempted zones and find the min attempts.
		for _, c := range attemptedZones {
			if c < minAttempt {
				minAttempt = c
			}
		}
	}
	for _, instance := range set.Instances {
		if slices.Contains(exclude, instance.Addr) {
			continue
		}
		// If zone awareness is not enabled, pick first non-excluded instance.
		// Otherwise, keep iterating until we find an instance in a zone where
		// we have the least retries.
		if !zoneAwarenessEnabled || attemptedZones[instance.Zone] == minAttempt {
			return instance
		}
	}

	return ring.InstanceDesc{}
}