Function shouldIncludeReadonlyInstanceInTheShard

ring/ring.go:1124–1138

shouldIncludeReadonlyInstanceInTheShard returns true if instance is not read-only, or when it is read-only and should be included in the shuffle shard.

(instance InstanceDesc, lookbackPeriod time.Duration, lookbackUntil int64)

// shouldIncludeReadonlyInstanceInTheShard returns true if instance is not read-only, or when it is read-only and should be included in the shuffle shard.
func shouldIncludeReadonlyInstanceInTheShard(instance InstanceDesc, lookbackPeriod time.Duration, lookbackUntil int64) bool {
	if !instance.ReadOnly {
		return true
	}
	// The lookbackPeriod is 0 when this function is called by ShuffleShard(). In this case, we want read only instances excluded.
	if lookbackPeriod == 0 {
		return false
	}
	// With lookback period >0, read only instances are only included if they have not changed read-only status in the lookback window.
	// If ReadOnlyUpdatedTimestamp is not set, we include the instance, and extend the shard later.
	if lookbackPeriod > 0 && instance.ReadOnlyUpdatedTimestamp > 0 && instance.ReadOnlyUpdatedTimestamp < lookbackUntil {
		return false
	}
	return true
}

// filterOutReadOnlyInstances removes all read-only instances from the ring, and returns the resulting ring.
func (r *Ring) filterOutReadOnlyInstances(lookbackPeriod time.Duration, now time.Time) *Ring {