Method FindDifference

pkg/ring/model.go:732–804

(o codec.MultiKey)

}

func (d *Desc) FindDifference(o codec.MultiKey) (any, []string, error) {
	out, ok := o.(*Desc)
	if !ok {
		// This method only deals with non-nil rings.
		return nil, nil, fmt.Errorf("expected *ring.Desc, got %T", out)
	}

	toUpdated := NewDesc()
	toDelete := make([]string, 0)
	tokensChanged := false

	// If both are null
	if d == nil && out == nil {
		return toUpdated, toDelete, nil
	}

	// If new data is empty
	if out == nil {
		for k := range d.Ingesters {
			toDelete = append(toDelete, k)
		}
		return toUpdated, toDelete, nil
	}

	//If existent data is empty
	if d == nil {
		maps.Copy(toUpdated.Ingesters, out.Ingesters)
		return toUpdated, toDelete, nil
	}

	//If new added
	for name, oing := range out.Ingesters {
		if _, ok := d.Ingesters[name]; !ok {
			tokensChanged = true
			toUpdated.Ingesters[name] = oing
		}
	}

	// If removed or updated
	for name, ing := range d.Ingesters {
		oing, ok := out.Ingesters[name]
		if !ok {
			toDelete = append(toDelete, name)
		} else if !ing.Equal(oing) {
			if oing.Timestamp > ing.Timestamp {
				toUpdated.Ingesters[name] = oing
				if !tokensEqual(ing.Tokens, oing.Tokens) {
					tokensChanged = true
				}
			} else if oing.Timestamp == ing.Timestamp && ing.State != LEFT && oing.State == LEFT {
				// we accept LEFT even if timestamp hasn't changed
				toUpdated.Ingesters[name] = oing
				if !tokensEqual(ing.Tokens, oing.Tokens) {
					tokensChanged = true
				}
			}
		}
	}