Function ParseConfig

internal/balancer/gracefulswitch/config.go:49–84

ParseConfig parses a child config list and returns a LB config for the gracefulswitch Balancer. cfg is expected to be a json.RawMessage containing a JSON array of LB policy names + configs as the format of the "loadBalancingConfig" field in ServiceConfig. It returns a type that should be passed to

(cfg json.RawMessage)

// ServiceConfig.  It returns a type that should be passed to
// UpdateClientConnState in the BalancerConfig field.
func ParseConfig(cfg json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
	var lbCfg []map[string]json.RawMessage
	if err := json.Unmarshal(cfg, &lbCfg); err != nil {
		return nil, err
	}
	for i, e := range lbCfg {
		if len(e) != 1 {
			return nil, fmt.Errorf("expected a JSON struct with one entry; received entry %v at index %d", e, i)
		}

		var name string
		var jsonCfg json.RawMessage
		for name, jsonCfg = range e {
		}

		builder := balancer.Get(name)
		if builder == nil {
			// Skip unregistered balancer names.
			continue
		}

		parser, ok := builder.(balancer.ConfigParser)
		if !ok {
			// This is a valid child with no config.
			return &lbConfig{childBuilder: builder}, nil
		}

		cfg, err := parser.ParseConfig(jsonCfg)
		if err != nil {
			return nil, fmt.Errorf("error parsing config for policy %q: %v", name, err)
		}
		return &lbConfig{childBuilder: builder, childConfig: cfg}, nil
	}

	return nil, fmt.Errorf("no supported policies found in config: %v", string(cfg))
}