Function newClient

ais/backend/aws.go:482–529

static helpers newClient creates new S3 client on a per-region basis or, more precisely, per (region, endpoint) pair - and note that s3 endpoint is per-bucket configurable. If the client already exists newClient simply returns it. From S3 SDK: "S3 methods are safe to use concurrently. It is not s

(conf sessConf, tag string)

//     "S3 methods are safe to use concurrently. It is not safe to
//      modify mutate any of the struct's properties though."
func newClient(conf sessConf, tag string) (svc *s3.S3, region string, err error) {
	endpoint := s3Endpoint
	region = conf.region
	if conf.bck != nil && conf.bck.Props != nil {
		if region == "" {
			region = conf.bck.Props.Extra.AWS.CloudRegion
		}
		if conf.bck.Props.Extra.AWS.Endpoint != "" {
			endpoint = conf.bck.Props.Extra.AWS.Endpoint
		}
	}

	// reuse
	if region != "" {
		cmu.RLock()
		svc = clients[region][endpoint]
		cmu.RUnlock()
		if svc != nil {
			return
		}
	}
	// create
	var (
		sess    = _session(endpoint)
		awsConf = &aws.Config{}
	)
	if region == "" {
		if tag != "" {
			err = fmt.Errorf("%s: unknown region for bucket %s -- proceeding with default", tag, conf.bck)
		}
		svc = s3.New(sess)
		return
	}
	// ok
	awsConf.Region = aws.String(region)
	svc = s3.New(sess, awsConf)
	debug.Assertf(region == *svc.Config.Region, "%s != %s", region, *svc.Config.Region)

	cmu.Lock()
	eps := clients[region]
	if eps == nil {
		eps = make(map[string]*s3.S3, 1)
		clients[region] = eps
	}
	eps[endpoint] = svc
	cmu.Unlock()
	return
}

// Create session using default creds from ~/.aws/credentials and environment variables.
func _session(endpoint string) *session.Session {