Function NewClient

clientconn.go:185–260

NewClient creates a new gRPC "channel" for the target URI provided. No I/O is performed. Use of the ClientConn for RPCs will automatically cause it to connect. The Connect method may be called to manually create a connection, but for most users this should be unnecessary. The target name syntax

(target string, opts ...DialOption)

// WithReturnConnectionError, and FailOnNonTempDialError are ignored by this
// function.
func NewClient(target string, opts ...DialOption) (conn *ClientConn, err error) {
	cc := &ClientConn{
		target: target,
		conns:  make(map[*addrConn]struct{}),
		dopts:  defaultDialOptions(),
	}

	cc.retryThrottler.Store((*retryThrottler)(nil))
	cc.safeConfigSelector.UpdateConfigSelector(&defaultConfigSelector{nil})
	cc.ctx, cc.cancel = context.WithCancel(context.Background())

	// Apply dial options.
	disableGlobalOpts := false
	for _, opt := range opts {
		if _, ok := opt.(*disableGlobalDialOptions); ok {
			disableGlobalOpts = true
			break
		}
	}

	if !disableGlobalOpts {
		for _, opt := range globalDialOptions {
			opt.apply(&cc.dopts)
		}
	}

	for _, opt := range opts {
		opt.apply(&cc.dopts)
	}

	// Determine the resolver to use.
	if err := cc.initParsedTargetAndResolverBuilder(); err != nil {
		return nil, err
	}

	for _, opt := range globalPerTargetDialOptions {
		opt.DialOptionForTarget(cc.parsedTarget.URL).apply(&cc.dopts)
	}

	chainUnaryClientInterceptors(cc)
	chainStreamClientInterceptors(cc)

	if err := cc.validateTransportCredentials(); err != nil {
		return nil, err
	}

	if cc.dopts.defaultServiceConfigRawJSON != nil {
		scpr := parseServiceConfig(*cc.dopts.defaultServiceConfigRawJSON, cc.dopts.maxCallAttempts)
		if scpr.Err != nil {
			return nil, fmt.Errorf("%s: %v", invalidDefaultServiceConfigErrPrefix, scpr.Err)
		}
		cc.dopts.defaultServiceConfig, _ = scpr.Config.(*ServiceConfig)
	}
	cc.keepaliveParams = cc.dopts.copts.KeepaliveParams

	if err = cc.initAuthority(); err != nil {
		return nil, err
	}