[#117] rpc: Allow to specify custom gRPC dialer

After grpc upgrade there is no DialContext call.
So connection is not actually established after created.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

rpc/client/call_options.go

@@ -2,6 +2,8 @@ package client
 
 import (
 	"context"
+
+	"google.golang.org/grpc"
 )
 
 // CallOption is a messaging session option within Protobuf RPC.
@@ -9,6 +11,7 @@ type CallOption func(*callParameters)
 
 type callParameters struct {
 	ctx    context.Context // nolint:containedctx
+	dialer func(context.Context, grpc.ClientConnInterface) error
 }
 
 func defaultCallParameters() *callParameters {
@@ -27,3 +30,11 @@ func WithContext(ctx context.Context) CallOption {
 		prm.ctx = ctx
 	}
 }
+
+// WithContext returns option to specify grpc dialer. If passed, it will be
+// called after the connection is successfully created.
+func WithDialer(dialer func(context.Context, grpc.ClientConnInterface) error) CallOption {
+	return func(prm *callParameters) {
+		prm.dialer = dialer
+	}
+}

rpc/client/connect.go

@@ -12,7 +12,7 @@ import (
 
 var errInvalidEndpoint = errors.New("invalid endpoint options")
 
-func (c *Client) openGRPCConn(ctx context.Context) error {
+func (c *Client) openGRPCConn(ctx context.Context, dialer func(ctx context.Context, cc grpcstd.ClientConnInterface) error) error {
 	if c.conn != nil {
 		return nil
 	}
@@ -21,16 +21,22 @@ func (c *Client) openGRPCConn(ctx context.Context) error {
 		return errInvalidEndpoint
 	}
 
-	dialCtx, cancel := context.WithTimeout(ctx, c.dialTimeout)
 	var err error
 
-	c.conn, err = grpcstd.DialContext(dialCtx, c.addr, c.grpcDialOpts...)
+	c.conn, err = grpcstd.NewClient(c.addr, c.grpcDialOpts...)
-
-	cancel()
-
 	if err != nil {
+		return fmt.Errorf("gRPC new client: %w", err)
+	}
+
+	if dialer != nil {
+		ctx, cancel := context.WithTimeout(ctx, c.dialTimeout)
+		defer cancel()
+
+		if err := dialer(ctx, c.conn); err != nil {
+			_ = c.conn.Close()
 			return fmt.Errorf("gRPC dial: %w", err)
 		}
+	}
 
 	return nil
 }

rpc/client/init.go

@@ -46,7 +46,7 @@ func (c *Client) Init(info common.CallMethodInfo, opts ...CallOption) (MessageRe
 		opt(prm)
 	}
 
-	if err := c.openGRPCConn(prm.ctx); err != nil {
+	if err := c.openGRPCConn(prm.ctx, prm.dialer); err != nil {
 		return nil, err
 	}
 

rpc/client/options.go

@@ -37,7 +37,6 @@ func (c *cfg) initDefault() {
 	c.dialTimeout = defaultDialTimeout
 	c.rwTimeout = defaultRWTimeout
 	c.grpcDialOpts = []grpc.DialOption{
-		grpc.WithBlock(),
 		grpc.WithTransportCredentials(insecure.NewCredentials()),
 	}
 }