expose codec options

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

codec/codec.go

@@ -22,6 +22,10 @@ var (
 	ErrUnknownContentType = errors.New("unknown content-type")
 )
 
+var (
+	DefaultMaxMessageSize = 1024 * 1024 * 4 // 4Mb
+)
+
 // MessageType
 type MessageType int
 
@@ -55,6 +59,18 @@ type Message struct {
 	Body   []byte
 }
 
+type Option func(*Options)
+
+type Options struct {
+	MaxMessageSize int64
+}
+
+func MaxMessageSize(n int64) Option {
+	return func(o *Options) {
+		o.MaxMessageSize = n
+	}
+}
+
 func NewMessage(t MessageType) *Message {
 	return &Message{Type: t, Header: metadata.New(0)}
 }