broker: add PublishOption

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

broker/context.go

@@ -42,6 +42,16 @@ func SetSubscribeOption(k, v interface{}) SubscribeOption {
 	}
 }
 
+// SetPublishOption returns a function to setup a context with given value
+func SetPublishOption(k, v interface{}) PublishOption {
+	return func(o *PublishOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}
+
 // SetOption returns a function to setup a context with given value
 func SetOption(k, v interface{}) Option {
 	return func(o *Options) {

broker/options.go

@@ -79,11 +79,15 @@ type PublishOptions struct {
 	// BodyOnly flag says the message contains raw body bytes and don't need
 	// codec Marshal method
 	BodyOnly bool
+	// Context holds custom options
+	Context context.Context
 }
 
 // NewPublishOptions creates PublishOptions struct
 func NewPublishOptions(opts ...PublishOption) PublishOptions {
-	options := PublishOptions{}
+	options := PublishOptions{
+		Context: context.Background(),
+	}
 	for _, o := range opts {
 		o(&options)
 	}