expose useful broker and server methods

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

broker/context.go

@@ -0,0 +1,46 @@
+package broker
+
+import (
+	"context"
+)
+
+type brokerKey struct{}
+
+func FromContext(ctx context.Context) (Broker, bool) {
+	c, ok := ctx.Value(brokerKey{}).(Broker)
+	return c, ok
+}
+
+func NewContext(ctx context.Context, s Broker) context.Context {
+	return context.WithValue(ctx, brokerKey{}, s)
+}
+
+// SetSubscribeOption returns a function to setup a context with given value
+func SetSubscribeOption(k, v interface{}) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}
+
+// SetBrokerOption returns a function to setup a context with given value
+func SetBrokerOption(k, v interface{}) Option {
+	return func(o *Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}
+
+// 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)
+	}
+}

server/context.go

@@ -14,3 +14,13 @@ func FromContext(ctx context.Context) (Server, bool) {
 func NewContext(ctx context.Context, s Server) context.Context {
 	return context.WithValue(ctx, serverKey{}, s)
 }
+
+// SetServerSubscriberOption returns a function to setup a context with given value
+func SetServerSubscriberOption(k, v interface{}) SubscriberOption {
+	return func(o *SubscriberOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}