// Unsubscribe broadcasts that the current Node is no longer interested in a Topic, preventing it from receiving future event notifications for that Topic.
func (p *Peter) Unsubscribe(t Topic) error {
key, err := wendy.NodeIDFromBytes([]byte(string(t)))
if err != nil {
return err
}
msg := p.cluster.NewMessage(MSG_UNSUBSCRIBE, key, []byte{})
err = p.cluster.Send(msg)
return err
}
// Broadcast sends an event notification for a Topic that will be sent to every Node subscribed to that Topic.
func (p *Peter) Broadcast(t Topic, body []byte) error {
key, err := wendy.NodeIDFromBytes([]byte(string(t)))
if err != nil {
return err
}
msg := p.cluster.NewMessage(MSG_EVENT, key, body)
err = p.cluster.Send(msg)
return err
}
// OnNodeJoin fulfills the wendy.Application interface, and will be called whenever a Node leaves the Cluster. Peter will detect which topics would use that Node as a parent in the subscription tree, and re-subscribe to those topics to repair the subscription tree.
func (p *Peter) OnNodeJoin(node wendy.Node) {
topics := p.parents.topics()
for _, topic := range topics {
key, err := wendy.NodeIDFromBytes([]byte(string(topic)))
if err != nil {
p.err(err.Error())
}
target, err := p.cluster.Route(key)
if err != nil {
p.err(err.Error())
}
if node.ID.Equals(target.ID) {
err = p.Unsubscribe(topic)
if err != nil {
p.err(err.Error())
}
err = p.Subscribe(topic)
if err != nil {
p.err(err.Error())
}
}
}
}
