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package broadcast
//import "github.com/gobwas/glob"
// Router performs internal message routing to multiple subscribers.
type Router struct {
wildcard map[string]wildcard
routes map[string][]chan *Message
}
// wildcard handles number of topics via glob pattern.
type wildcard struct {
//glob glob.Glob
upstream []chan *Message
}
// helper for blocking join/leave flow
type subscriber struct {
upstream chan *Message
done chan error
topics []string
pattern string
}
// NewRouter creates new topic and pattern router.
func NewRouter() *Router {
return &Router{
wildcard: make(map[string]wildcard),
routes: make(map[string][]chan *Message),
}
}
// Dispatch to all connected topics.
func (r *Router) Dispatch(msg *Message) {
for _, w := range r.wildcard {
if w.glob.Match(msg.Topic) {
for _, upstream := range w.upstream {
upstream <- msg
}
}
}
if routes, ok := r.routes[msg.Topic]; ok {
for _, upstream := range routes {
upstream <- msg
}
}
}
// Subscribe to topic and return list of newly assigned topics.
func (r *Router) Subscribe(upstream chan *Message, topics ...string) (newTopics []string) {
newTopics = make([]string, 0)
for _, topic := range topics {
if _, ok := r.routes[topic]; !ok {
r.routes[topic] = []chan *Message{upstream}
if !r.collapsed(topic) {
newTopics = append(newTopics, topic)
}
continue
}
joined := false
for _, up := range r.routes[topic] {
if up == upstream {
joined = true
break
}
}
if !joined {
r.routes[topic] = append(r.routes[topic], upstream)
}
}
return newTopics
}
// Unsubscribe from given list of topics and return list of topics which are no longer claimed.
func (r *Router) Unsubscribe(upstream chan *Message, topics ...string) (dropTopics []string) {
dropTopics = make([]string, 0)
for _, topic := range topics {
if _, ok := r.routes[topic]; !ok {
// no such topic, ignore
continue
}
for i := range r.routes[topic] {
if r.routes[topic][i] == upstream {
r.routes[topic] = append(r.routes[topic][:i], r.routes[topic][i+1:]...)
break
}
}
if len(r.routes[topic]) == 0 {
delete(r.routes, topic)
// standalone empty subscription
if !r.collapsed(topic) {
dropTopics = append(dropTopics, topic)
}
}
}
return dropTopics
}
// SubscribePattern subscribes to glob parent and return true and return array of newly added patterns. Error in
// case if blob is invalid.
func (r *Router) SubscribePattern(upstream chan *Message, pattern string) (newPatterns []string, err error) {
if w, ok := r.wildcard[pattern]; ok {
joined := false
for _, up := range w.upstream {
if up == upstream {
joined = true
break
}
}
if !joined {
w.upstream = append(w.upstream, upstream)
}
return nil, nil
}
g, err := glob.Compile(pattern)
if err != nil {
return nil, err
}
r.wildcard[pattern] = wildcard{glob: g, upstream: []chan *Message{upstream}}
return []string{pattern}, nil
}
// UnsubscribePattern unsubscribe from the pattern and returns an array of patterns which are no longer claimed.
func (r *Router) UnsubscribePattern(upstream chan *Message, pattern string) (dropPatterns []string) {
// todo: store and return collapsed topics
w, ok := r.wildcard[pattern]
if !ok {
// no such pattern
return nil
}
for i, up := range w.upstream {
if up == upstream {
w.upstream[i] = w.upstream[len(w.upstream)-1]
w.upstream[len(w.upstream)-1] = nil
w.upstream = w.upstream[:len(w.upstream)-1]
if len(w.upstream) == 0 {
delete(r.wildcard, pattern)
return []string{pattern}
}
}
}
return nil
}
func (r *Router) collapsed(topic string) bool {
for _, w := range r.wildcard {
if w.glob.Match(topic) {
return true
}
}
return false
}
|
