Code cleanup for event listening and publishing
Co-Authored-By: Jakob <schrej@users.noreply.github.com>
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@ -27,7 +27,7 @@ type Event struct {
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type EventBus struct {
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sync.RWMutex
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subscribers map[string][]chan Event
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subscribers map[string]map[chan Event]struct{}
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}
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// Returns the server's emitter instance.
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@ -37,7 +37,7 @@ func (s *Server) Events() *EventBus {
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if s.emitter == nil {
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s.emitter = &EventBus{
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subscribers: map[string][]chan Event{},
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subscribers: make(map[string]map[chan Event]struct{}),
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}
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}
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@ -46,29 +46,30 @@ func (s *Server) Events() *EventBus {
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// Publish data to a given topic.
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func (e *EventBus) Publish(topic string, data string) {
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t := topic
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// Some of our topics for the socket support passing a more specific namespace,
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// such as "backup completed:1234" to indicate which specific backup was completed.
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//
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// In these cases, we still need to the send the event using the standard listener
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// name of "backup completed".
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if strings.Contains(topic, ":") {
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parts := strings.SplitN(topic, ":", 2)
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if len(parts) == 2 {
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t = parts[0]
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}
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}
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// Acquire a read lock and loop over all of the channels registered for the topic. This
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// avoids a panic crash if the process tries to unregister the channel while this routine
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// is running.
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go func() {
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e.RLock()
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defer e.RUnlock()
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t := topic
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// Some of our topics for the socket support passing a more specific namespace,
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// such as "backup completed:1234" to indicate which specific backup was completed.
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//
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// In these cases, we still need to the send the event using the standard listener
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// name of "backup completed".
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if strings.Contains(topic, ":") {
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parts := strings.SplitN(topic, ":", 2)
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if len(parts) == 2 {
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t = parts[0]
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}
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}
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if ch, ok := e.subscribers[t]; ok {
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data := Event{Data: data, Topic: topic}
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for _, channel := range ch {
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channel <- data
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for channel := range ch {
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channel <- Event{Data: data, Topic: topic}
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}
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}
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}()
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@ -90,44 +91,25 @@ func (e *EventBus) Subscribe(topic string, ch chan Event) {
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e.Lock()
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defer e.Unlock()
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p, ok := e.subscribers[topic]
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// If there is nothing currently subscribed to this topic just go ahead and create
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// the item and then return.
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if !ok {
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e.subscribers[topic] = append([]chan Event{}, ch)
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return
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if _, exists := e.subscribers[topic]; !exists {
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e.subscribers[topic] = make(map[chan Event]struct{})
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}
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// If this topic is already setup, first iterate over the event channels currently in there
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// and confirm there is not a match. If there _is_ a match do nothing since that means this
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// channel is already being tracked. This avoids registering two identical handlers for the
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// same topic, and means the Unsubscribe function can safely assume there will only be a
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// single match for an event.
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for i := range e.subscribers[topic] {
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if ch == e.subscribers[topic][i] {
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return
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}
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// Only set the channel if there is not currently a matching one for this topic. This
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// avoids registering two identical listeners for the same topic and causing pain in
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// the unsubscribe functionality as well.
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if _, exists := e.subscribers[topic][ch]; !exists {
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e.subscribers[topic][ch] = struct{}{}
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}
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e.subscribers[topic] = append(p, ch)
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}
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// Unsubscribe a channel from a topic.
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// Unsubscribe a channel from a given topic.
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func (e *EventBus) Unsubscribe(topic string, ch chan Event) {
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e.Lock()
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defer e.Unlock()
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if _, ok := e.subscribers[topic]; ok {
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for i := range e.subscribers[topic] {
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if ch == e.subscribers[topic][i] {
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e.subscribers[topic] = append(e.subscribers[topic][:i], e.subscribers[topic][i+1:]...)
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// Subscribe enforces a unique event channel for the topic, so we can safely exit
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// this loop once matched since there should not be any additional matches after
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// this point.
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break
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}
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}
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if _, exists := e.subscribers[topic][ch]; exists {
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delete(e.subscribers[topic], ch)
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}
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}
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@ -139,9 +121,6 @@ func (e *EventBus) UnsubscribeAll() {
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e.Lock()
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defer e.Unlock()
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// Loop over all of the subscribers and just remove all of the events
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// for them.
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for t := range e.subscribers {
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e.subscribers[t] = make([]chan Event, 0)
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}
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// Reset the entire struct into an empty map.
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e.subscribers = make(map[string]map[chan Event]struct{})
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}
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