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70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
package events
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import (
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"sync"
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"golang.org/x/exp/slices"
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)
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type ListenerFunc func(interface{})
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type Listener struct {
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Event string
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Handle ListenerFunc
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}
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type EventBus struct {
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lock sync.RWMutex
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listeners map[string][]*Listener
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}
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func NewEventBus() *EventBus {
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return &EventBus{
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listeners: map[string][]*Listener{},
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}
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}
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// Subscribe a listener for the given event type
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func (eb *EventBus) Subscribe(event string, f ListenerFunc) *Listener {
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l := &Listener{event, f}
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eb.lock.Lock()
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if prev, found := eb.listeners[event]; !found {
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eb.listeners[event] = []*Listener{l}
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} else {
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eb.listeners[event] = append(prev, l)
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}
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eb.lock.Unlock()
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return l
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}
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// Unsubscribe removes a listener for the given event type
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func (eb *EventBus) Unsubscribe(l *Listener) {
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eb.lock.Lock()
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listeners := eb.listeners[l.Event]
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i := slices.Index(listeners, l)
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if i >= 0 {
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// TODO: Magari usare la tecnica di spostare l'ultimo alla posizione dell'elemento rimosso e accorciare lo slice, tanto alla fine l'ordine dei listener non conta veramente
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eb.listeners[l.Event] = append(listeners[:i], listeners[i+1:]...)
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}
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eb.lock.Unlock()
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}
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// Dispatch
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func (eb *EventBus) Dispatch(event string, data interface{}) {
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eb.lock.RLock()
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if listeners, found := eb.listeners[event]; found {
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// make a copy of "listeners" to pass to the goroutine and not block the dispatcher thread
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tmpListeners := append([]*Listener{}, listeners...)
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go func() {
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for _, listener := range tmpListeners {
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listener.Handle(data)
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}
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}()
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}
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eb.lock.RUnlock()
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}
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