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package raft
import (
"reflect"
"sync"
)
// eventDispatcher is responsible for managing listeners for named events
// and dispatching event notifications to those listeners.
type eventDispatcher struct {
sync.RWMutex
source interface{}
listeners map[string]eventListeners
}
// EventListener is a function that can receive event notifications.
type EventListener func(Event)
// EventListeners represents a collection of individual listeners.
type eventListeners []EventListener
// newEventDispatcher creates a new eventDispatcher instance.
func newEventDispatcher(source interface{}) *eventDispatcher {
return &eventDispatcher{
source: source,
listeners: make(map[string]eventListeners),
}
}
// AddEventListener adds a listener function for a given event type.
func (d *eventDispatcher) AddEventListener(typ string, listener EventListener) {
d.Lock()
defer d.Unlock()
d.listeners[typ] = append(d.listeners[typ], listener)
}
// RemoveEventListener removes a listener function for a given event type.
func (d *eventDispatcher) RemoveEventListener(typ string, listener EventListener) {
d.Lock()
defer d.Unlock()
// Grab a reference to the function pointer once.
ptr := reflect.ValueOf(listener).Pointer()
// Find listener by pointer and remove it.
listeners := d.listeners[typ]
for i, l := range listeners {
if reflect.ValueOf(l).Pointer() == ptr {
d.listeners[typ] = append(listeners[:i], listeners[i+1:]...)
}
}
}
// DispatchEvent dispatches an event.
func (d *eventDispatcher) DispatchEvent(e Event) {
d.RLock()
defer d.RUnlock()
// Automatically set the event source.
if e, ok := e.(*event); ok {
e.source = d.source
}
// Dispatch the event to all listeners.
for _, l := range d.listeners[e.Type()] {
l(e)
}
}
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