cwtch/event/eventmanager.go

91 lines
2.5 KiB
Go

package event
import (
"git.openprivacy.ca/openprivacy/libricochet-go/log"
"git.openprivacy.ca/openprivacy/libricochet-go/utils"
"sync"
)
// Event is a structure which binds a given set of data to an Type
type Event struct {
EventType Type
EventID string
Data map[string]string
}
// NewEvent creates a new event object with a unique ID and the given type and data.
func NewEvent(eventType Type, data map[string]string) Event {
return Event{EventType: eventType, EventID: utils.GetRandNumber().String(), Data: data}
}
// Manager is an Event Bus which allows subsystems to subscribe to certain EventTypes and publish others.
type Manager struct {
subscribers map[Type][]chan Event
events chan Event
mapMutex sync.Mutex
internal chan bool
}
// Initialize sets up the Manager.
func (em *Manager) Initialize() {
em.subscribers = make(map[Type][]chan Event)
em.events = make(chan Event)
em.internal = make(chan bool)
go em.eventBus()
}
// Subscribe takes an eventType and an Channel and associates them in the eventBus. All future events of that type
// will be sent to the eventChannel.
func (em *Manager) Subscribe(eventType Type, eventChannel chan Event) {
em.mapMutex.Lock()
defer em.mapMutex.Unlock()
em.subscribers[eventType] = append(em.subscribers[eventType], eventChannel)
}
// Publish takes an Event and sends it to the internal eventBus where it is distributed to all Subscribers
func (em *Manager) Publish(event Event) {
if event.EventType != "" {
em.events <- event
}
}
// eventBus is an internal function that is used to distribute events to all subscribers
func (em *Manager) eventBus() {
for {
event := <-em.events
// In the case on an empty event. Teardown the Queue
if event.EventType == "" {
break
}
// maps aren't thread safe
em.mapMutex.Lock()
subscribers := em.subscribers[event.EventType]
em.mapMutex.Unlock()
// Send the event to any subscribers to that event type
for _, subscriber := range subscribers {
select {
case subscriber <- event:
log.Debugf("Sending %v to %v", event.EventType, subscriber)
default:
log.Errorf("Failed to send %v to %v. The subsystem might be running too slow!", event.EventType, subscriber)
}
}
}
// We are about to exit the eventbus thread, fire off an event internally
em.internal <- true
}
// Shutdown triggers, and waits for, the internal eventBus goroutine to finish
func (em *Manager) Shutdown() {
em.events <- Event{}
// wait for eventBus to finish
<-em.internal
close(em.events)
close(em.internal)
}