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