add message bug with payload

Author: codemodify

Helpers/event-manager-wtith-data.go

@@ -0,0 +1,123 @@
+package Helpers
+
+import (
+	"reflect"
+	"sync"
+)
+
+var eventManagerWithDataInstance *EventManagerWithData
+var eventManagerWithDataOnce sync.Once
+
+// EventHandlerWithData - eventWithData handler prototype
+type EventHandlerWithData func([]byte)
+
+type eventWithData struct {
+	subscribers  []EventHandlerWithData
+	lastData     []byte
+	happenedOnce bool
+}
+
+// EventManagerWithData - eventWithData manager
+type EventManagerWithData struct {
+	events     map[string]*eventWithData
+	eventsSync sync.RWMutex
+}
+
+// EventsWithData - Singleton to get the events manager instance
+func EventsWithData() *EventManagerWithData {
+	eventManagerWithDataOnce.Do(func() {
+		eventManagerWithDataInstance = &EventManagerWithData{
+			events:     make(map[string]*eventWithData),
+			eventsSync: sync.RWMutex{},
+		}
+	})
+
+	return eventManagerWithDataInstance
+}
+
+// On - Tells EventManagerWithData to add a subscriber for an eventWithData
+func (thisRef *EventManagerWithData) On(eventName string, eventHandler EventHandlerWithData) {
+	thisRef.addEventIfNotExists(eventName)
+	thisRef.addSubscriberIfNotExists(eventName, eventHandler)
+
+	thisRef.eventsSync.RLock()
+	defer thisRef.eventsSync.RUnlock()
+
+	if thisRef.events[eventName].happenedOnce {
+		go eventHandler(thisRef.events[eventName].lastData)
+	}
+}
+
+// Off - Tells EventManagerWithData to remove a subscriber for an eventWithData
+func (thisRef *EventManagerWithData) Off(eventName string, eventHandler EventHandlerWithData) {
+	thisRef.addEventIfNotExists(eventName)
+
+	thisRef.eventsSync.RLock()
+	defer thisRef.eventsSync.RUnlock()
+
+	var foundIndex = -1
+	for index, existingEventHandler := range thisRef.events[eventName].subscribers {
+		if reflect.ValueOf(eventHandler) == reflect.ValueOf(existingEventHandler) {
+			foundIndex = index
+			break
+		}
+	}
+
+	if foundIndex != -1 {
+		thisRef.events[eventName].subscribers = append(
+			thisRef.events[eventName].subscribers[:foundIndex],
+			thisRef.events[eventName].subscribers[foundIndex+1:]...,
+		)
+	}
+}
+
+// Raise - Informs all subscribers about the eventWithData
+func (thisRef *EventManagerWithData) Raise(eventName string, data []byte) {
+	thisRef.addEventIfNotExists(eventName)
+
+	thisRef.eventsSync.RLock()
+	defer thisRef.eventsSync.RUnlock()
+
+	thisRef.events[eventName].happenedOnce = true
+	thisRef.events[eventName].lastData = data
+	for _, eventHandler := range thisRef.events[eventName].subscribers {
+		go eventHandler(data)
+	}
+}
+
+func (thisRef *EventManagerWithData) addEventIfNotExists(eventName string) {
+	thisRef.eventsSync.Lock()
+	defer thisRef.eventsSync.Unlock()
+
+	if _, ok := thisRef.events[eventName]; !ok {
+		thisRef.events[eventName] = &eventWithData{
+			subscribers:  []EventHandlerWithData{},
+			happenedOnce: false,
+		}
+	}
+}
+
+func (thisRef *EventManagerWithData) addSubscriberIfNotExists(eventName string, eventHandler EventHandlerWithData) bool {
+	thisRef.eventsSync.RLock()
+	defer thisRef.eventsSync.RUnlock()
+
+	// 1. Check if delegate for the eventWithData already there, assumes map-key exists
+	var alreadyThere = false
+
+	for _, existingEventHandler := range thisRef.events[eventName].subscribers {
+		alreadyThere = (reflect.ValueOf(eventHandler) == reflect.ValueOf(existingEventHandler))
+		if alreadyThere {
+			break
+		}
+	}
+
+	// 2. Add the delegate
+	if !alreadyThere {
+		thisRef.events[eventName].subscribers = append(
+			thisRef.events[eventName].subscribers,
+			eventHandler,
+		)
+	}
+
+	return alreadyThere
+}

Helpers/event-manager.go

@@ -5,8 +5,6 @@ import (
 	"sync"
 )
 
-// TODO: Add locking at some point for Add/Remove operations
-
 var eventManagerInstance *EventManager
 var eventManagerOnce sync.Once