Extract the api so that plugins and app can have independent lifecycles.

API is found at https://github.com/metacosm/odo-event-api.
This, however, doesn't work well with vendoring so right now, both the
app and plugin can only be built against an api that's in the same spot
in $GOPATH. See golang/go#20481 for more
details.

cmd/odo/odo.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"github.com/golang/glog"
+	api "github.com/metacosm/odo-event-api/odo/api/events"
 	"github.com/posener/complete"
 	"github.com/redhat-developer/odo/pkg/config"
 	"github.com/redhat-developer/odo/pkg/log"
@@ -145,7 +146,7 @@ func loadPlugins() {
 			}
 
 			// Assert that Listener is indeed a Listener :)
-			listener, ok := candidate.(events.Listener)
+			listener, ok := candidate.(api.Listener)
 			if !ok {
 				log.Error("exported Listener variable is not implementing the Listener interface")
 				os.Exit(1)

pkg/odo/events/bus.go

@@ -2,18 +2,19 @@ package events
 
 import (
 	"fmt"
+	api "github.com/metacosm/odo-event-api/odo/api/events"
 	"github.com/spf13/cobra"
 )
 
-type typesToListeners map[EventType][]Listener
+type typesToListeners map[api.EventType][]api.Listener
 
 type EventBus struct {
 	listeners    map[string]typesToListeners
-	allListeners []Listener
+	allListeners []api.Listener
 }
 
 var bus = &EventBus{
-	allListeners: make([]Listener, 0, 5),
+	allListeners: make([]api.Listener, 0, 5),
 }
 
 func GetEventBus() *EventBus {
@@ -27,9 +28,9 @@ func EventNameFrom(cmd *cobra.Command) string {
 	return cmd.Name()
 }
 
-func DispatchEvent(cmd *cobra.Command, eventType EventType, payload interface{}) error {
+func DispatchEvent(cmd *cobra.Command, eventType api.EventType, payload interface{}) error {
 	eventBus := GetEventBus()
-	err := eventBus.DispatchEvent(Event{
+	err := eventBus.DispatchEvent(api.Event{
 		Name:    EventNameFrom(cmd),
 		Type:    eventType,
 		Payload: payload,
@@ -38,13 +39,13 @@ func DispatchEvent(cmd *cobra.Command, eventType EventType, payload interface{})
 	return err
 }
 
-func (bus *EventBus) RegisterToAll(listener Listener) {
+func (bus *EventBus) RegisterToAll(listener api.Listener) {
 	bus.allListeners = append(bus.allListeners, listener)
 }
 
 type Subscription struct {
-	Listener        Listener
-	SupportedEvents map[string]EventType
+	Listener        api.Listener
+	SupportedEvents map[string]api.EventType
 }
 
 func (bus *EventBus) Register(subscription Subscription) {
@@ -53,7 +54,7 @@ func (bus *EventBus) Register(subscription Subscription) {
 	}
 }
 
-func (bus *EventBus) RegisterSingle(event string, eventType EventType, listener Listener) {
+func (bus *EventBus) RegisterSingle(event string, eventType api.EventType, listener api.Listener) {
 	listenersForEvent, ok := bus.listeners[event]
 	if !ok {
 		listenersForEvent = make(typesToListeners, 10)
@@ -62,16 +63,16 @@ func (bus *EventBus) RegisterSingle(event string, eventType EventType, listener
 
 	listenersForType, ok := listenersForEvent[eventType]
 	if !ok {
-		listenersForType = make([]Listener, 0, 10)
+		listenersForType = make([]api.Listener, 0, 10)
 	}
 
 	listenersForEvent[eventType] = append(listenersForType, listener)
 }
 
-func (bus *EventBus) DispatchEvent(event Event) (err error) {
+func (bus *EventBus) DispatchEvent(event api.Event) (err error) {
 	errors := make([]error, 0, 10)
 	listenersForEvent, ok := bus.listeners[event.Name]
-	processedListeners := make([]Listener, 0, 10)
+	processedListeners := make([]api.Listener, 0, 10)
 	var abort bool
 	if ok {
 		listenersForType, ok := listenersForEvent[event.Type]
@@ -80,7 +81,7 @@ func (bus *EventBus) DispatchEvent(event Event) (err error) {
 				listener := listenersForType[i]
 				err := listener.OnEvent(event)
 				if err != nil {
-					if IsEventCausedAbort(err) {
+					if api.IsEventCausedAbort(err) {
 						abort = true
 						return err
 					}
@@ -96,7 +97,7 @@ func (bus *EventBus) DispatchEvent(event Event) (err error) {
 		listener := bus.allListeners[i]
 		err := listener.OnEvent(event)
 		if err != nil {
-			if IsEventCausedAbort(err) {
+			if api.IsEventCausedAbort(err) {
 				abort = true
 				return err
 			}
@@ -118,11 +119,11 @@ func (bus *EventBus) DispatchEvent(event Event) (err error) {
 	return
 }
 
-func revertProcessedListenersOnAbort(abort bool, err error, listeners []Listener) {
+func revertProcessedListenersOnAbort(abort bool, err error, listeners []api.Listener) {
 	if abort {
 
 		for i := range listeners {
-			listeners[i].OnAbort(err.(*EventCausedAbortError))
+			listeners[i].OnAbort(err.(*api.EventCausedAbortError))
 		}
 	}
 }

pkg/odo/genericclioptions/runnable.go

@@ -1,6 +1,7 @@
 package genericclioptions
 
 import (
+	api "github.com/metacosm/odo-event-api/odo/api/events"
 	"github.com/redhat-developer/odo/pkg/log"
 	"github.com/redhat-developer/odo/pkg/odo/events"
 	"github.com/redhat-developer/odo/pkg/odo/util"
@@ -15,17 +16,17 @@ type Runnable interface {
 }
 
 func GenericRun(o Runnable, cmd *cobra.Command, args []string) {
-	exitIfAbort(events.DispatchEvent(cmd, events.PreRun, args), cmd)
+	exitIfAbort(events.DispatchEvent(cmd, api.PreRun, args), cmd)
 	util.CheckError(o.Complete(cmd.Name(), cmd, args), "")
-	exitIfAbort(events.DispatchEvent(cmd, events.PostComplete, o), cmd)
+	exitIfAbort(events.DispatchEvent(cmd, api.PostComplete, o), cmd)
 	util.CheckError(o.Validate(), "")
-	exitIfAbort(events.DispatchEvent(cmd, events.PostValidate, o), cmd)
+	exitIfAbort(events.DispatchEvent(cmd, api.PostValidate, o), cmd)
 	util.CheckError(o.Run(), "")
-	exitIfAbort(events.DispatchEvent(cmd, events.PostRun, o), cmd)
+	exitIfAbort(events.DispatchEvent(cmd, api.PostRun, o), cmd)
 }
 
 func exitIfAbort(err error, cmd *cobra.Command) {
-	if events.IsEventCausedAbort(err) {
+	if api.IsEventCausedAbort(err) {
 		log.Errorf("Processing of %s command was aborted: %v", cmd.Name(), err)
 		os.Exit(1)
 	}