Migrate cluster to use Server struct directly. (#10101)

app/cluster.go

@@ -4,28 +4,27 @@
 package app
 
 import (
-	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 )
 
 // Registers a given function to be called when the cluster leader may have changed. Returns a unique ID for the
 // listener which can later be used to remove it. If clustering is not enabled in this build, the callback will never
 // be called.
-func (a *App) AddClusterLeaderChangedListener(listener func()) string {
+func (s *Server) AddClusterLeaderChangedListener(listener func()) string {
 	id := model.NewId()
-	a.Srv.clusterLeaderListeners.Store(id, listener)
+	s.clusterLeaderListeners.Store(id, listener)
 	return id
 }
 
 // Removes a listener function by the unique ID returned when AddConfigListener was called
-func (a *App) RemoveClusterLeaderChangedListener(id string) {
-	a.Srv.clusterLeaderListeners.Delete(id)
+func (s *Server) RemoveClusterLeaderChangedListener(id string) {
+	s.clusterLeaderListeners.Delete(id)
 }
 
-func (a *App) InvokeClusterLeaderChangedListeners() {
-	mlog.Info("Cluster leader changed. Invoking ClusterLeaderChanged listeners.")
-	a.Srv.Go(func() {
-		a.Srv.clusterLeaderListeners.Range(func(_, listener interface{}) bool {
+func (s *Server) InvokeClusterLeaderChangedListeners() {
+	s.Log.Info("Cluster leader changed. Invoking ClusterLeaderChanged listeners.")
+	s.Go(func() {
+		s.clusterLeaderListeners.Range(func(_, listener interface{}) bool {
 			listener.(func())()
 			return true
 		})