Initial migration of the store to be sync (#10592)

* Migrating audit store

* Final migration example for the audit store

* async example

* Ending migration

* Removing Async helper

* Fixing tests

* Fixing govet problems with the StoreResult instanstiation

app/session.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/store"
 )
 
 func (a *App) CreateSession(session *model.Session) (*model.Session, *model.AppError) {
@@ -247,7 +248,12 @@ func (a *App) CreateUserAccessToken(token *model.UserAccessToken) (*model.UserAc
 
 	token.Token = model.NewId()
 
-	uchan := a.Srv.Store.User().Get(token.UserId)
+	uchan := make(chan store.StoreResult, 1)
+	go func() {
+		user, err := a.Srv.Store.User().Get(token.UserId)
+		uchan <- store.StoreResult{Data: user, Err: err}
+		close(uchan)
+	}()
 
 	result := <-a.Srv.Store.UserAccessToken().Save(token)
 	if result.Err != nil {
@@ -284,12 +290,10 @@ func (a *App) createSessionForUserAccessToken(tokenString string) (*model.Sessio
 		return nil, model.NewAppError("createSessionForUserAccessToken", "app.user_access_token.invalid_or_missing", nil, "inactive_token", http.StatusUnauthorized)
 	}
 
-	var user *model.User
-	result = <-a.Srv.Store.User().Get(token.UserId)
-	if result.Err != nil {
-		return nil, result.Err
+	user, err := a.Srv.Store.User().Get(token.UserId)
+	if err != nil {
+		return nil, err
 	}
-	user = result.Data.(*model.User)
 
 	if user.DeleteAt != 0 {
 		return nil, model.NewAppError("createSessionForUserAccessToken", "app.user_access_token.invalid_or_missing", nil, "inactive_user_id="+user.Id, http.StatusUnauthorized)