Performance improvements for 40M posts (#7708)

* Optimizing get root posts SQL query

* Setting session invalidation to be reliable

* Adding app reciever to SessionHasPermissionToUser

* Adding app reciever to SessionHasPermissionToTeam

* Adding app reciever to SessionHasPermissionTo

* Clear session cache if permission was denied

* Fixing rebase issues

* Revert "Optimizing get root posts SQL query"

This reverts commit f364757e7015cfb4ec673d0a4fc3d57cd25d8dd7.

* Fixing build

api/post.go

@@ -58,7 +58,7 @@ func createPost(c *Context, w http.ResponseWriter, r *http.Request) {
 		hasPermission = true
 	} else if channel, err := c.App.GetChannel(post.ChannelId); err == nil {
 		// Temporary permission check method until advanced permissions, please do not copy
-		if channel.Type == model.CHANNEL_OPEN && app.SessionHasPermissionToTeam(c.Session, channel.TeamId, model.PERMISSION_CREATE_POST_PUBLIC) {
+		if channel.Type == model.CHANNEL_OPEN && c.App.SessionHasPermissionToTeam(c.Session, channel.TeamId, model.PERMISSION_CREATE_POST_PUBLIC) {
 			hasPermission = true
 		}
 	}
@@ -68,7 +68,7 @@ func createPost(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if post.CreateAt != 0 && !app.SessionHasPermissionTo(c.Session, model.PERMISSION_MANAGE_SYSTEM) {
+	if post.CreateAt != 0 && !c.App.SessionHasPermissionTo(c.Session, model.PERMISSION_MANAGE_SYSTEM) {
 		post.CreateAt = 0
 	}
 
@@ -175,7 +175,7 @@ func getFlaggedPosts(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if !app.SessionHasPermissionToTeam(c.Session, c.TeamId, model.PERMISSION_VIEW_TEAM) {
+	if !c.App.SessionHasPermissionToTeam(c.Session, c.TeamId, model.PERMISSION_VIEW_TEAM) {
 		c.SetPermissionError(model.PERMISSION_VIEW_TEAM)
 		return
 	}