How to create a thread safe singleton in vala?

I want to create a thread-safe singleton instance for my vala class.

As you know, singletons may lead to threading issues if not properly implemented.

The recommended way is to use the GLib.Once construct:

public class MyClass : Object {

    private static GLib.Once<MyClass> _instance;
     
    public static unowned MyClass instance () {
        return _instance.once (() => { return new MyClass (); });
    }
}