单身和线程安全？(Singleton and Thread Safety?)

 我目前正在开发一个“Singleton”类，但它必须承受线程安全，因为我不仅访问，而且设置一些东西..我想知道我怎么能这样 - 因为它似乎锁定的东西与当我不知道它在做什么以及我是否必须使每个方法线程都安全时， lock(object)感觉有点hacky？ 
 
 到目前为止，我有这个非线程安全的代码 - 因为在每个线程中应该访问相同的数据。 我怎样才能最好地使它保持线程安全并保持单身？ 
 
public class AppSession() {
    private static AppSession _instance = new AppSession();
    public static AppSession Instance { get { return _instance; } }

    private AppSession() { }

    private string _actionName = "none";
    private DateTime? _actionTime = null;        
    public void ActionExecuted(string action) {
        _actionName = action ?? String.Empty;
        _actionTime = DateTime.UtcNow;
    }

    public LastAction {
       get { return $"{_action} at {_actionTime?.Value.ToString()}"; }
    }
}

I'm currently developping a "Singleton" class, but it has to withstand thread safety as I'm not only accessing, but also settings some stuff.. I was wondering how I could to this - as it seems the locking of stuff with lock(object) feels somewhat hacky when I don't know what it's actually doing and if I have to make every single method thread safe as well?
 
So far I have this non thread safe code - as in each thread should access the same data. How would I best go about making it thread safe and keep it a singleton?
 
public class AppSession() {
    private static AppSession _instance = new AppSession();
    public static AppSession Instance { get { return _instance; } }

    private AppSession() { }

    private string _actionName = "none";
    private DateTime? _actionTime = null;        
    public void ActionExecuted(string action) {
        _actionName = action ?? String.Empty;
        _actionTime = DateTime.UtcNow;
    }

    public LastAction {
       get { return $"{_action} at {_actionTime?.Value.ToString()}"; }
    }
}

原文：https://stackoverflow.com/questions/42470041