C# Events and Thread Safety

Question

UPDATE

As of C# 6, the answer to this question is:

SomeEvent?.Invoke(this, e);

---

I frequently hear/read the fo

Answer 1

I've been using this design pattern to ensure that event handlers aren't executed after they're unsubscribed. It's working pretty well so far, although I haven't tried any performance profiling.

private readonly object eventMutex = new object();

private event EventHandler _onEvent = null;

public event EventHandler OnEvent
{
  add
  {
    lock(eventMutex)
    {
      _onEvent += value;
    }
  }

  remove
  {
    lock(eventMutex)
    {
      _onEvent -= value;
    }
  }

}

private void HandleEvent(EventArgs args)
{
  lock(eventMutex)
  {
    if (_onEvent != null)
      _onEvent(args);
  }
}

I'm mostly working with Mono for Android these days, and Android doesn't seem to like it when you try to update a View after its Activity has been sent to the background.