Probing for events having a single callback on .NET and Mono

gistfile1.txt

const BindingFlags SEARCH_FLAGS = BindingFlags.NonPublic | BindingFlags.Instance;
var hasSingleTargetMethod = typeof(MulticastDelegate).GetMethod("InvocationListLogicallyNull", SEARCH_FLAGS) ??
                typeof(MulticastDelegate).GetMethod("get_HasSingleTarget", SEARCH_FLAGS);
 
if (hasSingleTargetMethod != null)
        HasSingleTarget = (HasSingleTargetFn)Delegate.CreateDelegate(typeof(HasSingleTargetFn), hasSingleTargetMethod, true);
else // gracefull degradation
        HasSingleTarget = md => md.GetInvocationList().Length == 1;    
// ...
 
static void QueueContinuation(WaitCallback continuation)
{
        if (!HasSingleTarget(continuation))
        {
                foreach (WaitCallback act in continuation.GetInvocationList())
                    QueueContinuation(act);
                return;
        }
 
	ThreadPool.QueueUserWorkItem(continuation);
}