System.Net.LazyAsyncResult.ProtectedInvokeCallback C# (CSharp) Method

        protected void ProtectedInvokeCallback(object result, IntPtr userToken)
        {
            if (NetEventSource.IsEnabled) NetEventSource.Enter(this, result, userToken);

            // Critical to disallow DBNull here - it could result in a stuck spinlock in WaitForCompletion.
            if (result == DBNull.Value)
            {
                throw new ArgumentNullException(nameof(result));
            }

#if DEBUG
            // Always safe to ask for the state now.
            _protectState = false;
#endif

            if ((_intCompleted & ~HighBit) == 0 && (Interlocked.Increment(ref _intCompleted) & ~HighBit) == 1)
            {
                // DBNull.Value is used to guarantee that the first caller wins,
                // even if the result was set to null.
                if (_result == DBNull.Value)
                {
                    _result = result;
                }

                ManualResetEvent asyncEvent = (ManualResetEvent)_event;
                if (asyncEvent != null)
                {
                    try
                    {
                        asyncEvent.Set();
                    }
                    catch (ObjectDisposedException)
                    {
                        // Simply ignore this exception - There is apparently a rare race condition
                        // where the event is disposed before the completion method is called.
                    }
                }

                Complete(userToken);
            }
        }