System.Net.WebSockets.WebSocketHttpListenerDuplexStream.CloseNetworkConnectionAsync C# (CSharp) Method

        public async Task CloseNetworkConnectionAsync(CancellationToken cancellationToken)
        {
            // need to yield here to make sure that we don't get any exception synchronously
            await Task.Yield();

            if (NetEventSource.IsEnabled)
            {
                NetEventSource.Enter(this);
            }

            CancellationTokenRegistration cancellationTokenRegistration = new CancellationTokenRegistration();

            try
            {
                if (cancellationToken.CanBeCanceled)
                {
                    cancellationTokenRegistration = cancellationToken.Register(s_OnCancel, this, false);
                }
#if DEBUG
                // When using fast path only one outstanding read is permitted. By switching into opaque mode
                // via IWebSocketStream.SwitchToOpaqueMode (see more detailed comments in interface definition)
                // caller takes responsibility for enforcing this constraint.
                Debug.Assert(Interlocked.Increment(ref _outstandingOperations._writes) == 1,
                    "Only one outstanding write allowed at any given time.");
#endif
                _writeTaskCompletionSource = new TaskCompletionSource<object>();
                _writeEventArgs.SetShouldCloseOutput();
                if (WriteAsyncFast(_writeEventArgs))
                {
                    await _writeTaskCompletionSource.Task.SuppressContextFlow();
                }
            }
            catch (Exception error)
            {
                if (!s_CanHandleException(error))
                {
                    throw;
                }

                // throw OperationCancelledException when canceled by the caller
                // otherwise swallow the exception
                cancellationToken.ThrowIfCancellationRequested();
            }
            finally
            {
                cancellationTokenRegistration.Dispose();

                if (NetEventSource.IsEnabled)
                {
                    NetEventSource.Exit(this);
                }
            }
        }