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

        private async Task MultipleWriteAsyncCore(IList<ArraySegment<byte>> sendBuffers, CancellationToken cancellationToken)
        {
            Debug.Assert(sendBuffers != null, "'sendBuffers' MUST NOT be NULL.");
            Debug.Assert(sendBuffers.Count == 2, "'sendBuffers.Count' MUST be '2' at this point.");

            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.SetBuffer(null, 0, 0);
                _writeEventArgs.BufferList = sendBuffers;
                if (WriteAsyncFast(_writeEventArgs))
                {
                    await _writeTaskCompletionSource.Task.SuppressContextFlow();
                }
            }
            catch (Exception error)
            {
                if (s_CanHandleException(error))
                {
                    cancellationToken.ThrowIfCancellationRequested();
                }

                throw;
            }
            finally
            {
                cancellationTokenRegistration.Dispose();

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