private async Task SendCloseFrameAsync()

in src/Microsoft.Azure.Relay/WebSockets/NetStandard20/ManagedWebSocket.cs [1069:1111]
38 lines of code
4 McCabe index (conditional complexity)

        private async Task SendCloseFrameAsync(WebSocketCloseStatus closeStatus, string closeStatusDescription, CancellationToken cancellationToken)
        {
            // Close payload is two bytes containing the close status followed by a UTF8-encoding of the status description, if it exists.

            byte[] buffer = null;
            try
            {
                int count = 2;
                if (string.IsNullOrEmpty(closeStatusDescription))
                {
                    buffer = ArrayPool<byte>.Shared.Rent(count);
                }
                else
                {
                    count += s_textEncoding.GetByteCount(closeStatusDescription);
                    buffer = ArrayPool<byte>.Shared.Rent(count);
                    int encodedLength = s_textEncoding.GetBytes(closeStatusDescription, 0, closeStatusDescription.Length, buffer, 2);
                    Debug.Assert(count - 2 == encodedLength, $"GetByteCount and GetBytes encoded count didn't match");
                }

                ushort closeStatusValue = (ushort)closeStatus;
                buffer[0] = (byte)(closeStatusValue >> 8);
                buffer[1] = (byte)(closeStatusValue & 0xFF);

                await SendFrameAsync(MessageOpcode.Close, true, new ArraySegment<byte>(buffer, 0, count), cancellationToken).ConfigureAwait(false);
            }
            finally
            {
                if (buffer != null)
                {
                    ArrayPool<byte>.Shared.Return(buffer);
                }
            }

            lock (StateUpdateLock)
            {
                _sentCloseFrame = true;
                if (_state <= WebSocketState.CloseReceived)
                {
                    _state = WebSocketState.CloseSent;
                }
            }
        }