System.Net.Cache.CombinedReadStream.ReadCallback C# (CSharp) Method

        private void ReadCallback(IAsyncResult transportResult) {
            GlobalLog.Assert(transportResult.AsyncState is InnerAsyncResult, "InnerAsyncResult::ReadCallback|The state expected to be of type InnerAsyncResult, received {0}.", transportResult.GetType().FullName);
            if (transportResult.CompletedSynchronously)
            {
                return;
            }

            InnerAsyncResult userResult = transportResult.AsyncState as InnerAsyncResult;
            try {
                // Complete transport IO, in this callback that is always the head stream
                int count;
                if (!m_HeadEOF) {
                    count = m_HeadStream.EndRead(transportResult);
                    m_HeadLength += count;
                }
                else {
                    count = m_TailStream.EndRead(transportResult);
                }


                //check on EOF condition
                if (!m_HeadEOF && count == 0 && userResult.Count != 0) {
                    //Got a first stream EOF
                    m_HeadEOF = true;
                    m_HeadStream.Close();
                    IAsyncResult ar = m_TailStream.BeginRead(userResult.Buffer, userResult.Offset, userResult.Count, m_ReadCallback, userResult);
                    if (!ar.CompletedSynchronously) {
                        return;
                    }
                    count = m_TailStream.EndRead(ar);
                }
                // just complete user IO
                userResult.Buffer = null;
                userResult.InvokeCallback(count);
            }
            catch (Exception e) {
                //ASYNC: try to swallow even serious exceptions (nothing to loose?)
                if (userResult.InternalPeekCompleted)
                    throw;

                userResult.InvokeCallback(e);
            }
            catch {
                //ASYNC: try to swallow even serious exceptions (nothing to loose?)
                if (userResult.InternalPeekCompleted)
                    throw;

                userResult.InvokeCallback(new Exception(SR.GetString(SR.net_nonClsCompliantException)));
            }
        }