/// <summary>
/// Checks if received data is queued and optionally waits.
/// </summary>
/// <param name="bWait">
/// A value of <c>true</c> makes this call blocking.
/// </param>
/// <param name="bSingle">
/// A value of <c>true</c> causes the reader thread to stop
/// after the next line received (single line mode).
/// </param>
/// <returns>
/// - <c>true</c> if data is queued.
/// </returns>
/// <remarks>
/// The underlying IMAP TCP/IP stream may have a timeout set, which can
/// (when expired) cause this routine to return from blocking state.
/// </remarks>
protected bool ReaderPoll(bool bWait, bool bSingle)
{
if(stream == null) return false; // called after close()
// initialize the reader
if(rdr_dlg == null) // see also ReaderStop()
{ if(rdr_lines == null) // only once
rdr_lines = new List<object>();
rdr_dlg = new Reader(ReaderImpl);
MonitorDebug("ReaderPoll: Initialise Reader");
rdr_res = rdr_dlg.BeginInvoke(null, null);
}
// check background status - must lock!
lock(rdr_lines)
{ if(rdr_res.IsCompleted && stream != null)
{ MonitorDebug("ReaderPoll: Continue Reader");
rdr_dlg.EndInvoke(rdr_res); // would re-throw exception
rdr_res = rdr_dlg.BeginInvoke(null, null);
}
bool bok = rdr_lines.Count > 0;
if(bSingle) // single line: request stop
{ rdr_wait = true;
if(bok) return true;
}
else if(bok) // have data, don't stop
{ rdr_wait = false;
return true;
}
else // for wait: request stop
rdr_wait = bWait;
}
// lock released - have no input
if(!bWait) // no wait
return false;
// wait for the reader thread
if(timeout == 0)
rdr_res.AsyncWaitHandle.WaitOne(); // wait forever
else
{ if(!rdr_res.AsyncWaitHandle.WaitOne((int)timeout*1000, false))
{ MonitorError("ReaderPoll: Timeout ");
haveTimeout = true;
return false;
}
}
// restart reader
if(ReaderPoll(false, bSingle)) return true;
MonitorDebug("ReaderPoll: No Input after WaitOne");
return ReaderPoll(true, bSingle);
}