🚀 go-pugleaf

Hi all, posted a few weeks ago about an event log system I was developing. 
I have a basic system where events are created and stuck on a queue.  I then 
have a thread that takes events of the queue and writes them to an event log 
using CreateFile / WriteFile.

However, I have found that each time the thread starts, and opens / writes 
data for the first time, it deletes some of the previous data.  This only 
happens when the thread first starts, thereafter, the data is written 
correctly.  I assume there must be some issue with the file pointer but i'm 
not sure how to initialise it.

My code looks like this:

void TEventLogThread::WriteEventToLog(TSTR_LOG_ONLY_EVENT &p_strEvtLogData)
{
   if ((!hEventLog)||(hEventLog == INVALID_HANDLE_VALUE))
   {
      hEventLog = CreateFile(szEventLogPath.c_str(), GENERIC_WRITE, 
FILE_SHARE_READ, NULL, OPEN_ALWAYS,
                             FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_SYSTEM, 
0);
   }

   if (hEventLog != INVALID_HANDLE_VALUE)
   {
      DWORD dwWritten;
      AnsiString szBuff;
      TDateTime dtEvntWhen;
      dtEvntWhen = SystemTimeToDateTime(p_strEvtLogData.stWhen);
      szBuff = AnsiString(FormatDateTime(SHORT_DATE_FORMAT, dtEvntWhen) + 
"," +
                          FormatDateTime(SHORT_TIME_FORMAT, dtEvntWhen) + 
"," +
                          IntToStr(p_strEvtLogData.iEventId)  + "," +
                          IntToStr(p_strEvtLogData.iStatusId) + "," +
                          IntToStr(p_strEvtLogData.iReasonId) + "," +
                          p_strEvtLogData.cUserSID            + "," +
                          p_strEvtLogData.cObject             + "\r\n");


      dwWritten = szBuff.Length();
      WriteFile(hEventLog, szBuff.c_str(), szBuff.Length(), &dwWritten, 
NULL);
      //FlushFileBuffers(hEventLog); // <- wasn't sure about this...
   }
}

I keep the file handle open whilst the thread is alive, then it is closed.

Many thanks in advance,

Mike C