Subj : Re: IOCP problem
To   : comp.programming.threads
From : SenderX
Date : Wed Jan 26 2005 05:36 pm

> unsigned __stdcall ThreadPoolProc( void * lpParam)
> {
> ULONG nSocket;
> DWORD nBytesToBeRead, dwLastErr;
> OVERLAPPED * lpo = NULL;
> BOOL b;
> BYTE read_buffer[PIPE_MSG_MAX];
>
>
> for(;;)
> {
>  BOOL bIORet = GetQueuedCompletionStatus(
>   g_hCompletionPort,
>   &nBytesToBeRead,
>   &nSocket,
>   &lpo,
>   INFINITE);
>
>  dwLastErr = GetLastError();
>
>  HANDLE hPipe = m_hPipes[nSocket];
>  DWORD dwActivePipe = nSocket;
>  int & state = m_states[dwActivePipe];
>
>  if(!bIORet && dwLastErr != WAIT_TIMEOUT)
>  {


An overlapped pointer can still be dequeued even though bIORet == FALSE.




>   break;
>  }
>
>  if(bIORet && NULL != lpo)
>  {

Again, an overlapped pointer can still be dequeued even though bIORet == 
FALSE.




>   DWORD dwBytesRead = nBytesToBeRead;
>   DWORD dwBytesWritten;
>
>   if( state == 0 )
>   {
>    b = ReadFile( hPipe,
>     &read_buffer,
>     PIPE_MSG_MAX,
>     &dwBytesRead,
>     lpo
>    );
>
>    dwLastErr = GetLastError();
>
>    if(!b)
>    {
>     if( dwLastErr == ERROR_IO_PENDING )
>     {

ERROR_IO_PENDING means that the completion will come in with GQCS(). You 
will deadlock right here:

>      DWORD event = WaitForSingleObject(lpo->hEvent, INFINITE);
>
>      b = GetOverlappedResult(hPipe,
>       lpo,
>       &dwBytesRead,
>       FALSE);
>
>      if(!b)
>      {
>       dwLastErr = GetLastError();
>      }

GetOverlappedResult? You are mixing two different completion detection 
methods together.




>     }
>     else
>     {
>      TRACE1("ReadFile dwLastErr = %d\n", dwLastErr);
>     }
>    }
>
>    if(!b)
>    {
>     DisconnectNamedPipe( hPipe );
>     ConnectNamedPipe( hPipe, lpo );
>     state = 0;
>     continue;
>    }
>
>    // do something with message
>
>    state++;
>   }
>   else if(state == 1)
>   {
>    b = WriteFile(hPipe,
>     "OK",
>     3,
>     &dwBytesWritten,
>     lpo);
>
>    dwLastErr = GetLastError();
>
>    if(!b)
>    {
>     if( dwLastErr == ERROR_IO_PENDING )
>     {

Again, ERROR_IO_PENDING means that the completion will come in with GQCS(). 
You will deadlock right here:

>      DWORD event = WaitForSingleObject(lpo->hEvent, INFINITE );
>
>      if( event == WAIT_OBJECT_0 )
>      {
>       b = GetOverlappedResult(hPipe,
>        lpo,
>        &dwBytesWritten,
>        TRUE);
>      }
>     }
>     else
>     {
>      TRACE1("WriteFile dwLastErr = %d\n", dwLastErr);
>     }
>    }
>
>    if(!b)
>    {
>     DisconnectNamedPipe( hPipe );
>     ConnectNamedPipe( hPipe, lpo );
>     state = 0;
>     continue;
>    }
>
>    state++;
>   }
>   else if(state == 2)
>   {
>    DisconnectNamedPipe( hPipe );
>    ConnectNamedPipe( hPipe, lpo );
>    state = 0;
>   }
>  }
> }
>
> _endthreadex(0);
>
> return 0;
> }

.