Re: [Tigervnc-devel] Peculiar Refresh Issue with TLS

Robert Goley Tue, 01 Mar 2011 20:53:03 -0800

Good work digging into this problem. I am glad to hear this is only a Windows problem. It confirms my limited testing of this issue on other platforms. Do you have any preferences of the two solutions?

Robert

On 02/26/2011 12:42 PM, Martin Koegler wrote:

The problem is, that the viewer is (for windows) too busy for
delivering the WM_PAINT. TLS seems to be a reliable trigger, but it
should be possible to construct work loads for the non-TLS case too,
where the screen updates are stalled.


How can it be fixed:

1) The situation can be improved, if in win/vncviewer/CConn.cxx the priority of
the Windows events is raised:
In CConn::blockCallback():
    // Wait for socket data, or a message to process
    DWORD result = MsgWaitForMultipleObjects(1, &sockEvent.h, FALSE, INFINITE, QS_ALLINPUT);
    if (result == WAIT_OBJECT_0) {
      // - Network event notification.  Return control to I/O routine.
      break;
    } else if (result == WAIT_FAILED) {
      // - The wait operation failed - raise an exception
      throw rdr::SystemException("blockCallback wait error", GetLastError());
    }

    // - There should be a message in the message queue
    MSG msg;
    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
      // IMPORTANT: We mustn't call TranslateMessage() here, because instead we
      // call ToAscii() in CKeyboard::keyEvent().  ToAscii() stores dead key
      // state from one call to the next, which would be messed up by calls to
      // TranslateMessage() (actually it looks like TranslateMessage() calls
      // ToAscii() internally).
      DispatchMessage(&msg);
    }
=>
    // Wait for socket data, or a message to process
    DWORD result = MsgWaitForMultipleObjects(1, &sockEvent.h, FALSE, INFINITE, QS_ALLINPUT);
    if (result == WAIT_FAILED) {
      // - The wait operation failed - raise an exception
      throw rdr::SystemException("blockCallback wait error", GetLastError());
    }

    MSG msg;
    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
      // IMPORTANT: We mustn't call TranslateMessage() here, because instead we
      // call ToAscii() in CKeyboard::keyEvent().  ToAscii() stores dead key
      // state from one call to the next, which would be messed up by calls to
      // TranslateMessage() (actually it looks like TranslateMessage() calls
      // ToAscii() internally).
      DispatchMessage(&msg);
    }
    if (result == WAIT_OBJECT_0) {
      // - Network event notification.  Return control to I/O routine.
      break;
    }

2) Add regular explicit calls to UpdateWindow(hWnd) to force an immediate update.

Maybe in DesktopWindow::processMessage, case WM_TIMER after the call
to updateWindow().

Robert Goley

FOSS Implementation Specialist
Toll Free: (800) 338-4984
Local: (770) 479-7933
Fax: (770) 479-4076
www.openrda.com

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