Fixing krunner's threading

[Thiago Macieira]

Em Segunda-feira 22 Fevereiro 2010, às 19:18:15, Andreas Hartmetz escreveu:
> Now that many of the more prominent crashes in krunner have been fixed
> I think it's time to attack something more "theoretic": runners run in
> threads and often don't pay any attention to thread-safety of API they
> use. Two weeks ago I've added a warning to KIO::Scheduler() to warn
> about its use from non-main threads, but so far nobody paid attention.

I'm actually raising the bar here.

I'm turning on QT_FATAL_WARNINGS by default in Qt debug builds (starting with 
Qt 4.7).

It's time people stopped ignoring Qt warnings, which indicate that there are 
problems in your code. I can see these warnings coming out of plasma:

Object::disconnect: Unexpected null parameter
QGraphicsScene::removeItem: cannot remove 0-item

This from krunner:
QObject::killTimer: timers cannot be stopped from another thread
QObject::startTimer: timers cannot be started from another thread

These from khtml:
QPainter::font: Painter not active
QPainter::setFont: Painter not active
QPainter::setPen: Painter not active
QWidget::repaint: Recursive repaint detected
QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::translate: Painter not active
QPainter::setClipRect: Painter not active
QPainter::setPen: Painter not active
QPainter::worldTransform: Painter not active
QPainter::font: Painter not active
QPainter::setFont: Painter not active
QPainter::setPen: Painter not active
QWidget::repaint: Recursive repaint detected

etc.

This means applications triggering Qt warnings will result in SIGABRT and Dr 
Konqi popping up.

I'm hoping to finally bring these warnings to attention. Because clearly filling 
up people's $HOME/.xsession-errors isn't enough (mine was over 4GB the other 
day).

If the warning is a problem in Qt or cannot be fixed without Qt help, says so! 
I don't care who's to blame, just as long as those warnings stop showing up.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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