Synchronize a config file handled QSettings on SMB

[nightghost]

We already thought about this mechanism, but that is not our main problem. Our main problem is, that its not predicable when QSettings wants to write, but after looking into the sources we found out, that is responds to a QEvent::UpdateRequest

bool QSettings::event(QEvent *event)
{
    Q_D(QSettings);
    if (event->type() == QEvent::UpdateRequest) {
        d->update();
        return true;
    }
    return QObject::event(event);
}
 
void QSettingsPrivate::update()
{
    flush();
    pendingChanges = false;
}
 
 
void QConfFileSettingsPrivate::flush()
{
    sync();
}

bool QSettings::event(QEvent *event)
{
    Q_D(QSettings);
    if (event->type() == QEvent::UpdateRequest) {
        d->update();
        return true;
    }
    return QObject::event(event);
}

void QSettingsPrivate::update()
{
    flush();
    pendingChanges = false;
}


void QConfFileSettingsPrivate::flush()
{
    sync();
}

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sync is only called in the constructor/destructor and on request. So we think, that there is a good chance to get around this issue by using QObject#eventFilter and saving on our just before the destructor is called. (constructor is uncritical since it just reads the file)

[JohannesMunk]

Why don't you subclass QSettings? In the constructor you enable the lock (create the lock-file), and in the destructor you disable the lock.

Then you use only local instances of your subclass - as the troll suggest for QSettings.

HIH

Johannes

[nightghost]

That sounds to me like the best solution. But since in our current implementation we hold the QSettings we implemented it with the event filter. We're currently testing it, but it seems to work. But for the next release we're considering to use the local instances approach.