Preventing scripts blocking Amarok - any taker?

[Mark Kretschmann]

On Thu, Dec 16, 2010 at 2:48 PM, Bart Cerneels <bart.cerneels at kde.org> wrote:
> On Thu, Dec 16, 2010 at 14:20, Mark Kretschmann <kretschmann at kde.org> wrote:
>> On Thu, Dec 16, 2010 at 2:17 PM, Bart Cerneels <bart.cerneels at kde.org> wrote:
>>> On Thu, Dec 16, 2010 at 13:59, Mark Kretschmann <kretschmann at kde.org> wrote:
>>>> On Thu, Dec 16, 2010 at 12:22 PM, Myriam Schweingruber <myriam at kde.org> wrote:
>>>>> Hi all,
>>>>>
>>>>> it happens sometimes that a 3rd-party script is running wild and
>>>>> blocks Amarok. Mark already started to write a mockup checking if a
>>>>> script takes too long that should suggest killing it when it stalls.
>>>>> The string already is prepared here:
>>>>>
>>>>> src/dialogs/ScriptManager.cpp line 609
>>>>>
>>>>> //MOCKUP method, see API docs
>>>>> void
>>>>> ScriptManager::showScriptStalledDialog()  // SLOT
>>>>> {
>>>>>    const QString script = "FIXME";
>>>>>
>>>>>    const int reply = KMessageBox::questionYesNo( 0, i18n( "The script
>>>>> '%1' appears to have stalled.\n\n"
>>>>>                                                           "Would you
>>>>> like to stop it?", script ),
>>>>>                                                           i18n(
>>>>> "Script Manager - Amarok" ),
>>>>>
>>>>> KStandardGuiItem::yes(),
>>>>>
>>>>> KStandardGuiItem::no(),
>>>>>                                                           QString(),
>>>>>
>>>>> KMessageBox::Dangerous );
>>>>>    Q_UNUSED(reply)
>>>>> }
>>>>>
>>>>>
>>>>> Mark being very busy at the moment with his day job it would be nice
>>>>> if somebody could give this the final push. The string is already in,
>>>>> so this would not cause a string change and can still be committed for
>>>>> 2.4
>>>>
>>>> My original idea for solving this was the following:
>>>>
>>>> We start a "watchdog" thread that checks regularly if the GUI blocks.
>>>> I'm not quite sure how to check this, but it should be possible. And
>>>> if we detect that it is blocking in a script, we kill that script.
>>>>
>>>> I dunno if the idea is too simplistic, or if it might work. But the
>>>> "watchdog" thread is probably needed, I guess.
>>>
>>> Have the mainloop update a counter. If counter == counter_previous:
>>> warning dialog.
>>
>> Right, that could work.
>>
>> More difficult: Actually "killing" the script. They are running in-process...
>>
>
> Build-in break in the ScriptEngine? Best idea I can come up with
> without enabling exceptions.

Only problem: Exactly that thread is blocked. So we have to invoke
that code from the other thread.

Doable?

-- 
Mark Kretschmann
Amarok Developer, Software Engineer at KO GmbH
Fellow of the Free Software Foundation Europe
http://amarok.kde.org - http://fsfe.org - http://kogmbh.com