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List: konsole-devel
Subject: Re: [Konsole-devel] Review Request 118839: Fix crash on close
From: Aurélien Gâteau <agateau () kde ! org>
Date: 2014-06-20 12:09:39
Message-ID: 20140620120939.30184.89564 () probe ! kde ! org
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> On June 19, 2014, 5:30 p.m., Eike Hein wrote:
> >
>
> Kurt Hindenburg wrote:
> yes go ahead - you are committing to frameworks branch? Do you think this might \
> help in master/KDE4?
> Alexander Richardson wrote:
> I doubt this is useful for KDE4 because the actual reason for this crash seems to \
> be is due to a Qt5 behaviour change in QPointer:
> Note that Qt 5 introduces a slight change in behavior when using QPointer.
>
> When using QPointer on a QWidget (or a subclass of QWidget), previously the \
> QPointer would be cleared by the QWidget destructor. Now, the QPointer is cleared \
> by the QObject destructor (since this is when QWeakPointers are cleared). Any \
> QPointers tracking a widget will NOT be cleared before the QWidget destructor \
> destroys the children for the widget being tracked.
@Kurt: Konsole master does not suffer from this issue, so I'd rather not fix what \
aren't broken
@Alexander: Oh I wasn't aware about this change. Good to know, it is indeed likely \
the reason for the crash.
- Aurélien
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/118839/#review60530
-----------------------------------------------------------
On June 20, 2014, 2:04 p.m., Aurélien Gâteau wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/118839/
> -----------------------------------------------------------
>
> (Updated June 20, 2014, 2:04 p.m.)
>
>
> Review request for Konsole.
>
>
> Bugs: 331724
> http://bugs.kde.org/show_bug.cgi?id=331724
>
>
> Repository: konsole
>
>
> Description
> -------
>
> Move code responsible for 'forgetting' a view outside of code responding to the
> TerminalDisplay deletion.
>
> This avoids a loop like this:
>
> ~MainWindow
> => ~QStackedWidget
> => ~TerminalDisplay
> => QObject::destroyed
> => ViewContainer::viewDestroyed
> => ViewContainer::removeViewWidget
> - internal cleanup
> - try to remove TerminalDisplay from QStackedWidget which is being deleted and
> crash
>
> Instead the code now does:
>
> ~MainWindow
> => ~QStackedWidget
> => ~TerminalDisplay
> => QObject::destroyed
> => ViewContainer::viewDestroyed
> => ViewContainer::forgetView (does the internal clean up)
>
> And if one tries to explicitly remove a view, sequence is:
>
> ViewContainer::removeView
> => ViewContainer::forgetView
> => ViewContainer::removeViewWidget
>
> The patch also removes ViewManager::focusActiveView() because it causes a crash
> when closing a TerminalDisplay as it tries to put the focus on the deleted
> TerminalDisplay. I initially called it through a queued connection, but realized
> it is actually not needed for focus to be passed to the correct view, so just
> removed it.
>
>
> Diffs
> -----
>
> src/ViewContainer.h 60d2bd9
> src/ViewContainer.cpp 79c24d5
> src/ViewManager.h 047b7ee
> src/ViewManager.cpp 75473e9
> src/ViewSplitter.cpp bfc727e
>
> Diff: https://git.reviewboard.kde.org/r/118839/diff/
>
>
> Testing
> -------
>
> Started and closed Konsole, created and deleted tabs, created and deleted split \
> views. No crash.
>
> Thanks,
>
> Aurélien Gâteau
>
>
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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/118839/">https://git.reviewboard.kde.org/r/118839/</a>
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<p>On June 19th, 2014, 5:33 p.m. CEST, <b>Kurt Hindenburg</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">yes go ahead - you are \
committing to frameworks branch? Do you think this might help in master/KDE4?</pre> \
</blockquote>
<p>On June 20th, 2014, 1:52 a.m. CEST, <b>Alexander Richardson</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">I doubt this is useful \
for KDE4 because the actual reason for this crash seems to be is due to a Qt5 \
behaviour change in QPointer:
Note that Qt 5 introduces a slight change in behavior when using QPointer.
When using QPointer on a QWidget (or a subclass of QWidget), previously the \
QPointer would be cleared by the QWidget destructor. Now, the QPointer is cleared by \
the QObject destructor (since this is when QWeakPointers are cleared). Any QPointers \
tracking a widget will NOT be cleared before the QWidget destructor destroys the \
children for the widget being tracked. </pre>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">@Kurt: Konsole master \
does not suffer from this issue, so I'd rather not fix what aren't broken
@Alexander: Oh I wasn't aware about this change. Good to know, it is indeed \
likely the reason for the crash.
</pre>
<br />
<p>- Aurélien</p>
<br />
<p>On June 20th, 2014, 2:04 p.m. CEST, Aurélien Gâteau wrote:</p>
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<div>Review request for Konsole.</div>
<div>By Aurélien Gâteau.</div>
<p style="color: grey;"><i>Updated June 20, 2014, 2:04 p.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="http://bugs.kde.org/show_bug.cgi?id=331724">331724</a>
</div>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
konsole
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Move code responsible for 'forgetting' a view outside of code \
responding to the TerminalDisplay deletion.
This avoids a loop like this:
~MainWindow
=> ~QStackedWidget
=> ~TerminalDisplay
=> QObject::destroyed
=> ViewContainer::viewDestroyed
=> ViewContainer::removeViewWidget
- internal cleanup
- try to remove TerminalDisplay from QStackedWidget which is being deleted and
crash
Instead the code now does:
~MainWindow
=> ~QStackedWidget
=> ~TerminalDisplay
=> QObject::destroyed
=> ViewContainer::viewDestroyed
=> ViewContainer::forgetView (does the internal clean up)
And if one tries to explicitly remove a view, sequence is:
ViewContainer::removeView
=> ViewContainer::forgetView
=> ViewContainer::removeViewWidget
The patch also removes ViewManager::focusActiveView() because it causes a crash
when closing a TerminalDisplay as it tries to put the focus on the deleted
TerminalDisplay. I initially called it through a queued connection, but realized
it is actually not needed for focus to be passed to the correct view, so just
removed it.
</pre>
</td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Started and closed Konsole, created and deleted tabs, created and \
deleted split views. No crash.</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/ViewContainer.h <span style="color: grey">(60d2bd9)</span></li>
<li>src/ViewContainer.cpp <span style="color: grey">(79c24d5)</span></li>
<li>src/ViewManager.h <span style="color: grey">(047b7ee)</span></li>
<li>src/ViewManager.cpp <span style="color: grey">(75473e9)</span></li>
<li>src/ViewSplitter.cpp <span style="color: grey">(bfc727e)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/118839/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>
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