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List:       kwin
Subject:    Re: Review Request: Protect animation list iterators against external changes
From:       Martin_Gräßlin <kde () martin-graesslin ! com>
Date:       2013-01-04 7:55:19
Message-ID: 20130104075519.25925.37006 () vidsolbach ! de
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Ship it!


Fine for me and I don't think we have to worry about the performance of the \
re-evaluation of the iterators. It's not like this is in the hot code path.


kwin/libkwineffects/kwinanimationeffect.cpp
<http://git.reviewboard.kde.org/r/108151/#comment18907>

    comment does not sound like valid English :-)


- Martin Gräßlin


On Jan. 3, 2013, 11:15 p.m., Thomas Lübking wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/108151/
> -----------------------------------------------------------
> 
> (Updated Jan. 3, 2013, 11:15 p.m.)
> 
> 
> Review request for kwin and Martin Gräßlin.
> 
> 
> Description
> -------
> 
> I recently started to run into random crashes on the heap and slightly started to \
> fear to have broken sth. on activities... whatever.
> Turned out* that moving BE::Faded to AnimationEffect and for the very first time \
> actually using "animationEnded" to chain animations (fade out -> fade in) would \
> (actually obviously) alter the m_animations list what unfortunately turns our nice \
> little iterators into random junk. 
> So this patch tracks list manipulations (in this case during the iteration calling \
> animationEnded, being the natural candidate) and when they happen, re-validates the \
> iterators (the map traversion is required due to the internals of QMap/QHash; the \
> list could instead also be accessed by entry->first.at(animationCounter) instead; \
> not sure about performance impact but it would have made the patch much larger ;-) 
> * I actually figured it because resizing on fullscreen changes always worked like \
> crap because the window gets to resizes in a row (once for the decoration being \
> removed and then the actual resize to the FS geometry) what got me multiplicative \
> traslation/scaling. Chaining this made the crashes pretty reproducible but the \
> result is pretty cool =) 
> 
> Diffs
> -----
> 
> kwin/libkwineffects/kwinanimationeffect.cpp e0a6694 
> 
> Diff: http://git.reviewboard.kde.org/r/108151/diff/
> 
> 
> Testing
> -------
> 
> hehe - i un/fullscreened mplayer about a hundred times the last few minutes.
> That crashed nearly *each* time before the patch.
> 
> 
> Thanks,
> 
> Thomas Lübking
> 
> 


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      This is an automatically generated e-mail. To reply, visit:
      <a href="http://git.reviewboard.kde.org/r/108151/">http://git.reviewboard.kde.org/r/108151/</a>
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 <p>Ship it!</p>



 <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Fine for me and I \
don&#39;t think we have to worry about the performance of the re-evaluation of the \
iterators. It&#39;s not like this is in the hot code path.</pre>  <br />





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   <th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;">  <a \
href="http://git.reviewboard.kde.org/r/108151/diff/1/?file=104419#file104419line242" \
style="color: black; font-weight: bold; text-decoration: \
underline;">kwin/libkwineffects/kwinanimationeffect.cpp</a>  <span \
style="font-weight: normal;">

     (Diff revision 1)

    </span>
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   <td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">void \
AnimationEffect::prePaintScreen( ScreenPrePaintData&amp; data, int time )</pre></td>

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    <th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>  <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">242</font></th>  <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">              \
<span class="n">Q_ASSERT</span><span class="p">(</span><span class="n">entry</span> \
<span class="o">!=</span> <span class="n">mapEnd</span><span class="p">);</span> \
<span class="c1">// the user should for not delete animations from \
animationEnded</span></pre></td>  </tr>

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<pre style="margin-left: 2em; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">comment \
does not sound like valid English :-)</pre> </div>
<br />



<p>- Martin</p>


<br />
<p>On January 3rd, 2013, 11:15 p.m., Thomas Lübking wrote:</p>






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<div>Review request for kwin and Martin Gräßlin.</div>
<div>By Thomas Lübking.</div>


<p style="color: grey;"><i>Updated Jan. 3, 2013, 11:15 p.m.</i></p>






<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;">I recently started to run into random crashes on the heap and slightly \
started to fear to have broken sth. on activities... whatever.
Turned out* that moving BE::Faded to AnimationEffect and for the very first time \
actually using &quot;animationEnded&quot; to chain animations (fade out -&gt; fade \
in) would (actually obviously) alter the m_animations list what unfortunately turns \
our nice little iterators into random junk.

So this patch tracks list manipulations (in this case during the iteration calling \
animationEnded, being the natural candidate) and when they happen, re-validates the \
iterators (the map traversion is required due to the internals of QMap/QHash; the \
list could instead also be accessed by entry-&gt;first.at(animationCounter) instead; \
not sure about performance impact but it would have made the patch much larger ;-)

* I actually figured it because resizing on fullscreen changes always worked like \
crap because the window gets to resizes in a row (once for the decoration being \
removed and then the actual resize to the FS geometry) what got me multiplicative \
traslation/scaling. Chaining this made the crashes pretty reproducible but the result \
is pretty cool =)</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;">hehe - i un/fullscreened mplayer about a hundred times the last few \
minutes. That crashed nearly *each* time before the patch.</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>kwin/libkwineffects/kwinanimationeffect.cpp <span style="color: \
grey">(e0a6694)</span></li>

</ul>

<p><a href="http://git.reviewboard.kde.org/r/108151/diff/" style="margin-left: \
3em;">View Diff</a></p>




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