'Re: Review Request 128040: [shellcorona] Containment can be nullptr'

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List:       kde-panel-devel
Subject:    Re: Review Request 128040: [shellcorona] Containment can be nullptr
From:       David Edmundson <david () davidedmundson ! co ! uk>
Date:       2016-05-31 7:56:15
Message-ID: 20160531075615.29452.12836 () mimi ! kde ! org
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> On May 30, 2016, 11:32 a.m., Aleix Pol Gonzalez wrote:
> > Could you look a bit into why is the containment null?
> 
> Anthony Fieroni wrote:
> So i can speculate, because i have 2 Samsung TV, 1 smart, 1 LCD and i can't \
> reproduce crash, KScreen is not finish recognazing, which i write above, \
> corona.cpp:211 if (screen >= 0 && screen < numScreens()) is not satisfied for some \
> reason and returning containment is nullptr. I can't figure out any other possible \
> way. 
> Aleix Pol Gonzalez wrote:
> But `createContainmentForActivity` should return a containment nevertheless, it's \
> not related to KScreen after all. 
> Marco Martin wrote:
> so may the issue go away with the port to qscreen?
> 
> Anthony Fieroni wrote:
> createContainmentForActivity calls containmentForScreen() from corona which use \
> numScreen() overridden in shellCorona and depend on KScreen configuration. So for \
> me is KScreen related. 
> David Edmundson wrote:
> > so may the issue go away with the port to qscreen?
> 
> It should do.
> 
> It's a continuation of https://bugs.kde.org/show_bug.cgi?id=351777 
> 
> there I list the events which cause the crash:
> 
> > Corona.cpp checks we are requesting a containment for a valid screen if (screen \
> > >= 0 && screen < numScreens()) {
> 
> > This fails as numScreens() is Qt API based, whereas the signal we're adding the \
> > output for is ShellCorona::addOutput
> 
> If Qt proceses the DBus event before we get the X event. You're out of sync.
> (note they weren't in Plasma 5.0,it changed in ~5.2 when the XCB backend for \
> kscreen was split into a separate process) 
> I fixed the case of them being out of sync at startup which was the main time we \
> got the crash, but it still apparently happens on unplugging/plugging in a monitor. \
>  As for this patch; sure you'll stop a crash, but you'll leave those setups that \
> would have crashed with a blank screen on the monitor they've just plugged in. 
> Anthony Fieroni wrote:
> *but you'll leave those setups that would have crashed with a blank screen*
> 
> Are you sure about that? So i'm not, still think KScreen has a false positive \
> signals, i.e. he will be done with screen recognazing

doesn't really matter: https://git.reviewboard.kde.org/r/125451/ is submitted and \
fixes the root cause.

- David

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/128040/#review96027
-----------------------------------------------------------

On May 30, 2016, 4:33 a.m., Anthony Fieroni wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/128040/
> -----------------------------------------------------------
> 
> (Updated May 30, 2016, 4:33 a.m.)
> 
> 
> Review request for Plasma, Aleix Pol Gonzalez and David Edmundson.
> 
> 
> Bugs: 361548
> https://bugs.kde.org/show_bug.cgi?id=361548
> 
> 
> Repository: plasma-workspace
> 
> 
> Description
> -------
> 
> I can't reproduce this tons of bug reports and i event can't undertaind how \
> containment can be nullptr, when i see corona.cpp \
> http://api.kde.org/frameworks/plasma-framework/html/corona_8cpp_source.html#l00447 
> 
> Diffs
> -----
> 
> shell/shellcorona.cpp 2a78ca9 
> 
> Diff: https://git.reviewboard.kde.org/r/128040/diff/
> 
> 
> Testing
> -------
> 
> To stop crash ?!
> 
> 
> Thanks,
> 
> Anthony Fieroni
> 
> 

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      This is an automatically generated e-mail. To reply, visit:
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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;">  <p style="margin-top: 0;">On May 30th, 2016, 11:32 a.m. UTC, <b>Aleix Pol \
Gonzalez</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;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Could you look a bit into why is the containment \
null?</p></pre>  </blockquote>

 <p>On May 30th, 2016, 1:14 p.m. UTC, <b>Anthony Fieroni</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">So i \
can speculate, because i have 2 Samsung TV, 1 smart, 1 LCD and i can't reproduce \
crash, KScreen is not finish recognazing, which i write above, corona.cpp:211 if \
(screen &gt;= 0 &amp;&amp; screen &lt; numScreens()) is not satisfied for some reason \
and returning containment is nullptr. I can't figure out any other possible \
way.</p></pre>  </blockquote>

 <p>On May 30th, 2016, 1:16 p.m. UTC, <b>Aleix Pol Gonzalez</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">But \
<code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: \
normal;margin: 0;line-height: inherit;">createContainmentForActivity</code> should \
return a containment nevertheless, it's not related to KScreen after all.</p></pre>  \
</blockquote>

 <p>On May 30th, 2016, 1:34 p.m. UTC, <b>Marco Martin</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">so \
may the issue go away with the port to qscreen?</p></pre>  </blockquote>

 <p>On May 30th, 2016, 1:45 p.m. UTC, <b>Anthony Fieroni</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">createContainmentForActivity calls containmentForScreen() from corona which \
use numScreen() overridden in shellCorona and depend on KScreen configuration. So for \
me is KScreen related.</p></pre>  </blockquote>

 <p>On May 31st, 2016, 4:36 a.m. UTC, <b>David Edmundson</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;"><blockquote \
style="text-rendering: inherit;padding: 0 0 0 1em;border-left: 1px solid \
#bbb;white-space: normal;margin: 0 0 0 0.5em;line-height: inherit;"> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">so may the issue go away with the port to qscreen?</p> </blockquote>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">It should do.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">It's a continuation of \
https://bugs.kde.org/show_bug.cgi?id=351777 </p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">there I list the events \
which cause the crash:</p> <blockquote style="text-rendering: inherit;padding: 0 0 0 \
1em;border-left: 1px solid #bbb;white-space: normal;margin: 0 0 0 0.5em;line-height: \
inherit;"> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Corona.cpp checks we are requesting a containment for \
a valid screen if (screen &gt;= 0 &amp;&amp; screen &lt; numScreens()) {</p> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">This fails as numScreens() is Qt API based, whereas the signal we're adding \
the output for is ShellCorona::addOutput</p> </blockquote>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">If Qt proceses the DBus event before we get the X \
event. You're out of sync. (note they weren't in Plasma 5.0,it changed in ~5.2 when \
the XCB backend for kscreen was split into a separate process)</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I \
fixed the case of them being out of sync at startup which was the main time we got \
the crash, but it still apparently happens on unplugging/plugging in a monitor.</p> \
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">As for this patch; sure you'll stop a crash, but \
you'll leave those setups that would have crashed with a blank screen on the monitor \
they've just plugged in.</p></pre>  </blockquote>

 <p>On May 31st, 2016, 7:24 a.m. UTC, <b>Anthony Fieroni</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;"><em \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">but you'll leave those setups that would have crashed with a blank \
screen</em></p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Are you sure about that? So i'm not, still think \
KScreen has a false positive signals, i.e. he will be done with screen \
recognazing</p></pre>  </blockquote>

</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;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">doesn't really matter: https://git.reviewboard.kde.org/r/125451/ is \
submitted and fixes the root cause.</p></pre> <br />

<p>- David</p>

<br />
<p>On May 30th, 2016, 4:33 a.m. UTC, Anthony Fieroni wrote:</p>

<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
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<div>Review request for Plasma, Aleix Pol Gonzalez and David Edmundson.</div>
<div>By Anthony Fieroni.</div>

<p style="color: grey;"><i>Updated May 30, 2016, 4:33 a.m.</i></p>

<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>

 <a href="https://bugs.kde.org/show_bug.cgi?id=361548">361548</a>

</div>

<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
plasma-workspace
</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;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">I can't reproduce this tons of bug reports and i event \
can't undertaind how containment can be nullptr, when i see corona.cpp \
http://api.kde.org/frameworks/plasma-framework/html/corona_8cpp_source.html#l00447</p></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;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">To stop crash ?!</p></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>shell/shellcorona.cpp <span style="color: grey">(2a78ca9)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/128040/diff/" style="margin-left: \
3em;">View Diff</a></p>

  </td>
 </tr>
</table>

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