'Review Request: single shot deleteLater needed in'

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List:       kde-panel-devel
Subject:    Review Request: single shot deleteLater needed in
From:       "Jonathan Marten" <jjm () keelhaul ! me ! uk>
Date:       2011-11-26 15:43:20
Message-ID: 20111126154320.13002.7956 () vidsolbach ! de
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http://git.reviewboard.kde.org/r/103247/
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Review request for Plasma.

Description
-------

The referenced bug describes a Plasma crash caused by a TaskSource (used by the \
"tasks" data engine) retaining a pointer to a Task.  When its associated window is \
closed, the Task is deleted but somehow the TaskSource is not.  This causes a \
dangling pointer crash when the TaskSource next gets the currentDesktopChanged() \
signal (and presumably also currentActivityChanged() if activities are in use).

The source should get deleted in DataEngine::removeSource() via deleteLater().  This \
does not seem to work - if a single shot timer is used instead (as also in commits \
0f40b577 and 52783c6c), the TaskSource gets deleted correctly and the crash does not \
happen.

(This also resulted in a TaskSource memory leak).

This addresses bug 286353.
    http://bugs.kde.org/show_bug.cgi?id=286353

Diffs
-----

  plasma/dataengine.cpp c33b103 

Diff: http://git.reviewboard.kde.org/r/103247/diff/diff

Testing
-------

Verified that the TaskSource destructor is never called by adding a kDebug() there.

Built kdelibs and kdeworkspace with this change, used for day-to-day work (when the \
crash used to happen quite regularly) and with the crash scenario described in the \
bug.  The TaskSource destructor is called as expected, and the crash does not happen.

Thanks,

Jonathan Marten

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      This is an automatically generated e-mail. To reply, visit:
      <a href="http://git.reviewboard.kde.org/r/103247/">http://git.reviewboard.kde.org/r/103247/</a>
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<div>Review request for Plasma.</div>
<div>By Jonathan Marten.</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;">The referenced bug describes a Plasma crash caused by a TaskSource (used \
by the &quot;tasks&quot; data engine) retaining a pointer to a Task.  When its \
associated window is closed, the Task is deleted but somehow the TaskSource is not.  \
This causes a dangling pointer crash when the TaskSource next gets the \
currentDesktopChanged() signal (and presumably also currentActivityChanged() if \
activities are in use).

The source should get deleted in DataEngine::removeSource() via deleteLater().  This \
does not seem to work - if a single shot timer is used instead (as also in commits \
0f40b577 and 52783c6c), the TaskSource gets deleted correctly and the crash does not \
happen.

(This also resulted in a TaskSource memory leak).</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;">Verified that the TaskSource destructor is never called by adding a \
kDebug() there.

Built kdelibs and kdeworkspace with this change, used for day-to-day work (when the \
crash used to happen quite regularly) and with the crash scenario described in the \
bug.  The TaskSource destructor is called as expected, and the crash does not \
happen.</pre>  </td>
 </tr>
</table>

<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=286353">286353</a>

</div>

<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>plasma/dataengine.cpp <span style="color: grey">(c33b103)</span></li>

</ul>

<p><a href="http://git.reviewboard.kde.org/r/103247/diff/" style="margin-left: \
3em;">View Diff</a></p>

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