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This is an automatically generated e-mail. To reply, visit:
<a href="http://git.reviewboard.kde.org/r/107573/">http://git.reviewboard.kde.org/r/107573/</a>
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<a href="http://git.reviewboard.kde.org/r/107573/diff/1/?file=97141#file97141line149" style="color: black; font-weight: bold; text-decoration: underline;">libnepomukcore/datamanagement/resourcewatcher.cpp</a>
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(Diff revision 1)
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<td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">void Nepomuk2::ResourceWatcher::stop()</pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="c1">// This is for the case when ~ResourceManger removes its ResourceWatcher,</span></pre></td>
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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;">Spelling: ~ResourceManger -> ~ResourceManager</pre>
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<a href="http://git.reviewboard.kde.org/r/107573/diff/1/?file=97142#file97142line54" style="color: black; font-weight: bold; text-decoration: underline;">libnepomukcore/resource/resource.cpp</a>
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(Diff revision 1)
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">Q_ASSERT_X</span><span class="p">(</span> <span class="n">ResourceManager</span><span class="o">::</span><span class="n">instance</span><span class="p">(),</span> <span class="s">"Nepomuk2::Resource"</span><span class="p">,</span></pre></td>
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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;">Might it be better to simply return some empty resource, instead of asserting?
In 292996 , we just figured out that a Resource can continue being accessed after QApplication has been destroyed, because QRunnable cannot be cancelled. If that thread, instead of accessing the Resource, had constructed a new Resource, with this code we would crash on exit in a release build.
Since we would likely only hit the race in a release build, we would get another difficult-to-debug crash on exit.</pre>
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<p>- Simeon</p>
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<p>On December 4th, 2012, 11:36 a.m., Vishesh Handa wrote:</p>
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<div>Review request for Nepomuk, Sebastian Trueg and Simeon Bird.</div>
<div>By Vishesh Handa.</div>
<p style="color: grey;"><i>Updated Dec. 4, 2012, 11:36 a.m.</i></p>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
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<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;"> ResourceWatcher: Do no create a new ResourceManager on quit
The ResourceManager contains a ResourceWatcher. This ResourceWatcher is
initialized only when a Resource class requires it. On destruction it
calls ResourceWatcher::stop, which tries to disconnect it from
ResourceManager::nepomukSystemStarted signal.
The problem arises when the application is exiting, and the
ResourceManager (being a child of QCoreApplication) is being destroyed.
It in turn destroys the ResourceWatcher, which calls
ResourceWatcher::stop, which calls ResourceManager::instance() which
results in the creation of a new ResourceManager whose parent is
QCoreApplication::instance, which is 0, cause the application is
shutting down.
This whole extra ResourceManager being allocated is not required and can
be avoided by checking if QCoreApplication != 0, in
ResourceManager::instance.
Also, since ResourceManager::instance() can now return 0. I've added an
assert check in the Resource class.
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
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<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;">Added breakpoints in gdb, and wrote a simple application. The extra ResourceManager is no longer being created.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>libnepomukcore/datamanagement/resourcewatcher.cpp <span style="color: grey">(a09b646)</span></li>
<li>libnepomukcore/resource/resource.cpp <span style="color: grey">(4601eba)</span></li>
<li>libnepomukcore/resource/resourcemanager.cpp <span style="color: grey">(457c042)</span></li>
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<p><a href="http://git.reviewboard.kde.org/r/107573/diff/" style="margin-left: 3em;">View Diff</a></p>
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