Review Request: Avoid terminating a QThread in kio/kio/hostinfo.cpp

[David Faure]

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Starting and stopping threads all the time is much more wasteful than Albert's approach (which Thiago and I designed) where a single thread is being reused for all queries. And waiting 250ms doesn't seem efficient either.

I don't understand why we are still diving into this solution when Albert's patch seems to do the job much more nicely.

- David


On Aug. 18, 2011, 9:45 p.m., Dawit Alemayehu wrote:
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> http://git.reviewboard.kde.org/r/102238/
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> 
> (Updated Aug. 18, 2011, 9:45 p.m.)
> 
> 
> Review request for kdelibs, David Faure and Thiago Macieira.
> 
> 
> Summary
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> The attached patch is an alternate approach to address the issue of crashes that arise from terminating an active thread than the one proposed at https://git.reviewboard.kde.org/r/102179/. With this patch the function "QHostInfo::lookupHost(QString, int)" avoids the use of QThread::terminate with the following fairly simple changes:
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> - Connect its finished signal to its parent deleteLater slot in the ctor so that the thread is automatically deleted later.
> - Store the looked up DNS info in  the global cache to avoid unnecessary queries for the same request.
> - Check for cached DNS information and avoid doing reverse look ups before resorting to performing DNS queries in a separate thread.
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> 
> Diffs
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>   kio/kio/hostinfo.cpp 344b1d8 
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> Diff: http://git.reviewboard.kde.org/r/102238/diff
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> 
> Testing
> -------
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> Tested with the following code based on Albert's post. 
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> #include "hostinfo_p.h"
> #include <QtGui/QApplication>
> #include <QtCore/QElapsedTimer>
> #include <QtNetwork/QHostInfo>
> 
> int main(int a, char **b)
> {
>     QApplication app(a, b);
>     QElapsedTimer t;
>     t.start();
>     qDebug() << KIO::HostInfo::lookupHost("www.kde.org", 0).addresses();
>     qDebug() << "Time:" << t.elapsed() << "ms";
> }
> 
> 
> Thanks,
> 
> Dawit
> 
>

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