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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/118586/">https://git.reviewboard.kde.org/r/118586/</a>
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<div>Review request for kdelibs, David Faure, Matthew Dawson, and Oswald Buddenhagen.</div>
<div>By Milian Wolff.</div>
<p style="color: grey;"><i>Updated June 6, 2014, 11:22 a.m.</i></p>
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<b style="color: #575012; font-size: 10pt;">Repository: </b>
kdelibs
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<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;">Optimize KConfigGroup::exists and similar operations.
Before, these kind of read-only operations did a lot of allocations:
1) allocate a list of all sub groups
2) for the above, also allocate a sub-group match key
3) iterate over sub groups, allocate a list of all keys in there
and then finally check whether that list is non-empty
All of the above is now done without a single allocation, by simply
iterating over the list of entries.
Note: The whole list was iterated even before in allSubGroups. Now
we still do that, but check for non-empty keys in the group or
sub group directly. Much more efficient.
Note2: While at it, allSubGroups is also optimized to not require the
allocation of the subgroup match key.</pre>
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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;">The unit tests all run just fine. I broke it while implementing this patch, so I'm confident this functionality is actually properly tested and covered :)
The saved allocations are plenty. This is e.g. from the startup of kwrite:
2844 allocations at:
0x7ff7fbc490e9 QHashData::allocateNode(int) /usr/lib/libQtCore.so.4
0x7ff7fc152f8e QHash<QString, QHashDummyValue>::createNode(unsigned int, QString const&, QHashDummyValue const&, QHashNode<QString, QHashDumm
yValue>**) in /usr/include/qt4/QtCore/qhash.h:543 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc152472 QHash<QString, QHashDummyValue>::insert(QString const&, QHashDummyValue const&) in /usr/include/qt4/QtCore/qhash.h:763 /ssd/mi
lian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc1515f9 QSet<QString>::insert(QString const&) in /usr/include/qt4/QtCore/qset.h:181 /ssd/milian/projects/compiled/kde4/lib/libkdecore.
so.5
0x7ff7fc1501ab QSet<QString>::operator<<(QString const&) in /usr/include/qt4/QtCore/qset.h:201 /ssd/milian/projects/compiled/kde4/lib/libkdec
ore.so.5
0x7ff7fc14b4a7 KConfigPrivate::keyListImpl(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:367 /ssd/
milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc14b25d KConfigPrivate::hasNonDeletedEntries(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:
347 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc14dfeb KConfig::hasGroupImpl(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:856 /ssd/milian
/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc1536b4 KConfigBase::hasGroup(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfigbase.cpp:42 /ssd/mil
ian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc158fcd KConfigGroup::exists() const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfiggroup.cpp:592 /ssd/milian/projects/com
piled/kde4/lib/libkdecore.so.5
2844 allocations at:
0x7ff7fbc71426 QString::QString(int, Qt::Initialization) /usr/lib/libQtCore.so.4
0x7ff7fbd66820 ? /usr/lib/libQtCore.so.4
0x7ff7fbc737db QString::fromUtf8(char const*, int) /usr/lib/libQtCore.so.4
0x7ff7fc14b494 KConfigPrivate::keyListImpl(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:367 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc14b25d KConfigPrivate::hasNonDeletedEntries(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:347 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc14dfeb KConfig::hasGroupImpl(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfig.cpp:856 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc1536b4 KConfigBase::hasGroup(QByteArray const&) const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfigbase.cpp:42 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
0x7ff7fc158fcd KConfigGroup::exists() const in /ssd/milian/projects/kde4/kdelibs/kdecore/config/kconfiggroup.cpp:592 /ssd/milian/projects/compiled/kde4/lib/libkdecore.so.5
All of these are gone with the patch.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>kdecore/config/kconfig.cpp <span style="color: grey">(b941983)</span></li>
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<p><a href="https://git.reviewboard.kde.org/r/118586/diff/" style="margin-left: 3em;">View Diff</a></p>
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