SVN commit 1175071 by mpyne:

Apply a patch to speedup stringifying the cache keys used in KIconLoader.
Patch was developed by Matthias Fuchs and improved on by Ingo Klöcker. This will
be in KDE Platform 4.6.

On a simple warm-cache benchmark, the makeCacheKey method being improved went from
34% of loadIcon's execution time to 13%, for an overall 8% speed improvement in icon
loading. The results become less impressive on a cold cache, but such is to be
expected.


 M  +13 -19    kiconloader.cpp  


--- trunk/KDE/kdelibs/kdeui/icons/kiconloader.cpp #1175070:1175071
@@ -37,6 +37,7 @@
 #include <QtCore/QBuffer>
 #include <QtCore/QDataStream>
 #include <QtCore/QByteArray>
+#include <QtCore/QStringBuilder> // % operator for QString
 #include <QtGui/QIcon>
 #include <QtGui/QPainter>
 #include <QMovie>
@@ -758,28 +759,21 @@
 QString KIconLoaderPrivate::makeCacheKey(const QString &name, KIconLoader::Group group,
                                          const QStringList &overlays, int size, int state) const
 {
-    // The KSharedDataCache is shared so add some namespacing.
-    QString key;
+    // The KSharedDataCache is shared so add some namespacing. The following code
+    // uses QStringBuilder (new in Qt 4.6)
 
-    if (group == KIconLoader::User) {
-        key = QLatin1String("$kicou_");
+    return (group == KIconLoader::User
+                  ? QLatin1Literal("$kicou_")
+                  : QLatin1Literal("$kico_"))
+           % name
+           % QLatin1Char('_')
+           % QString::number(size)
+           % QLatin1Char('_')
+           % overlays.join("_")
+           % ( group >= 0 ? mpEffect.fingerprint(group, state)
+                          : QString::fromAscii("noeffect"));
     }
-    else {
-        key = QLatin1String("$kico_");
-    }
 
-    key.append(QString("%1_%2_%3").arg(name).arg(size).arg(overlays.join("_")));
-
-    if (group >= 0) {
-        key.append(mpEffect.fingerprint(group, state));
-    }
-    else {
-        key.append(QLatin1String("noeffect"));
-    }
-
-    return key;
-}
-
 QImage KIconLoaderPrivate::createIconImage(const QString &path, int size)
 {
     // Use the extension as the format. Works for XPM and PNG, but not for SVG. The