From 2b1a48742876a5fb548a71e7a6a52717dcb55ada Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20K=C3=BCgler?= <sebas@kde.org>
Date: Wed, 8 Apr 2015 04:21:09 +0200
Subject: [PATCH] Use KPluginLoader to load dataengines

KPluginLoader has all the needed machinery to identify a plugin by its
pluginId. No need to use the query parser here, replace it with a
lambda.

Look for C++ dataengines first. These are much more common, especially
in essential cases. By looking up the plugins through KPluginLoader
first, we can save querying ksycoca.

REVIEW:123297
CHANGELOG:Use KPluginLoader instead of ksycoca for loading C++ dataengines
---
 src/plasma/pluginloader.cpp | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/plasma/pluginloader.cpp b/src/plasma/pluginloader.cpp
index a5999916b..0ce349a7e 100644
--- a/src/plasma/pluginloader.cpp
+++ b/src/plasma/pluginloader.cpp
@@ -25,6 +25,7 @@
 #include <kservice.h>
 #include <kservicetypetrader.h>
 #include <kplugintrader.h>
+#include <KPluginLoader>
 #include <kpackage/packageloader.h>
 
 #include "config-plasma.h"
@@ -251,6 +252,27 @@ DataEngine *PluginLoader::loadDataEngine(const QString &name)
         return engine;
     }
 
+    // Look for C++ plugins first
+    auto filter = [&name](const KPluginMetaData &md) -> bool
+    {
+        return md.pluginId() == name;
+    };
+    QVector<KPluginMetaData> plugins = KPluginLoader::findPlugins(d->dataEnginePluginDir, filter);
+
+    if (plugins.count()) {
+        KPluginInfo::List lst = KPluginInfo::fromMetaData(plugins);
+        KPluginLoader loader(lst.first().libraryPath());
+        const QVariantList argsWithMetaData = QVariantList() << loader.metaData().toVariantMap();
+        KPluginFactory *factory = loader.factory();
+        if (factory) {
+            engine = factory->create<Plasma::DataEngine>(0, argsWithMetaData);
+        }
+    }
+    if (engine) {
+        return engine;
+    }
+
+    // Fall back to querying scripted plugins
     QString constraint = QString("[X-KDE-PluginInfo-Name] == '%1'").arg(name);
 
     // First check with KServiceTypeTrader as that is where scripted engines will be
@@ -258,10 +280,7 @@ DataEngine *PluginLoader::loadDataEngine(const QString &name)
 
     if (!offers.isEmpty()) {
         const QString api = offers.first()->property("X-Plasma-API").toString();
-        if (api.isEmpty()) {
-            // it is a C++ plugin, fetch it with KPluginTrader
-            engine = KPluginTrader::createInstanceFromQuery<Plasma::DataEngine>(d->dataEnginePluginDir, "Plasma/DataEngine", constraint, 0);
-        } else {
+        if (!api.isEmpty()) {
             // it is a scripted plugin, load it via a package
             engine = new DataEngine(KPluginInfo(offers.first()), 0);
         }