Reduce open and stat system calls for QSettings

The patch moves the global static QSettings object
from QLibrary to QCoreApplication and reduces a
few stat and open calls.

Without the patch, a large Trolltech.conf was
pushed out of the unused settings cache during
startup, meaning Trolltech.conf was parsed
more than once.

Reviewed-by: Liang Qi
(cherry picked from commit 31ef8fa6abc2ea23c6f0a996b36494d88aafb0b5)

1 files changed, 12 insertions, 0 deletions

diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index e0841cbadc..2eef70a480 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -270,6 +270,8 @@ bool QCoreApplicationPrivate::is_app_closing = false;
 Q_CORE_EXPORT bool qt_locale_initialized = false;
 
 
+QSettings *QCoreApplicationPrivate::trolltechConf = 0;
+
 Q_CORE_EXPORT uint qGlobalPostedEventsCount()
 {
     QThreadData *currentThreadData = QThreadData::current();
@@ -371,6 +373,9 @@ QCoreApplicationPrivate::~QCoreApplicationPrivate()
         threadData->postEventList.recursion = 0;
         threadData->quitNow = false;
     }
+
+    delete trolltechConf;
+    trolltechConf = 0;
 }
 
 void QCoreApplicationPrivate::createEventDispatcher()
@@ -692,6 +697,13 @@ void QCoreApplication::init()
     }
 #endif
 
+
+    /*
+      Create an instance of Trolltech.conf. This ensures that the settings will not
+      be thrown out of QSetting's cache for unused settings.
+      */
+    d->trolltechConf = new QSettings(QSettings::UserScope, QLatin1String("Trolltech"));
+
     qt_startup_hook();
 }