Improve performance of writing settings

By wrapping related ones in a single transaction, instead of
(implicitly) doing a transaction per settings value that is written.

Task-number: QTCREATORBUG-11524
Change-Id: I28e06c9d6cd4ebad024f9c277796abb37df5f992
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/plugins/coreplugin/editormanager/editormanager.cpp

@@ -2287,10 +2287,12 @@ static const char autoSaveIntervalKey[] = "EditorManager/AutoSaveInterval";
 void EditorManager::saveSettings()
 {
     SettingsDatabase *settings = ICore::settingsDatabase();
+    settings->beginTransaction();
     settings->setValue(QLatin1String(documentStatesKey), d->m_editorStates);
     settings->setValue(QLatin1String(reloadBehaviorKey), d->m_reloadSetting);
     settings->setValue(QLatin1String(autoSaveEnabledKey), d->m_autoSaveEnabled);
     settings->setValue(QLatin1String(autoSaveIntervalKey), d->m_autoSaveInterval);
+    settings->endTransaction();
 }
 
 void EditorManager::readSettings()

src/plugins/coreplugin/locator/locator.cpp

@@ -186,6 +186,7 @@ void Locator::saveSettings()
 {
     if (m_settingsInitialized) {
         SettingsDatabase *s = ICore::settingsDatabase();
+        s->beginTransaction();
         s->beginGroup(QLatin1String("QuickOpen"));
         s->remove(QString());
         s->setValue(QLatin1String("RefreshInterval"), refreshInterval());
@@ -202,6 +203,7 @@ void Locator::saveSettings()
         }
         s->endGroup();
         s->endGroup();
+        s->endTransaction();
     }
 }
 

src/plugins/coreplugin/settingsdatabase.cpp

@@ -252,6 +252,20 @@ QStringList SettingsDatabase::childKeys() const
     return children;
 }
 
+void SettingsDatabase::beginTransaction()
+{
+    if (!d->m_db.isOpen())
+        return;
+    d->m_db.exec(QLatin1String("BEGIN TRANSACTION;"));
+}
+
+void SettingsDatabase::endTransaction()
+{
+    if (!d->m_db.isOpen())
+        return;
+    d->m_db.exec(QLatin1String("END TRANSACTION;"));
+}
+
 void SettingsDatabase::sync()
 {
     // TODO: Delay writing of dirty keys and save them here

src/plugins/coreplugin/settingsdatabase.h

@@ -57,6 +57,9 @@ public:
     QString group() const;
     QStringList childKeys() const;
 
+    void beginTransaction();
+    void endTransaction();
+
     void sync();
 
 private:

src/plugins/updateinfo/updateinfoplugin.cpp

@@ -150,6 +150,7 @@ void UpdateInfoPlugin::saveSettings()
 {
     SettingsDatabase *settings = ICore::settingsDatabase();
     if (settings) {
+        settings->beginTransaction();
         settings->beginGroup(QLatin1String("Updater"));
         settings->setValue(QLatin1String("Application"), d->updaterProgram);
         settings->setValue(QLatin1String("LastDayChecked"), d->m_lastDayChecked);
@@ -157,6 +158,7 @@ void UpdateInfoPlugin::saveSettings()
         settings->setValue(QLatin1String("CheckOnlyArgument"), d->updaterCheckOnlyArgument);
         settings->setValue(QLatin1String("ScheduledUpdateTime"), d->m_scheduledUpdateTime);
         settings->endGroup();
+        settings->endTransaction();
     }
 }