dbus: Use QList::reserve(), reduces reallocations.

Change-Id: I5d60220c4d3014067a45a3d3553f0523c9fc7c74
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/dbus/qdbusabstractadaptor.cpp

@@ -317,7 +317,9 @@ void QDBusAdaptorConnector::relay(QObject *senderObj, int lastSignalIdx, void **
     }
 
     QVariantList args;
-    for (int i = 1; i < types.count(); ++i)
+    const int numTypes = types.count();
+    args.reserve(numTypes - 1);
+    for (int i = 1; i < numTypes; ++i)
         args << QVariant(types.at(i), argv[i]);
 
     // now emit the signal with all the information

src/dbus/qdbusintegrator.cpp

@@ -952,14 +952,19 @@ void QDBusConnectionPrivate::deliverCall(QObject *object, int /*flags*/, const Q
     }
 
     // output arguments
+    const int numMetaTypes = metaTypes.count();
     QVariantList outputArgs;
     void *null = 0;
     if (metaTypes[0] != QMetaType::Void && metaTypes[0] != QMetaType::UnknownType) {
+        outputArgs.reserve(numMetaTypes - i + 1);
         QVariant arg(metaTypes[0], null);
         outputArgs.append( arg );
         params[0] = const_cast<void*>(outputArgs.at( outputArgs.count() - 1 ).constData());
+    } else {
+        outputArgs.reserve(numMetaTypes - i);
     }
-    for ( ; i < metaTypes.count(); ++i) {
+
+    for ( ; i < numMetaTypes; ++i) {
         QVariant arg(metaTypes[i], null);
         outputArgs.append( arg );
         params.append(const_cast<void*>(outputArgs.at( outputArgs.count() - 1 ).constData()));

src/dbus/qdbusinterface.cpp

@@ -278,6 +278,7 @@ int QDBusInterfacePrivate::metacall(QMetaObject::Call c, int id, void **argv)
 
             // we will assume that the input arguments were passed correctly
             QVariantList args;
+            args.reserve(inputTypesCount);
             int i = 1;
             for ( ; i <= inputTypesCount; ++i)
                 args << QVariant(inputTypes[i], argv[i]);