New QMetaType representation

the QMetaType is represented as a pointer to a "vtable" in the form of
a QtPrivate::QMetaTypeInterface*

The recomanded use of QMetaType is to construct an object with
QMetaType::fromType. This does not require any registration.

There is still an id() function which will do some registration
for compatibility with Qt5. Also the patch does not really touch
the other extra things that can be registered (data stream operator,
comparison operator, iteratable, ...) and this still uses the previous
system.

This is only the change in QMetaType, other changes to use it in QVariant
and QMetaObject will follow

Change-Id: Iffad20085cf33f33447f58a68236013a8b60fdbf
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 22 insertions, 18 deletions

diff --git a/src/dbus/qdbusmetaobject.cpp b/src/dbus/qdbusmetaobject.cpp
index dabd417a32..bfda2aa9b6 100644
--- a/src/dbus/qdbusmetaobject.cpp
+++ b/src/dbus/qdbusmetaobject.cpp
@@ -127,27 +127,31 @@ QDBusMetaObjectGenerator::QDBusMetaObjectGenerator(const QString &interfaceName,
     }
 }
 
-static int registerComplexDBusType(const char *typeName)
+static int registerComplexDBusType(const QByteArray &typeName)
 {
-    struct QDBusRawTypeHandler {
-        static void destruct(void *)
-        {
-            qFatal("Cannot destruct placeholder type QDBusRawType");
-        }
-
-        static void *construct(void *, const void *)
-        {
-            qFatal("Cannot construct placeholder type QDBusRawType");
-            return nullptr;
-        }
+    struct QDBusRawTypeHandler : QtPrivate::QMetaTypeInterface
+    {
+        const QByteArray name;
+        QDBusRawTypeHandler(const QByteArray &name)
+            : QtPrivate::QMetaTypeInterface {
+                0, sizeof(void *), sizeof(void *), QMetaType::MovableType, nullptr,
+                name.constData(), 0, QtPrivate::RefCount{0},
+                [](QtPrivate::QMetaTypeInterface *self) {
+                    delete static_cast<QDBusRawTypeHandler *>(self);
+                },
+                nullptr, nullptr, nullptr, nullptr, nullptr
+            },
+            name(name)
+        {}
     };
 
-    return QMetaType::registerNormalizedType(typeName,
-                                             QDBusRawTypeHandler::destruct,
-                                             QDBusRawTypeHandler::construct,
-                                             sizeof(void *),
-                                             QMetaType::MovableType,
-                                             nullptr);
+    static QBasicMutex mutex;
+    static QHash<QByteArray, QMetaType> hash;
+    QMutexLocker lock(&mutex);
+    QMetaType &metatype = hash[typeName];
+    if (!metatype.isValid())
+        metatype = QMetaType(new QDBusRawTypeHandler(typeName));
+    return metatype.id();
 }
 
 Q_DBUS_EXPORT bool qt_dbus_metaobject_skip_annotations = false;