Do proper memory management on the metatype interfaces we create

Those interfaces are always registered in pairs. Add an external
refcount to CompositeMetaTypeIds, and do registration and
de-registration through this class.

Change-Id: I4f3a53ad935a43a734d6506ffc768f507b48ee1f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 85 insertions, 19 deletions

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 4326002575..f1c79fe8b3 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -649,10 +649,8 @@ QQmlEnginePrivate::~QQmlEnginePrivate()
 
     QQmlMetaType::freeUnusedTypesAndCaches();
 
-    for (auto iter = m_compositeTypes.cbegin(), end = m_compositeTypes.cend(); iter != end; ++iter) {
+    for (auto iter = m_compositeTypes.cbegin(), end = m_compositeTypes.cend(); iter != end; ++iter)
         iter.value()->isRegisteredWithEngine = false;
-        QQmlMetaType::unregisterInternalCompositeType(iter.value()->typeIds);
-    }
 #if QT_CONFIG(qml_debug)
     delete profiler;
 #endif
diff --git a/src/qml/qml/qqmlmetatype.cpp b/src/qml/qml/qqmlmetatype.cpp
index cb2522a675..06fdb0fab0 100644
--- a/src/qml/qml/qqmlmetatype.cpp
+++ b/src/qml/qml/qqmlmetatype.cpp
@@ -54,6 +54,32 @@ Q_DECLARE_LOGGING_CATEGORY(DBG_DISK_CACHE)
 
 QT_BEGIN_NAMESPACE
 
+CompositeMetaTypeIds CompositeMetaTypeIds::fromCompositeName(const QByteArray &name)
+{
+    auto ids = QQmlMetaType::registerInternalCompositeType(name);
+    ids.refCount = new int;
+    *ids.refCount = 1;
+    return ids;
+}
+
+void CompositeMetaTypeIds::deref()
+{
+    Q_ASSERT(refCount);
+    --*refCount;
+    if (!*refCount) {
+        delete refCount;
+        QQmlMetaType::unregisterInternalCompositeType(*this);
+        refCount = nullptr;
+    }
+}
+
+CompositeMetaTypeIds::~CompositeMetaTypeIds()
+{
+    if (refCount)
+        deref();
+}
+
+
 struct LockedData : private QQmlMetaTypeData
 {
     friend class QQmlMetaTypeDataPtr;
@@ -542,11 +568,11 @@ QQmlType QQmlMetaType::registerCompositeType(const QQmlPrivate::RegisterComposit
 
 
 
-template <typename T>
 struct QQmlMetaTypeInterface : QtPrivate::QMetaTypeInterface
 {
     const QByteArray name;
-    QQmlMetaTypeInterface(const QByteArray &name)
+    template <typename T>
+    QQmlMetaTypeInterface(const QByteArray &name, T *)
         : QMetaTypeInterface {
             /*.revision=*/ 0,
             /*.alignment=*/ alignof(T),
@@ -580,8 +606,8 @@ CompositeMetaTypeIds QQmlMetaType::registerInternalCompositeType(const QByteArra
     QByteArray ptr = className + '*';
     QByteArray lst = "QQmlListProperty<" + className + '>';
 
-    QMetaType ptr_type(new QQmlMetaTypeInterface<QObject*>(ptr));
-    QMetaType lst_type(new QQmlMetaTypeInterface<QQmlListProperty<QObject>>(lst));
+    QMetaType ptr_type(new QQmlMetaTypeInterface(ptr, (QObject **)nullptr));
+    QMetaType lst_type(new QQmlMetaTypeInterface(lst, (QQmlListProperty<QObject> *)nullptr));
 
     QQmlMetaTypeDataPtr data;
     data->qmlLists.insert(lst_type.id(), ptr_type.id());
@@ -593,6 +619,8 @@ void QQmlMetaType::unregisterInternalCompositeType(const CompositeMetaTypeIds &t
 {
     QQmlMetaTypeDataPtr data;
     data->qmlLists.remove(typeIds.listId.id());
+    delete static_cast<QQmlMetaTypeInterface *>(QMetaType(typeIds.id).iface());
+    delete static_cast<QQmlMetaTypeInterface *>(QMetaType(typeIds.listId).iface());
 }
 
 int QQmlMetaType::registerUnitCacheHook(
diff --git a/src/qml/qml/qqmlmetatype_p.h b/src/qml/qml/qqmlmetatype_p.h
index 58968a1c26..b1fe58af6e 100644
--- a/src/qml/qml/qqmlmetatype_p.h
+++ b/src/qml/qml/qqmlmetatype_p.h
@@ -66,6 +66,52 @@ namespace QV4 { class ExecutableCompilationUnit; }
 
 struct CompositeMetaTypeIds
 {
+private:
+    int *refCount = nullptr;
+    void deref();
+    void ref()
+    {
+        Q_ASSERT(refCount);
+        ++*refCount;
+    }
+public:
+    CompositeMetaTypeIds() = default;
+    CompositeMetaTypeIds(QMetaType id, QMetaType listId) : id(id), listId(listId) {}
+    CompositeMetaTypeIds(const CompositeMetaTypeIds &other)
+        : refCount(other.refCount), id(other.id), listId(other.listId)
+    {
+        if (refCount)
+            ref();
+    }
+    CompositeMetaTypeIds(CompositeMetaTypeIds &&other)
+        : refCount(other.refCount), id(other.id), listId(other.listId)
+    {
+        other.refCount = nullptr;
+    }
+    CompositeMetaTypeIds &operator=(const CompositeMetaTypeIds &other)
+    {
+        if (refCount)
+            deref();
+        refCount = other.refCount;
+        id = other.id;
+        listId = other.listId;
+        if (refCount)
+            ref();
+        return *this;
+    }
+    CompositeMetaTypeIds &operator=(CompositeMetaTypeIds &&other)
+    {
+        if (refCount)
+            deref();
+        refCount = other.refCount;
+        id = other.id;
+        listId = other.listId;
+        other.refCount = nullptr;
+        return *this;
+    }
+    ~CompositeMetaTypeIds();
+    static CompositeMetaTypeIds fromCompositeName(const QByteArray &name);
+public:
     QMetaType id;
     QMetaType listId;
     bool isValid() const { return id.isValid() && listId.isValid(); }
@@ -73,6 +119,10 @@ struct CompositeMetaTypeIds
 
 class Q_QML_PRIVATE_EXPORT QQmlMetaType
 {
+    friend struct CompositeMetaTypeIds;
+    static CompositeMetaTypeIds registerInternalCompositeType(const QByteArray &className);
+    static void unregisterInternalCompositeType(const CompositeMetaTypeIds &typeIds);
+
 public:
     enum class RegistrationResult {
         Success,
@@ -94,8 +144,6 @@ public:
 
     static void unregisterType(int type);
 
-    static CompositeMetaTypeIds registerInternalCompositeType(const QByteArray &className);
-    static void unregisterInternalCompositeType(const CompositeMetaTypeIds &typeIds);
     static void registerModule(const char *uri, QTypeRevision version);
     static bool protectModule(const QString &uri, QTypeRevision version,
                               bool protectAllVersions = false);
diff --git a/src/qml/qml/qqmltypedata.cpp b/src/qml/qml/qqmltypedata.cpp
index d41685b047..60c56d2b02 100644
--- a/src/qml/qml/qqmltypedata.cpp
+++ b/src/qml/qml/qqmltypedata.cpp
@@ -286,7 +286,7 @@ void setupICs(const ObjectContainer &container, QHash<int, InlineComponentData>
             auto url = finalUrl;
             url.setFragment(QString::number(it->objectIndex));
             const QByteArray &className = QQmlPropertyCacheCreatorBase::createClassNameTypeByUrl(url);
-            InlineComponentData icDatum(QQmlMetaType::registerInternalCompositeType(className), int(it->objectIndex), int(it->nameIndex), 0, 0, 0);
+            InlineComponentData icDatum(CompositeMetaTypeIds::fromCompositeName(className), int(it->objectIndex), int(it->nameIndex), 0, 0, 0);
             icData->insert(it->objectIndex, icDatum);
         }
     }
@@ -402,21 +402,13 @@ void QQmlTypeData::done()
 
     m_typeClassName = QQmlPropertyCacheCreatorBase::createClassNameTypeByUrl(finalUrl());
     if (!m_typeClassName.isEmpty())
-        m_typeIds = QQmlMetaType::registerInternalCompositeType(m_typeClassName);
+        m_typeIds = CompositeMetaTypeIds::fromCompositeName(m_typeClassName);
 
     if (m_document) {
         setupICs(m_document, &m_inlineComponentData, finalUrl());
     } else {
         setupICs(m_compiledData, &m_inlineComponentData, finalUrl());
     }
-    auto typeCleanupGuard = qScopeGuard([&]() {
-        if (isError() && m_typeIds.isValid()) {
-            QQmlMetaType::unregisterInternalCompositeType(m_typeIds);
-            for (auto&& icData: qAsConst(m_inlineComponentData)) {
-                QQmlMetaType::unregisterInternalCompositeType(icData.typeIds);
-            }
-        }
-    });
 
     QV4::ResolvedTypeReferenceMap resolvedTypeCache;
     QQmlRefPointer<QQmlTypeNameCache> typeNameCache;