Don't cache item indexes in VisualDataModel.

Sacrifice constant time lookup of indexes for rarely used features for
reduced memory usage.

Applications which use neither Packages, nor the VisualDataGroup api
don't ever need to query the index of an item so caching and maintaining
those indexes in unnecessary. Where they are used this add a cost
scanning for the index of an item in the cache, and in some instances
a lookup cost in the compositor.

Change-Id: I7d3c21a27a8a3c068c5ae2e1e326ff573c44d712
Reviewed-by: Martin Jones <martin.jones@nokia.com>

4 files changed, 144 insertions, 117 deletions

diff --git a/src/quick/items/qquickvisualadaptormodel.cpp b/src/quick/items/qquickvisualadaptormodel.cpp
index fa88932faa..4151c3695e 100644
--- a/src/quick/items/qquickvisualadaptormodel.cpp
+++ b/src/quick/items/qquickvisualadaptormodel.cpp
@@ -70,7 +70,7 @@ static v8::Handle<v8::Value> get_index(v8::Local<v8::String>, const v8::Accessor
     if (!data)
         V8THROW_ERROR("Not a valid VisualData object");
 
-    return v8::Int32::New(data->index[0]);
+    return v8::Int32::New(data->index);
 }
 
 static v8::Local<v8::ObjectTemplate> createConstructor()
@@ -252,7 +252,7 @@ int QQuickVDMCachedModelData::metaCall(QMetaObject::Call call, int id, void **ar
 {
     if (call == QMetaObject::ReadProperty && id >= type->propertyOffset) {
         const int propertyIndex = id - type->propertyOffset;
-        if (index[0] == -1) {
+        if (index == -1) {
             if (!cachedData.isEmpty()) {
                 *static_cast<QVariant *>(arguments[0]) = cachedData.at(
                     type->hasModelData ? 0 : propertyIndex);
@@ -263,7 +263,7 @@ int QQuickVDMCachedModelData::metaCall(QMetaObject::Call call, int id, void **ar
         return -1;
     } else if (call == QMetaObject::WriteProperty && id >= type->propertyOffset) {
         const int propertyIndex = id - type->propertyOffset;
-        if (index[0] == -1) {
+        if (index == -1) {
             const QMetaObject *meta = metaObject();
             if (cachedData.count() > 1) {
                 cachedData[propertyIndex] = *static_cast<QVariant *>(arguments[0]);
@@ -297,9 +297,9 @@ void QQuickVDMCachedModelData::setValue(const QString &role, const QVariant &val
 
 bool QQuickVDMCachedModelData::resolveIndex(const QQuickVisualAdaptorModel &, int idx)
 {
-    if (index[0] == -1) {
+    if (index == -1) {
         Q_ASSERT(idx >= 0);
-        index[0] = idx;
+        index = idx;
         cachedData.clear();
         emit modelIndexChanged();
         const QMetaObject *meta = metaObject();
@@ -321,7 +321,7 @@ v8::Handle<v8::Value> QQuickVDMCachedModelData::get_property(
 
     QQuickVDMCachedModelData *modelData = static_cast<QQuickVDMCachedModelData *>(data);
     const int propertyId = info.Data()->Int32Value();
-    if (data->index[0] == -1) {
+    if (data->index == -1) {
         if (!modelData->cachedData.isEmpty()) {
             return data->engine->fromVariant(
                     modelData->cachedData.at(modelData->type->hasModelData ? 0 : propertyId));
@@ -341,7 +341,7 @@ void QQuickVDMCachedModelData::set_property(
         V8THROW_ERROR_SETTER("Not a valid VisualData object");
 
     const int propertyId = info.Data()->Int32Value();
-    if (data->index[0] == -1) {
+    if (data->index == -1) {
         QQuickVDMCachedModelData *modelData = static_cast<QQuickVDMCachedModelData *>(data);
         if (!modelData->cachedData.isEmpty()) {
             if (modelData->cachedData.count() > 1) {
@@ -375,9 +375,9 @@ public:
 
     bool hasModelChildren() const
     {
-        if (index[0] >= 0 && *type->model) {
+        if (index >= 0 && *type->model) {
             const QAbstractItemModel * const model = type->model->aim();
-            return model->hasChildren(model->index(index[0], 0, type->model->rootIndex));
+            return model->hasChildren(model->index(index, 0, type->model->rootIndex));
         } else {
             return false;
         }
@@ -385,13 +385,13 @@ public:
 
     QVariant value(int role) const
     {
-        return type->model->aim()->index(index[0], 0, type->model->rootIndex).data(role);
+        return type->model->aim()->index(index, 0, type->model->rootIndex).data(role);
     }
 
     void setValue(int role, const QVariant &value)
     {
         type->model->aim()->setData(
-                type->model->aim()->index(index[0], 0, type->model->rootIndex), value, role);
+                type->model->aim()->index(index, 0, type->model->rootIndex), value, role);
     }
 
     v8::Handle<v8::Value> get()
@@ -414,9 +414,9 @@ public:
             V8THROW_ERROR("Not a valid VisualData object");
 
         const QQuickVisualAdaptorModel *const model = static_cast<QQuickVDMCachedModelData *>(data)->type->model;
-        if (data->index[0] >= 0 && *model) {
+        if (data->index >= 0 && *model) {
             const QAbstractItemModel * const aim = model->aim();
-            return v8::Boolean::New(aim->hasChildren(aim->index(data->index[0], 0, model->rootIndex)));
+            return v8::Boolean::New(aim->hasChildren(aim->index(data->index, 0, model->rootIndex)));
         } else {
             return v8::Boolean::New(false);
         }
@@ -549,7 +549,7 @@ public:
 
     QVariant value(int role) const
     {
-        return type->model->lmi()->data(index[0], role);
+        return type->model->lmi()->data(index, role);
     }
 
     void setValue(int, const QVariant &) {}
@@ -673,7 +673,7 @@ public:
 
     void setModelData(const QVariant &data)
     {
-        if (index[0] == -1 && data != cachedData) {
+        if (index == -1 && data != cachedData) {
             cachedData = data;
             emit modelDataChanged();
         }
@@ -706,8 +706,8 @@ public:
 
     bool resolveIndex(const QQuickVisualAdaptorModel &model, int idx)
     {
-        if (index[0] == -1) {
-            index[0] = idx;
+        if (index == -1) {
+            index = idx;
             cachedData = model.list.at(idx);
             emit modelIndexChanged();
             emit modelDataChanged();
diff --git a/src/quick/items/qquickvisualdatamodel.cpp b/src/quick/items/qquickvisualdatamodel.cpp
index b8e51d75eb..fe0dd00cbe 100644
--- a/src/quick/items/qquickvisualdatamodel.cpp
+++ b/src/quick/items/qquickvisualdatamodel.cpp
@@ -735,16 +735,16 @@ QObject *QQuickVisualDataModel::parts()
     return d->m_parts;
 }
 
-void QQuickVisualDataModelPrivate::emitCreatedPackage(QQuickVisualDataModelItem *cacheItem, QQuickPackage *package)
+void QQuickVisualDataModelPrivate::emitCreatedPackage(QVDMIncubationTask *incubationTask, QQuickPackage *package)
 {
     for (int i = 1; i < m_groupCount; ++i)
-        QQuickVisualDataGroupPrivate::get(m_groups[i])->createdPackage(cacheItem->index[i], package);
+        QQuickVisualDataGroupPrivate::get(m_groups[i])->createdPackage(incubationTask->index[i], package);
 }
 
-void QQuickVisualDataModelPrivate::emitInitPackage(QQuickVisualDataModelItem *cacheItem, QQuickPackage *package)
+void QQuickVisualDataModelPrivate::emitInitPackage(QVDMIncubationTask *incubationTask, QQuickPackage *package)
 {
     for (int i = 1; i < m_groupCount; ++i)
-        QQuickVisualDataGroupPrivate::get(m_groups[i])->initPackage(cacheItem->index[i], package);
+        QQuickVisualDataGroupPrivate::get(m_groups[i])->initPackage(incubationTask->index[i], package);
 }
 
 void QQuickVisualDataModelPrivate::emitDestroyingPackage(QQuickPackage *package)
@@ -793,9 +793,9 @@ void QQuickVisualDataModelPrivate::incubatorStatusChanged(QVDMIncubationTask *in
 
     if (status == QQmlIncubator::Ready) {
         if (QQuickItem *item = qmlobject_cast<QQuickItem *>(cacheItem->object))
-            emitCreatedItem(cacheItem, item);
+            emitCreatedItem(incubationTask, item);
         else if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
-            emitCreatedPackage(cacheItem, package);
+            emitCreatedPackage(incubationTask, package);
     } else if (status == QQmlIncubator::Error) {
         qmlInfo(q, m_delegate->errors()) << "Error creating delegate";
     }
@@ -827,10 +827,10 @@ void QQuickVisualDataModelPrivate::setInitialState(QVDMIncubationTask *incubatio
     QQuickVisualDataModelItem *cacheItem = incubationTask->incubating;
     cacheItem->object = o;
 
-    if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
-        emitInitPackage(cacheItem, package);
-    else if (QQuickItem *item = qmlobject_cast<QQuickItem *>(cacheItem->object))
-        emitInitItem(cacheItem, item);
+    if (QQuickItem *item = qmlobject_cast<QQuickItem *>(cacheItem->object))
+        emitInitItem(incubationTask, item);
+    else if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
+        emitInitPackage(incubationTask, package);
 }
 
 QObject *QQuickVisualDataModelPrivate::object(Compositor::Group group, int index, bool asynchronous)
@@ -850,9 +850,6 @@ QObject *QQuickVisualDataModelPrivate::object(Compositor::Group group, int index
         if (!cacheItem)
             return 0;
 
-        for (int i = 1; i < m_groupCount; ++i)
-            cacheItem->index[i] = it.index[i];
-
         cacheItem->groups = it->flags;
 
         m_cache.insert(it.cacheIndex, cacheItem);
@@ -879,6 +876,9 @@ QObject *QQuickVisualDataModelPrivate::object(Compositor::Group group, int index
         cacheItem->incubationTask->incubating = cacheItem;
         cacheItem->incubationTask->clear();
 
+        for (int i = 1; i < m_groupCount; ++i)
+            cacheItem->incubationTask->index[i] = it.index[i];
+
         QQmlContextData *ctxt = new QQmlContextData;
         ctxt->setParent(QQmlContextData::get(creationContext  ? creationContext : m_context));
         ctxt->contextObject = cacheItem;
@@ -968,7 +968,7 @@ int QQuickVisualDataModel::indexOf(QQuickItem *item, QObject *) const
 {
     Q_D(const QQuickVisualDataModel);
     if (QQuickVisualDataModelItem *cacheItem = QQuickVisualDataModelItem::dataForObject(item))
-        return cacheItem->index[d->m_compositorGroup];
+        return cacheItem->groupIndex(d->m_compositorGroup);
     return -1;
 }
 
@@ -1059,6 +1059,18 @@ void QQuickVisualDataModel::_q_itemsChanged(int index, int count, const QList<in
     }
 }
 
+static void incrementIndexes(QQuickVisualDataModelItem *cacheItem, int count, const int *deltas)
+{
+    if (QVDMIncubationTask *incubationTask = cacheItem->incubationTask) {
+        for (int i = 1; i < count; ++i)
+            incubationTask->index[i] += deltas[i];
+    }
+    if (QQuickVisualDataModelAttached *attached = cacheItem->attached) {
+        for (int i = 1; i < count; ++i)
+            attached->m_currentIndex[i] += deltas[i];
+    }
+}
+
 void QQuickVisualDataModelPrivate::itemsInserted(
         const QVector<Compositor::Insert> &inserts,
         QVarLengthArray<QVector<QQuickChangeSet::Insert>, Compositor::MaximumGroupCount> *translatedInserts,
@@ -1071,11 +1083,9 @@ void QQuickVisualDataModelPrivate::itemsInserted(
         inserted[i] = 0;
 
     foreach (const Compositor::Insert &insert, inserts) {
-        for (; cacheIndex < insert.cacheIndex; ++cacheIndex) {
-            QQuickVisualDataModelItem *cacheItem = m_cache.at(cacheIndex);
-            for (int i = 1; i < m_groupCount; ++i)
-                cacheItem->index[i] += inserted[i];
-        }
+        for (; cacheIndex < insert.cacheIndex; ++cacheIndex)
+            incrementIndexes(m_cache.at(cacheIndex), m_groupCount, inserted);
+
         for (int i = 1; i < m_groupCount; ++i) {
             if (insert.inGroup(i)) {
                 (*translatedInserts)[i].append(
@@ -1096,21 +1106,26 @@ void QQuickVisualDataModelPrivate::itemsInserted(
             for (int offset = 0; cacheIndex < insert.cacheIndex + insert.count; ++cacheIndex, ++offset) {
                 QQuickVisualDataModelItem *cacheItem = m_cache.at(cacheIndex);
                 cacheItem->groups |= insert.flags & Compositor::GroupMask;
-                for (int i = 1; i < m_groupCount; ++i) {
-                    cacheItem->index[i] = cacheItem->groups & (1 << i)
-                            ? insert.index[i] + offset
-                            : insert.index[i];
+
+                if (QVDMIncubationTask *incubationTask = cacheItem->incubationTask) {
+                    for (int i = 1; i < m_groupCount; ++i)
+                        incubationTask->index[i] = cacheItem->groups & (1 << i)
+                                ? insert.index[i] + offset
+                                : insert.index[i];
+                }
+                if (QQuickVisualDataModelAttached *attached = cacheItem->attached) {
+                    for (int i = 1; i < m_groupCount; ++i)
+                        attached->m_currentIndex[i] = cacheItem->groups & (1 << i)
+                                ? insert.index[i] + offset
+                                : insert.index[i];
                 }
             }
         } else {
             cacheIndex = insert.cacheIndex + insert.count;
         }
     }
-    for (; cacheIndex < m_cache.count(); ++cacheIndex) {
-        QQuickVisualDataModelItem *cacheItem = m_cache.at(cacheIndex);
-        for (int i = 1; i < m_groupCount; ++i)
-            cacheItem->index[i] += inserted[i];
-    }
+    for (; cacheIndex < m_cache.count(); ++cacheIndex)
+        incrementIndexes(m_cache.at(cacheIndex), m_groupCount, inserted);
 }
 
 void QQuickVisualDataModelPrivate::itemsInserted(const QVector<Compositor::Insert> &inserts)
@@ -1159,16 +1174,14 @@ void QQuickVisualDataModelPrivate::itemsRemoved(
         removed[i] = 0;
 
     foreach (const Compositor::Remove &remove, removes) {
-        for (; cacheIndex < remove.cacheIndex; ++cacheIndex) {
-            QQuickVisualDataModelItem *cacheItem = m_cache.at(cacheIndex);
-            for (int i = 1; i < m_groupCount; ++i)
-                cacheItem->index[i] -= removed[i];
-        }
+        for (; cacheIndex < remove.cacheIndex; ++cacheIndex)
+            incrementIndexes(m_cache.at(cacheIndex), m_groupCount, removed);
+
         for (int i = 1; i < m_groupCount; ++i) {
             if (remove.inGroup(i)) {
                 (*translatedRemoves)[i].append(
                         QQuickChangeSet::Remove(remove.index[i], remove.count, remove.moveId));
-                removed[i] += remove.count;
+                removed[i] -= remove.count;
             }
         }
 
@@ -1201,12 +1214,26 @@ void QQuickVisualDataModelPrivate::itemsRemoved(
                     Q_ASSERT(m_cache.count() == m_compositor.count(Compositor::Cache));
                 } else if (remove.groups() == cacheItem->groups) {
                     cacheItem->groups = 0;
-                    for (int i = 1; i < m_groupCount; ++i)
-                        cacheItem->index[i] = -1;
+                    if (QVDMIncubationTask *incubationTask = cacheItem->incubationTask) {
+                        for (int i = 1; i < m_groupCount; ++i)
+                            incubationTask->index[i] = -1;
+                    }
+                    if (QQuickVisualDataModelAttached *attached = cacheItem->attached) {
+                        for (int i = 1; i < m_groupCount; ++i)
+                            attached->m_currentIndex[i] = -1;
+                    }
                 } else {
-                    for (int i = 1; i < m_groupCount; ++i) {
-                        if (remove.inGroup(i))
-                            cacheItem->index[i] = remove.index[i];
+                    if (QVDMIncubationTask *incubationTask = cacheItem->incubationTask) {
+                        for (int i = 1; i < m_groupCount; ++i) {
+                            if (remove.inGroup(i))
+                                incubationTask->index[i] = remove.index[i];
+                        }
+                    }
+                    if (QQuickVisualDataModelAttached *attached = cacheItem->attached) {
+                        for (int i = 1; i < m_groupCount; ++i) {
+                            if (remove.inGroup(i))
+                                attached->m_currentIndex[i] = remove.index[i];
+                        }
                     }
                     cacheItem->groups &= ~remove.flags;
                 }
@@ -1214,11 +1241,8 @@ void QQuickVisualDataModelPrivate::itemsRemoved(
         }
     }
 
-    for (; cacheIndex < m_cache.count(); ++cacheIndex) {
-        QQuickVisualDataModelItem *cacheItem = m_cache.at(cacheIndex);
-        for (int i = 1; i < m_groupCount; ++i)
-            cacheItem->index[i] -= removed[i];
-    }
+    for (; cacheIndex < m_cache.count(); ++cacheIndex)
+        incrementIndexes(m_cache.at(cacheIndex), m_groupCount, removed);
 }
 
 void QQuickVisualDataModelPrivate::itemsRemoved(const QVector<Compositor::Remove> &removes)
@@ -1446,9 +1470,6 @@ bool QQuickVisualDataModelPrivate::insert(
     if (!cacheItem)
         return false;
 
-    for (int i = 1; i < m_groupCount; ++i)
-        cacheItem->index[i] = before.index[i];
-
     v8::Local<v8::Array> propertyNames = object->GetPropertyNames();
     for (uint i = 0; i < propertyNames->Length(); ++i) {
         v8::Local<v8::String> propertyName = propertyNames->Get(i)->ToString();
@@ -1635,13 +1656,9 @@ void QQuickVisualDataModelItemMetaType::set_groups(
     QQuickVisualDataModelPrivate *model = QQuickVisualDataModelPrivate::get(cacheItem->metaType->model);
 
     const int groupFlags = model->m_cacheMetaType->parseGroups(value);
-    for (int i = 1; i < cacheItem->metaType->groupCount; ++i) {
-        if (cacheItem->groups & (1 << i)) {
-            Compositor::iterator it = model->m_compositor.find(Compositor::Group(i), cacheItem->index[i]);
-            model->setGroups(it, 1, Compositor::Group(i), groupFlags);
-            break;
-        }
-    }
+    const int cacheIndex = model->m_cache.indexOf(cacheItem);
+    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
+    model->setGroups(it, 1, Compositor::Cache, groupFlags);
 }
 
 v8::Handle<v8::Value> QQuickVisualDataModelItemMetaType::get_member(
@@ -1671,16 +1688,12 @@ void QQuickVisualDataModelItemMetaType::set_member(
     if (member == ((cacheItem->groups & groupFlag) != 0))
         return;
 
-    for (int i = 1; i < cacheItem->metaType->groupCount; ++i) {
-        if (cacheItem->groups & (1 << i)) {
-            Compositor::iterator it = model->m_compositor.find(Compositor::Group(i), cacheItem->index[i]);
-            if (member)
-                model->addGroups(it, 1, Compositor::Group(i), groupFlag);
-            else
-                model->removeGroups(it, 1, Compositor::Group(i), groupFlag);
-            break;
-        }
-    }
+    const int cacheIndex = model->m_cache.indexOf(cacheItem);
+    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
+    if (member)
+        model->addGroups(it, 1, Compositor::Cache, groupFlag);
+    else
+        model->removeGroups(it, 1, Compositor::Cache, groupFlag);
 }
 
 v8::Handle<v8::Value> QQuickVisualDataModelItemMetaType::get_index(
@@ -1690,7 +1703,7 @@ v8::Handle<v8::Value> QQuickVisualDataModelItemMetaType::get_index(
     if (!cacheItem)
         V8THROW_ERROR("Not a valid VisualData object");
 
-    return v8::Integer::New(cacheItem->index[info.Data()->Int32Value()]);
+    return v8::Integer::New(cacheItem->groupIndex(Compositor::Group(info.Data()->Int32Value())));
 }
 
 
@@ -1707,8 +1720,8 @@ QQuickVisualDataModelItem::QQuickVisualDataModelItem(
     , objectRef(0)
     , scriptRef(0)
     , groups(0)
+    , index(modelIndex)
 {
-    index[0] = modelIndex;
     metaType->addref();
 }
 
@@ -1803,6 +1816,16 @@ QQuickVisualDataModelItem *QQuickVisualDataModelItem::dataForObject(QObject *obj
     return 0;
 }
 
+int QQuickVisualDataModelItem::groupIndex(Compositor::Group group)
+{
+    if (QQuickVisualDataModelPrivate * const model = metaType->model
+            ? QQuickVisualDataModelPrivate::get(metaType->model)
+            : 0) {
+        return model->m_compositor.find(Compositor::Cache, model->m_cache.indexOf(this)).index[group];
+    }
+    return -1;
+}
+
 //---------------------------------------------------------------------------
 
 QQuickVisualDataModelAttachedMetaObject::QQuickVisualDataModelAttachedMetaObject(
@@ -1834,7 +1857,7 @@ int QQuickVisualDataModelAttachedMetaObject::metaCall(QObject *object, QMetaObje
     if (call == QMetaObject::ReadProperty) {
         if (_id >= indexPropertyOffset) {
             Compositor::Group group = Compositor::Group(_id - indexPropertyOffset + 1);
-            *static_cast<int *>(arguments[0]) = attached->m_cacheItem->index[group];
+            *static_cast<int *>(arguments[0]) = attached->m_currentIndex[group];
             return -1;
         } else if (_id >= memberPropertyOffset) {
             Compositor::Group group = Compositor::Group(_id - memberPropertyOffset + 1);
@@ -1851,13 +1874,13 @@ int QQuickVisualDataModelAttachedMetaObject::metaCall(QObject *object, QMetaObje
             const bool member = attached->m_cacheItem->groups & groupFlag;
             if (member && !*static_cast<bool *>(arguments[0])) {
                 Compositor::iterator it = model->m_compositor.find(
-                        group, attached->m_cacheItem->index[group]);
+                        group, attached->m_currentIndex[group]);
                 model->removeGroups(it, 1, group, groupFlag);
             } else if (!member && *static_cast<bool *>(arguments[0])) {
                 for (int i = 1; i < metaType->groupCount; ++i) {
                     if (attached->m_cacheItem->groups & (1 << i)) {
                         Compositor::iterator it = model->m_compositor.find(
-                                Compositor::Group(i), attached->m_cacheItem->index[i]);
+                                Compositor::Group(i), attached->m_currentIndex[i]);
                         model->addGroups(it, 1, Compositor::Group(i), groupFlag);
                         break;
                     }
@@ -1884,8 +1907,16 @@ QQuickVisualDataModelAttached::QQuickVisualDataModelAttached(
     , m_modelChanged(false)
 {
     QQml_setParent_noEvent(this, parent);
-    for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i)
-        m_previousIndex[i] = m_cacheItem->index[i];
+    if (QVDMIncubationTask *incubationTask = m_cacheItem->incubationTask) {
+        for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i)
+            m_currentIndex[i] = m_previousIndex[i] = incubationTask->index[i];
+    } else {
+        QQuickVisualDataModelPrivate * const model = QQuickVisualDataModelPrivate::get(m_cacheItem->metaType->model);
+        Compositor::iterator it = model->m_compositor.find(
+                Compositor::Cache, model->m_cache.indexOf(m_cacheItem));
+        for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i)
+            m_currentIndex[i] = m_previousIndex[i] = it.index[i];
+    }
 
     if (!cacheItem->metaType->metaObject)
         cacheItem->metaType->initializeMetaObject();
@@ -1936,13 +1967,9 @@ void QQuickVisualDataModelAttached::setGroups(const QStringList &groups)
     QQuickVisualDataModelPrivate *model = QQuickVisualDataModelPrivate::get(m_cacheItem->metaType->model);
 
     const int groupFlags = model->m_cacheMetaType->parseGroups(groups);
-    for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i) {
-        if (m_cacheItem->groups & (1 << i)) {
-            Compositor::iterator it = model->m_compositor.find(Compositor::Group(i), m_cacheItem->index[i]);
-            model->setGroups(it, 1, Compositor::Group(i), groupFlags);
-            return;
-        }
-    }
+    const int cacheIndex = model->m_cache.indexOf(m_cacheItem);
+    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
+    model->setGroups(it, 1, Compositor::Cache, groupFlags);
 }
 
 bool QQuickVisualDataModelAttached::isUnresolved() const
@@ -2003,8 +2030,8 @@ void QQuickVisualDataModelAttached::emitChanges()
 
     int indexChanges = 0;
     for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i) {
-        if (m_previousIndex[i] != m_cacheItem->index[i]) {
-            m_previousIndex[i] = m_cacheItem->index[i];
+        if (m_previousIndex[i] != m_currentIndex[i]) {
+            m_previousIndex[i] = m_currentIndex[i];
             indexChanges |= (1 << i);
         }
     }
@@ -2214,8 +2241,6 @@ QQmlV8Handle QQuickVisualDataGroup::get(int index)
                 model->m_cacheMetaType, model->m_context->engine(), it.modelIndex());
         if (!cacheItem)
             return QQmlV8Handle::fromHandle(v8::Undefined());
-        for (int i = 1; i < model->m_groupCount; ++i)
-            cacheItem->index[i] = it.index[i];
         cacheItem->groups = it->flags;
 
         model->m_cache.insert(it.cacheIndex, cacheItem);
@@ -2244,12 +2269,12 @@ bool QQuickVisualDataGroupPrivate::parseIndex(
     } else if (value->IsObject()) {
         v8::Local<v8::Object> object = value->ToObject();
         QQuickVisualDataModelItem * const cacheItem = v8_resource_cast<QQuickVisualDataModelItem>(object);
-        for (int i = 1; cacheItem && i < cacheItem->metaType->groupCount; ++i) {
-            if (cacheItem->groups & (1 << i)) {
-                *group = Compositor::Group(i);
-                *index = cacheItem->index[i];
-                return true;
-            }
+        if (QQuickVisualDataModelPrivate *model = cacheItem && cacheItem->metaType->model
+                ? QQuickVisualDataModelPrivate::get(cacheItem->metaType->model)
+                : 0) {
+            *index = model->m_cache.indexOf(cacheItem);
+            *group = Compositor::Cache;
+            return true;
         }
     }
     return false;
@@ -2878,7 +2903,7 @@ int QQuickVisualPartsModel::indexOf(QQuickItem *item, QObject *) const
     QHash<QObject *, QQuickPackage *>::const_iterator it = m_packaged.find(item);
     if (it != m_packaged.end()) {
         if (QQuickVisualDataModelItem *cacheItem = QQuickVisualDataModelItem::dataForObject(*it))
-            return cacheItem->index[m_compositorGroup];
+            return cacheItem->groupIndex(m_compositorGroup);
     }
     return -1;
 }
diff --git a/src/quick/items/qquickvisualdatamodel_p.h b/src/quick/items/qquickvisualdatamodel_p.h
index 114d394dc2..38939b64ab 100644
--- a/src/quick/items/qquickvisualdatamodel_p.h
+++ b/src/quick/items/qquickvisualdatamodel_p.h
@@ -221,6 +221,7 @@ Q_SIGNALS:
 public:
     QQuickVisualDataModelItem *m_cacheItem;
     int m_previousGroups;
+    int m_currentIndex[QQuickListCompositor::MaximumGroupCount];
     int m_previousIndex[QQuickListCompositor::MaximumGroupCount];
     bool m_modelChanged;
 
diff --git a/src/quick/items/qquickvisualdatamodel_p_p.h b/src/quick/items/qquickvisualdatamodel_p_p.h
index 7389da8c17..9a6c8c3738 100644
--- a/src/quick/items/qquickvisualdatamodel_p_p.h
+++ b/src/quick/items/qquickvisualdatamodel_p_p.h
@@ -136,8 +136,10 @@ public:
 
     static QQuickVisualDataModelItem *dataForObject(QObject *object);
 
-    int modelIndex() const { return index[0]; }
-    void setModelIndex(int idx) { index[0] = idx; emit modelIndexChanged(); }
+    int groupIndex(Compositor::Group group);
+
+    int modelIndex() const { return index; }
+    void setModelIndex(int idx) { index = idx; emit modelIndexChanged(); }
 
     virtual v8::Handle<v8::Value> get() { return engine->newQObject(this); }
 
@@ -154,7 +156,7 @@ public:
     int objectRef;
     int scriptRef;
     int groups;
-    int index[QQuickListCompositor::MaximumGroupCount];
+    int index;
 
 
 Q_SIGNALS:
@@ -178,9 +180,8 @@ public:
     virtual void setInitialState(QObject *);
 
     QQuickVisualDataModelItem *incubating;
-
-private:
     QQuickVisualDataModelPrivate *vdm;
+    int index[QQuickListCompositor::MaximumGroupCount];
 };
 
 
@@ -247,12 +248,12 @@ public:
     QObject *object(Compositor::Group group, int index, bool asynchronous);
     QQuickVisualDataModel::ReleaseFlags release(QObject *object);
     QString stringValue(Compositor::Group group, int index, const QString &name);
-    void emitCreatedPackage(QQuickVisualDataModelItem *cacheItem, QQuickPackage *package);
-    void emitInitPackage(QQuickVisualDataModelItem *cacheItem, QQuickPackage *package);
-    void emitCreatedItem(QQuickVisualDataModelItem *cacheItem, QQuickItem *item) {
-        emit q_func()->createdItem(cacheItem->index[m_compositorGroup], item); }
-    void emitInitItem(QQuickVisualDataModelItem *cacheItem, QQuickItem *item) {
-        emit q_func()->initItem(cacheItem->index[m_compositorGroup], item); }
+    void emitCreatedPackage(QVDMIncubationTask *incubationTask, QQuickPackage *package);
+    void emitInitPackage(QVDMIncubationTask *incubationTask, QQuickPackage *package);
+    void emitCreatedItem(QVDMIncubationTask *incubationTask, QQuickItem *item) {
+        emit q_func()->createdItem(incubationTask->index[m_compositorGroup], item); }
+    void emitInitItem(QVDMIncubationTask *incubationTask, QQuickItem *item) {
+        emit q_func()->initItem(incubationTask->index[m_compositorGroup], item); }
     void emitDestroyingPackage(QQuickPackage *package);
     void emitDestroyingItem(QQuickItem *item) { emit q_func()->destroyingItem(item); }
     void removeCacheItem(QQuickVisualDataModelItem *cacheItem);