Remove deleted transport objects

Added a QMultiHash which maps transport objects to wrapped object ids.
transportRemoved iterates over all matching wrapped objects and removes
the passed transport object from their transports-vector. If the
transports-vector is empty after removing the passed transport object
the objectDestroyed will be called on the wrapped object.
transportRemoved will be called either on the transports destoryed
signal or on disconnecting the webchannel from it.

Without this changes the QMetaObjectPublisher::wrappedObjects and
::registeredObjectIds would only be cleaned up if the website calls
deleteLater on QObjects but not on website reloads.

Task-number: QTBUG-50074
Change-Id: If294564fee2406edd7fb578852aeb269cac23a92
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>
(cherry picked from commit fa2374d7c4dedea907e2df26fdad28bdee73b122)
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/webchannel/qmetaobjectpublisher.cpp b/src/webchannel/qmetaobjectpublisher.cpp
index b3fc53d..cd6ad70 100644
--- a/src/webchannel/qmetaobjectpublisher.cpp
+++ b/src/webchannel/qmetaobjectpublisher.cpp
@@ -449,6 +449,29 @@ void QMetaObjectPublisher::objectDestroyed(const QObject *object)
     pendingPropertyUpdates.remove(object);
 }
 
+void QMetaObjectPublisher::transportRemoved(QWebChannelAbstractTransport *transport)
+{
+    QHash<QWebChannelAbstractTransport*, QString>::iterator it = transportedWrappedObjects.find(transport);
+    // It is not allowed to modify a container while iterating over it. So save
+    // objects which should be removed and call objectDestroyed() on them later.
+    QVector<QObject*> objectsForDeletion;
+    while (it != transportedWrappedObjects.end() && it.key() == transport) {
+        if (wrappedObjects.contains(it.value())) {
+            QVector<QWebChannelAbstractTransport*> &transports = wrappedObjects[it.value()].transports;
+            transports.removeOne(transport);
+            if (transports.isEmpty())
+                objectsForDeletion.append(wrappedObjects[it.value()].object);
+        }
+
+        it++;
+    }
+
+    transportedWrappedObjects.remove(transport);
+
+    foreach (QObject *obj, objectsForDeletion)
+        objectDestroyed(obj);
+}
+
 QObject *QMetaObjectPublisher::unwrapObject(const QString &objectId) const
 {
     if (!objectId.isEmpty()) {
@@ -520,6 +543,7 @@ QJsonValue QMetaObjectPublisher::wrapResult(const QVariant &result, QWebChannelA
                     oi.transports = webChannel->d_func()->transports;
             }
             wrappedObjects.insert(id, oi);
+            transportedWrappedObjects.insert(transport, id);
 
             initializePropertyUpdates(object, classInfo);
         } else if (wrappedObjects.contains(id)) {