Shared node bookkeeping

Any time a property references a QNode there is a risk that the node gets
destroyed and then the property is left pointing to a dangling pointer.

To handle such cases, setters of such properties are able to use a helper
that internally connect QObject::destroyed signal to a setter removal method.

Change-Id: I42428c851d0e3d2d88ab0cf6a5b75605334ec648
Task-number: QTBUG-53456
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/render/framegraph/qrenderpassfilter.cpp b/src/render/framegraph/qrenderpassfilter.cpp
index 202a10a35..21f90a998 100644
--- a/src/render/framegraph/qrenderpassfilter.cpp
+++ b/src/render/framegraph/qrenderpassfilter.cpp
@@ -81,6 +81,9 @@ void QRenderPassFilter::addMatch(QFilterKey *filterKey)
     if (!d->m_matchList.contains(filterKey)) {
         d->m_matchList.append(filterKey);
 
+        // Ensures proper bookkeeping
+        d->registerDestructionHelper(filterKey, &QRenderPassFilter::removeMatch, d->m_matchList);
+
         // We need to add it as a child of the current node if it has been declared inline
         // Or not previously added as a child of the current node so that
         // 1) The backend gets notified about it's creation
@@ -107,6 +110,8 @@ void QRenderPassFilter::removeMatch(QFilterKey *filterKey)
         d->notifyObservers(change);
     }
     d->m_matchList.removeOne(filterKey);
+    // Remove bookkeeping connection
+    d->unregisterDestructionHelper(filterKey);
 }
 
 void QRenderPassFilter::addParameter(QParameter *parameter)
@@ -116,6 +121,9 @@ void QRenderPassFilter::addParameter(QParameter *parameter)
     if (!d->m_parameters.contains(parameter)) {
         d->m_parameters.append(parameter);
 
+        // Ensures proper bookkeeping
+        d->registerDestructionHelper(parameter, &QRenderPassFilter::removeParameter, d->m_parameters);
+
         // We need to add it as a child of the current node if it has been declared inline
         // Or not previously added as a child of the current node so that
         // 1) The backend gets notified about it's creation
@@ -142,6 +150,8 @@ void QRenderPassFilter::removeParameter(QParameter *parameter)
         d->notifyObservers(change);
     }
     d->m_parameters.removeOne(parameter);
+    // Remove bookkeeping connection
+    d->unregisterDestructionHelper(parameter);
 }
 
 QVector<QParameter *> QRenderPassFilter::parameters() const