Possible fix for the Generator Dialog update crash

The dialog should also care about the thread safety and use
the cookie returned by the updating threads.

BUG:428014

libs/image/generator/kis_generator_layer.cpp

@@ -146,12 +146,13 @@ void KisGeneratorLayer::requestUpdateJobsWithStroke(KisStrokeId strokeId, KisFil
     m_d->preparedForFilter = filterConfig;
 }
 
-void KisGeneratorLayer::previewWithStroke(const KisStrokeId strokeId)
+QWeakPointer<bool> KisGeneratorLayer::previewWithStroke(const KisStrokeId strokeId)
 {
     KisFilterConfigurationSP filterConfig = filter();
-    KIS_SAFE_ASSERT_RECOVER_RETURN(filterConfig);
+    KIS_SAFE_ASSERT_RECOVER_RETURN_VALUE(filterConfig, QWeakPointer<bool>());
 
     requestUpdateJobsWithStroke(strokeId, filterConfig);
+    return m_d->updateCookie;
 }
 
 void KisGeneratorLayer::update()

libs/image/generator/kis_generator_layer.h

@@ -65,7 +65,7 @@ public:
      * re-runs the generator with the specified configuration.
      * Used for previewing the layer inside the stroke.
      */
-    void previewWithStroke(const KisStrokeId stroke);
+    QWeakPointer<bool> previewWithStroke(const KisStrokeId stroke);
 
     using KisSelectionBasedLayer::setDirty;
     void setDirty(const QVector<QRect> &rects) override;

libs/image/generator/kis_generator_stroke_strategy.cpp

@@ -43,26 +43,26 @@ QVector<KisStrokeJobData *>KisGeneratorStrokeStrategy::createJobsData(const KisG
             for(const auto& tile: tiles) {
                 KisProcessingInformation dstCfg(dev, tile.topLeft(), KisSelectionSP());
                 addJobConcurrent(jobsData, [=]() {
-                    const_cast<QSharedPointer<bool> &>(cookie).clear();
-
                     f->generate(dstCfg, tile.size(), filterConfig, helper->updater());
 
                     // HACK ALERT!!!
                     // this avoids cyclic loop with KisRecalculateGeneratorLayerJob::run()
                     const_cast<KisGeneratorLayerSP &>(layer)->setDirtyWithoutUpdate({tile});
+
+                    const_cast<QSharedPointer<bool> &>(cookie).clear();
                 });
             }
         } else {
             KisProcessingInformation dstCfg(dev, rc.topLeft(), KisSelectionSP());
 
             addJobSequential(jobsData, [=]() {
-                const_cast<QSharedPointer<bool>&>(cookie).clear();
-
                 f->generate(dstCfg, rc.size(), filterConfig, helper->updater());
 
                 // HACK ALERT!!!
                 // this avoids cyclic loop with KisRecalculateGeneratorLayerJob::run()
                 const_cast<KisGeneratorLayerSP &>(layer)->setDirtyWithoutUpdate({rc});
+
+                const_cast<QSharedPointer<bool>&>(cookie).clear();
             });
         }
     }

libs/ui/dialogs/kis_dlg_generator_layer.cpp

@@ -127,8 +127,12 @@ void KisDlgGeneratorLayer::slotNameChanged(const QString & text)
 void KisDlgGeneratorLayer::slotDelayedPreviewGenerator()
 {
     if (!m_stroke.isNull()) {
-        layer->setFilterWithoutUpdate(configuration()->cloneWithResourcesSnapshot());
-        layer->previewWithStroke(m_stroke);
+        if (m_updateCookie) {
+            m_compressor.start();
+        } else {
+            layer->setFilterWithoutUpdate(configuration()->cloneWithResourcesSnapshot());
+            m_updateCookie = layer->previewWithStroke(m_stroke);
+        }
     } else {
         KIS_ASSERT_RECOVER_RETURN(layer);
         layer->setFilter(configuration()->cloneWithResourcesSnapshot());

libs/ui/dialogs/kis_dlg_generator_layer.h

@@ -65,6 +65,7 @@ private:
     bool m_freezeName;
     KisStrokeId m_stroke;
     KisThreadSafeSignalCompressor m_compressor;
+    QWeakPointer<bool> m_updateCookie;
 };
 
 #endif