Follow-up to c3fec7b34934b44cef9334160d30cb02e36444f1

WIP: Invalidating shared support spots in Print::apply()
The background slicing background was modified to call Print::cleanup()
any time any data of any print step or print object step could become
invalid. Cleaning up such invalid data will reduce memory footprint.

src/libslic3r/Print.hpp

@@ -517,6 +517,7 @@ public:
     void                set_task(const TaskParams &params) override { PrintBaseWithState<PrintStep, psCount>::set_task_impl(params, m_objects); }
     void                process() override;
     void                finalize() override { PrintBaseWithState<PrintStep, psCount>::finalize_impl(m_objects); }
+    void                cleanup() override;
 
     // Exports G-code into a file name based on the path_template, returns the file path of the generated G-code file.
     // If preview_data is not null, the preview_data is filled in for the G-code visualization (not used by the command line Slic3r).

src/libslic3r/PrintApply.cpp

@@ -1451,7 +1451,18 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
     for (PrintObject *object : m_objects)
         object->update_slicing_parameters();
 
-    if (apply_status == APPLY_STATUS_INVALIDATED) {
+    if (apply_status == APPLY_STATUS_CHANGED || apply_status == APPLY_STATUS_INVALIDATED)
+        this->cleanup();
+
+#ifdef _DEBUG
+    check_model_ids_equal(m_model, model);
+#endif /* _DEBUG */
+
+	return static_cast<ApplyStatus>(apply_status);
+}
+
+void Print::cleanup()
+{
     // Invalidate data of a single ModelObject shared by multiple PrintObjects.
     // Find spans of PrintObjects sharing the same PrintObjectRegions.
     std::vector<PrintObject*> all_objects(m_objects);
@@ -1464,13 +1475,6 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
         if (Print::is_shared_print_object_step_valid_unguarded(this_objects, posSupportSpotsSearch))
             shared_regions->generated_support_points.reset();
     }    
-    }
-
-#ifdef _DEBUG
-    check_model_ids_equal(m_model, model);
-#endif /* _DEBUG */
-
-	return static_cast<ApplyStatus>(apply_status);
 }
 
 bool Print::is_shared_print_object_step_valid_unguarded(SpanOfConstPtrs<PrintObject> print_objects, PrintObjectStep print_object_step)

src/libslic3r/PrintBase.hpp

@@ -408,6 +408,10 @@ public:
     // Clean up after process() finished, either with success, error or if canceled.
     // The adjustments on the Print / PrintObject data due to set_task() are to be reverted here.
     virtual void            finalize() = 0;
+    // Clean up print step / print object step data after
+    // 1) some print step / print object step was invalidated inside PrintBase::apply() while holding the milestone mutex locked.
+    // 2) background thread finished being canceled.
+    virtual void            cleanup() = 0;
 
     struct SlicingStatus {
 		SlicingStatus(int percent, const std::string &text, unsigned int flags = 0) : percent(percent), text(text), flags(flags) {}

src/libslic3r/SLAPrint.hpp

@@ -412,6 +412,7 @@ public:
     void                set_task(const TaskParams &params) override { PrintBaseWithState<SLAPrintStep, slapsCount>::set_task_impl(params, m_objects); }
     void                process() override;
     void                finalize() override { PrintBaseWithState<SLAPrintStep, slapsCount>::finalize_impl(m_objects); }
+    void                cleanup() override {}
     // Returns true if an object step is done on all objects and there's at least one object.
     bool                is_step_done(SLAPrintObjectStep step) const;
     // Returns true if the last step was finished with success.

src/slic3r/GUI/BackgroundSlicingProcess.cpp

@@ -251,6 +251,9 @@ void BackgroundSlicingProcess::thread_proc()
 				(m_state == STATE_CANCELED) ? SlicingProcessCompletedEvent::Cancelled :
 				exception ? SlicingProcessCompletedEvent::Error : SlicingProcessCompletedEvent::Finished, exception);
         	wxQueueEvent(GUI::wxGetApp().mainframe->m_plater, evt.Clone());
+        	// Cancelled by the user, not internally, thus cleanup() was not called yet.
+        	// Otherwise cleanup() is called from Print::apply()
+        	m_print->cleanup();
         }
 	    m_print->restart();
 		lck.unlock();