fix(QgsVectorLayer-dependencies): don't emit too many dataChanged sig…

…nals

src/core/vector/qgsvectorlayer.cpp

@@ -6110,6 +6110,14 @@ void QgsVectorLayer::emitDataChanged()
   if ( mDataChangedFired )
     return;
 
+  // If we are asked to fire dataChanged from a layer we depend on,
+  // be sure that this layer is not in the process of committing its changes, because
+  // we will be asked to fire dataChanged at the end of his commit, and we don't
+  // want to fire this signal more than necessary.
+  if ( QgsVectorLayer *layerWeDependUpon = qobject_cast<QgsVectorLayer *>( sender() );
+       layerWeDependUpon && layerWeDependUpon->mCommitChangesActive )
+    return;
+
   updateExtents(); // reset cached extent to reflect data changes
 
   mDataChangedFired = true;
@@ -6144,7 +6152,7 @@ bool QgsVectorLayer::setDependencies( const QSet<QgsMapLayerDependency> &oDeps )
       disconnect( lyr, &QgsVectorLayer::geometryChanged, this, &QgsVectorLayer::emitDataChanged );
       disconnect( lyr, &QgsVectorLayer::dataChanged, this, &QgsVectorLayer::emitDataChanged );
       disconnect( lyr, &QgsVectorLayer::repaintRequested, this, &QgsVectorLayer::triggerRepaint );
-      disconnect( lyr, &QgsVectorLayer::afterCommitChanges, this, &QgsVectorLayer::reload );
+      disconnect( lyr, &QgsVectorLayer::afterCommitChanges, this, &QgsVectorLayer::emitDataChanged );
     }
   }
 
@@ -6168,7 +6176,7 @@ bool QgsVectorLayer::setDependencies( const QSet<QgsMapLayerDependency> &oDeps )
       connect( lyr, &QgsVectorLayer::geometryChanged, this, &QgsVectorLayer::emitDataChanged );
       connect( lyr, &QgsVectorLayer::dataChanged, this, &QgsVectorLayer::emitDataChanged );
       connect( lyr, &QgsVectorLayer::repaintRequested, this, &QgsVectorLayer::triggerRepaint );
-      connect( lyr, &QgsVectorLayer::afterCommitChanges, this, &QgsVectorLayer::reload );
+      connect( lyr, &QgsVectorLayer::afterCommitChanges, this, &QgsVectorLayer::emitDataChanged );
     }
   }
 

tests/src/python/test_layer_dependencies.py

@@ -192,11 +192,19 @@ def test_circular_dependencies_with_2_layers(self):
         self.assertEqual(len(spy_points_data_changed), 3)
         self.assertEqual(len(spy_lines_data_changed), 2)
 
-        # added feature is deleted and added with its new defined id
-        # (it was -1 before) so it fires 3 more signal dataChanged on
-        # depending line (on featureAdded and on featureDeleted and on afterCommitChanges)
-        # and so 2 more signal on points because it depends on line
-        self.pointsLayer.commitChanges()
+        # commit changes fires dataChanged because external changes could happen (provider side)
+        self.pointsLayer.commitChanges(False)
+        self.assertEqual(len(spy_points_data_changed), 4)
+        self.assertEqual(len(spy_lines_data_changed), 3)
+
+        # points fire dataChanged on geometryChanged
+        # line depends on point, so fire dataChanged
+        self.pointsLayer.changeGeometry(f.id(), QgsGeometry.fromWkt("POINT(0 2)"))
+        self.assertEqual(len(spy_points_data_changed), 5)
+        self.assertEqual(len(spy_lines_data_changed), 4)
+
+        # commit changes fires dataChanged because external changes could happen (provider side)
+        self.assertTrue(self.pointsLayer.commitChanges())
         self.assertEqual(len(spy_points_data_changed), 6)
         self.assertEqual(len(spy_lines_data_changed), 5)
 
@@ -228,23 +236,21 @@ def test_circular_dependencies_with_1_layer(self):
         self.linesLayer.addFeatures([f])
         self.assertEqual(len(spy_lines_data_changed), 2)
 
-        # added feature is deleted and added with its new defined id
-        # (it was -1 before) so it fires 3 more signal dataChanged on
-        # depending line (on featureAdded and on featureDeleted and on afterCommitChanges)
+        # line fire dataChanged on commitChanges
         self.linesLayer.commitChanges(False)
-        self.assertEqual(len(spy_lines_data_changed), 5)
+        self.assertEqual(len(spy_lines_data_changed), 3)
 
         # repaintRequested is called only once on commit changes on line
         # (ideally only one repaintRequested signal is fired, but it's harmless to fire multiple ones)
         self.assertGreaterEqual(len(spy_lines_repaint_requested), 2)
 
         # line fire dataChanged on geometryChanged
         self.linesLayer.changeGeometry(f.id(), QgsGeometry.fromWkt("LINESTRING(0 0, 2 2)"))
-        self.assertEqual(len(spy_lines_data_changed), 6)
+        self.assertEqual(len(spy_lines_data_changed), 4)
 
-        # line fire dataChanged on commitChanges
+        # commit changes fires dataChanged because external changes could happen (provider side)
         self.linesLayer.commitChanges()
-        self.assertEqual(len(spy_lines_data_changed), 7)
+        self.assertEqual(len(spy_lines_data_changed), 5)
 
     def test_layerDefinitionRewriteId(self):
         tmpfile = os.path.join(tempfile.tempdir, "test.qlr")