Merge pull request #8184 from rouault/fix_20098

[OGR provider] Make again a feature iterator to be resetable on a OSM layer (fixes #20098)

src/providers/ogr/qgsogrfeatureiterator.cpp

@@ -311,7 +311,7 @@ bool QgsOgrFeatureIterator::fetchFeature( QgsFeature &feature )
   // see more details here: https://trac.osgeo.org/gdal/wiki/rfc66_randomlayerreadwrite
 
 #if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(2,2,0)
-  if ( mSource->mDriverName == QLatin1String( "OSM" ) )
+  if ( !QgsOgrProviderUtils::canDriverShareSameDatasetAmongLayers( mSource->mDriverName ) )
   {
     OGRLayerH nextFeatureBelongingLayer;
     while ( fet.reset( GDALDatasetGetNextFeature( mConn->ds, &nextFeatureBelongingLayer, nullptr, nullptr, nullptr ) ), fet )
@@ -323,6 +323,7 @@ bool QgsOgrFeatureIterator::fetchFeature( QgsFeature &feature )
     }
   }
   else
+#endif
   {
 
     while ( fet.reset( OGR_L_GetNextFeature( mOgrLayer ) ), fet )
@@ -333,20 +334,25 @@ bool QgsOgrFeatureIterator::fetchFeature( QgsFeature &feature )
       }
     }
   }
-#else
-  while ( fet.reset( OGR_L_GetNextFeature( mOgrLayer ) ), fet )
-  {
-    if ( checkFeature( fet, feature ) )
-    {
-      return true;
-    }
-  }
-#endif
 
   close();
   return false;
 }
 
+void QgsOgrFeatureIterator::resetReading()
+{
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(2,2,0)
+  if ( !QgsOgrProviderUtils::canDriverShareSameDatasetAmongLayers( mSource->mDriverName ) )
+  {
+    GDALDatasetResetReading( mConn->ds );
+  }
+  else
+#endif
+  {
+    OGR_L_ResetReading( mOgrLayer );
+  }
+}
+
 
 bool QgsOgrFeatureIterator::rewind()
 {
@@ -355,7 +361,7 @@ bool QgsOgrFeatureIterator::rewind()
   if ( mClosed || !mOgrLayer )
     return false;
 
-  OGR_L_ResetReading( mOgrLayer );
+  resetReading();
 
   mFilterFidsIt = mFilterFids.constBegin();
 
@@ -387,7 +393,7 @@ bool QgsOgrFeatureIterator::close()
   // Will for example release SQLite3 statements
   if ( mOgrLayer )
   {
-    OGR_L_ResetReading( mOgrLayer );
+    resetReading();
   }
 
   if ( mOgrOrigLayer )

src/providers/ogr/qgsogrfeatureiterator.h

@@ -100,6 +100,8 @@ class QgsOgrFeatureIterator : public QgsAbstractFeatureIteratorFromSource<QgsOgr
     QgsFields mFieldsWithoutFid;
 
     bool fetchFeatureWithId( QgsFeatureId id, QgsFeature &feature ) const;
+
+    void resetReading();
 };
 
 #endif // QGSOGRFEATUREITERATOR_H

tests/src/python/test_provider_ogr.py

@@ -454,6 +454,10 @@ def testOSM(self):
         self.assertTrue(iter_multipolygons.nextFeature(f))
         self.assertFalse(iter_multipolygons.nextFeature(f))
 
+        # Re-start an iterator (tests #20098)
+        iter_multipolygons = vl_multipolygons.getFeatures(QgsFeatureRequest())
+        self.assertTrue(iter_multipolygons.nextFeature(f))
+
 
 if __name__ == '__main__':
     unittest.main()