Removing source processed by the layer

[LukasPaczos]

When removing a Source that's being currently processed by a Layer we are failing silently and printing a log.

We should improve the experience during this unusual condition by maybe printing a higher level log, and on the Android side updating docs and returning null instead of the Source object in the MapboxMap#removeSource when it fails.

Example that will fail:

mapView.getMapAsync(mapboxMap -> {
  GeoJsonSource source = new GeoJsonSource("source", Point.fromLngLat(0, 0));
  mapboxMap.addSource(source);
  mapboxMap.addLayer(new CircleLayer("layer", "source"));
  mapboxMap.removeSource("source");
});

How's @mapbox/maps-ios handling this scenario?

[LukasPaczos]

Whoops, obviously we first need to remove a Layer to be able to remove a Source... That said, we still can improve the returned values and logs.

[tobrun]

My idea was to patch this up as part of #10947

[1ec5]

How's @mapbox/maps-ios handling this scenario?

MGLStyle doesn’t explicitly document the fact that the developer shouldn’t remove sources or images that are currently being used by layers. If they try to do that, mbgl logs a warning to the console and fails silently (or gracefully, depending on your point of view).

mapbox-gl-native/src/mbgl/style/style_impl.cpp

Line 170 in 60cbedc

Log::Warning(Event::General, "Source '%s' is in use, cannot remove", id.c_str());

Since we subsequently nil out the source’s map view backpointer and pending source pointer, we’re unable to prevent the developer from adding the same source to a different map view’s style:

mapbox-gl-native/platform/darwin/src/MGLSource.mm

Lines 62 to 63 in 60cbedc

	_pendingSource = mapView.style.rawStyle->removeSource(self.identifier.UTF8String);
	_mapView = nil;

mapbox-gl-native/platform/darwin/src/MGLSource.mm

Lines 51 to 53 in 60cbedc

	[NSException raise:MGLRedundantSourceException
	format:@"This instance %@ was already added to %@. Adding the same source instance " \
	"to the style more than once is invalid.", self, mapView.style];

[lilykaiser]

Can we move forward in 10947 as @tobrun suggests?

[tobrun]

android equivalent of #9692