387 clean reset of applet state when scan is overwritten

ndscan/experiment/entry_point.py

@@ -319,17 +319,18 @@ def build(self,
 
     def run(self):
         """Run the (possibly trivial) scan."""
-        self._broadcast_metadata()
-
         if not self.spec.axes and not self._is_time_series:
+            self._broadcast_metadata()
             self._run_continuous()
             return None, {c: s.get_last() for c, s in self._scan_result_sinks.items()}
 
         if self._is_time_series:
             self._timestamp_sink = AppendingDatasetSink(
                 self, self.dataset_prefix + "points.axis_0")
+            self._timestamp_sink.clear()
             self._coordinate_sinks = [self._timestamp_sink]
             self._time_series_start = time.monotonic()
+            self._broadcast_metadata()
             self._run_continuous()
         else:
             runner = select_runner_class(self.fragment)(
@@ -342,6 +343,9 @@ def run(self):
                 AppendingDatasetSink(self, self.dataset_prefix + f"points.axis_{i}")
                 for i in range(len(self.spec.axes))
             ]
+            for sink in self._coordinate_sinks:
+                sink.clear()
+            self._broadcast_metadata()
             runner.run(self.fragment, self.spec, self._coordinate_sinks)
             self._set_completed()
 
@@ -499,6 +503,9 @@ def push(name, value):
             else:
                 push(name, ds_value)
 
+        for sink in self._scan_result_sinks.values():
+            sink.clear()
+
     def create_applet(self, title: str, group: str = "ndscan"):
         cmd = [
             "${python}", "-m ndscan.applet", "--server=${server}",

ndscan/experiment/result_channels.py

@@ -122,6 +122,9 @@ def get_all(self) -> list[Any]:
         """Read back the previously pushed values from the target dataset (if any)."""
         return [] if (self.last_value is None) else self.get_dataset(self.key)
 
+    def clear(self):
+        self.set_dataset(self.key, [], broadcast=self.broadcast)
+
 
 class ScalarDatasetSink(ResultSink, HasEnvironment):
     """Sink that writes pushed results to a dataset, overwriting its previous value
@@ -143,6 +146,9 @@ def get_last(self) -> Any:
         """Return the last pushed value, or ``None`` if none yet."""
         return self.get_dataset(self.key) if self.has_pushed else None
 
+    def clear(self):
+        pass
+
 
 class ResultChannel:
     """

ndscan/plots/model/subscriber.py

@@ -37,14 +37,25 @@ def d(name):
         if schema_revision is None:
             return
 
-        fqn = d("fragment_fqn")
-        if not self._title_set or self._context.get_title() != fqn:
+        source_id = d("source_id")
+        if self._context.get_source_id() != source_id:
+            # If the source_id changed, clear the applet.
+            self._model = None
+            self._title_set = False
+            self._source_id_set = False
+            self._axes_initialised = False
+            keys = list(values.keys())
+            for key in keys:
+                if "points." in key:
+                    del values[key]
+
+        if not self._title_set:
+            fqn = d("fragment_fqn")
             if fqn:
                 self._context.set_title(fqn)
                 self._title_set = True
 
-        source_id = d("source_id")
-        if not self._source_id_set or self._context.get_source_id() != source_id:
+        if not self._source_id_set:
             if source_id:
                 self._context.set_source_id(source_id)
                 self._source_id_set = True
@@ -194,21 +205,10 @@ def data_changed(self, values: dict[str, Any], mods: Iterable[dict[str,
         for name, source in self._analysis_result_sources.items():
             source.set(values.get(self._prefix + "analysis_result." + name))
 
-        point_data_changed = False
         for name in ([f"axis_{i}" for i in range(len(self.axes))] +
                      ["channel_" + c for c in self._channel_schemata.keys()]):
-            point_values = values.get(self._prefix + "points." + name, [])
-            if not point_data_changed:
-                # Check if points were appended or rewritten.
-                if name in self._point_data:
-                    imax = min(len(point_values), len(self._point_data[name]))
-                    if point_values[:imax] != self._point_data[name][:imax]:
-                        point_data_changed = True
-            self._point_data[name] = point_values
-        if point_data_changed:
-            self.points_rewritten.emit(self._point_data)
-        else:
-            self.points_appended.emit(self._point_data)
+            self._point_data[name] = values.get(self._prefix + "points." + name, [])
+        self.points_appended.emit(self._point_data)
 
     def get_annotations(self) -> list[Annotation]:
         return self._annotations

ndscan/plots/rolling_1d.py

@@ -136,7 +136,7 @@ def _initialise_series(self):
 
         if len(self.panes) > 1:
             self.link_x_axes()
-            add_source_id_label(self.panes[-1].getViewBox(), self.model.context)
+        add_source_id_label(self.panes[-1].getViewBox(), self.model.context)
 
         self.ready.emit()
 

ndscan/plots/xy_1d.py

@@ -171,6 +171,7 @@ def __init__(self, model: ScanModel, get_alternate_plot_names):
         self.model.channel_schemata_changed.connect(self._initialise_series)
         self.model.points_appended.connect(self._update_points)
         self.model.annotations_changed.connect(self._update_annotations)
+        # FIXME: Just re-set values instead of throwing away everything.
         self.model.points_rewritten.connect(self._rewrite)
 
         self.selected_point_model = SelectPointFromScanModel(self.model)

test/test_plots_model_subscriber.py

@@ -13,6 +13,7 @@ def setUp(self):
         self.context = Context()
         self.root = SubscriberRoot("ndscan.", self.context)
         self.datasets = Notifier({
+            "ndscan.source_id": (False, "rid_0", {}),
             "ndscan.axes": (False, "[]", {}),
             "ndscan.channels": (False,
                                 json.dumps({