fixup! Add DataSourcingActor

Call `_update_streams` only if a request is received for a metric
that's not being handled already.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/sdk/actor/data_sourcing/microgrid_api_source.py

@@ -351,7 +351,14 @@ async def add_metric(self, request: ComponentMetricRequest) -> None:
 
         self._req_streaming_metrics.setdefault(comp_id, {}).setdefault(
             request.metric_id, []
-        ).append(request)
+        )
+
+        for existing_request in self._req_streaming_metrics[comp_id][request.metric_id]:
+            if existing_request.get_channel_name() == request.get_channel_name():
+                # the requested metric is already being handled, so nothing to do.
+                return
+
+        self._req_streaming_metrics[comp_id][request.metric_id].append(request)
 
         await self._update_streams(
             comp_id,