Log when no relevant samples are found for resampling

These additional logs will help in understanding
why certain microgrid components, such as meters,
fail to provide relevant samples for resampling.

Signed-off-by: Daniel Zullo <daniel.zullo@frequenz.com>

benchmarks/timeseries/resampling.py

@@ -46,7 +46,7 @@ def _do_work() -> None:
             for _n_sample in range(samples):
                 now = now + timedelta(seconds=1 / samples)
                 helper.add_sample(Sample(now, Quantity(0.0)))
-            helper.resample(now)
+            helper.resample(now, helper._name)  # pylint: disable=protected-access
 
     print(timeit(_do_work, number=5))
 

src/frequenz/sdk/timeseries/_resampling.py

@@ -702,11 +702,13 @@ def _update_buffer_len(self) -> bool:
 
         return True
 
-    def resample(self, timestamp: datetime) -> Sample[Quantity]:
+    def resample(self, timestamp: datetime, component_name: str) -> Sample[Quantity]:
         """Generate a new sample based on all the current *relevant* samples.
 
         Args:
             timestamp: The timestamp to be used to calculate the new sample.
+            component_name: The name of the component that is being resampled
+                (for debugging purposes).
 
         Returns:
             A new sample generated by calling the resampling function with all
@@ -745,6 +747,11 @@ def resample(self, timestamp: datetime) -> Sample[Quantity]:
         # So if we need more performance beyond this point, we probably need to
         # resort to some C (or similar) implementation.
         relevant_samples = list(itertools.islice(self._buffer, min_index, max_index))
+        if not relevant_samples:
+            _logger.warning(
+                "No relevant samples found for component: %s",
+                component_name,
+            )
         value = (
             conf.resampling_function(relevant_samples, conf, props)
             if relevant_samples
@@ -826,4 +833,5 @@ async def resample(self, timestamp: datetime) -> None:
                 raise recv_exception
             raise SourceStoppedError(self._source)
 
-        await self._sink(self._helper.resample(timestamp))
+        # pylint: disable=protected-access
+        await self._sink(self._helper.resample(timestamp, self._helper._name))

tests/timeseries/test_resampling.py

@@ -160,7 +160,9 @@ async def test_helper_buffer_too_big(
         helper.add_sample(sample)
         await _advance_time(fake_time, 1)
 
-    _ = helper.resample(datetime.now(timezone.utc))
+    _ = helper.resample(
+        datetime.now(timezone.utc), helper._name  # pylint: disable=protected-access
+    )
     # Ignore errors produced by wrongly finalized gRPC server in unrelated tests
     assert (
         "frequenz.sdk.timeseries._resampling",