Treat NaNs as missing values for gaps in ring buffer

Signed-off-by: cwasicki <[email protected]>

Author: cwasicki

RELEASE_NOTES.md

@@ -20,6 +20,7 @@
 
 - A new class `Fuse` has been added to represent fuses. This class has a member variable `max_current` which represents the maximum current that can course through the fuse. If the current flowing through a fuse is greater than this limit, then the fuse will break the circuit.
 
+- NaN values are treated as missing when gaps are determined in the `OrderedRingBuffer`.
 
 ## Bug Fixes
 

src/frequenz/sdk/timeseries/_ringbuffer/buffer.py

@@ -108,6 +108,17 @@ def gaps(self) -> List[Gap]:
         """
         return self._gaps
 
+    def is_missing_value(self, value: QuantityT | None) -> bool:
+        """Check if a value should be considered as missing.
+
+        Args:
+            value: quantity to check.
+
+        Returns:
+            True if the value should be considered as missing.
+        """
+        return (value is None) or value.isnan()
+
     @property
     def maxlen(self) -> int:
         """Get the max length.
@@ -154,10 +165,14 @@ def update(self, sample: Sample[QuantityT]) -> None:
         )
 
         # Update data
-        value: float = np.nan if sample.value is None else sample.value.base_value
+        if self.is_missing_value(sample.value):
+            value = np.nan
+        else:
+            assert sample.value is not None
+            value = sample.value.base_value
         self._buffer[self.datetime_to_index(timestamp)] = value
 
-        self._update_gaps(timestamp, prev_newest, sample.value is None)
+        self._update_gaps(timestamp, prev_newest, self.is_missing_value(sample.value))
 
     @property
     def time_bound_oldest(self) -> datetime:

tests/timeseries/test_ringbuffer.py

@@ -216,7 +216,7 @@ def test_gaps() -> None:
     buffer.update(Sample(dt(3), None))
     assert len(buffer.gaps) == 2
     buffer.update(Sample(dt(3), Quantity(np.nan)))
-    assert len(buffer.gaps) == 1  # should be 2
+    assert len(buffer.gaps) == 2
     buffer.update(Sample(dt(3), Quantity(3)))
     assert len(buffer.gaps) == 1