Change the default alignment to UNIX_EPOCH

This is to be consistent with the resampler.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -52,6 +52,8 @@
 
     Note that the parameter `sampling_period` has been renamed to `input_sampling_period` to better distinguish it from the sampling period parameter in the `resampler_config`.
 
+  * Use the `UNIX_EPOCH` as the default alignment.
+
 * `Resampler`
 
   * The `ResamplerConfig` now takes the resampling period as a `timedelta`. The configuration was renamed from `resampling_period_s` to `resampling_period` accordingly.

src/frequenz/sdk/timeseries/_moving_window.py

@@ -9,7 +9,7 @@
 import logging
 import math
 from collections.abc import Sequence
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta
 from typing import SupportsIndex, overload
 
 import numpy as np
@@ -18,6 +18,7 @@
 
 from .._internal.asyncio import cancel_and_await
 from . import Sample
+from ._base_types import UNIX_EPOCH
 from ._resampling import Resampler, ResamplerConfig
 from ._ringbuffer import OrderedRingBuffer
 
@@ -106,7 +107,7 @@ def __init__(  # pylint: disable=too-many-arguments
         resampled_data_recv: Receiver[Sample],
         input_sampling_period: timedelta,
         resampler_config: ResamplerConfig | None = None,
-        window_alignment: datetime = datetime(1, 1, 1, tzinfo=timezone.utc),
+        window_alignment: datetime = UNIX_EPOCH,
     ) -> None:
         """
         Initialize the MovingWindow.
@@ -122,9 +123,8 @@ def __init__(  # pylint: disable=too-many-arguments
             input_sampling_period: The time interval between consecutive input samples.
             resampler_config: The resampler configuration in case resampling is required.
             window_alignment: A datetime object that defines a point in time to which
-                the window is aligned to modulo window size.
-                (default is 0001-01-01T00:00:00+00:00)
-                For further information, consult the class level documentation.
+                the window is aligned to modulo window size. For further
+                information, consult the class level documentation.
 
         Raises:
             asyncio.CancelledError: when the task gets cancelled.

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

@@ -15,6 +15,7 @@
 import numpy.typing as npt
 
 from .. import Sample
+from .._base_types import UNIX_EPOCH
 
 FloatArray = TypeVar("FloatArray", List[float], npt.NDArray[np.float64])
 
@@ -53,7 +54,7 @@ def __init__(
         self,
         buffer: FloatArray,
         sampling_period: timedelta,
-        time_index_alignment: datetime = datetime(1, 1, 1, tzinfo=timezone.utc),
+        time_index_alignment: datetime = UNIX_EPOCH,
     ) -> None:
         """Initialize the time aware ringbuffer.