Use plain floats in the resampler buffer

When resampling we know we are working always with the same units, so
using a `Quantity` doesn't add any advantages to plain `float`s.
Instead, it makes the resampler slower, as it needs to do an extra
lookup each time a buffer value is needed and potentially avoids the
need to create `Quantity`s from the inputs.

The performance can be improved by about 25% (for resamples=1000
samples=1000, before 3.7s, now 2.8s) according to the resampling
benchmark.

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

Author: llucax

RELEASE_NOTES.md

@@ -7,6 +7,7 @@
 ## Upgrading
 
 * The microgrid client dependency has been updated to version 0.9.0
+* The resampling function now takes plain `float`s as values instead of `Quantity` objects.
 
 ## New Features
 

benchmarks/timeseries/resampling.py

@@ -7,15 +7,13 @@
 from datetime import datetime, timedelta, timezone
 from timeit import timeit
 
-from frequenz.quantities import Quantity
-
 from frequenz.sdk.timeseries import ResamplerConfig
 from frequenz.sdk.timeseries._resampling._base_types import SourceProperties
 from frequenz.sdk.timeseries._resampling._resampler import _ResamplingHelper
 
 
 def nop(  # pylint: disable=unused-argument
-    samples: Sequence[tuple[datetime, Quantity]],
+    samples: Sequence[tuple[datetime, float]],
     resampler_config: ResamplerConfig,
     source_properties: SourceProperties,
 ) -> float:
@@ -43,7 +41,7 @@ def _do_work() -> None:
         for _n_resample in range(resamples):
             for _n_sample in range(samples):
                 now = now + timedelta(seconds=1 / samples)
-                helper.add_sample((now, Quantity(0.0)))
+                helper.add_sample((now, 0.0))
             helper.resample(now)
 
     print(timeit(_do_work, number=5))

src/frequenz/sdk/timeseries/_resampling/_config.py

@@ -11,9 +11,7 @@
 from datetime import datetime, timedelta
 from typing import Protocol
 
-from frequenz.quantities import Quantity
-
-from .._base_types import UNIX_EPOCH, QuantityT
+from .._base_types import UNIX_EPOCH
 from ._base_types import SourceProperties
 
 _logger = logging.getLogger(__name__)
@@ -60,7 +58,7 @@ class ResamplingFunction(Protocol):
 
     def __call__(
         self,
-        input_samples: Sequence[tuple[datetime, Quantity]],
+        input_samples: Sequence[tuple[datetime, float]],
         resampler_config: ResamplerConfig,
         source_properties: SourceProperties,
         /,
@@ -82,7 +80,7 @@ def __call__(
 
 
 def average(
-    samples: Sequence[tuple[datetime, QuantityT]],
+    samples: Sequence[tuple[datetime, float]],
     resampler_config: ResamplerConfig,  # pylint: disable=unused-argument
     source_properties: SourceProperties,  # pylint: disable=unused-argument
 ) -> float:
@@ -98,7 +96,7 @@ def average(
         The average of all `samples` values.
     """
     assert len(samples) > 0, "Average cannot be given an empty list of samples"
-    values = list(sample[1].base_value for sample in samples)
+    values = list(sample[1] for sample in samples)
     return sum(values) / len(values)
 
 

src/frequenz/sdk/timeseries/_resampling/_resampler.py

@@ -258,7 +258,7 @@ def __init__(self, name: str, config: ResamplerConfig) -> None:
         """
         self._name = name
         self._config = config
-        self._buffer: deque[tuple[datetime, Quantity]] = deque(
+        self._buffer: deque[tuple[datetime, float]] = deque(
             maxlen=config.initial_buffer_len
         )
         self._source_properties: SourceProperties = SourceProperties()
@@ -272,7 +272,7 @@ def source_properties(self) -> SourceProperties:
         """
         return self._source_properties
 
-    def add_sample(self, sample: tuple[datetime, Quantity]) -> None:
+    def add_sample(self, sample: tuple[datetime, float]) -> None:
         """Add a new sample to the internal buffer.
 
         Args:
@@ -511,7 +511,7 @@ async def _receive_samples(self) -> None:
         """
         async for sample in self._source:
             if sample.value is not None and not sample.value.isnan():
-                self._helper.add_sample((sample.timestamp, sample.value))
+                self._helper.add_sample((sample.timestamp, sample.value.base_value))
 
     # We need the noqa because pydoclint can't figure out that `recv_exception` is an
     # `Exception` instance.

tests/timeseries/test_resampling.py

@@ -7,7 +7,6 @@
 import asyncio
 import logging
 from collections.abc import AsyncIterator
-from dataclasses import astuple
 from datetime import datetime, timedelta, timezone
 from unittest.mock import AsyncMock, MagicMock
 
@@ -55,6 +54,12 @@ async def source_chan() -> AsyncIterator[Broadcast[Sample[Quantity]]]:
     await chan.close()
 
 
+def as_float_tuple(sample: Sample[Quantity]) -> tuple[datetime, float]:
+    """Convert a sample to a tuple of datetime and float value."""
+    assert sample.value is not None, "Sample value should not be None"
+    return (sample.timestamp, sample.value.base_value)
+
+
 async def _advance_time(fake_time: time_machine.Coordinates, seconds: float) -> None:
     """Advance the time by the given number of seconds.
 
@@ -160,7 +165,7 @@ async def test_helper_buffer_too_big(
     helper = _ResamplingHelper("test", config)
 
     for i in range(DEFAULT_BUFFER_LEN_MAX + 1):
-        sample = (datetime.now(timezone.utc), Quantity(i))
+        sample = (datetime.now(timezone.utc), i)
         helper.add_sample(sample)
         await _advance_time(fake_time, 1)
 
@@ -315,7 +320,7 @@ async def test_resampling_window_size_is_constant(
         )
     )
     resampling_fun_mock.assert_called_once_with(
-        a_sequence(astuple(sample1s)), config, source_props
+        a_sequence(as_float_tuple(sample1s)), config, source_props
     )
     sink_mock.reset_mock()
     resampling_fun_mock.reset_mock()
@@ -343,9 +348,9 @@ async def test_resampling_window_size_is_constant(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -415,8 +420,8 @@ async def test_timer_errors_are_logged(  # pylint: disable=too-many-statements
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample0s),
-            astuple(sample1s),
+            as_float_tuple(sample0s),
+            as_float_tuple(sample1s),
         ),
         config,
         source_props,
@@ -454,10 +459,10 @@ async def test_timer_errors_are_logged(  # pylint: disable=too-many-statements
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample1s),
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample1s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -493,11 +498,11 @@ async def test_timer_errors_are_logged(  # pylint: disable=too-many-statements
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample3s),
-            astuple(sample4s),
-            astuple(sample4_5s),
-            astuple(sample5s),
-            astuple(sample6s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
+            as_float_tuple(sample4_5s),
+            as_float_tuple(sample5s),
+            as_float_tuple(sample6s),
         ),
         config,
         source_props,
@@ -570,8 +575,8 @@ async def test_future_samples_not_included(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample0s),
-            astuple(sample1s),
+            as_float_tuple(sample0s),
+            as_float_tuple(sample1s),
         ),
         config,
         source_props,  # sample2_1s is not here
@@ -600,9 +605,9 @@ async def test_future_samples_not_included(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample1s),
-            astuple(sample2_1s),
-            astuple(sample3s),
+            as_float_tuple(sample1s),
+            as_float_tuple(sample2_1s),
+            as_float_tuple(sample3s),
         ),
         config,
         source_props,  # sample4_1s is not here
@@ -662,7 +667,7 @@ async def test_resampling_with_one_window(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample1s),
+            as_float_tuple(sample1s),
         ),
         config,
         source_props,
@@ -693,9 +698,9 @@ async def test_resampling_with_one_window(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -786,8 +791,8 @@ async def test_resampling_with_one_and_a_half_windows(  # pylint: disable=too-ma
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample0s),
-            astuple(sample1s),
+            as_float_tuple(sample0s),
+            as_float_tuple(sample1s),
         ),
         config,
         source_props,
@@ -819,9 +824,9 @@ async def test_resampling_with_one_and_a_half_windows(  # pylint: disable=too-ma
     # It should include samples in the interval (1, 4] seconds
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -851,9 +856,9 @@ async def test_resampling_with_one_and_a_half_windows(  # pylint: disable=too-ma
     # It should include samples in the interval (3, 6] seconds
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample4s),
-            astuple(sample5s),
-            astuple(sample6s),
+            as_float_tuple(sample4s),
+            as_float_tuple(sample5s),
+            as_float_tuple(sample6s),
         ),
         config,
         source_props,
@@ -885,7 +890,7 @@ async def test_resampling_with_one_and_a_half_windows(  # pylint: disable=too-ma
     )
     # It should include samples in the interval (5, 8] seconds
     resampling_fun_mock.assert_called_once_with(
-        a_sequence(astuple(sample6s)),
+        a_sequence(as_float_tuple(sample6s)),
         config,
         source_props,
     )
@@ -965,8 +970,8 @@ async def test_resampling_with_two_windows(  # pylint: disable=too-many-statemen
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample0s),
-            astuple(sample1s),
+            as_float_tuple(sample0s),
+            as_float_tuple(sample1s),
         ),
         config,
         source_props,
@@ -998,10 +1003,10 @@ async def test_resampling_with_two_windows(  # pylint: disable=too-many-statemen
     # It should include samples in the interval (0, 4] seconds
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample1s),
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample1s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -1031,11 +1036,11 @@ async def test_resampling_with_two_windows(  # pylint: disable=too-many-statemen
     # It should include samples in the interval (2, 6] seconds
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
-            astuple(sample5s),
-            astuple(sample6s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
+            as_float_tuple(sample5s),
+            as_float_tuple(sample6s),
         ),
         config,
         source_props,
@@ -1061,8 +1066,8 @@ async def test_resampling_with_two_windows(  # pylint: disable=too-many-statemen
     # It should include samples in the interval (4, 8] seconds
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample5s),
-            astuple(sample6s),
+            as_float_tuple(sample5s),
+            as_float_tuple(sample6s),
         ),
         config,
         source_props,
@@ -1130,7 +1135,7 @@ async def test_receiving_stopped_resampling_error(
         )
     )
     resampling_fun_mock.assert_called_once_with(
-        a_sequence(astuple(sample0s)), config, source_props
+        a_sequence(as_float_tuple(sample0s)), config, source_props
     )
     sink_mock.reset_mock()
     resampling_fun_mock.reset_mock()
@@ -1266,11 +1271,11 @@ async def test_timer_is_aligned(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample1s),
-            astuple(sample1_5s),
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample1s),
+            as_float_tuple(sample1_5s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,
@@ -1337,7 +1342,7 @@ async def test_resampling_all_zeros(
         )
     )
     resampling_fun_mock.assert_called_once_with(
-        a_sequence(astuple(sample1s)), config, source_props
+        a_sequence(as_float_tuple(sample1s)), config, source_props
     )
     assert source_props == SourceProperties(
         sampling_start=timestamp, received_samples=2, sampling_period=None
@@ -1365,9 +1370,9 @@ async def test_resampling_all_zeros(
     )
     resampling_fun_mock.assert_called_once_with(
         a_sequence(
-            astuple(sample2_5s),
-            astuple(sample3s),
-            astuple(sample4s),
+            as_float_tuple(sample2_5s),
+            as_float_tuple(sample3s),
+            as_float_tuple(sample4s),
         ),
         config,
         source_props,