Make the resampler use timedelta for periods (#334)

As a step towards [using proper units], now the resampler uses
`timedelta` for specifying periods. It also includes a couple of cleanup
commits.

- Move private method to the end of the class
- Remove unused timer
- Make the resampling period a `timedelta`
- Make source properties' sampling period a `timedelta`

[using proper units]:
#6

Author: llucax

RELEASE_NOTES.md

@@ -18,6 +18,8 @@
   Notice that the parameter `sampling_period` has been renamed to `input_sampling_period`
   to better distinguish it from the sampling period parameter in the resampler.
 * The serialization feature for the ringbuffer was made more flexible. The `dump` and `load` methods can now work directly with a ringbuffer instance.
+* The `ResamplerConfig` now takes the resampling period as a `timedelta`. The configuration was renamed from `resampling_period_s` to `resampling_period` accordingly.
+* The `SourceProperties` of the resampler now uses a `timedelta` for the input sampling period. The attribute was renamed from `sampling_period_s` to `sampling_period` accordingly.
 
 ## New Features
 

benchmarks/power_distribution/power_distributor.py

@@ -8,6 +8,7 @@
 import random
 import timeit
 from dataclasses import dataclass
+from datetime import timedelta
 from typing import Any, Coroutine, Dict, List, Set  # pylint: disable=unused-import
 
 from frequenz.channels import Bidirectional, Broadcast
@@ -154,7 +155,9 @@ async def run() -> None:
     """Create microgrid api and run tests."""
     # pylint: disable=protected-access
 
-    await microgrid.initialize(HOST, PORT, ResamplerConfig(resampling_period_s=1.0))
+    await microgrid.initialize(
+        HOST, PORT, ResamplerConfig(resampling_period=timedelta(seconds=1.0))
+    )
 
     all_batteries: Set[Component] = connection_manager.get().component_graph.components(
         component_category={ComponentCategory.BATTERY}

benchmarks/timeseries/resampling.py

@@ -29,7 +29,7 @@ def _benchmark_resampling_helper(resamples: int, samples: int) -> None:
     helper = _ResamplingHelper(
         "benchmark",
         ResamplerConfig(
-            resampling_period_s=1.0,
+            resampling_period=timedelta(seconds=1.0),
             max_data_age_in_periods=3.0,
             resampling_function=nop,
             initial_buffer_len=samples * 3,

examples/battery_pool.py

@@ -7,6 +7,7 @@
 
 import asyncio
 import logging
+from datetime import timedelta
 from typing import Any, Dict
 
 from frequenz.channels import Receiver
@@ -25,7 +26,9 @@ async def main() -> None:
         level=logging.DEBUG, format="%(asctime)s %(name)s %(levelname)s:%(message)s"
     )
     await microgrid.initialize(
-        host=HOST, port=PORT, resampler_config=ResamplerConfig(resampling_period_s=1.0)
+        host=HOST,
+        port=PORT,
+        resampler_config=ResamplerConfig(resampling_period=timedelta(seconds=1.0)),
     )
 
     battery_pool = microgrid.battery_pool()

examples/battery_status.py

@@ -9,6 +9,7 @@
 
 import asyncio
 import logging
+from datetime import timedelta
 
 from frequenz.channels import Broadcast
 
@@ -31,7 +32,9 @@ async def main() -> None:
     logging.basicConfig(
         level=logging.DEBUG, format="%(asctime)s %(name)s %(levelname)s:%(message)s"
     )
-    await microgrid.initialize(HOST, PORT, ResamplerConfig(resampling_period_s=1.0))
+    await microgrid.initialize(
+        HOST, PORT, ResamplerConfig(resampling_period=timedelta(seconds=1.0))
+    )
     batteries = {
         bat.component_id
         for bat in connection_manager.get().component_graph.components(

examples/power_distribution.py

@@ -12,7 +12,7 @@
 
 import asyncio
 import logging
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 from queue import Queue
 from typing import List, Optional, Set
 
@@ -159,7 +159,9 @@ async def run() -> None:
     logging.basicConfig(
         level=logging.DEBUG, format="%(asctime)s %(name)s %(levelname)s:%(message)s"
     )
-    await microgrid.initialize(HOST, PORT, ResamplerConfig(resampling_period_s=1.0))
+    await microgrid.initialize(
+        HOST, PORT, ResamplerConfig(resampling_period=timedelta(seconds=1.0))
+    )
 
     channel_registry = ChannelRegistry(name="Microgrid Channel Registry")
 
@@ -180,7 +182,7 @@ async def run() -> None:
         channel_registry=channel_registry,
         data_sourcing_request_sender=data_source_request_channel.new_sender(),
         resampling_request_receiver=resampling_actor_request_channel.new_receiver(),
-        config=ResamplerConfig(resampling_period_s=1.0),
+        config=ResamplerConfig(resampling_period=timedelta(seconds=1.0)),
     )
 
     logical_meter = LogicalMeter(

examples/resampling.py

@@ -4,7 +4,7 @@
 """Frequenz Python SDK resampling example."""
 
 import asyncio
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 
 from frequenz.channels import Broadcast
 from frequenz.channels.util import Merge
@@ -43,7 +43,9 @@ async def _print_sample(sample: Sample) -> None:
 
 async def run() -> None:  # pylint: disable=too-many-locals
     """Run main functions that initializes and creates everything."""
-    await microgrid.initialize(HOST, PORT, ResamplerConfig(resampling_period_s=0.2))
+    await microgrid.initialize(
+        HOST, PORT, ResamplerConfig(resampling_period=timedelta(seconds=0.2))
+    )
 
     channel_registry = ChannelRegistry(name="data-registry")
 
@@ -66,7 +68,7 @@ async def run() -> None:  # pylint: disable=too-many-locals
         channel_registry=channel_registry,
         data_sourcing_request_sender=data_source_request_sender,
         resampling_request_receiver=resampling_request_receiver,
-        config=ResamplerConfig(resampling_period_s=1),
+        config=ResamplerConfig(resampling_period=timedelta(seconds=1)),
     )
 
     components = await connection_manager.get().api_client.components()
@@ -105,7 +107,9 @@ async def run() -> None:  # pylint: disable=too-many-locals
     # Create a channel to calculate an average for all the data
     average_chan = Broadcast[Sample]("average")
 
-    second_stage_resampler = Resampler(ResamplerConfig(resampling_period_s=3.0))
+    second_stage_resampler = Resampler(
+        ResamplerConfig(resampling_period=timedelta(seconds=3.0))
+    )
     second_stage_resampler.add_timeseries(
         "avg", average_chan.new_receiver(), _print_sample
     )

src/frequenz/sdk/microgrid/_data_pipeline.py

@@ -13,7 +13,6 @@
 import typing
 from collections import abc
 from dataclasses import dataclass
-from datetime import timedelta
 
 from frequenz.channels import Bidirectional, Broadcast, Sender
 
@@ -175,9 +174,7 @@ def battery_pool(
                 batteries_status_receiver=self._battery_status_channel.new_receiver(
                     maxsize=1
                 ),
-                min_update_interval=timedelta(
-                    seconds=self._resampler_config.resampling_period_s
-                ),
+                min_update_interval=self._resampler_config.resampling_period,
                 batteries_id=battery_ids,
             )
 

src/frequenz/sdk/timeseries/_moving_window.py

@@ -142,13 +142,12 @@ def __init__(  # pylint: disable=too-many-arguments
         self._resampler_task: asyncio.Task[None] | None = None
 
         if resampler_config:
-            resampling_period = timedelta(seconds=resampler_config.resampling_period_s)
             assert (
-                resampling_period <= size
+                resampler_config.resampling_period <= size
             ), "The resampling period should be equal to or lower than the window size."
 
             self._resampler = Resampler(resampler_config)
-            sampling = resampling_period
+            sampling = resampler_config.resampling_period
 
         # Sampling period might not fit perfectly into the window size.
         num_samples = math.ceil(size.total_seconds() / sampling.total_seconds())