Use -sys.maxsize - 1 as default priority for BatteryPool

When no priorities are specified, we should use the lowest possible
priority.  Zero was supposed to be this lowest possible value, until
it was mentioned that negative priorities should be possible as well.

This commit also updates the BatteryPool's `charge` and `discharge` to
use the pool's priority rather than the minimum.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/sdk/microgrid/_data_pipeline.py

@@ -11,6 +11,7 @@
 from __future__ import annotations
 
 import logging
+import sys
 import typing
 from collections import abc
 from dataclasses import dataclass
@@ -186,7 +187,7 @@ def battery_pool(
         self,
         battery_ids: abc.Set[int] | None = None,
         source_id: str | None = None,
-        priority: int = 0,
+        priority: int = -sys.maxsize - 1,
     ) -> BatteryPoolWrapper:
         """Return the corresponding BatteryPool instance for the given ids.
 
@@ -424,7 +425,7 @@ def ev_charger_pool(ev_charger_ids: set[int] | None = None) -> EVChargerPool:
 def battery_pool(
     battery_ids: abc.Set[int] | None = None,
     source_id: str | None = None,
-    priority: int = 0,
+    priority: int = -sys.maxsize - 1,
 ) -> BatteryPoolWrapper:
     """Return the corresponding BatteryPool instance for the given ids.
 

src/frequenz/sdk/timeseries/battery_pool/_battery_pool_wrapper.py

@@ -139,7 +139,7 @@ async def charge(
                 preferred_power=power,
                 bounds=timeseries.Bounds(None, None),
                 battery_ids=self._battery_pool._batteries,
-                priority=0,
+                priority=self._priority,
                 request_timeout=request_timeout,
                 include_broken_batteries=include_broken_batteries,
             )
@@ -182,7 +182,7 @@ async def discharge(
                 preferred_power=power,
                 bounds=timeseries.Bounds(None, None),
                 battery_ids=self._battery_pool._batteries,
-                priority=0,
+                priority=self._priority,
                 request_timeout=request_timeout,
                 include_broken_batteries=include_broken_batteries,
             )