fix(coordinator): rely on our own _SCHEDULE_MAX_DELAY insted of priva…

…te DataUpdateCoordinator property

custom_components/omie/coordinator.py

@@ -22,6 +22,9 @@
 _HOURS = list(range(25))
 """Max number of hours in a day (on the day that DST ends)."""
 
+_SCHEDULE_MAX_DELAY = timedelta(seconds=3)
+"""The maximum delay after the scheduled time that we will fetch from OMIE to avoid thundering herd."""
+
 # language=Markdown
 #
 # OMIE market sessions and the values that they influence. Time shown below is publication time in the CET timezone plus 10 minutes.
@@ -63,7 +66,9 @@ def __init__(self,
                          update_method=market_updater(async_get_clientsession(hass), market_date))
         self._market_date = market_date
         self._none_before = list(map(int, none_before.split(":"))) if none_before is not None else [0, 0]
-        self._second = random.randint(0, 3)
+        delay_μs = random.randint(0, _SCHEDULE_MAX_DELAY.seconds * 10 ** 6)
+        self._schedule_second = delay_μs // 10 ** 6
+        self._schedule_microsecond = delay_μs % 10 ** 6
 
     async def _async_update_data(self) -> OMIEModel | None:
         if self._wait_for_none_before():
@@ -93,8 +98,9 @@ def _schedule_refresh(self) -> None:
 
         cet_hour, cet_minute = self._none_before
         now_cet = utcnow().astimezone(CET)
-        none_before = now_cet.replace(hour=cet_hour, minute=cet_minute, second=self._second, microsecond=int(self._microsecond * 10 ** 6))
-        next_hour = now_cet.replace(minute=0, second=self._second, microsecond=int(self._microsecond * 10 ** 6)) + timedelta(hours=1)
+        none_before = now_cet.replace(hour=cet_hour, minute=cet_minute, second=self._schedule_second,
+                                      microsecond=self._schedule_microsecond)
+        next_hour = now_cet.replace(minute=0, second=self._schedule_second, microsecond=self._schedule_microsecond) + timedelta(hours=1)
 
         # next hour or the none_before time, whichever is soonest
         next_refresh = (none_before if cet_hour == now_cet.hour and none_before > now_cet else next_hour).astimezone()
@@ -111,8 +117,8 @@ def _wait_for_none_before(self) -> bool:
         none_before = cet_now.replace(
             hour=cet_hour,
             minute=cet_minute,
-            second=self._second,
-            microsecond=int(self._microsecond * 10 ** 6))
+            second=self._schedule_second,
+            microsecond=self._schedule_microsecond)
 
         return cet_now < none_before and none_before.date() == cet_now.date()