Use loop.time in DataUpdateCoordinator

homeassistant/components/tomorrowio/__init__.py

@@ -221,7 +221,10 @@ async def async_setup_entry(self, entry: ConfigEntry) -> None:
             await self.async_refresh()
 
         self.update_interval = async_set_update_interval(self.hass, self._api)
-        self._schedule_refresh()
+        self._next_refresh = None
+        self._async_unsub_refresh()
+        if self._listeners:
+            self._schedule_refresh()
 
     async def async_unload_entry(self, entry: ConfigEntry) -> bool | None:
         """Unload a config entry from coordinator.

homeassistant/helpers/event.py

@@ -1434,6 +1434,37 @@ def unsub_point_in_time_listener() -> None:
 track_point_in_utc_time = threaded_listener_factory(async_track_point_in_utc_time)
 
 
+@callback
+@bind_hass
+def async_call_at(
+    hass: HomeAssistant,
+    action: HassJob[[datetime], Coroutine[Any, Any, None] | None]
+    | Callable[[datetime], Coroutine[Any, Any, None] | None],
+    loop_time: float,
+) -> CALLBACK_TYPE:
+    """Add a listener that is called at <loop_time>."""
+
+    @callback
+    def run_action(job: HassJob[[datetime], Coroutine[Any, Any, None] | None]) -> None:
+        """Call the action."""
+        hass.async_run_hass_job(job, time_tracker_utcnow())
+
+    job = (
+        action
+        if isinstance(action, HassJob)
+        else HassJob(action, f"call_at {loop_time}")
+    )
+    cancel_callback = hass.loop.call_at(loop_time, run_action, job)
+
+    @callback
+    def unsub_call_later_listener() -> None:
+        """Cancel the call_later."""
+        assert cancel_callback is not None
+        cancel_callback.cancel()
+
+    return unsub_call_later_listener
+
+
 @callback
 @bind_hass
 def async_call_later(

homeassistant/helpers/update_coordinator.py

@@ -81,6 +81,7 @@ def __init__(
         self._shutdown_requested = False
         self.config_entry = config_entries.current_entry.get()
         self.always_update = always_update
+        self._next_refresh: float | None = None
 
         # It's None before the first successful update.
         # Components should call async_config_entry_first_refresh
@@ -89,10 +90,11 @@ def __init__(
         # when it was already checked during setup.
         self.data: _DataT = None  # type: ignore[assignment]
 
-        # Pick a random microsecond to stagger the refreshes
+        # Pick a random microsecond in range 0.05..0.50 to stagger the refreshes
         # and avoid a thundering herd.
-        self._microsecond = randint(
-            event.RANDOM_MICROSECOND_MIN, event.RANDOM_MICROSECOND_MAX
+        self._microsecond = (
+            randint(event.RANDOM_MICROSECOND_MIN, event.RANDOM_MICROSECOND_MAX)
+            / 10**6
         )
 
         self._listeners: dict[CALLBACK_TYPE, tuple[CALLBACK_TYPE, object | None]] = {}
@@ -182,6 +184,7 @@ def _unschedule_refresh(self) -> None:
         """Unschedule any pending refresh since there is no longer any listeners."""
         self._async_unsub_refresh()
         self._debounced_refresh.async_cancel()
+        self._next_refresh = None
 
     def async_contexts(self) -> Generator[Any, None, None]:
         """Return all registered contexts."""
@@ -214,20 +217,16 @@ def _schedule_refresh(self) -> None:
         # than the debouncer cooldown, this would cause the debounce to never be called
         self._async_unsub_refresh()
 
-        # We _floor_ utcnow to create a schedule on a rounded second,
-        # minimizing the time between the point and the real activation.
-        # That way we obtain a constant update frequency,
-        # as long as the update process takes less than 500ms
-        #
-        # We do not align everything to happen at microsecond 0
-        # since it increases the risk of a thundering herd
-        # when multiple coordinators are scheduled to update at the same time.
-        #
-        # https://github.com/home-assistant/core/issues/82231
-        self._unsub_refresh = event.async_track_point_in_utc_time(
+        # We use event.async_call_at because DataUpdateCoordinator does
+        # not need an exact update interval.
+        now = self.hass.loop.time()
+        if self._next_refresh is None or self._next_refresh <= now:
+            self._next_refresh = int(now) + self._microsecond
+        self._next_refresh += self.update_interval.total_seconds()
+        self._unsub_refresh = event.async_call_at(
             self.hass,
             self._job,
-            utcnow().replace(microsecond=self._microsecond) + self.update_interval,
+            self._next_refresh,
         )
 
     async def _handle_refresh_interval(self, _now: datetime) -> None:
@@ -266,6 +265,7 @@ async def async_config_entry_first_refresh(self) -> None:
 
     async def async_refresh(self) -> None:
         """Refresh data and log errors."""
+        self._next_refresh = None
         await self._async_refresh(log_failures=True)
 
     async def _async_refresh(  # noqa: C901
@@ -405,6 +405,7 @@ def async_set_updated_data(self, data: _DataT) -> None:
         """Manually update data, notify listeners and reset refresh interval."""
         self._async_unsub_refresh()
         self._debounced_refresh.async_cancel()
+        self._next_refresh = None
 
         self.data = data
         self.last_update_success = True

tests/common.py

@@ -412,12 +412,9 @@ def async_fire_time_changed(
     else:
         utc_datetime = dt_util.as_utc(datetime_)
 
-    if utc_datetime.microsecond < event.RANDOM_MICROSECOND_MAX:
-        # Allow up to 500000 microseconds to be added to the time
-        # to handle update_coordinator's and
-        # async_track_time_interval's
-        # staggering to avoid thundering herd.
-        utc_datetime = utc_datetime.replace(microsecond=event.RANDOM_MICROSECOND_MAX)
+    # Increase the mocked time by 0.5 s to account for up to 0.5 s delay
+    # added to events scheduled by update_coordinator and async_track_time_interval
+    utc_datetime += timedelta(microseconds=event.RANDOM_MICROSECOND_MAX)
 
     _async_fire_time_changed(hass, utc_datetime, fire_all)
 

tests/helpers/test_event.py

@@ -4174,27 +4174,27 @@ async def test_periodic_task_entering_dst_2(
     )
 
     freezer.move_to(f"{today} 01:59:59.999999+01:00")
-    async_fire_time_changed(hass)
+    async_fire_time_changed_exact(hass)
     await hass.async_block_till_done()
     assert len(specific_runs) == 0
 
     freezer.move_to(f"{today} 03:00:00.999999+02:00")
-    async_fire_time_changed(hass)
+    async_fire_time_changed_exact(hass)
     await hass.async_block_till_done()
     assert len(specific_runs) == 1
 
     freezer.move_to(f"{today} 03:00:01.999999+02:00")
-    async_fire_time_changed(hass)
+    async_fire_time_changed_exact(hass)
     await hass.async_block_till_done()
     assert len(specific_runs) == 2
 
     freezer.move_to(f"{tomorrow} 01:59:59.999999+02:00")
-    async_fire_time_changed(hass)
+    async_fire_time_changed_exact(hass)
     await hass.async_block_till_done()
     assert len(specific_runs) == 3
 
     freezer.move_to(f"{tomorrow} 02:00:00.999999+02:00")
-    async_fire_time_changed(hass)
+    async_fire_time_changed_exact(hass)
     await hass.async_block_till_done()
     assert len(specific_runs) == 4
 

tests/helpers/test_update_coordinator.py

@@ -6,6 +6,7 @@
 import urllib.error
 
 import aiohttp
+from freezegun.api import FrozenDateTimeFactory
 import pytest
 import requests
 
@@ -329,11 +330,14 @@ async def test_refresh_no_update_method(
 
 
 async def test_update_interval(
-    hass: HomeAssistant, crd: update_coordinator.DataUpdateCoordinator[int]
+    hass: HomeAssistant,
+    freezer: FrozenDateTimeFactory,
+    crd: update_coordinator.DataUpdateCoordinator[int],
 ) -> None:
     """Test update interval works."""
     # Test we don't update without subscriber
-    async_fire_time_changed(hass, utcnow() + crd.update_interval)
+    freezer.tick(crd.update_interval)
+    async_fire_time_changed(hass)
     await hass.async_block_till_done()
     assert crd.data is None
 
@@ -342,18 +346,21 @@ async def test_update_interval(
     unsub = crd.async_add_listener(update_callback)
 
     # Test twice we update with subscriber
-    async_fire_time_changed(hass, utcnow() + crd.update_interval)
+    freezer.tick(crd.update_interval)
+    async_fire_time_changed(hass)
     await hass.async_block_till_done()
     assert crd.data == 1
 
-    async_fire_time_changed(hass, utcnow() + crd.update_interval)
+    freezer.tick(crd.update_interval)
+    async_fire_time_changed(hass)
     await hass.async_block_till_done()
     assert crd.data == 2
 
     # Test removing listener
     unsub()
 
-    async_fire_time_changed(hass, utcnow() + crd.update_interval)
+    freezer.tick(crd.update_interval)
+    async_fire_time_changed(hass)
     await hass.async_block_till_done()
 
     # Test we stop updating after we lose last subscriber