Significantly reduce clock_gettime syscalls on platforms with broken …

…vdso (home-assistant#81257)

homeassistant/components/bluetooth/active_update_coordinator.py

@@ -3,13 +3,13 @@
 
 from collections.abc import Callable, Coroutine
 import logging
-import time
 from typing import Any, Generic, TypeVar
 
 from bleak import BleakError
 
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.helpers.debounce import Debouncer
+from homeassistant.util.dt import monotonic_time_coarse
 
 from . import BluetoothChange, BluetoothScanningMode, BluetoothServiceInfoBleak
 from .passive_update_processor import PassiveBluetoothProcessorCoordinator
@@ -94,7 +94,7 @@ def needs_poll(self, service_info: BluetoothServiceInfoBleak) -> bool:
         """Return true if time to try and poll."""
         poll_age: float | None = None
         if self._last_poll:
-            poll_age = time.monotonic() - self._last_poll
+            poll_age = monotonic_time_coarse() - self._last_poll
         return self._needs_poll_method(service_info, poll_age)
 
     async def _async_poll_data(
@@ -124,7 +124,7 @@ async def _async_poll(self) -> None:
                 self.last_poll_successful = False
             return
         finally:
-            self._last_poll = time.monotonic()
+            self._last_poll = monotonic_time_coarse()
 
         if not self.last_poll_successful:
             self.logger.debug("%s: Polling recovered")

homeassistant/components/bluetooth/manager.py

@@ -7,7 +7,6 @@
 from datetime import datetime, timedelta
 import itertools
 import logging
-import time
 from typing import TYPE_CHECKING, Any, Final
 
 from bleak.backends.scanner import AdvertisementDataCallback
@@ -22,6 +21,7 @@
 )
 from homeassistant.helpers import discovery_flow
 from homeassistant.helpers.event import async_track_time_interval
+from homeassistant.util.dt import monotonic_time_coarse
 
 from .advertisement_tracker import AdvertisementTracker
 from .const import (
@@ -69,7 +69,7 @@
     APPLE_DEVICE_ID_START_BYTE,
 }
 
-MONOTONIC_TIME: Final = time.monotonic
+MONOTONIC_TIME: Final = monotonic_time_coarse
 
 _LOGGER = logging.getLogger(__name__)
 

homeassistant/components/bluetooth/scanner.py

@@ -6,7 +6,6 @@
 from datetime import datetime
 import logging
 import platform
-import time
 from typing import Any
 
 import async_timeout
@@ -22,6 +21,7 @@
 from homeassistant.core import CALLBACK_TYPE, HomeAssistant, callback as hass_callback
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers.event import async_track_time_interval
+from homeassistant.util.dt import monotonic_time_coarse
 from homeassistant.util.package import is_docker_env
 
 from .const import (
@@ -35,7 +35,7 @@
 from .util import adapter_human_name, async_reset_adapter
 
 OriginalBleakScanner = bleak.BleakScanner
-MONOTONIC_TIME = time.monotonic
+MONOTONIC_TIME = monotonic_time_coarse
 
 # or_patterns is a workaround for the fact that passive scanning
 # needs at least one matcher to be set. The below matcher

homeassistant/components/bluetooth/util.py

@@ -2,11 +2,11 @@
 from __future__ import annotations
 
 import platform
-import time
 
 from bluetooth_auto_recovery import recover_adapter
 
 from homeassistant.core import callback
+from homeassistant.util.dt import monotonic_time_coarse
 
 from .const import (
     DEFAULT_ADAPTER_BY_PLATFORM,
@@ -29,7 +29,7 @@ async def async_load_history_from_system() -> dict[str, BluetoothServiceInfoBlea
 
     bluez_dbus = BlueZDBusObjects()
     await bluez_dbus.load()
-    now = time.monotonic()
+    now = monotonic_time_coarse()
     return {
         address: BluetoothServiceInfoBleak(
             name=history.advertisement_data.local_name

homeassistant/components/esphome/bluetooth/scanner.py

@@ -19,6 +19,7 @@
 )
 from homeassistant.core import CALLBACK_TYPE, HomeAssistant, callback
 from homeassistant.helpers.event import async_track_time_interval
+from homeassistant.util.dt import monotonic_time_coarse
 
 TWO_CHAR = re.compile("..")
 
@@ -84,7 +85,7 @@ def discovered_devices_and_advertisement_data(
     @callback
     def async_on_advertisement(self, adv: BluetoothLEAdvertisement) -> None:
         """Call the registered callback."""
-        now = time.monotonic()
+        now = monotonic_time_coarse()
         address = ":".join(TWO_CHAR.findall("%012X" % adv.address))  # must be upper
         name = adv.name
         if prev_discovery := self._discovered_device_advertisement_datas.get(address):

homeassistant/util/dt.py

@@ -4,7 +4,9 @@
 import bisect
 from contextlib import suppress
 import datetime as dt
+import platform
 import re
+import time
 from typing import Any
 import zoneinfo
 
@@ -13,6 +15,7 @@
 DATE_STR_FORMAT = "%Y-%m-%d"
 UTC = dt.timezone.utc
 DEFAULT_TIME_ZONE: dt.tzinfo = dt.timezone.utc
+CLOCK_MONOTONIC_COARSE = 6
 
 # EPOCHORDINAL is not exposed as a constant
 # https://github.com/python/cpython/blob/3.10/Lib/zoneinfo/_zoneinfo.py#L12
@@ -461,3 +464,26 @@ def _datetime_ambiguous(dattim: dt.datetime) -> bool:
     assert dattim.tzinfo is not None
     opposite_fold = dattim.replace(fold=not dattim.fold)
     return _datetime_exists(dattim) and dattim.utcoffset() != opposite_fold.utcoffset()
+
+
+def __monotonic_time_coarse() -> float:
+    """Return a monotonic time in seconds.
+
+    This is the coarse version of time_monotonic, which is faster but less accurate.
+
+    Since many arm64 and 32-bit platforms don't support VDSO with time.monotonic
+    because of errata, we can't rely on the kernel to provide a fast
+    monotonic time.
+
+    https://lore.kernel.org/lkml/20170404171826.25030-1-marc.zyngier@arm.com/
+    """
+    return time.clock_gettime(CLOCK_MONOTONIC_COARSE)
+
+
+monotonic_time_coarse = time.monotonic
+with suppress(Exception):
+    if (
+        platform.system() == "Linux"
+        and abs(time.monotonic() - __monotonic_time_coarse()) < 1
+    ):
+        monotonic_time_coarse = __monotonic_time_coarse

tests/util/test_dt.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 from datetime import datetime, timedelta
+import time
 
 import pytest
 
@@ -719,3 +720,8 @@ def test_find_next_time_expression_tenth_second_pattern_does_not_drift_entering_
         assert (next_target - prev_target).total_seconds() == 60
         assert next_target.second == 10
         prev_target = next_target
+
+
+def test_monotonic_time_coarse():
+    """Test monotonic time coarse."""
+    assert abs(time.monotonic() - dt_util.monotonic_time_coarse()) < 1