bleak: fix leaking of ensure_future()

CHANGELOG.rst

@@ -10,6 +10,12 @@ and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0
 `Unreleased`_
 =============
 
+Fixed
+-----
+* Fixed possible garbage collection of running async callback from ``BleakClient.start_notify()``.
+* Fixed possible garbage collection of running async callback from ``BleakScanner(detection_callback=)``.
+* Fixed possible garbage collection of disconnect monitor in BlueZ backend. Fixed #1258.
+
 `0.20.0`_ (2023-03-17)
 ======================
 

bleak/__init__.py

@@ -22,6 +22,7 @@
  Iterable,
  List,
  Optional,
+ Set,
  Tuple,
  Type,
  Union,
@@ -70,6 +71,10 @@
  _logger.setLevel(logging.DEBUG)
 
 
+# prevent tasks from being garbage collected
+_background_tasks: Set[asyncio.Task] = set()
+
+
 class BleakScanner:
  """
  Interface for Bleak Bluetooth LE Scanners.
@@ -702,7 +707,9 @@ def callback(sender: BleakGATTCharacteristic, data: bytearray):
  if inspect.iscoroutinefunction(callback):
 
  def wrapped_callback(data):
- asyncio.ensure_future(callback(characteristic, data))
+ task = asyncio.create_task(callback(characteristic, data))
+ _background_tasks.add(task)
+ task.add_done_callback(_background_tasks.discard)
 
  else:
  wrapped_callback = functools.partial(callback, characteristic)

bleak/backends/bluezdbus/client.py

@@ -35,6 +35,9 @@
 
 logger = logging.getLogger(__name__)
 
+# prevent tasks from being garbage collected
+_background_tasks: Set[asyncio.Task] = set()
+
 
 class BleakClientBlueZDBus(BaseBleakClient):
  """A native Linux Bleak Client
@@ -243,13 +246,15 @@ def on_value_changed(char_path: str, value: bytes) -> None:
  self._is_connected = True
 
  # Create a task that runs until the device is disconnected.
- asyncio.ensure_future(
+ task = asyncio.create_task(
  self._disconnect_monitor(
  self._bus,
  self._device_path,
  local_disconnect_monitor_event,
  )
  )
+ _background_tasks.add(task)
+ task.add_done_callback(_background_tasks.discard)
 
  #
  # We will try to use the cache if it exists and `dangerous_use_bleak_cache`

bleak/backends/scanner.py

@@ -11,13 +11,17 @@
  List,
  NamedTuple,
  Optional,
+ Set,
  Tuple,
  Type,
 )
 
 from ..exc import BleakError
 from .device import BLEDevice
 
+# prevent tasks from being garbage collected
+_background_tasks: Set[asyncio.Task] = set()
+
 
 class AdvertisementData(NamedTuple):
  """
@@ -165,7 +169,9 @@ def register_detection_callback(
  if inspect.iscoroutinefunction(callback):
 
  def detection_callback(s, d):
- asyncio.ensure_future(callback(s, d))
+ task = asyncio.create_task(callback(s, d))
+ _background_tasks.add(task)
+ task.add_done_callback(_background_tasks.discard)
 
  else:
  detection_callback = callback