backends/bluezdbus/manager: Cancel the discovery on disconnect to avo…

…id a timeout

If a device disconnects while waiting for the services to be
discovered, the manager will wait forever.
This commit fixes that by throwing an exception in case of a disconnect.

CHANGELOG.rst

@@ -13,6 +13,8 @@ and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0
 Fixed
 -----
 * Fixed crash in Android backend introduced in v0.19.0. Fixes #1085.
+* BlueZ: Cancel the device discovery wait task if the device disconnects in
+  between to avoid a timeout
 
 `0.19.0`_ (2022-10-13)
 ======================

bleak/backends/bluezdbus/manager.py

@@ -570,7 +570,7 @@ async def get_services(
                 logger.debug("Using cached services for %s", device_path)
                 return services
 
-        await self._wait_condition(device_path, "ServicesResolved", True)
+        await self._wait_for_service_disovery(device_path)
 
         services = BleakGATTServiceCollection()
 
@@ -648,6 +648,29 @@ def is_connected(self, device_path: str) -> bool:
         except KeyError:
             return False
 
+    async def _wait_for_service_disovery(self, device_path: str) -> None:
+        """Wait for the device services to be discovered.
+
+        If a disconnect happens before the completion a BleakError exception is raised.
+
+        """
+        services_discovered_wait_task = asyncio.create_task(
+            self._wait_condition(device_path, "ServicesResolved", True)
+        )
+        device_disconnected_wait_task = asyncio.create_task(
+            self._wait_condition(device_path, "Connected", False)
+        )
+        done, pending = await asyncio.wait(
+            {services_discovered_wait_task, device_disconnected_wait_task},
+            return_when=asyncio.FIRST_COMPLETED,
+        )
+
+        for p in pending:
+            p.cancel()
+
+        if device_disconnected_wait_task in done:
+            raise BleakError("failed to discover services, device disconnected")
+
     async def _wait_condition(
         self, device_path: str, property_name: str, property_value: Any
     ) -> None: