Fix unavailable property for wemo switch (#13106)

* Fix unavailable property for wemo switch

* Have subscriptions respect the lock

* Move subscription callback to added to hass section

homeassistant/components/switch/wemo.py

@@ -4,16 +4,19 @@ Support for WeMo switches.
 For more details about this component, please refer to the documentation at
 https://home-assistant.io/components/switch.wemo/
 """
+import asyncio
 import logging
 from datetime import datetime, timedelta
 
+import async_timeout
+
 from homeassistant.components.switch import SwitchDevice
 from homeassistant.util import convert
 from homeassistant.const import (
     STATE_OFF, STATE_ON, STATE_STANDBY, STATE_UNKNOWN)
-from homeassistant.loader import get_component
 
 DEPENDENCIES = ['wemo']
+SCAN_INTERVAL = timedelta(seconds=10)
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -54,29 +57,35 @@ class WemoSwitch(SwitchDevice):
         self.maker_params = None
         self.coffeemaker_mode = None
         self._state = None
+        self._available = True
+        self._update_lock = None
         # look up model name once as it incurs network traffic
         self._model_name = self.wemo.model_name
 
-        wemo = get_component('wemo')
-        wemo.SUBSCRIPTION_REGISTRY.register(self.wemo)
-        wemo.SUBSCRIPTION_REGISTRY.on(self.wemo, None, self._update_callback)
-
-    def _update_callback(self, _device, _type, _params):
+    def _subscription_callback(self, _device, _type, _params):
         """Update the state by the Wemo device."""
-        _LOGGER.info("Subscription update for  %s", _device)
+        _LOGGER.info("Subscription update for %s", self.name)
         updated = self.wemo.subscription_update(_type, _params)
-        self._update(force_update=(not updated))
+        self.hass.add_job(
+            self._async_locked_subscription_callback(not updated))
 
-        if not hasattr(self, 'hass'):
+    async def _async_locked_subscription_callback(self, force_update):
+        """Helper to handle an update from a subscription."""
+        # If an update is in progress, we don't do anything
+        if self._update_lock.locked():
             return
-        self.schedule_update_ha_state()
+
+        await self._async_locked_update(force_update)
+        self.async_schedule_update_ha_state()
 
     @property
     def should_poll(self):
-        """No polling needed with subscriptions."""
-        if self._model_name == 'Insight':
-            return True
-        return False
+        """Device should poll.
+
+        Subscriptions push the state, however it won't detect if a device
+        is no longer available. Use polling to detect if a device is available.
+        """
+        return True
 
     @property
     def unique_id(self):
@@ -172,13 +181,7 @@ class WemoSwitch(SwitchDevice):
     @property
     def available(self):
         """Return true if switch is available."""
-        if self._model_name == 'Insight' and self.insight_params is None:
-            return False
-        if self._model_name == 'Maker' and self.maker_params is None:
-            return False
-        if self._model_name == 'CoffeeMaker' and self.coffeemaker_mode is None:
-            return False
-        return True
+        return self._available
 
     @property
     def icon(self):
@@ -189,21 +192,46 @@ class WemoSwitch(SwitchDevice):
 
     def turn_on(self, **kwargs):
         """Turn the switch on."""
-        self._state = WEMO_ON
         self.wemo.on()
-        self.schedule_update_ha_state()
 
     def turn_off(self, **kwargs):
         """Turn the switch off."""
-        self._state = WEMO_OFF
         self.wemo.off()
-        self.schedule_update_ha_state()
 
-    def update(self):
-        """Update WeMo state."""
-        self._update(force_update=True)
+    async def async_added_to_hass(self):
+        """Wemo switch added to HASS."""
+        # Define inside async context so we know our event loop
+        self._update_lock = asyncio.Lock()
 
-    def _update(self, force_update=True):
+        registry = self.hass.components.wemo.SUBSCRIPTION_REGISTRY
+        await self.hass.async_add_job(registry.register, self.wemo)
+        registry.on(self.wemo, None, self._subscription_callback)
+
+    async def async_update(self):
+        """Update WeMo state.
+
+        Wemo has an aggressive retry logic that sometimes can take over a
+        minute to return. If we don't get a state after 5 seconds, assume the
+        Wemo switch is unreachable. If update goes through, it will be made
+        available again.
+        """
+        # If an update is in progress, we don't do anything
+        if self._update_lock.locked():
+            return
+
+        try:
+            with async_timeout.timeout(5):
+                await asyncio.shield(self._async_locked_update(True))
+        except asyncio.TimeoutError:
+            _LOGGER.warning('Lost connection to %s', self.name)
+            self._available = False
+
+    async def _async_locked_update(self, force_update):
+        """Try updating within an async lock."""
+        async with self._update_lock:
+            await self.hass.async_add_job(self._update, force_update)
+
+    def _update(self, force_update):
         """Update the device state."""
         try:
             self._state = self.wemo.get_state(force_update)
@@ -215,6 +243,11 @@ class WemoSwitch(SwitchDevice):
                 self.maker_params = self.wemo.maker_params
             elif self._model_name == 'CoffeeMaker':
                 self.coffeemaker_mode = self.wemo.mode
+
+            if not self._available:
+                _LOGGER.info('Reconnected to %s', self.name)
+                self._available = True
         except AttributeError as err:
             _LOGGER.warning("Could not update status for %s (%s)",
                             self.name, err)
+            self._available = False