Have template platforms never leave the event loop

homeassistant/components/binary_sensor/template.py

@@ -4,6 +4,7 @@ Support for exposing a templated binary sensor.
 For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/binary_sensor.template/
 """
+import asyncio
 import logging
 
 import voluptuous as vol
@@ -81,9 +82,10 @@ class BinarySensorTemplate(BinarySensorDevice):
 
         self.update()
 
+        @asyncio.coroutine
         def template_bsensor_state_listener(entity, old_state, new_state):
             """Called when the target device changes state."""
-            self.update_ha_state(True)
+            yield from self.async_update_ha_state(True)
 
         track_state_change(hass, entity_ids, template_bsensor_state_listener)
 
@@ -107,10 +109,11 @@ class BinarySensorTemplate(BinarySensorDevice):
         """No polling needed."""
         return False
 
-    def update(self):
+    @asyncio.coroutine
+    def async_update(self):
         """Get the latest data and update the state."""
         try:
-            self._state = self._template.render().lower() == 'true'
+            self._state = self._template.async_render().lower() == 'true'
         except TemplateError as ex:
             if ex.args and ex.args[0].startswith(
                     "UndefinedError: 'None' has no attribute"):

homeassistant/components/sensor/template.py

@@ -4,6 +4,7 @@ Allows the creation of a sensor that breaks out state_attributes.
 For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/sensor.template/
 """
+import asyncio
 import logging
 
 import voluptuous as vol
@@ -78,9 +79,10 @@ class SensorTemplate(Entity):
 
         self.update()
 
+        @asyncio.coroutine
         def template_sensor_state_listener(entity, old_state, new_state):
             """Called when the target device changes state."""
-            self.update_ha_state(True)
+            yield from self.async_update_ha_state(True)
 
         track_state_change(hass, entity_ids, template_sensor_state_listener)
 
@@ -104,10 +106,11 @@ class SensorTemplate(Entity):
         """No polling needed."""
         return False
 
-    def update(self):
+    @asyncio.coroutine
+    def async_update(self):
         """Get the latest data and update the states."""
         try:
-            self._state = self._template.render()
+            self._state = self._template.async_render()
         except TemplateError as ex:
             if ex.args and ex.args[0].startswith(
                     "UndefinedError: 'None' has no attribute"):

homeassistant/components/switch/template.py

@@ -4,6 +4,7 @@ Support for switches which integrates with other components.
 For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/switch.template/
 """
+import asyncio
 import logging
 
 import voluptuous as vol
@@ -87,9 +88,10 @@ class SwitchTemplate(SwitchDevice):
 
         self.update()
 
+        @asyncio.coroutine
         def template_switch_state_listener(entity, old_state, new_state):
             """Called when the target device changes state."""
-            self.update_ha_state(True)
+            yield from self.async_update_ha_state(True)
 
         track_state_change(hass, entity_ids, template_switch_state_listener)
 
@@ -121,10 +123,11 @@ class SwitchTemplate(SwitchDevice):
         """Fire the off action."""
         self._off_script.run()
 
-    def update(self):
+    @asyncio.coroutine
+    def async_update(self):
         """Update the state from the template."""
         try:
-            state = self._template.render().lower()
+            state = self._template.async_render().lower()
 
             if state in _VALID_STATES:
                 self._state = state in ('true', STATE_ON)

homeassistant/helpers/entity.py

@@ -49,6 +49,11 @@ class Entity(object):
     # SAFE TO OVERWRITE
     # The properties and methods here are safe to overwrite when inheriting
     # this class. These may be used to customize the behavior of the entity.
+    entity_id = None  # type: str
+
+    # Owning hass instance. Will be set by EntityComponent
+    hass = None  # type: Optional[HomeAssistant]
+
     @property
     def should_poll(self) -> bool:
         """Return True if entity has to be polled for state.
@@ -128,18 +133,22 @@ class Entity(object):
         return False
 
     def update(self):
-        """Retrieve latest state."""
+        """Retrieve latest state.
-        pass
 
-    entity_id = None  # type: str
+        When not implemented, will forward call to async version if available.
+        """
+        async_update = getattr(self, 'async_update', None)
+
+        if async_update is None:
+            return
+
+        run_coroutine_threadsafe(async_update(), self.hass.loop).result()
 
     # DO NOT OVERWRITE
     # These properties and methods are either managed by Home Assistant or they
     # are used to perform a very specific function. Overwriting these may
     # produce undesirable effects in the entity's operation.
 
-    hass = None  # type: Optional[HomeAssistant]
-
     def update_ha_state(self, force_refresh=False):
         """Update Home Assistant with current state of entity.
 
@@ -172,7 +181,7 @@ class Entity(object):
         if force_refresh:
             if hasattr(self, 'async_update'):
                 # pylint: disable=no-member
-                self.async_update()
+                yield from self.async_update()
             else:
                 # PS: Run this in our own thread pool once we have
                 #     future support?

tests/components/binary_sensor/test_template.py

@@ -119,7 +119,7 @@ class TestBinarySensorTemplate(unittest.TestCase):
         vs.update_ha_state()
         self.hass.block_till_done()
 
-        with mock.patch.object(vs, 'update') as mock_update:
+        with mock.patch.object(vs, 'async_update') as mock_update:
             self.hass.bus.fire(EVENT_STATE_CHANGED)
             self.hass.block_till_done()
             assert mock_update.call_count == 1

tests/helpers/test_entity.py

@@ -53,7 +53,12 @@ def test_async_update_support(event_loop):
     assert len(sync_update) == 1
     assert len(async_update) == 0
 
-    ent.async_update = lambda: async_update.append(1)
+    @asyncio.coroutine
+    def async_update_func():
+        """Async update."""
+        async_update.append(1)
+
+    ent.async_update = async_update_func
 
     event_loop.run_until_complete(test())
 
@@ -95,3 +100,19 @@ class TestHelpersEntity(object):
         assert entity.generate_entity_id(
             fmt, 'overwrite hidden true',
             hass=self.hass) == 'test.overwrite_hidden_true_2'
+
+    def test_update_calls_async_update_if_available(self):
+        """Test async update getting called."""
+        async_update = []
+
+        class AsyncEntity(entity.Entity):
+            hass = self.hass
+            entity_id = 'sensor.test'
+
+            @asyncio.coroutine
+            def async_update(self):
+                async_update.append([1])
+
+        ent = AsyncEntity()
+        ent.update()
+        assert len(async_update) == 1