Init statistics sensor upon HASS start (#18236)

* Update query to include maxAge

Updated the query from recorded to include MaxAge if set; reducing the amount of records retrieved that would otherwise be purged anyway for the sensor.

* Initialization upon HASS start

Register the state listener and read previous information from recorder once HASS is started.

* Updated test_statistics.py for HASS start

Updated test_statistics.py to start HASS and wait it is completed before running test.

* Added newline in docstring

Added newline in docstring.

* Added start of HASS to test_initialize_from_database_with_maxage

Added start of HASS to new test test_initialize_from_database_with_maxage.

* Updates based on review

Following updates based on review:
-) Removed self._hass and passing hass
-) Changed async_add_job to async_create_task
-) For state update, calling async_schedule_update_ha_state

homeassistant/components/sensor/statistics.py

@@ -13,7 +13,8 @@ import voluptuous as vol
 import homeassistant.helpers.config_validation as cv
 from homeassistant.components.sensor import PLATFORM_SCHEMA
 from homeassistant.const import (
-    CONF_NAME, CONF_ENTITY_ID, STATE_UNKNOWN, ATTR_UNIT_OF_MEASUREMENT)
+    CONF_NAME, CONF_ENTITY_ID, EVENT_HOMEASSISTANT_START, STATE_UNKNOWN,
+    ATTR_UNIT_OF_MEASUREMENT)
 from homeassistant.core import callback
 from homeassistant.helpers.entity import Entity
 from homeassistant.helpers.event import async_track_state_change
@@ -66,7 +67,7 @@ async def async_setup_platform(hass, config, async_add_entities,
     max_age = config.get(CONF_MAX_AGE, None)
     precision = config.get(CONF_PRECISION)
 
-    async_add_entities([StatisticsSensor(hass, entity_id, name, sampling_size,
+    async_add_entities([StatisticsSensor(entity_id, name, sampling_size,
                                          max_age, precision)], True)
 
     return True
@@ -75,10 +76,9 @@ async def async_setup_platform(hass, config, async_add_entities,
 class StatisticsSensor(Entity):
     """Representation of a Statistics sensor."""
 
-    def __init__(self, hass, entity_id, name, sampling_size, max_age,
+    def __init__(self, entity_id, name, sampling_size, max_age,
                  precision):
         """Initialize the Statistics sensor."""
-        self._hass = hass
         self._entity_id = entity_id
         self.is_binary = True if self._entity_id.split('.')[0] == \
             'binary_sensor' else False
@@ -99,10 +99,8 @@ class StatisticsSensor(Entity):
         self.min_age = self.max_age = None
         self.change = self.average_change = self.change_rate = None
 
-        if 'recorder' in self._hass.config.components:
-            # only use the database if it's configured
-            hass.async_add_job(self._initialize_from_database)
-
+    async def async_added_to_hass(self):
+        """Register callbacks."""
         @callback
         def async_stats_sensor_state_listener(entity, old_state, new_state):
             """Handle the sensor state changes."""
@@ -111,10 +109,24 @@ class StatisticsSensor(Entity):
 
             self._add_state_to_queue(new_state)
 
-            hass.async_add_job(self.async_update_ha_state, True)
+            self.async_schedule_update_ha_state(True)
 
-        async_track_state_change(
-            hass, entity_id, async_stats_sensor_state_listener)
+        @callback
+        def async_stats_sensor_startup(event):
+            """Add listener and get recorded state."""
+            _LOGGER.debug("Startup for %s", self.entity_id)
+
+            async_track_state_change(
+                self.hass, self._entity_id, async_stats_sensor_state_listener)
+
+            if 'recorder' in self.hass.config.components:
+                # only use the database if it's configured
+                self.hass.async_create_task(
+                    self._async_initialize_from_database()
+                )
+
+        self.hass.bus.async_listen_once(
+            EVENT_HOMEASSISTANT_START, async_stats_sensor_startup)
 
     def _add_state_to_queue(self, new_state):
         try:
@@ -241,7 +253,7 @@ class StatisticsSensor(Entity):
                 self.change = self.average_change = STATE_UNKNOWN
                 self.change_rate = STATE_UNKNOWN
 
-    async def _initialize_from_database(self):
+    async def _async_initialize_from_database(self):
         """Initialize the list of states from the database.
 
         The query will get the list of states in DESCENDING order so that we
@@ -255,7 +267,7 @@ class StatisticsSensor(Entity):
         _LOGGER.debug("%s: initializing values from the database",
                       self.entity_id)
 
-        with session_scope(hass=self._hass) as session:
+        with session_scope(hass=self.hass) as session:
             query = session.query(States)\
                 .filter(States.entity_id == self._entity_id.lower())
 
@@ -275,5 +287,7 @@ class StatisticsSensor(Entity):
         for state in reversed(states):
             self._add_state_to_queue(state)
 
+        self.async_schedule_update_ha_state(True)
+
         _LOGGER.debug("%s: initializing from database completed",
                       self.entity_id)

tests/components/sensor/test_statistics.py

@@ -49,6 +49,9 @@ class TestStatisticsSensor(unittest.TestCase):
             }
         })
 
+        self.hass.start()
+        self.hass.block_till_done()
+
         for value in values:
             self.hass.states.set('binary_sensor.test_monitored', value)
             self.hass.block_till_done()
@@ -67,6 +70,9 @@ class TestStatisticsSensor(unittest.TestCase):
             }
         })
 
+        self.hass.start()
+        self.hass.block_till_done()
+
         for value in self.values:
             self.hass.states.set('sensor.test_monitored', value,
                                  {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS})
@@ -100,6 +106,9 @@ class TestStatisticsSensor(unittest.TestCase):
             }
         })
 
+        self.hass.start()
+        self.hass.block_till_done()
+
         for value in self.values:
             self.hass.states.set('sensor.test_monitored', value,
                                  {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS})
@@ -121,6 +130,9 @@ class TestStatisticsSensor(unittest.TestCase):
             }
         })
 
+        self.hass.start()
+        self.hass.block_till_done()
+
         for value in self.values[-3:]:  # just the last 3 will do
             self.hass.states.set('sensor.test_monitored', value,
                                  {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS})
@@ -162,6 +174,9 @@ class TestStatisticsSensor(unittest.TestCase):
                 }
             })
 
+            self.hass.start()
+            self.hass.block_till_done()
+
             for value in self.values:
                 self.hass.states.set('sensor.test_monitored', value,
                                      {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS})
@@ -194,6 +209,9 @@ class TestStatisticsSensor(unittest.TestCase):
                 }
             })
 
+            self.hass.start()
+            self.hass.block_till_done()
+
             for value in self.values:
                 self.hass.states.set('sensor.test_monitored', value,
                                      {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS})
@@ -231,6 +249,10 @@ class TestStatisticsSensor(unittest.TestCase):
                 'sampling_size': 100,
             }
         })
+
+        self.hass.start()
+        self.hass.block_till_done()
+
         # check if the result is as in test_sensor_source()
         state = self.hass.states.get('sensor.test_mean')
         assert str(self.mean) == state.state
@@ -284,6 +306,9 @@ class TestStatisticsSensor(unittest.TestCase):
                 }
             })
 
+            self.hass.start()
+            self.hass.block_till_done()
+
             # check if the result is as in test_sensor_source()
             state = self.hass.states.get('sensor.test_mean')