huawei_lte: Fetch only required data (#17618)

When debug logging is enabled, still fetch everything in order to
provide indication of available/supported data to users, as instructed
in docs.

homeassistant/components/device_tracker/huawei_lte.py

@@ -23,10 +23,13 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_URL): cv.url,
 })
 
+HOSTS_PATH = "wlan_host_list.Hosts"
+
 
 def get_scanner(hass, config):
     """Get a Huawei LTE router scanner."""
     data = hass.data[DATA_KEY].get_data(config)
+    data.subscribe(HOSTS_PATH)
     return HuaweiLteScanner(data)
 
 
@@ -43,7 +46,7 @@ class HuaweiLteScanner(DeviceScanner):
         self.data.update()
         self._hosts = {
             x["MacAddress"]: x
-            for x in self.data["wlan_host_list.Hosts.Host"]
+            for x in self.data[HOSTS_PATH + ".Host"]
             if x.get("MacAddress")
         }
         return list(self._hosts)

homeassistant/components/huawei_lte.py

@@ -50,6 +50,14 @@ class RouterData:
     traffic_statistics = attr.ib(init=False, factory=dict)
     wlan_host_list = attr.ib(init=False, factory=dict)
 
+    _subscriptions = attr.ib(init=False, factory=set)
+
+    def __attrs_post_init__(self) -> None:
+        """Fetch device information once, for serial number in @unique_ids."""
+        self.subscribe("device_information")
+        self._update()
+        self.unsubscribe("device_information")
+
     def __getitem__(self, path: str):
         """
         Get value corresponding to a dotted path.
@@ -65,17 +73,34 @@ class RouterData:
             raise KeyError from err
         return reduce(operator.getitem, rest, data)
 
+    def subscribe(self, path: str) -> None:
+        """Subscribe to given router data entries."""
+        self._subscriptions.add(path.split(".")[0])
+
+    def unsubscribe(self, path: str) -> None:
+        """Unsubscribe from given router data entries."""
+        self._subscriptions.discard(path.split(".")[0])
+
     @Throttle(MIN_TIME_BETWEEN_UPDATES)
     def update(self) -> None:
         """Call API to update data."""
-        self.device_information = self.client.device.information()
-        _LOGGER.debug("device_information=%s", self.device_information)
-        self.device_signal = self.client.device.signal()
-        _LOGGER.debug("device_signal=%s", self.device_signal)
-        self.traffic_statistics = self.client.monitoring.traffic_statistics()
-        _LOGGER.debug("traffic_statistics=%s", self.traffic_statistics)
-        self.wlan_host_list = self.client.wlan.host_list()
-        _LOGGER.debug("wlan_host_list=%s", self.wlan_host_list)
+        self._update()
+
+    def _update(self) -> None:
+        debugging = _LOGGER.isEnabledFor(logging.DEBUG)
+        if debugging or "device_information" in self._subscriptions:
+            self.device_information = self.client.device.information()
+            _LOGGER.debug("device_information=%s", self.device_information)
+        if debugging or "device_signal" in self._subscriptions:
+            self.device_signal = self.client.device.signal()
+            _LOGGER.debug("device_signal=%s", self.device_signal)
+        if debugging or "traffic_statistics" in self._subscriptions:
+            self.traffic_statistics = \
+                self.client.monitoring.traffic_statistics()
+            _LOGGER.debug("traffic_statistics=%s", self.traffic_statistics)
+        if debugging or "wlan_host_list" in self._subscriptions:
+            self.wlan_host_list = self.client.wlan.host_list()
+            _LOGGER.debug("wlan_host_list=%s", self.wlan_host_list)
 
 
 @attr.s
@@ -120,7 +145,6 @@ def _setup_lte(hass, lte_config) -> None:
     client = Client(connection)
 
     data = RouterData(client)
-    data.update()
     hass.data[DATA_KEY].data[url] = data
 
     def cleanup(event):

homeassistant/components/sensor/huawei_lte.py

@@ -117,6 +117,7 @@ def setup_platform(
     data = hass.data[DATA_KEY].get_data(config)
     sensors = []
     for path in config.get(CONF_MONITORED_CONDITIONS):
+        data.subscribe(path)
         sensors.append(HuaweiLteSensor(
             data, path, SENSOR_META.get(path, {})))
     add_entities(sensors, True)