Prevent legacy device tracker from creating hundreds of executor jobs (#90690)

* Prevent legacy device tracker from creating hundreds of executor jobs

The legacy device tracker would create an executor job for
each set of extra state attributes and device name lookup.

For routers this meant hundreds of jobs

* Prevent legacy device tracker from creating hundreds of executor jobs

The legacy device tracker would create an executor job for
each set of extra state attributes and device name lookup.

For routers this meant hundreds of jobs

* tweak

* simplify

homeassistant/components/device_tracker/legacy.py

@@ -356,6 +356,27 @@ async def async_create_platform_type(
     return DeviceTrackerPlatform(p_type, platform, p_config)
 
 
+def _load_device_names_and_attributes(
+    scanner: DeviceScanner,
+    device_name_uses_executor: bool,
+    extra_attributes_uses_executor: bool,
+    seen: set[str],
+    found_devices: list[str],
+) -> tuple[dict[str, str | None], dict[str, dict[str, Any]]]:
+    """Load device names and attributes in a single executor job."""
+    host_name_by_mac: dict[str, str | None] = {}
+    extra_attributes_by_mac: dict[str, dict[str, Any]] = {}
+    for mac in found_devices:
+        if device_name_uses_executor and mac not in seen:
+            host_name_by_mac[mac] = scanner.get_device_name(mac)
+        if extra_attributes_uses_executor:
+            try:
+                extra_attributes_by_mac[mac] = scanner.get_extra_attributes(mac)
+            except NotImplementedError:
+                extra_attributes_by_mac[mac] = {}
+    return host_name_by_mac, extra_attributes_by_mac
+
+
 @callback
 def async_setup_scanner_platform(
     hass: HomeAssistant,
@@ -373,7 +394,7 @@ def async_setup_scanner_platform(
     scanner.hass = hass
 
     # Initial scan of each mac we also tell about host name for config
-    seen: Any = set()
+    seen: set[str] = set()
 
     async def async_device_tracker_scan(now: datetime | None) -> None:
         """Handle interval matches."""
@@ -391,15 +412,42 @@ def async_setup_scanner_platform(
         async with update_lock:
             found_devices = await scanner.async_scan_devices()
 
+        device_name_uses_executor = (
+            scanner.async_get_device_name.__func__  # type: ignore[attr-defined]
+            is DeviceScanner.async_get_device_name
+        )
+        extra_attributes_uses_executor = (
+            scanner.async_get_extra_attributes.__func__  # type: ignore[attr-defined]
+            is DeviceScanner.async_get_extra_attributes
+        )
+        host_name_by_mac: dict[str, str | None] = {}
+        extra_attributes_by_mac: dict[str, dict[str, Any]] = {}
+        if device_name_uses_executor or extra_attributes_uses_executor:
+            (
+                host_name_by_mac,
+                extra_attributes_by_mac,
+            ) = await hass.async_add_executor_job(
+                _load_device_names_and_attributes,
+                scanner,
+                device_name_uses_executor,
+                extra_attributes_uses_executor,
+                seen,
+                found_devices,
+            )
+
         for mac in found_devices:
             if mac in seen:
                 host_name = None
             else:
-                host_name = await scanner.async_get_device_name(mac)
+                host_name = host_name_by_mac.get(
+                    mac, await scanner.async_get_device_name(mac)
+                )
                 seen.add(mac)
 
             try:
-                extra_attributes = await scanner.async_get_extra_attributes(mac)
+                extra_attributes = extra_attributes_by_mac.get(
+                    mac, await scanner.async_get_extra_attributes(mac)
+                )
             except NotImplementedError:
                 extra_attributes = {}