Pre-filter zeroconf service browser updates (#35518)

Each ServerBrowser currently runs in its own thread which
processes every A or AAAA record update per instance.

As the list of zeroconf names we watch for grows, each additional
ServiceBrowser would process all the A and AAAA updates on the network.

To avoid overwhemling the system we pre-filter here and only process
DNSPointers for the configured record name (type)

homeassistant/components/zeroconf/__init__.py

@@ -5,6 +5,8 @@ import socket
 
 import voluptuous as vol
 from zeroconf import (
+    DNSPointer,
+    DNSRecord,
     InterfaceChoice,
     NonUniqueNameException,
     ServiceBrowser,
@@ -75,6 +77,27 @@ def _get_instance(hass, default_interface=False):
     return zeroconf
 
 
+class HaServiceBrowser(ServiceBrowser):
+    """ServiceBrowser that only consumes DNSPointer records."""
+
+    def update_record(self, zc: "Zeroconf", now: float, record: DNSRecord) -> None:
+        """Pre-Filter update_record to DNSPointers for the configured type."""
+
+        #
+        # Each ServerBrowser currently runs in its own thread which
+        # processes every A or AAAA record update per instance.
+        #
+        # As the list of zeroconf names we watch for grows, each additional
+        # ServiceBrowser would process all the A and AAAA updates on the network.
+        #
+        # To avoid overwhemling the system we pre-filter here and only process
+        # DNSPointers for the configured record name (type)
+        #
+        if record.name != self.type or not isinstance(record, DNSPointer):
+            return
+        super().update_record(zc, now, record)
+
+
 class HaZeroconf(Zeroconf):
     """Zeroconf that cannot be closed."""
 
@@ -166,10 +189,10 @@ def setup(hass, config):
             )
 
     for service in ZEROCONF:
-        ServiceBrowser(zeroconf, service, handlers=[service_update])
+        HaServiceBrowser(zeroconf, service, handlers=[service_update])
 
     if HOMEKIT_TYPE not in ZEROCONF:
-        ServiceBrowser(zeroconf, HOMEKIT_TYPE, handlers=[service_update])
+        HaServiceBrowser(zeroconf, HOMEKIT_TYPE, handlers=[service_update])
 
     return True
 

tests/components/zeroconf/test_init.py

@@ -68,7 +68,7 @@ async def test_setup(hass, mock_zeroconf):
     with patch.object(
         hass.config_entries.flow, "async_init"
     ) as mock_config_flow, patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ) as mock_service_browser:
         mock_zeroconf.get_service_info.side_effect = get_service_info_mock
         assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
@@ -87,7 +87,7 @@ async def test_setup(hass, mock_zeroconf):
 async def test_setup_with_default_interface(hass, mock_zeroconf):
     """Test default interface config."""
     with patch.object(hass.config_entries.flow, "async_init"), patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ):
         mock_zeroconf.get_service_info.side_effect = get_service_info_mock
         assert await async_setup_component(
@@ -100,7 +100,7 @@ async def test_setup_with_default_interface(hass, mock_zeroconf):
 async def test_setup_without_default_interface(hass, mock_zeroconf):
     """Test without default interface config."""
     with patch.object(hass.config_entries.flow, "async_init"), patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ):
         mock_zeroconf.get_service_info.side_effect = get_service_info_mock
         assert await async_setup_component(
@@ -117,7 +117,7 @@ async def test_homekit_match_partial_space(hass, mock_zeroconf):
     ), patch.object(
         hass.config_entries.flow, "async_init"
     ) as mock_config_flow, patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ) as mock_service_browser:
         mock_zeroconf.get_service_info.side_effect = get_homekit_info_mock("LIFX bulb")
         assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
@@ -134,7 +134,7 @@ async def test_homekit_match_partial_dash(hass, mock_zeroconf):
     ), patch.object(
         hass.config_entries.flow, "async_init"
     ) as mock_config_flow, patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ) as mock_service_browser:
         mock_zeroconf.get_service_info.side_effect = get_homekit_info_mock(
             "Rachio-fa46ba"
@@ -153,7 +153,7 @@ async def test_homekit_match_full(hass, mock_zeroconf):
     ), patch.object(
         hass.config_entries.flow, "async_init"
     ) as mock_config_flow, patch.object(
-        zeroconf, "ServiceBrowser", side_effect=service_update_mock
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
     ) as mock_service_browser:
         mock_zeroconf.get_service_info.side_effect = get_homekit_info_mock("BSB002")
         assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})