perf: precompute address hash instead of per-instance lru_cache (#1774)

bluetoothbot · bdraco · web-flow · commit 868f28f82eb7 · 2026-06-21T18:00:25.000-05:00
Co-authored-by: J. Nick Koston &lt;nick@koston.org&gt;
diff --git a/src/zeroconf/_utils/ipaddress.py b/src/zeroconf/_utils/ipaddress.py
@@ -22,7 +22,7 @@
 
 from __future__ import annotations
 
-from functools import cache, lru_cache
+from functools import lru_cache
 from ipaddress import AddressValueError, IPv4Address, IPv6Address, NetmaskValueError
 from typing import Any
 
@@ -34,7 +34,7 @@
 
 
 class ZeroconfIPv4Address(IPv4Address):
-    __slots__ = ("__hash__", "_is_link_local", "_is_loopback", "_is_unspecified", "_str", "zc_integer")
+    __slots__ = ("_hash", "_is_link_local", "_is_loopback", "_is_unspecified", "_str", "zc_integer")
 
     def __init__(self, *args: Any, **kwargs: Any) -> None:
         """Initialize a new IPv4 address."""
@@ -43,13 +43,17 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         self._is_link_local = super().is_link_local
         self._is_unspecified = super().is_unspecified
         self._is_loopback = super().is_loopback
-        self.__hash__ = cache(lambda: IPv4Address.__hash__(self))  # type: ignore[method-assign]
+        self._hash = IPv4Address.__hash__(self)
         self.zc_integer = int(self)
 
     def __str__(self) -> str:
         """Return the string representation of the IPv4 address."""
         return self._str
 
+    def __hash__(self) -> int:
+        """Return the precomputed hash of the IPv4 address."""
+        return self._hash
+
     @property
     def is_link_local(self) -> bool:
         """Return True if this is a link-local address."""
@@ -67,7 +71,7 @@ def is_loopback(self) -> bool:
 
 
 class ZeroconfIPv6Address(IPv6Address):
-    __slots__ = ("__hash__", "_is_link_local", "_is_loopback", "_is_unspecified", "_str", "zc_integer")
+    __slots__ = ("_hash", "_is_link_local", "_is_loopback", "_is_unspecified", "_str", "zc_integer")
 
     def __init__(self, *args: Any, **kwargs: Any) -> None:
         """Initialize a new IPv6 address."""
@@ -76,13 +80,17 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         self._is_link_local = super().is_link_local
         self._is_unspecified = super().is_unspecified
         self._is_loopback = super().is_loopback
-        self.__hash__ = cache(lambda: IPv6Address.__hash__(self))  # type: ignore[method-assign]
+        self._hash = IPv6Address.__hash__(self)
         self.zc_integer = int(self)
 
     def __str__(self) -> str:
         """Return the string representation of the IPv6 address."""
         return self._str
 
+    def __hash__(self) -> int:
+        """Return the precomputed hash of the IPv6 address."""
+        return self._hash
+
     @property
     def is_link_local(self) -> bool:
         """Return True if this is a link-local address."""
diff --git a/tests/utils/test_ipaddress.py b/tests/utils/test_ipaddress.py
@@ -48,6 +48,20 @@ def test_cached_ip_addresses_wrapper():
     assert ipv6.is_unspecified is True
 
 
+def test_address_hash_matches_stdlib_and_dedups():
+    """Cached address objects hash like their stdlib equals and dedup in sets."""
+    v4 = ipaddress.cached_ip_addresses("192.168.1.1")
+    assert v4 is not None
+    assert hash(v4) == hash(ipaddress.IPv4Address("192.168.1.1"))
+    assert hash(v4) == hash(v4)
+    assert len({v4, ipaddress.ZeroconfIPv4Address("192.168.1.1")}) == 1
+
+    v6 = ipaddress.cached_ip_addresses("fe80::1")
+    assert v6 is not None
+    assert hash(v6) == hash(ipaddress.IPv6Address("fe80::1"))
+    assert len({v6, ipaddress.ZeroconfIPv6Address("fe80::1")}) == 1
+
+
 def test_get_ip_address_object_from_record():
     """Test the get_ip_address_object_from_record."""
     # not link local
