feat: reorder incoming data handler to reduce overhead (#1189)

bdraco · web-flow · commit 32756ff113f6 · 2023-06-18T15:29:31.000-05:00
diff --git a/src/zeroconf/_core.py b/src/zeroconf/_core.py
@@ -271,21 +271,9 @@ def datagram_received(
         self, data: bytes, addrs: Union[Tuple[str, int], Tuple[str, int, int, int]]
     ) -> None:
         assert self.transport is not None
-        v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = ()
         data_len = len(data)
         debug = log.isEnabledFor(logging.DEBUG)
 
-        if len(addrs) == 2:
-            # https://github.com/python/mypy/issues/1178
-            addr, port = addrs  # type: ignore
-            scope = None
-        else:
-            # https://github.com/python/mypy/issues/1178
-            addr, port, flow, scope = addrs  # type: ignore
-            if debug:
-                log.debug('IPv6 scope_id %d associated to the receiving interface', scope)
-            v6_flow_scope = (flow, scope)
-
         if data_len > _MAX_MSG_ABSOLUTE:
             # Guard against oversized packets to ensure bad implementations cannot overwhelm
             # the system.
@@ -308,15 +296,26 @@ def datagram_received(
             # Guard against duplicate packets
             if debug:
                 log.debug(
-                    'Ignoring duplicate message with no unicast questions received from %r:%r [socket %s] (%d bytes) as [%r]',
-                    addr,
-                    port,
+                    'Ignoring duplicate message with no unicast questions received from %s [socket %s] (%d bytes) as [%r]',
+                    addrs,
                     self.sock_description,
                     data_len,
                     data,
                 )
             return
 
+        v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = ()
+        if len(addrs) == 2:
+            # https://github.com/python/mypy/issues/1178
+            addr, port = addrs  # type: ignore
+            scope = None
+        else:
+            # https://github.com/python/mypy/issues/1178
+            addr, port, flow, scope = addrs  # type: ignore
+            if debug:
+                log.debug('IPv6 scope_id %d associated to the receiving interface', scope)
+            v6_flow_scope = (flow, scope)
+
         msg = DNSIncoming(data, (addr, port), scope, now)
         self.data = data
         self.last_time = now
