feat: speed up instances only used to lookup answers

bdraco · bdraco · commit 15daf6b88aaf · 2023-11-11T23:15:13.000-06:00
If there is nothing in the ServiceRegistry we would still
process incoming questions. If we have no answers to give,
we can skip the handling queries completely as it significantly
reduces cpu time.
diff --git a/src/zeroconf/_listener.pxd b/src/zeroconf/_listener.pxd
@@ -3,6 +3,7 @@ import cython
 
 from ._handlers.record_manager cimport RecordManager
 from ._protocol.incoming cimport DNSIncoming
+from ._services.registry cimport ServiceRegistry
 from ._utils.time cimport current_time_millis, millis_to_seconds
 
 
@@ -18,6 +19,7 @@ cdef cython.uint _DUPLICATE_PACKET_SUPPRESSION_INTERVAL
 cdef class AsyncListener:
 
     cdef public object zc
+    cdef ServiceRegistry _registry
     cdef RecordManager _record_manager
     cdef public cython.bytes data
     cdef public cython.float last_time
@@ -34,3 +36,12 @@ cdef class AsyncListener:
     cpdef _process_datagram_at_time(self, bint debug, cython.uint data_len, cython.float now, bytes data, cython.tuple addrs)
 
     cdef _cancel_any_timers_for_addr(self, object addr)
+
+    cpdef handle_query_or_defer(
+        self,
+        DNSIncoming msg,
+        object addr,
+        object port,
+        object transport,
+        tuple v6_flow_scope
+    )
diff --git a/src/zeroconf/_listener.py b/src/zeroconf/_listener.py
@@ -57,6 +57,7 @@ class AsyncListener:
 
     __slots__ = (
         'zc',
+        '_registry',
         '_record_manager',
         'data',
         'last_time',
@@ -69,6 +70,7 @@ class AsyncListener:
 
     def __init__(self, zc: 'Zeroconf') -> None:
         self.zc = zc
+        self._registry = zc.registry
         self._record_manager = zc.record_manager
         self.data: Optional[bytes] = None
         self.last_time: float = 0
@@ -171,17 +173,21 @@ def _process_datagram_at_time(
             self._record_manager.async_updates_from_response(msg)
             return
 
+        if not self._registry.has_entries:
+            # If the registry is empty, we have no answers to give.
+            return
+
         if TYPE_CHECKING:
             assert self.transport is not None
         self.handle_query_or_defer(msg, addr, port, self.transport, v6_flow_scope)
 
     def handle_query_or_defer(
         self,
         msg: DNSIncoming,
-        addr: str,
-        port: int,
+        addr: _str,
+        port: _int,
         transport: _WrappedTransport,
-        v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
+        v6_flow_scope: Union[Tuple[()], Tuple[int, int]],
     ) -> None:
         """Deal with incoming query packets.  Provides a response if
         possible."""
diff --git a/src/zeroconf/_services/registry.pxd b/src/zeroconf/_services/registry.pxd
@@ -9,6 +9,7 @@ cdef class ServiceRegistry:
     cdef cython.dict _services
     cdef public cython.dict types
     cdef public cython.dict servers
+    cdef public bint has_entries
 
     @cython.locals(
         record_list=cython.list,
@@ -17,6 +18,10 @@ cdef class ServiceRegistry:
 
     cdef _add(self, ServiceInfo info)
 
+    @cython.locals(
+        info=ServiceInfo,
+        old_service_info=ServiceInfo
+    )
     cdef _remove(self, cython.list infos)
 
     cpdef ServiceInfo async_get_info_name(self, str name)
diff --git a/src/zeroconf/_services/registry.py b/src/zeroconf/_services/registry.py
@@ -35,7 +35,7 @@ class ServiceRegistry:
     the event loop as it is not thread safe.
     """
 
-    __slots__ = ("_services", "types", "servers")
+    __slots__ = ("_services", "types", "servers", "has_entries")
 
     def __init__(
         self,
@@ -44,6 +44,7 @@ def __init__(
         self._services: Dict[str, ServiceInfo] = {}
         self.types: Dict[str, List] = {}
         self.servers: Dict[str, List] = {}
+        self.has_entries: bool = False
 
     def async_add(self, info: ServiceInfo) -> None:
         """Add a new service to the registry."""
@@ -95,14 +96,17 @@ def _add(self, info: ServiceInfo) -> None:
         self._services[info.key] = info
         self.types.setdefault(info.type.lower(), []).append(info.key)
         self.servers.setdefault(info.server_key, []).append(info.key)
+        self.has_entries = True
 
     def _remove(self, infos: List[ServiceInfo]) -> None:
         """Remove a services under the lock."""
         for info in infos:
-            if info.key not in self._services:
+            old_service_info = self._services.get(info.key)
+            if old_service_info is None:
                 continue
-            old_service_info = self._services[info.key]
             assert old_service_info.server_key is not None
             self.types[old_service_info.type.lower()].remove(info.key)
             self.servers[old_service_info.server_key].remove(info.key)
             del self._services[info.key]
+
+        self.has_entries = bool(self._services)
