feat: reduce overhead to send responses (#1135)

src/zeroconf/_core.py

@@ -28,7 +28,7 @@
 import sys
 import threading
 from types import TracebackType  # noqa # used in type hints
-from typing import Awaitable, Dict, List, Optional, Tuple, Type, Union, cast
+from typing import Any, Awaitable, Dict, List, Optional, Tuple, Type, Union, cast
 
 from ._cache import DNSCache
 from ._dns import DNSQuestion, DNSQuestionType
@@ -105,6 +105,48 @@
 _REGISTER_BROADCASTS = 3
 
 
+class _WrappedTransport:
+    """A wrapper for transports."""
+
+    __slots__ = (
+        'transport',
+        'is_ipv6',
+        'sock',
+        'fileno',
+        'sock_name',
+    )
+
+    def __init__(
+        self,
+        transport: asyncio.DatagramTransport,
+        is_ipv6: bool,
+        sock: socket.socket,
+        fileno: int,
+        sock_name: Any,
+    ) -> None:
+        """Initialize the wrapped transport.
+
+        These attributes are used when sending packets.
+        """
+        self.transport = transport
+        self.is_ipv6 = is_ipv6
+        self.sock = sock
+        self.fileno = fileno
+        self.sock_name = sock_name
+
+
+def _make_wrapped_transport(transport: asyncio.DatagramTransport) -> _WrappedTransport:
+    """Make a wrapped transport."""
+    sock: socket.socket = transport.get_extra_info('socket')
+    return _WrappedTransport(
+        transport=transport,
+        is_ipv6=sock.family == socket.AF_INET6,
+        sock=sock,
+        fileno=sock.fileno(),
+        sock_name=sock.getsockname(),
+    )
+
+
 class AsyncEngine:
     """An engine wraps sockets in the event loop."""
 
@@ -117,8 +159,8 @@ def __init__(
         self.loop: Optional[asyncio.AbstractEventLoop] = None
         self.zc = zeroconf
         self.protocols: List[AsyncListener] = []
-        self.readers: List[asyncio.DatagramTransport] = []
-        self.senders: List[asyncio.DatagramTransport] = []
+        self.readers: List[_WrappedTransport] = []
+        self.senders: List[_WrappedTransport] = []
         self.running_event: Optional[asyncio.Event] = None
         self._listen_socket = listen_socket
         self._respond_sockets = respond_sockets
@@ -158,9 +200,9 @@ async def _async_create_endpoints(self) -> None:
         for s in reader_sockets:
             transport, protocol = await loop.create_datagram_endpoint(lambda: AsyncListener(self.zc), sock=s)
             self.protocols.append(cast(AsyncListener, protocol))
-            self.readers.append(cast(asyncio.DatagramTransport, transport))
+            self.readers.append(_make_wrapped_transport(cast(asyncio.DatagramTransport, transport)))
             if s in sender_sockets:
-                self.senders.append(cast(asyncio.DatagramTransport, transport))
+                self.senders.append(_make_wrapped_transport(cast(asyncio.DatagramTransport, transport)))
 
     def _async_cache_cleanup(self) -> None:
         """Periodic cache cleanup."""
@@ -186,8 +228,8 @@ def _async_shutdown(self) -> None:
         """Shutdown transports and sockets."""
         assert self.running_event is not None
         self.running_event.clear()
-        for transport in itertools.chain(self.senders, self.readers):
-            transport.close()
+        for wrapped_transport in itertools.chain(self.senders, self.readers):
+            wrapped_transport.transport.close()
 
     def close(self) -> None:
         """Close from sync context.
@@ -221,7 +263,7 @@ def __init__(self, zc: 'Zeroconf') -> None:
         self.zc = zc
         self.data: Optional[bytes] = None
         self.last_time: float = 0
-        self.transport: Optional[asyncio.DatagramTransport] = None
+        self.transport: Optional[_WrappedTransport] = None
         self.sock_description: Optional[str] = None
         self._deferred: Dict[str, List[DNSIncoming]] = {}
         self._timers: Dict[str, asyncio.TimerHandle] = {}
@@ -309,7 +351,7 @@ def handle_query_or_defer(
         msg: DNSIncoming,
         addr: str,
         port: int,
-        transport: asyncio.DatagramTransport,
+        transport: _WrappedTransport,
         v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
     ) -> None:
         """Deal with incoming query packets.  Provides a response if
@@ -341,7 +383,7 @@ def _respond_query(
         msg: Optional[DNSIncoming],
         addr: str,
         port: int,
-        transport: asyncio.DatagramTransport,
+        transport: _WrappedTransport,
         v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
     ) -> None:
         """Respond to a query and reassemble any truncated deferred packets."""
@@ -362,27 +404,25 @@ def error_received(self, exc: Exception) -> None:
         self.log_exception_once(exc, msg_str, exc)
 
     def connection_made(self, transport: asyncio.BaseTransport) -> None:
-        self.transport = cast(asyncio.DatagramTransport, transport)
-        sock_name = self.transport.get_extra_info('sockname')
-        sock_fileno = self.transport.get_extra_info('socket').fileno()
-        self.sock_description = f"{sock_fileno} ({sock_name})"
+        wrapped_transport = _make_wrapped_transport(cast(asyncio.DatagramTransport, transport))
+        self.transport = wrapped_transport
+        self.sock_description = f"{wrapped_transport.fileno} ({wrapped_transport.sock_name})"
 
     def connection_lost(self, exc: Optional[Exception]) -> None:
         """Handle connection lost."""
 
 
 def async_send_with_transport(
     log_debug: bool,
-    transport: asyncio.DatagramTransport,
+    transport: _WrappedTransport,
     packet: bytes,
     packet_num: int,
     out: DNSOutgoing,
     addr: Optional[str],
     port: int,
     v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
 ) -> None:
-    s = transport.get_extra_info('socket')
-    ipv6_socket = s.family == socket.AF_INET6
+    ipv6_socket = transport.is_ipv6
     if addr is None:
         real_addr = _MDNS_ADDR6 if ipv6_socket else _MDNS_ADDR
     else:
@@ -394,8 +434,8 @@ def async_send_with_transport(
             'Sending to (%s, %d) via [socket %s (%s)] (%d bytes #%d) %r as %r...',
             real_addr,
             port or _MDNS_PORT,
-            s.fileno(),
-            transport.get_extra_info('sockname'),
+            transport.fileno,
+            transport.sock_name,
             len(packet),
             packet_num + 1,
             out,
@@ -404,9 +444,9 @@ def async_send_with_transport(
     # Get flowinfo and scopeid for the IPV6 socket to create a complete IPv6
     # address tuple: https://docs.python.org/3.6/library/socket.html#socket-families
     if ipv6_socket and not v6_flow_scope:
-        _, _, sock_flowinfo, sock_scopeid = s.getsockname()
+        _, _, sock_flowinfo, sock_scopeid = transport.sock_name
         v6_flow_scope = (sock_flowinfo, sock_scopeid)
-    transport.sendto(packet, (real_addr, port or _MDNS_PORT, *v6_flow_scope))
+    transport.transport.sendto(packet, (real_addr, port or _MDNS_PORT, *v6_flow_scope))
 
 
 class Zeroconf(QuietLogger):
@@ -832,7 +872,7 @@ def handle_assembled_query(
         packets: List[DNSIncoming],
         addr: str,
         port: int,
-        transport: asyncio.DatagramTransport,
+        transport: _WrappedTransport,
         v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
     ) -> None:
         """Respond to a (re)assembled query.
@@ -870,7 +910,7 @@ def send(
         addr: Optional[str] = None,
         port: int = _MDNS_PORT,
         v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
-        transport: Optional[asyncio.DatagramTransport] = None,
+        transport: Optional[_WrappedTransport] = None,
     ) -> None:
         """Sends an outgoing packet threadsafe."""
         assert self.loop is not None
@@ -882,7 +922,7 @@ def async_send(
         addr: Optional[str] = None,
         port: int = _MDNS_PORT,
         v6_flow_scope: Union[Tuple[()], Tuple[int, int]] = (),
-        transport: Optional[asyncio.DatagramTransport] = None,
+        transport: Optional[_WrappedTransport] = None,
     ) -> None:
         """Sends an outgoing packet."""
         if self.done: