asyncio: Skip getaddrinfo if host is already resolved.
getaddrinfo takes an exclusive lock on some platforms, causing clients to queue
up waiting for the lock if many names are being resolved concurrently. Users
may want to handle name resolution in their own code, for the sake of caching,
using an alternate resolver, or to measure DNS duration separately from
connection duration. Skip getaddrinfo if the "host" passed into
create_connection is already resolved.
See https://github.com/python/asyncio/pull/302 for details.
Patch by A. Jesse Jiryu Davis.
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index c5ffad4..4505732 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -16,8 +16,10 @@
import collections
import concurrent.futures
+import functools
import heapq
import inspect
+import ipaddress
import itertools
import logging
import os
@@ -70,49 +72,83 @@
return repr(fd)
+# Linux's sock.type is a bitmask that can include extra info about socket.
+_SOCKET_TYPE_MASK = 0
+if hasattr(socket, 'SOCK_NONBLOCK'):
+ _SOCKET_TYPE_MASK |= socket.SOCK_NONBLOCK
+if hasattr(socket, 'SOCK_CLOEXEC'):
+ _SOCKET_TYPE_MASK |= socket.SOCK_CLOEXEC
+
+
+@functools.lru_cache(maxsize=1024)
+def _ipaddr_info(host, port, family, type, proto):
+ # Try to skip getaddrinfo if "host" is already an IP. Since getaddrinfo
+ # blocks on an exclusive lock on some platforms, users might handle name
+ # resolution in their own code and pass in resolved IPs.
+ if proto not in {0, socket.IPPROTO_TCP, socket.IPPROTO_UDP} or host is None:
+ return None
+
+ type &= ~_SOCKET_TYPE_MASK
+ if type == socket.SOCK_STREAM:
+ proto = socket.IPPROTO_TCP
+ elif type == socket.SOCK_DGRAM:
+ proto = socket.IPPROTO_UDP
+ else:
+ return None
+
+ if hasattr(socket, 'inet_pton'):
+ if family == socket.AF_UNSPEC:
+ afs = [socket.AF_INET, socket.AF_INET6]
+ else:
+ afs = [family]
+
+ for af in afs:
+ # Linux's inet_pton doesn't accept an IPv6 zone index after host,
+ # like '::1%lo0', so strip it. If we happen to make an invalid
+ # address look valid, we fail later in sock.connect or sock.bind.
+ try:
+ if af == socket.AF_INET6:
+ socket.inet_pton(af, host.partition('%')[0])
+ else:
+ socket.inet_pton(af, host)
+ return af, type, proto, '', (host, port)
+ except OSError:
+ pass
+
+ # "host" is not an IP address.
+ return None
+
+ # No inet_pton. (On Windows it's only available since Python 3.4.)
+ # Even though getaddrinfo with AI_NUMERICHOST would be non-blocking, it
+ # still requires a lock on some platforms, and waiting for that lock could
+ # block the event loop. Use ipaddress instead, it's just text parsing.
+ try:
+ addr = ipaddress.IPv4Address(host)
+ except ValueError:
+ try:
+ addr = ipaddress.IPv6Address(host.partition('%')[0])
+ except ValueError:
+ return None
+
+ af = socket.AF_INET if addr.version == 4 else socket.AF_INET6
+ if family not in (socket.AF_UNSPEC, af):
+ # "host" is wrong IP version for "family".
+ return None
+
+ return af, type, proto, '', (host, port)
+
+
def _check_resolved_address(sock, address):
# Ensure that the address is already resolved to avoid the trap of hanging
# the entire event loop when the address requires doing a DNS lookup.
- #
- # getaddrinfo() is slow (around 10 us per call): this function should only
- # be called in debug mode
- family = sock.family
- if family == socket.AF_INET:
- host, port = address
- elif family == socket.AF_INET6:
- host, port = address[:2]
- else:
+ if hasattr(socket, 'AF_UNIX') and sock.family == socket.AF_UNIX:
return
- # On Windows, socket.inet_pton() is only available since Python 3.4
- if hasattr(socket, 'inet_pton'):
- # getaddrinfo() is slow and has known issue: prefer inet_pton()
- # if available
- try:
- socket.inet_pton(family, host)
- except OSError as exc:
- raise ValueError("address must be resolved (IP address), "
- "got host %r: %s"
- % (host, exc))
- else:
- # Use getaddrinfo(flags=AI_NUMERICHOST) to ensure that the address is
- # already resolved.
- type_mask = 0
- if hasattr(socket, 'SOCK_NONBLOCK'):
- type_mask |= socket.SOCK_NONBLOCK
- if hasattr(socket, 'SOCK_CLOEXEC'):
- type_mask |= socket.SOCK_CLOEXEC
- try:
- socket.getaddrinfo(host, port,
- family=family,
- type=(sock.type & ~type_mask),
- proto=sock.proto,
- flags=socket.AI_NUMERICHOST)
- except socket.gaierror as err:
- raise ValueError("address must be resolved (IP address), "
- "got host %r: %s"
- % (host, err))
+ host, port = address[:2]
+ if _ipaddr_info(host, port, sock.family, sock.type, sock.proto) is None:
+ raise ValueError("address must be resolved (IP address),"
+ " got host %r" % host)
def _run_until_complete_cb(fut):
@@ -535,7 +571,12 @@
def getaddrinfo(self, host, port, *,
family=0, type=0, proto=0, flags=0):
- if self._debug:
+ info = _ipaddr_info(host, port, family, type, proto)
+ if info is not None:
+ fut = futures.Future(loop=self)
+ fut.set_result([info])
+ return fut
+ elif self._debug:
return self.run_in_executor(None, self._getaddrinfo_debug,
host, port, family, type, proto, flags)
else:
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index 7eac41e..14c0659 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -441,8 +441,7 @@
def sock_connect(self, sock, address):
try:
- if self._debug:
- base_events._check_resolved_address(sock, address)
+ base_events._check_resolved_address(sock, address)
except ValueError as err:
fut = futures.Future(loop=self)
fut.set_exception(err)
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
index a05f81c..5b26631 100644
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -397,8 +397,7 @@
raise ValueError("the socket must be non-blocking")
fut = futures.Future(loop=self)
try:
- if self._debug:
- base_events._check_resolved_address(sock, address)
+ base_events._check_resolved_address(sock, address)
except ValueError as err:
fut.set_exception(err)
else:
diff --git a/Lib/asyncio/test_utils.py b/Lib/asyncio/test_utils.py
index 8170533..396e6ae 100644
--- a/Lib/asyncio/test_utils.py
+++ b/Lib/asyncio/test_utils.py
@@ -446,9 +446,14 @@
finally:
logger.setLevel(old_level)
-def mock_nonblocking_socket():
+
+def mock_nonblocking_socket(proto=socket.IPPROTO_TCP, type=socket.SOCK_STREAM,
+ family=socket.AF_INET):
"""Create a mock of a non-blocking socket."""
- sock = mock.Mock(socket.socket)
+ sock = mock.MagicMock(socket.socket)
+ sock.proto = proto
+ sock.type = type
+ sock.family = family
sock.gettimeout.return_value = 0.0
return sock