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bpo-33530: Implement Happy Eyeballs in asyncio, v2 (GH-7237)

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Added two keyword arguments, `delay` and `interleave`, to
`BaseEventLoop.create_connection`. Happy eyeballs is activated if
`delay` is specified.

We now have documentation for the new arguments. `staggered_race()` is in its own module, but not exported to the main asyncio package.


https://bugs.python.org/issue33530
This commit is contained in:
twisteroid ambassador 2019-05-05 19:14:35 +08:00 • committed by Miss Islington (bot)
parent c4d92c8ada
commit 88f07a804a
5 changed files with 264 additions and 38 deletions
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125
Lib/asyncio/base_events.py
View file

@ -16,6 +16,7 @@ to modify the meaning of the API call itself.
import collections
import collections.abc
import concurrent.futures
import functools
import heapq
import itertools
import os
@ -41,6 +42,7 @@ from . import exceptions
from . import futures
from . import protocols
from . import sslproto
from . import staggered
from . import tasks
from . import transports
from .log import logger
@ -159,6 +161,28 @@ def _ipaddr_info(host, port, family, type, proto):
return None
def _interleave_addrinfos(addrinfos, first_address_family_count=1):
"""Interleave list of addrinfo tuples by family."""
# Group addresses by family
addrinfos_by_family = collections.OrderedDict()
for addr in addrinfos:
family = addr[0]
if family not in addrinfos_by_family:
addrinfos_by_family[family] = []
addrinfos_by_family[family].append(addr)
addrinfos_lists = list(addrinfos_by_family.values())
reordered = []
if first_address_family_count > 1:
reordered.extend(addrinfos_lists[0][:first_address_family_count - 1])
del addrinfos_lists[0][:first_address_family_count - 1]
reordered.extend(
a for a in itertools.chain.from_iterable(
itertools.zip_longest(*addrinfos_lists)
) if a is not None)
return reordered
def _run_until_complete_cb(fut):
if not fut.cancelled():
exc = fut.exception()
@ -871,12 +895,49 @@ class BaseEventLoop(events.AbstractEventLoop):
"offset must be a non-negative integer (got {!r})".format(
offset))
async def _connect_sock(self, exceptions, addr_info, local_addr_infos=None):
"""Create, bind and connect one socket."""
my_exceptions = []
exceptions.append(my_exceptions)
family, type_, proto, _, address = addr_info
sock = None
try:
sock = socket.socket(family=family, type=type_, proto=proto)
sock.setblocking(False)
if local_addr_infos is not None:
for _, _, _, _, laddr in local_addr_infos:
try:
sock.bind(laddr)
break
except OSError as exc:
msg = (
f'error while attempting to bind on '
f'address {laddr!r}: '
f'{exc.strerror.lower()}'
)
exc = OSError(exc.errno, msg)
my_exceptions.append(exc)
else: # all bind attempts failed
raise my_exceptions.pop()
await self.sock_connect(sock, address)
return sock
except OSError as exc:
my_exceptions.append(exc)
if sock is not None:
sock.close()
raise
except:
if sock is not None:
sock.close()
raise
async def create_connection(
self, protocol_factory, host=None, port=None,
*, ssl=None, family=0,
proto=0, flags=0, sock=None,
local_addr=None, server_hostname=None,
ssl_handshake_timeout=None):
ssl_handshake_timeout=None,
happy_eyeballs_delay=None, interleave=None):
"""Connect to a TCP server.
Create a streaming transport connection to a given Internet host and
@ -911,6 +972,10 @@ class BaseEventLoop(events.AbstractEventLoop):
raise ValueError(
'ssl_handshake_timeout is only meaningful with ssl')
if happy_eyeballs_delay is not None and interleave is None:
# If using happy eyeballs, default to interleave addresses by family
interleave = 1
if host is not None or port is not None:
if sock is not None:
raise ValueError(
@ -929,43 +994,31 @@ class BaseEventLoop(events.AbstractEventLoop):
flags=flags, loop=self)
if not laddr_infos:
raise OSError('getaddrinfo() returned empty list')
else:
laddr_infos = None
if interleave:
infos = _interleave_addrinfos(infos, interleave)
exceptions = []
for family, type, proto, cname, address in infos:
try:
sock = socket.socket(family=family, type=type, proto=proto)
sock.setblocking(False)
if local_addr is not None:
for _, _, _, _, laddr in laddr_infos:
try:
sock.bind(laddr)
break
except OSError as exc:
msg = (
f'error while attempting to bind on '
f'address {laddr!r}: '
f'{exc.strerror.lower()}'
)
exc = OSError(exc.errno, msg)
exceptions.append(exc)
else:
sock.close()
sock = None
continue
if self._debug:
logger.debug("connect %r to %r", sock, address)
await self.sock_connect(sock, address)
except OSError as exc:
if sock is not None:
sock.close()
exceptions.append(exc)
except:
if sock is not None:
sock.close()
raise
else:
break
else:
if happy_eyeballs_delay is None:
# not using happy eyeballs
for addrinfo in infos:
try:
sock = await self._connect_sock(
exceptions, addrinfo, laddr_infos)
break
except OSError:
continue
else: # using happy eyeballs
sock, _, _ = await staggered.staggered_race(
(functools.partial(self._connect_sock,
exceptions, addrinfo, laddr_infos)
for addrinfo in infos),
happy_eyeballs_delay, loop=self)
if sock is None:
exceptions = [exc for sub in exceptions for exc in sub]
if len(exceptions) == 1:
raise exceptions[0]
else: