import asyncio
from contextlib import suppress
from twisted.internet import asyncioreactor, error
from scrapy.utils.misc import load_object
def listen_tcp(portrange, host, factory):
"""Like reactor.listenTCP but tries different ports in a range."""
from twisted.internet import reactor
if len(portrange) > 2:
raise ValueError(f"invalid portrange: {portrange}")
if not portrange:
return reactor.listenTCP(0, factory, interface=host)
if not hasattr(portrange, '__iter__'):
return reactor.listenTCP(portrange, factory, interface=host)
if len(portrange) == 1:
return reactor.listenTCP(portrange[0], factory, interface=host)
for x in range(portrange[0], portrange[1] + 1):
try:
return reactor.listenTCP(x, factory, interface=host)
except error.CannotListenError:
if x == portrange[1]:
raise
class CallLaterOnce:
"""Schedule a function to be called in the next reactor loop, but only if
it hasn't been already scheduled since the last time it ran.
"""
def __init__(self, func, *a, **kw):
self._func = func
self._a = a
self._kw = kw
self._call = None
def schedule(self, delay=0):
from twisted.internet import reactor
if self._call is None:
self._call = reactor.callLater(delay, self)
def cancel(self):
if self._call:
self._call.cancel()
def __call__(self):
self._call = None
return self._func(*self._a, **self._kw)
[docs]def install_reactor(reactor_path, event_loop_path=None):
"""Installs the :mod:`~twisted.internet.reactor` with the specified
import path. Also installs the asyncio event loop with the specified import
path if the asyncio reactor is enabled"""
reactor_class = load_object(reactor_path)
if reactor_class is asyncioreactor.AsyncioSelectorReactor:
with suppress(error.ReactorAlreadyInstalledError):
if event_loop_path is not None:
event_loop_class = load_object(event_loop_path)
event_loop = event_loop_class()
asyncio.set_event_loop(event_loop)
else:
event_loop = asyncio.get_event_loop()
asyncioreactor.install(eventloop=event_loop)
else:
*module, _ = reactor_path.split(".")
installer_path = module + ["install"]
installer = load_object(".".join(installer_path))
with suppress(error.ReactorAlreadyInstalledError):
installer()
def verify_installed_reactor(reactor_path):
"""Raises :exc:`Exception` if the installed
:mod:`~twisted.internet.reactor` does not match the specified import
path."""
from twisted.internet import reactor
reactor_class = load_object(reactor_path)
if not isinstance(reactor, reactor_class):
msg = ("The installed reactor "
f"({reactor.__module__}.{reactor.__class__.__name__}) does not "
f"match the requested one ({reactor_path})")
raise Exception(msg)
def is_asyncio_reactor_installed():
from twisted.internet import reactor
return isinstance(reactor, asyncioreactor.AsyncioSelectorReactor)