mirror of https://github.com/scrapy/scrapy.git
136 lines
4.7 KiB
Python
136 lines
4.7 KiB
Python
import asyncio
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import sys
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from contextlib import suppress
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from twisted.internet import asyncioreactor, error
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from scrapy.utils.misc import load_object
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def listen_tcp(portrange, host, factory):
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"""Like reactor.listenTCP but tries different ports in a range."""
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from twisted.internet import reactor
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if len(portrange) > 2:
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raise ValueError(f"invalid portrange: {portrange}")
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if not portrange:
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return reactor.listenTCP(0, factory, interface=host)
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if not hasattr(portrange, '__iter__'):
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return reactor.listenTCP(portrange, factory, interface=host)
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if len(portrange) == 1:
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return reactor.listenTCP(portrange[0], factory, interface=host)
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for x in range(portrange[0], portrange[1] + 1):
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try:
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return reactor.listenTCP(x, factory, interface=host)
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except error.CannotListenError:
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if x == portrange[1]:
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raise
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class CallLaterOnce:
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"""Schedule a function to be called in the next reactor loop, but only if
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it hasn't been already scheduled since the last time it ran.
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"""
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def __init__(self, func, *a, **kw):
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self._func = func
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self._a = a
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self._kw = kw
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self._call = None
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def schedule(self, delay=0):
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from twisted.internet import reactor
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if self._call is None:
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self._call = reactor.callLater(delay, self)
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def cancel(self):
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if self._call:
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self._call.cancel()
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def __call__(self):
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self._call = None
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return self._func(*self._a, **self._kw)
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def get_asyncio_event_loop_policy():
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policy = asyncio.get_event_loop_policy()
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if (
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sys.version_info >= (3, 8)
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and sys.platform == "win32"
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and not isinstance(policy, asyncio.WindowsSelectorEventLoopPolicy)
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):
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policy = asyncio.WindowsSelectorEventLoopPolicy()
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asyncio.set_event_loop_policy(policy)
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return policy
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def install_reactor(reactor_path, event_loop_path=None):
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"""Installs the :mod:`~twisted.internet.reactor` with the specified
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import path. Also installs the asyncio event loop with the specified import
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path if the asyncio reactor is enabled"""
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reactor_class = load_object(reactor_path)
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if reactor_class is asyncioreactor.AsyncioSelectorReactor:
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with suppress(error.ReactorAlreadyInstalledError):
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event_loop = set_asyncio_event_loop(event_loop_path)
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asyncioreactor.install(eventloop=event_loop)
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else:
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*module, _ = reactor_path.split(".")
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installer_path = module + ["install"]
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installer = load_object(".".join(installer_path))
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with suppress(error.ReactorAlreadyInstalledError):
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installer()
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def set_asyncio_event_loop(event_loop_path):
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"""Sets and returns the event loop with specified import path."""
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policy = get_asyncio_event_loop_policy()
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if event_loop_path is not None:
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event_loop_class = load_object(event_loop_path)
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event_loop = event_loop_class()
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asyncio.set_event_loop(event_loop)
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else:
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try:
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event_loop = policy.get_event_loop()
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except RuntimeError:
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# `get_event_loop` is expected to fail when called from a new thread
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# with no asyncio event loop yet installed. Such is the case when
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# called from `scrapy shell`
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event_loop = policy.new_event_loop()
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asyncio.set_event_loop(event_loop)
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return event_loop
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def verify_installed_reactor(reactor_path):
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"""Raises :exc:`Exception` if the installed
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:mod:`~twisted.internet.reactor` does not match the specified import
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path."""
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from twisted.internet import reactor
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reactor_class = load_object(reactor_path)
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if not reactor.__class__ == reactor_class:
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msg = ("The installed reactor "
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f"({reactor.__module__}.{reactor.__class__.__name__}) does not "
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f"match the requested one ({reactor_path})")
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raise Exception(msg)
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def verify_installed_asyncio_event_loop(loop_path):
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from twisted.internet import reactor
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loop_class = load_object(loop_path)
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if isinstance(reactor._asyncioEventloop, loop_class):
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return
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installed = (
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f"{reactor._asyncioEventloop.__class__.__module__}"
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f".{reactor._asyncioEventloop.__class__.__qualname__}"
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)
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specified = f"{loop_class.__module__}.{loop_class.__qualname__}"
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raise Exception(
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"Scrapy found an asyncio Twisted reactor already "
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f"installed, and its event loop class ({installed}) does "
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"not match the one specified in the ASYNCIO_EVENT_LOOP "
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f"setting ({specified})"
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)
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def is_asyncio_reactor_installed():
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from twisted.internet import reactor
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return isinstance(reactor, asyncioreactor.AsyncioSelectorReactor)
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