import asyncio import sys from asyncio import AbstractEventLoop, AbstractEventLoopPolicy from contextlib import suppress from typing import Any, Callable, Dict, Optional, Sequence, Type from warnings import catch_warnings, filterwarnings, warn from twisted.internet import asyncioreactor, error from twisted.internet.base import DelayedCall from scrapy.exceptions import ScrapyDeprecationWarning 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: Callable, *a: Any, **kw: Any): self._func: Callable = func self._a: Sequence[Any] = a self._kw: Dict[str, Any] = kw self._call: Optional[DelayedCall] = None def schedule(self, delay: float = 0) -> None: from twisted.internet import reactor if self._call is None: self._call = reactor.callLater(delay, self) def cancel(self) -> None: if self._call: self._call.cancel() def __call__(self) -> Any: self._call = None return self._func(*self._a, **self._kw) def set_asyncio_event_loop_policy() -> None: """The policy functions from asyncio often behave unexpectedly, so we restrict their use to the absolutely essential case. This should only be used to install the reactor. """ _get_asyncio_event_loop_policy() def get_asyncio_event_loop_policy() -> AbstractEventLoopPolicy: warn( "Call to deprecated function " "scrapy.utils.reactor.get_asyncio_event_loop_policy().\n" "\n" "Please use get_event_loop, new_event_loop and set_event_loop" " from asyncio instead, as the corresponding policy methods may lead" " to unexpected behaviour.\n" "This function is replaced by set_asyncio_event_loop_policy and" " is meant to be used only when the reactor is being installed.", category=ScrapyDeprecationWarning, stacklevel=2, ) return _get_asyncio_event_loop_policy() def _get_asyncio_event_loop_policy() -> AbstractEventLoopPolicy: policy = asyncio.get_event_loop_policy() if ( sys.version_info >= (3, 8) and sys.platform == "win32" and not isinstance(policy, asyncio.WindowsSelectorEventLoopPolicy) ): policy = asyncio.WindowsSelectorEventLoopPolicy() asyncio.set_event_loop_policy(policy) return policy def install_reactor(reactor_path: str, event_loop_path: Optional[str] = None) -> 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: set_asyncio_event_loop_policy() with suppress(error.ReactorAlreadyInstalledError): event_loop = set_asyncio_event_loop(event_loop_path) 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 _get_asyncio_event_loop() -> AbstractEventLoop: return set_asyncio_event_loop(None) def set_asyncio_event_loop(event_loop_path: Optional[str]) -> AbstractEventLoop: """Sets and returns the event loop with specified import path.""" if event_loop_path is not None: event_loop_class: Type[AbstractEventLoop] = load_object(event_loop_path) event_loop = event_loop_class() asyncio.set_event_loop(event_loop) else: try: with catch_warnings(): # In Python 3.10.9, 3.11.1, 3.12 and 3.13, a DeprecationWarning # is emitted about the lack of a current event loop, because in # Python 3.14 and later `get_event_loop` will raise a # RuntimeError in that event. Because our code is already # prepared for that future behavior, we ignore the deprecation # warning. filterwarnings( "ignore", message="There is no current event loop", category=DeprecationWarning, ) event_loop = asyncio.get_event_loop() except RuntimeError: # `get_event_loop` raises RuntimeError when called with no asyncio # event loop yet installed in the following scenarios: # - Previsibly on Python 3.14 and later. # https://github.com/python/cpython/issues/100160#issuecomment-1345581902 event_loop = asyncio.new_event_loop() asyncio.set_event_loop(event_loop) return event_loop def verify_installed_reactor(reactor_path: str) -> None: """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 reactor.__class__ == 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 verify_installed_asyncio_event_loop(loop_path: str) -> None: from twisted.internet import reactor loop_class = load_object(loop_path) if isinstance(reactor._asyncioEventloop, loop_class): return installed = ( f"{reactor._asyncioEventloop.__class__.__module__}" f".{reactor._asyncioEventloop.__class__.__qualname__}" ) specified = f"{loop_class.__module__}.{loop_class.__qualname__}" raise Exception( "Scrapy found an asyncio Twisted reactor already " f"installed, and its event loop class ({installed}) does " "not match the one specified in the ASYNCIO_EVENT_LOOP " f"setting ({specified})" ) def is_asyncio_reactor_installed() -> bool: from twisted.internet import reactor return isinstance(reactor, asyncioreactor.AsyncioSelectorReactor)