Source code for scrapy.crawler

from __future__ import annotations

import logging
import pprint
import signal
import warnings
from typing import TYPE_CHECKING, Any, Dict, Generator, Optional, Set, Type, Union, cast

from twisted.internet.defer import (
    Deferred,
    DeferredList,
    inlineCallbacks,
    maybeDeferred,
)

try:
    # zope >= 5.0 only supports MultipleInvalid
    from zope.interface.exceptions import MultipleInvalid
except ImportError:
    MultipleInvalid = None

from zope.interface.verify import verifyClass

from scrapy import Spider, signals
from scrapy.addons import AddonManager
from scrapy.core.engine import ExecutionEngine
from scrapy.exceptions import ScrapyDeprecationWarning
from scrapy.extension import ExtensionManager
from scrapy.interfaces import ISpiderLoader
from scrapy.logformatter import LogFormatter
from scrapy.settings import BaseSettings, Settings, overridden_settings
from scrapy.signalmanager import SignalManager
from scrapy.statscollectors import StatsCollector
from scrapy.utils.log import (
    LogCounterHandler,
    configure_logging,
    get_scrapy_root_handler,
    install_scrapy_root_handler,
    log_reactor_info,
    log_scrapy_info,
)
from scrapy.utils.misc import build_from_crawler, load_object
from scrapy.utils.ossignal import install_shutdown_handlers, signal_names
from scrapy.utils.reactor import (
    install_reactor,
    is_asyncio_reactor_installed,
    verify_installed_asyncio_event_loop,
    verify_installed_reactor,
)

if TYPE_CHECKING:
    from scrapy.utils.request import RequestFingerprinter


logger = logging.getLogger(__name__)


[docs]class Crawler: def __init__( self, spidercls: Type[Spider], settings: Union[None, Dict[str, Any], Settings] = None, init_reactor: bool = False, ): if isinstance(spidercls, Spider): raise ValueError("The spidercls argument must be a class, not an object") if isinstance(settings, dict) or settings is None: settings = Settings(settings) self.spidercls: Type[Spider] = spidercls self.settings: Settings = settings.copy() self.spidercls.update_settings(self.settings) self._update_root_log_handler() self.addons: AddonManager = AddonManager(self) self.signals: SignalManager = SignalManager(self) self._init_reactor: bool = init_reactor self.crawling: bool = False self._started: bool = False self.extensions: Optional[ExtensionManager] = None self.stats: Optional[StatsCollector] = None self.logformatter: Optional[LogFormatter] = None self.request_fingerprinter: Optional[RequestFingerprinter] = None self.spider: Optional[Spider] = None self.engine: Optional[ExecutionEngine] = None def _update_root_log_handler(self) -> None: if get_scrapy_root_handler() is not None: # scrapy root handler already installed: update it with new settings install_scrapy_root_handler(self.settings) def _apply_settings(self) -> None: if self.settings.frozen: return self.addons.load_settings(self.settings) self.stats = load_object(self.settings["STATS_CLASS"])(self) handler = LogCounterHandler(self, level=self.settings.get("LOG_LEVEL")) logging.root.addHandler(handler) # lambda is assigned to Crawler attribute because this way it is not # garbage collected after leaving the scope self.__remove_handler = lambda: logging.root.removeHandler(handler) self.signals.connect(self.__remove_handler, signals.engine_stopped) lf_cls: Type[LogFormatter] = load_object(self.settings["LOG_FORMATTER"]) self.logformatter = lf_cls.from_crawler(self) self.request_fingerprinter = build_from_crawler( load_object(self.settings["REQUEST_FINGERPRINTER_CLASS"]), self, ) reactor_class: str = self.settings["TWISTED_REACTOR"] event_loop: str = self.settings["ASYNCIO_EVENT_LOOP"] if self._init_reactor: # this needs to be done after the spider settings are merged, # but before something imports twisted.internet.reactor if reactor_class: install_reactor(reactor_class, event_loop) else: from twisted.internet import reactor # noqa: F401 log_reactor_info() if reactor_class: verify_installed_reactor(reactor_class) if is_asyncio_reactor_installed() and event_loop: verify_installed_asyncio_event_loop(event_loop) log_reactor_info() self.extensions = ExtensionManager.from_crawler(self) self.settings.freeze() d = dict(overridden_settings(self.settings)) logger.info( "Overridden settings:\n%(settings)s", {"settings": pprint.pformat(d)} )
[docs] @inlineCallbacks def crawl(self, *args: Any, **kwargs: Any) -> Generator[Deferred, Any, None]: if self.crawling: raise RuntimeError("Crawling already taking place") if self._started: warnings.warn( "Running Crawler.crawl() more than once is deprecated.", ScrapyDeprecationWarning, stacklevel=2, ) self.crawling = self._started = True try: self.spider = self._create_spider(*args, **kwargs) self._apply_settings() self._update_root_log_handler() self.engine = self._create_engine() start_requests = iter(self.spider.start_requests()) yield self.engine.open_spider(self.spider, start_requests) yield maybeDeferred(self.engine.start) except Exception: self.crawling = False if self.engine is not None: yield self.engine.close() raise
def _create_spider(self, *args: Any, **kwargs: Any) -> Spider: return self.spidercls.from_crawler(self, *args, **kwargs) def _create_engine(self) -> ExecutionEngine: return ExecutionEngine(self, lambda _: self.stop())
[docs] @inlineCallbacks def stop(self) -> Generator[Deferred, Any, None]: """Starts a graceful stop of the crawler and returns a deferred that is fired when the crawler is stopped.""" if self.crawling: self.crawling = False assert self.engine yield maybeDeferred(self.engine.stop)
@staticmethod def _get_component(component_class, components): for component in components: if isinstance(component, component_class): return component return None def get_addon(self, cls): return self._get_component(cls, self.addons.addons) def get_downloader_middleware(self, cls): if not self.engine: raise RuntimeError( "Crawler.get_downloader_middleware() can only be called after " "the crawl engine has been created." ) return self._get_component(cls, self.engine.downloader.middleware.middlewares) def get_extension(self, cls): if not self.extensions: raise RuntimeError( "Crawler.get_extension() can only be called after the " "extension manager has been created." ) return self._get_component(cls, self.extensions.middlewares) def get_item_pipeline(self, cls): if not self.engine: raise RuntimeError( "Crawler.get_item_pipeline() can only be called after the " "crawl engine has been created." ) return self._get_component(cls, self.engine.scraper.itemproc.middlewares) def get_spider_middleware(self, cls): if not self.engine: raise RuntimeError( "Crawler.get_spider_middleware() can only be called after the " "crawl engine has been created." ) return self._get_component(cls, self.engine.scraper.spidermw.middlewares)
[docs]class CrawlerRunner: """ This is a convenient helper class that keeps track of, manages and runs crawlers inside an already setup :mod:`~twisted.internet.reactor`. The CrawlerRunner object must be instantiated with a :class:`~scrapy.settings.Settings` object. This class shouldn't be needed (since Scrapy is responsible of using it accordingly) unless writing scripts that manually handle the crawling process. See :ref:`run-from-script` for an example. """ crawlers = property( lambda self: self._crawlers, doc="Set of :class:`crawlers <scrapy.crawler.Crawler>` started by " ":meth:`crawl` and managed by this class.", ) @staticmethod def _get_spider_loader(settings: BaseSettings): """Get SpiderLoader instance from settings""" cls_path = settings.get("SPIDER_LOADER_CLASS") loader_cls = load_object(cls_path) verifyClass(ISpiderLoader, loader_cls) return loader_cls.from_settings(settings.frozencopy()) def __init__(self, settings: Union[Dict[str, Any], Settings, None] = None): if isinstance(settings, dict) or settings is None: settings = Settings(settings) self.settings = settings self.spider_loader = self._get_spider_loader(settings) self._crawlers: Set[Crawler] = set() self._active: Set[Deferred] = set() self.bootstrap_failed = False
[docs] def crawl( self, crawler_or_spidercls: Union[Type[Spider], str, Crawler], *args: Any, **kwargs: Any, ) -> Deferred: """ Run a crawler with the provided arguments. It will call the given Crawler's :meth:`~Crawler.crawl` method, while keeping track of it so it can be stopped later. If ``crawler_or_spidercls`` isn't a :class:`~scrapy.crawler.Crawler` instance, this method will try to create one using this parameter as the spider class given to it. Returns a deferred that is fired when the crawling is finished. :param crawler_or_spidercls: already created crawler, or a spider class or spider's name inside the project to create it :type crawler_or_spidercls: :class:`~scrapy.crawler.Crawler` instance, :class:`~scrapy.spiders.Spider` subclass or string :param args: arguments to initialize the spider :param kwargs: keyword arguments to initialize the spider """ if isinstance(crawler_or_spidercls, Spider): raise ValueError( "The crawler_or_spidercls argument cannot be a spider object, " "it must be a spider class (or a Crawler object)" ) crawler = self.create_crawler(crawler_or_spidercls) return self._crawl(crawler, *args, **kwargs)
def _crawl(self, crawler: Crawler, *args: Any, **kwargs: Any) -> Deferred: self.crawlers.add(crawler) d = crawler.crawl(*args, **kwargs) self._active.add(d) def _done(result: Any) -> Any: self.crawlers.discard(crawler) self._active.discard(d) self.bootstrap_failed |= not getattr(crawler, "spider", None) return result return d.addBoth(_done)
[docs] def create_crawler( self, crawler_or_spidercls: Union[Type[Spider], str, Crawler] ) -> Crawler: """ Return a :class:`~scrapy.crawler.Crawler` object. * If ``crawler_or_spidercls`` is a Crawler, it is returned as-is. * If ``crawler_or_spidercls`` is a Spider subclass, a new Crawler is constructed for it. * If ``crawler_or_spidercls`` is a string, this function finds a spider with this name in a Scrapy project (using spider loader), then creates a Crawler instance for it. """ if isinstance(crawler_or_spidercls, Spider): raise ValueError( "The crawler_or_spidercls argument cannot be a spider object, " "it must be a spider class (or a Crawler object)" ) if isinstance(crawler_or_spidercls, Crawler): return crawler_or_spidercls return self._create_crawler(crawler_or_spidercls)
def _create_crawler(self, spidercls: Union[str, Type[Spider]]) -> Crawler: if isinstance(spidercls, str): spidercls = self.spider_loader.load(spidercls) # temporary cast until self.spider_loader is typed return Crawler(cast(Type[Spider], spidercls), self.settings)
[docs] def stop(self) -> Deferred: """ Stops simultaneously all the crawling jobs taking place. Returns a deferred that is fired when they all have ended. """ return DeferredList([c.stop() for c in list(self.crawlers)])
[docs] @inlineCallbacks def join(self) -> Generator[Deferred, Any, None]: """ join() Returns a deferred that is fired when all managed :attr:`crawlers` have completed their executions. """ while self._active: yield DeferredList(self._active)
[docs]class CrawlerProcess(CrawlerRunner): """ A class to run multiple scrapy crawlers in a process simultaneously. This class extends :class:`~scrapy.crawler.CrawlerRunner` by adding support for starting a :mod:`~twisted.internet.reactor` and handling shutdown signals, like the keyboard interrupt command Ctrl-C. It also configures top-level logging. This utility should be a better fit than :class:`~scrapy.crawler.CrawlerRunner` if you aren't running another :mod:`~twisted.internet.reactor` within your application. The CrawlerProcess object must be instantiated with a :class:`~scrapy.settings.Settings` object. :param install_root_handler: whether to install root logging handler (default: True) This class shouldn't be needed (since Scrapy is responsible of using it accordingly) unless writing scripts that manually handle the crawling process. See :ref:`run-from-script` for an example. """ def __init__( self, settings: Union[Dict[str, Any], Settings, None] = None, install_root_handler: bool = True, ): super().__init__(settings) configure_logging(self.settings, install_root_handler) log_scrapy_info(self.settings) self._initialized_reactor = False def _signal_shutdown(self, signum: int, _: Any) -> None: from twisted.internet import reactor install_shutdown_handlers(self._signal_kill) signame = signal_names[signum] logger.info( "Received %(signame)s, shutting down gracefully. Send again to force ", {"signame": signame}, ) reactor.callFromThread(self._graceful_stop_reactor) def _signal_kill(self, signum: int, _: Any) -> None: from twisted.internet import reactor install_shutdown_handlers(signal.SIG_IGN) signame = signal_names[signum] logger.info( "Received %(signame)s twice, forcing unclean shutdown", {"signame": signame} ) reactor.callFromThread(self._stop_reactor) def _create_crawler(self, spidercls: Union[Type[Spider], str]) -> Crawler: if isinstance(spidercls, str): spidercls = self.spider_loader.load(spidercls) init_reactor = not self._initialized_reactor self._initialized_reactor = True # temporary cast until self.spider_loader is typed return Crawler( cast(Type[Spider], spidercls), self.settings, init_reactor=init_reactor )
[docs] def start( self, stop_after_crawl: bool = True, install_signal_handlers: bool = True ) -> None: """ This method starts a :mod:`~twisted.internet.reactor`, adjusts its pool size to :setting:`REACTOR_THREADPOOL_MAXSIZE`, and installs a DNS cache based on :setting:`DNSCACHE_ENABLED` and :setting:`DNSCACHE_SIZE`. If ``stop_after_crawl`` is True, the reactor will be stopped after all crawlers have finished, using :meth:`join`. :param bool stop_after_crawl: stop or not the reactor when all crawlers have finished :param bool install_signal_handlers: whether to install the OS signal handlers from Twisted and Scrapy (default: True) """ from twisted.internet import reactor if stop_after_crawl: d = self.join() # Don't start the reactor if the deferreds are already fired if d.called: return d.addBoth(self._stop_reactor) resolver_class = load_object(self.settings["DNS_RESOLVER"]) # We pass self, which is CrawlerProcess, instead of Crawler here, # which works because the default resolvers only use crawler.settings. resolver = build_from_crawler(resolver_class, self, reactor=reactor) # type: ignore[arg-type] resolver.install_on_reactor() tp = reactor.getThreadPool() tp.adjustPoolsize(maxthreads=self.settings.getint("REACTOR_THREADPOOL_MAXSIZE")) reactor.addSystemEventTrigger("before", "shutdown", self.stop) if install_signal_handlers: reactor.addSystemEventTrigger( "after", "startup", install_shutdown_handlers, self._signal_shutdown ) reactor.run(installSignalHandlers=install_signal_handlers) # blocking call
def _graceful_stop_reactor(self) -> Deferred: d = self.stop() d.addBoth(self._stop_reactor) return d def _stop_reactor(self, _: Any = None) -> None: from twisted.internet import reactor try: reactor.stop() except RuntimeError: # raised if already stopped or in shutdown stage pass