mirror of https://github.com/scrapy/scrapy.git
102 lines
3.4 KiB
Python
102 lines
3.4 KiB
Python
import signal
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from twisted.internet import reactor, defer
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from scrapy.xlib.pydispatch import dispatcher
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from scrapy.core.engine import ExecutionEngine
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from scrapy.resolver import CachingThreadedResolver
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from scrapy.extension import ExtensionManager
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from scrapy.utils.ossignal import install_shutdown_handlers, signal_names
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from scrapy.utils.misc import load_object
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from scrapy import log, signals
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class Crawler(object):
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def __init__(self, settings):
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self.configured = False
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self.settings = settings
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def install(self):
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import scrapy.project
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assert not hasattr(scrapy.project, 'crawler'), "crawler already installed"
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scrapy.project.crawler = self
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def uninstall(self):
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import scrapy.project
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assert hasattr(scrapy.project, 'crawler'), "crawler not installed"
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del scrapy.project.crawler
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def configure(self):
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if self.configured:
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return
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self.configured = True
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self.extensions = ExtensionManager.from_crawler(self)
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spman_cls = load_object(self.settings['SPIDER_MANAGER_CLASS'])
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self.spiders = spman_cls.from_crawler(self)
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self.engine = ExecutionEngine(self, self._spider_closed)
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def crawl(self, spider, requests=None):
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spider.set_crawler(self)
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if requests is None:
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requests = spider.start_requests()
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return self.engine.open_spider(spider, requests)
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def _spider_closed(self, spider=None):
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if not self.engine.open_spiders:
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self.stop()
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@defer.inlineCallbacks
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def start(self):
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yield defer.maybeDeferred(self.configure)
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yield defer.maybeDeferred(self.engine.start)
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@defer.inlineCallbacks
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def stop(self):
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if self.engine.running:
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yield defer.maybeDeferred(self.engine.stop)
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class CrawlerProcess(Crawler):
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"""A class to run a single Scrapy crawler in a process. It provides
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automatic control of the Twisted reactor and installs some convenient
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signals for shutting down the crawl.
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"""
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def __init__(self, *a, **kw):
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super(CrawlerProcess, self).__init__(*a, **kw)
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dispatcher.connect(self.stop, signals.engine_stopped)
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install_shutdown_handlers(self._signal_shutdown)
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def start(self):
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super(CrawlerProcess, self).start()
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if self.settings.getbool('DNSCACHE_ENABLED'):
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reactor.installResolver(CachingThreadedResolver(reactor))
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reactor.addSystemEventTrigger('before', 'shutdown', self.stop)
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reactor.run(installSignalHandlers=False) # blocking call
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def stop(self):
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d = super(CrawlerProcess, self).stop()
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d.addBoth(self._stop_reactor)
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return d
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def _stop_reactor(self, _=None):
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try:
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reactor.stop()
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except RuntimeError: # raised if already stopped or in shutdown stage
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pass
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def _signal_shutdown(self, signum, _):
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install_shutdown_handlers(self._signal_kill)
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signame = signal_names[signum]
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log.msg("Received %s, shutting down gracefully. Send again to force " \
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"unclean shutdown" % signame, level=log.INFO)
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reactor.callFromThread(self.stop)
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def _signal_kill(self, signum, _):
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install_shutdown_handlers(signal.SIG_IGN)
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signame = signal_names[signum]
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log.msg('Received %s twice, forcing unclean shutdown' % signame, \
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level=log.INFO)
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reactor.callFromThread(self._stop_reactor)
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