"""This module implements the Scraper component which parses responses and extracts information from them""" import logging from collections import deque from itemadapter import is_item from twisted.internet import defer from twisted.python.failure import Failure from scrapy import signals from scrapy.core.spidermw import SpiderMiddlewareManager from scrapy.exceptions import CloseSpider, DropItem, IgnoreRequest from scrapy.http import Request, Response from scrapy.utils.defer import defer_fail, defer_succeed, iter_errback, parallel from scrapy.utils.log import failure_to_exc_info, logformatter_adapter from scrapy.utils.misc import load_object, warn_on_generator_with_return_value from scrapy.utils.spider import iterate_spider_output logger = logging.getLogger(__name__) class Slot: """Scraper slot (one per running spider)""" MIN_RESPONSE_SIZE = 1024 def __init__(self, max_active_size=5000000): self.max_active_size = max_active_size self.queue = deque() self.active = set() self.active_size = 0 self.itemproc_size = 0 self.closing = None def add_response_request(self, response, request): deferred = defer.Deferred() self.queue.append((response, request, deferred)) if isinstance(response, Response): self.active_size += max(len(response.body), self.MIN_RESPONSE_SIZE) else: self.active_size += self.MIN_RESPONSE_SIZE return deferred def next_response_request_deferred(self): response, request, deferred = self.queue.popleft() self.active.add(request) return response, request, deferred def finish_response(self, response, request): self.active.remove(request) if isinstance(response, Response): self.active_size -= max(len(response.body), self.MIN_RESPONSE_SIZE) else: self.active_size -= self.MIN_RESPONSE_SIZE def is_idle(self): return not (self.queue or self.active) def needs_backout(self): return self.active_size > self.max_active_size class Scraper: def __init__(self, crawler): self.slot = None self.spidermw = SpiderMiddlewareManager.from_crawler(crawler) itemproc_cls = load_object(crawler.settings['ITEM_PROCESSOR']) self.itemproc = itemproc_cls.from_crawler(crawler) self.concurrent_items = crawler.settings.getint('CONCURRENT_ITEMS') self.crawler = crawler self.signals = crawler.signals self.logformatter = crawler.logformatter @defer.inlineCallbacks def open_spider(self, spider): """Open the given spider for scraping and allocate resources for it""" self.slot = Slot(self.crawler.settings.getint('SCRAPER_SLOT_MAX_ACTIVE_SIZE')) yield self.itemproc.open_spider(spider) def close_spider(self, spider): """Close a spider being scraped and release its resources""" slot = self.slot slot.closing = defer.Deferred() slot.closing.addCallback(self.itemproc.close_spider) self._check_if_closing(spider, slot) return slot.closing def is_idle(self): """Return True if there isn't any more spiders to process""" return not self.slot def _check_if_closing(self, spider, slot): if slot.closing and slot.is_idle(): slot.closing.callback(spider) def enqueue_scrape(self, response, request, spider): slot = self.slot dfd = slot.add_response_request(response, request) def finish_scraping(_): slot.finish_response(response, request) self._check_if_closing(spider, slot) self._scrape_next(spider, slot) return _ dfd.addBoth(finish_scraping) dfd.addErrback( lambda f: logger.error('Scraper bug processing %(request)s', {'request': request}, exc_info=failure_to_exc_info(f), extra={'spider': spider})) self._scrape_next(spider, slot) return dfd def _scrape_next(self, spider, slot): while slot.queue: response, request, deferred = slot.next_response_request_deferred() self._scrape(response, request, spider).chainDeferred(deferred) def _scrape(self, result, request, spider): """ Handle the downloaded response or failure through the spider callback/errback """ if not isinstance(result, (Response, Failure)): raise TypeError(f"Incorrect type: expected Response or Failure, got {type(result)}: {result!r}") dfd = self._scrape2(result, request, spider) # returns spider's processed output dfd.addErrback(self.handle_spider_error, request, result, spider) dfd.addCallback(self.handle_spider_output, request, result, spider) return dfd def _scrape2(self, result, request, spider): """ Handle the different cases of request's result been a Response or a Failure """ if isinstance(result, Response): return self.spidermw.scrape_response(self.call_spider, result, request, spider) else: # result is a Failure dfd = self.call_spider(result, request, spider) return dfd.addErrback(self._log_download_errors, result, request, spider) def call_spider(self, result, request, spider): if isinstance(result, Response): if getattr(result, "request", None) is None: result.request = request callback = result.request.callback or spider._parse warn_on_generator_with_return_value(spider, callback) dfd = defer_succeed(result) dfd.addCallback(callback, **result.request.cb_kwargs) else: # result is a Failure result.request = request warn_on_generator_with_return_value(spider, request.errback) dfd = defer_fail(result) dfd.addErrback(request.errback) return dfd.addCallback(iterate_spider_output) def handle_spider_error(self, _failure, request, response, spider): exc = _failure.value if isinstance(exc, CloseSpider): self.crawler.engine.close_spider(spider, exc.reason or 'cancelled') return logkws = self.logformatter.spider_error(_failure, request, response, spider) logger.log( *logformatter_adapter(logkws), exc_info=failure_to_exc_info(_failure), extra={'spider': spider} ) self.signals.send_catch_log( signal=signals.spider_error, failure=_failure, response=response, spider=spider ) self.crawler.stats.inc_value( f"spider_exceptions/{_failure.value.__class__.__name__}", spider=spider ) def handle_spider_output(self, result, request, response, spider): if not result: return defer_succeed(None) it = iter_errback(result, self.handle_spider_error, request, response, spider) dfd = parallel(it, self.concurrent_items, self._process_spidermw_output, request, response, spider) return dfd def _process_spidermw_output(self, output, request, response, spider): """Process each Request/Item (given in the output parameter) returned from the given spider """ if isinstance(output, Request): self.crawler.engine.crawl(request=output, spider=spider) elif is_item(output): self.slot.itemproc_size += 1 dfd = self.itemproc.process_item(output, spider) dfd.addBoth(self._itemproc_finished, output, response, spider) return dfd elif output is None: pass else: typename = type(output).__name__ logger.error( 'Spider must return request, item, or None, got %(typename)r in %(request)s', {'request': request, 'typename': typename}, extra={'spider': spider}, ) def _log_download_errors(self, spider_failure, download_failure, request, spider): """Log and silence errors that come from the engine (typically download errors that got propagated thru here) """ if isinstance(download_failure, Failure) and not download_failure.check(IgnoreRequest): if download_failure.frames: logkws = self.logformatter.download_error(download_failure, request, spider) logger.log( *logformatter_adapter(logkws), extra={'spider': spider}, exc_info=failure_to_exc_info(download_failure), ) else: errmsg = download_failure.getErrorMessage() if errmsg: logkws = self.logformatter.download_error( download_failure, request, spider, errmsg) logger.log( *logformatter_adapter(logkws), extra={'spider': spider}, ) if spider_failure is not download_failure: return spider_failure def _itemproc_finished(self, output, item, response, spider): """ItemProcessor finished for the given ``item`` and returned ``output`` """ self.slot.itemproc_size -= 1 if isinstance(output, Failure): ex = output.value if isinstance(ex, DropItem): logkws = self.logformatter.dropped(item, ex, response, spider) if logkws is not None: logger.log(*logformatter_adapter(logkws), extra={'spider': spider}) return self.signals.send_catch_log_deferred( signal=signals.item_dropped, item=item, response=response, spider=spider, exception=output.value) else: logkws = self.logformatter.item_error(item, ex, response, spider) logger.log(*logformatter_adapter(logkws), extra={'spider': spider}, exc_info=failure_to_exc_info(output)) return self.signals.send_catch_log_deferred( signal=signals.item_error, item=item, response=response, spider=spider, failure=output) else: logkws = self.logformatter.scraped(output, response, spider) if logkws is not None: logger.log(*logformatter_adapter(logkws), extra={'spider': spider}) return self.signals.send_catch_log_deferred( signal=signals.item_scraped, item=output, response=response, spider=spider)