def __init__(self, engine):
self.sites = {}
self.spidermw = SpiderMiddlewareManager()
self.itemproc = load_object(settings['ITEM_PROCESSOR'])()
self.concurrent_items = settings.getint('CONCURRENT_ITEMS')
self.engine = engine
class Scraper(object):
def __init__(self, engine):
self.sites = {}
self.spidermw = SpiderMiddlewareManager()
self.itemproc = load_object(settings['ITEM_PROCESSOR'])()
self.concurrent_items = settings.getint('CONCURRENT_ITEMS')
self.engine = engine
def open_spider(self, spider):
"""Open the given spider for scraping and allocate resources for it"""
if spider in self.sites:
raise RuntimeError('Scraper spider already opened: %s' % spider)
self.sites[spider] = SpiderInfo()
self.itemproc.open_spider(spider)
def close_spider(self, spider):
"""Close a spider being scraped and release its resources"""
if spider not in self.sites:
raise RuntimeError('Scraper spider already closed: %s' % spider)
self.sites.pop(spider)
self.itemproc.close_spider(spider)
def is_idle(self):
"""Return True if there isn't any more spiders to process"""
return not self.sites
def enqueue_scrape(self, response, request, spider):
site = self.sites[spider]
dfd = site.add_response_request(response, request)
# FIXME: this can't be called here because the stats spider may be
# already closed
#stats.max_value('scraper/max_active_size', site.active_size, \
# spider=spider)
def finish_scraping(_):
site.finish_response(response)
self._scrape_next(spider, site)
return _
dfd.addBoth(finish_scraping)
dfd.addErrback(log.err, 'Scraper bug processing %s' % request, \
spider=spider)
self._scrape_next(spider, site)
return dfd
def _scrape_next(self, spider, site):
while site.queue:
response, request, deferred = site.next_response_request_deferred()
self._scrape(response, request, spider).chainDeferred(deferred)
def _scrape(self, response, request, spider):
"""Handle the downloaded response or failure trough the spider
callback/errback"""
assert isinstance(response, (Response, Failure))
dfd = self._scrape2(response, request, spider) # returns spiders processed output
dfd.addErrback(self.handle_spider_error, request, spider)
dfd.addCallback(self.handle_spider_output, request, response, spider)
return dfd
def _scrape2(self, request_result, request, spider):
"""Handle the diferent cases of request's result been a Response or a
Failure"""
if not isinstance(request_result, Failure):
return self.spidermw.scrape_response(self.call_spider, \
request_result, request, spider)
else:
# FIXME: don't ignore errors in spider middleware
dfd = self.call_spider(request_result, request, spider)
return dfd.addErrback(self._check_propagated_failure, \
request_result, request, spider)
def call_spider(self, result, request, spider):
defer_result(result).chainDeferred(request.deferred)
return request.deferred.addCallback(iterate_spider_output)
def handle_spider_error(self, _failure, request, spider, propagated_failure=None):
referer = request.headers.get('Referer', None)
msg = "Spider exception caught while processing <%s> (referer: <%s>): %s" % \
(request.url, referer, _failure)
log.msg(msg, log.ERROR, spider=spider)
stats.inc_value("spider_exceptions/%s" % _failure.value.__class__.__name__, \
spider=spider)
def handle_spider_output(self, result, request, response, spider):
if not result:
return defer_succeed(None)
dfd = parallel(iter(result), 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
"""
# TODO: keep closing state internally instead of checking engine
if spider in self.engine.closing:
return
elif isinstance(output, Request):
send_catch_log(signal=signals.request_received, request=output, \
spider=spider)
self.engine.crawl(request=output, spider=spider)
elif isinstance(output, BaseItem):
log.msg("Scraped %s in <%s>" % (output, request.url), level=log.DEBUG, \
spider=spider)
send_catch_log(signal=signals.item_scraped, sender=self.__class__, \
item=output, spider=spider, response=response)
self.sites[spider].itemproc_size += 1
# FIXME: this can't be called here because the stats spider may be
# already closed
#stats.max_value('scraper/max_itemproc_size', \
# self.sites[spider].itemproc_size, spider=spider)
dfd = self.itemproc.process_item(output, spider)
dfd.addBoth(self._itemproc_finished, output, spider)
return dfd
elif output is None:
pass
else:
log.msg("Spider must return Request, BaseItem or None, got %r in %s" % \
(type(output).__name__, request), log.ERROR, spider=spider)
def _check_propagated_failure(self, spider_failure, propagated_failure, request, spider):
"""Log and silence the bugs raised outside of spiders, but still allow
spiders to be notified about general failures while downloading spider
generated requests
"""
# ignored requests are commonly propagated exceptions safes to be silenced
if isinstance(spider_failure.value, IgnoreRequest):
return
elif spider_failure is propagated_failure:
log.err(spider_failure, 'Unhandled error propagated to spider', \
spider=spider)
return # stop propagating this error
else:
return spider_failure # exceptions raised in the spider code
def _itemproc_finished(self, output, item, spider):
"""ItemProcessor finished for the given ``item`` and returned ``output``
"""
self.sites[spider].itemproc_size -= 1
if isinstance(output, Failure):
ex = output.value
if isinstance(ex, DropItem):
log.msg("Dropped %s - %s" % (item, str(ex)), level=log.WARNING, spider=spider)
send_catch_log(signal=signals.item_dropped, sender=self.__class__, \
item=item, spider=spider, exception=output.value)
else:
log.msg('Error processing %s - %s' % (item, output), \
log.ERROR, spider=spider)
else:
log.msg("Passed %s" % item, log.INFO, spider=spider)
send_catch_log(signal=signals.item_passed, sender=self.__class__, \
item=item, spider=spider, output=output)
