def open(self, spider):
"""
Open the scheduler for the spider and initializing the queue and
duplication filter.
"""
self.spider = spider
self.queue = RedisPriorityQueue(self.server, self.spider.name + ':queue')
self.dupefilter = RedisRFPDupefilter(self.server, self.spider.name + ':dupefilter', self.df_timeout)
class RedisScheduler(object):
def __init__(self, server, persist, timeout, retries):
self.server = server
self.persist = persist
self.df_timeout = timeout
self.item_retries = retries
self.spider = None
self.queue = None
self.dupefilter = None
@classmethod
def from_settings(cls, settings):
server = redis.StrictRedis(host=settings.get('REDIS_HOST'), port=settings.get('REDIS_PORT'))
persist = settings.get('SCHEDULER_PERSIST', False)
timeout = settings.get('DUPEFILTER_TIMEOUT', 600)
retries = settings.get('SCHEDULER_ITEM_RETRIES', 3)
return cls(server, persist, timeout, retries)
@classmethod
def from_crawler(cls, crawler):
return cls.from_settings(crawler.settings)
def open(self, spider):
"""
Open the scheduler for the spider and initializing the queue and
duplication filter.
"""
self.spider = spider
self.queue = RedisPriorityQueue(self.server, self.spider.name + ':queue')
self.dupefilter = RedisRFPDupefilter(self.server, self.spider.name + ':dupefilter', self.df_timeout)
def close(self, reason):
if not self.persist:
self.dupefilter.clear()
self.queue.clear()
def has_pending_requests(self):
return len(self.queue) > 0
def enqueue_request(self, request):
if not request.dont_filter and self.dupefilter.request_seen(request):
return False
req_dict = request_to_dict(request, self.spider)
self.queue.push(req_dict, request.priority)
return True
def next_request(self):
item = self._retrieve_from_queue()
if item:
try:
request = request_from_dict(item, self.spider)
except KeyError:
request = self._request_from_dict(item)
return self._populate_request(request, item)
else:
return None
def _retrieve_from_queue(self):
count = 0
while count <= self.item_retries:
item = self.queue.pop()
if item:
return item
count = count + 1
return None
def _request_from_dict(self, item):
request = Request(item['url'])
request.meta['crawlid'] = item.get('crawlid', 'default')
request.meta['maxdepth'] = item.get('maxdepth', 0)
request.priority = item.get('priority', 0)
request.meta['priority'] = request.priority
return request
def _populate_request(self, request, item):
if 'extra' in item:
extra = item['extra']
else:
extra = request.meta.copy()
extra.setdefault('priority', request.priority)
# link extractor related values
extra.setdefault('allow', ())
extra.setdefault('deny', ())
extra.setdefault('allow_domains', ())
extra.setdefault('deny_domains', ())
extra.setdefault('restrict_xpaths', ())
extra.setdefault('restrict_css', ())
request.meta.update(extra)
return request
