text: from __future__ import with_statement
  
  import os, cPickle as pickle
  
  from scrapy import signals
  from scrapy.exceptions import NotConfigured
  from scrapy.xlib.pydispatch import dispatcher
  
  class SpiderState(object):
      """Store and load spider state during a scraping job"""
  
      def __init__(self, jobdir=None):
          self.jobdir = jobdir
  
      @classmethod
      def from_crawler(cls, crawler):
          obj = cls(crawler.settings.get('JOBDIR'))
          dispatcher.connect(obj.spider_closed, signal=signals.spider_closed)
          dispatcher.connect(obj.spider_opened, signal=signals.spider_opened)
          return obj
  
      def spider_closed(self, spider):
          if self.jobdir:
              with open(self.statefn, 'wb') as f:
                  pickle.dump(spider.state, f, protocol=2)
  
      def spider_opened(self, spider):
          if self.jobdir and os.path.exists(self.statefn):
              with open(self.statefn) as f:
                  spider.state = pickle.load(f)
          else:
              spider.state = {}
  
      @property
      def statefn(self):
          return os.path.join(self.jobdir, 'spider.state')
  