# Source code for scrapy.extensions.logstats

    import logging

    from twisted.internet import task

    from scrapy.exceptions import NotConfigured
    from scrapy import signals

    logger = logging.getLogger(__name__)

    class LogStats:
        """Log basic scraping stats periodically"""

        def __init__(self, stats, interval=60.0):
            self.stats = stats
            self.interval = interval
            self.multiplier = 60.0 / self.interval
            self.task = None

        @classmethod
        def from_crawler(cls, crawler):
            interval = crawler.settings.getfloat('LOGSTATS_INTERVAL')
            if not interval:
                raise NotConfigured
            o = cls(crawler.stats, interval)
            crawler.signals.connect(o.spider_opened, signal=signals.spider_opened)
            crawler.signals.connect(o.spider_closed, signal=signals.spider_closed)
            return o

        def spider_opened(self, spider):
            self.pagesprev = 0
            self.itemsprev = 0

            self.task = task.LoopingCall(self.log, spider)
            self.task.start(self.interval)

        def log(self, spider):
            items = self.stats.get_value('item_scraped_count', 0)
            pages = self.stats.get_value('response_received_count', 0)
            irate = (items - self.itemsprev) * self.multiplier
            prate = (pages - self.pagesprev) * self.multiplier
            self.pagesprev, self.itemsprev = pages, items

            msg = ("Crawled %(pages)d pages (at %(pagerate)d pages/min), "
                   "scraped %(items)d items (at %(itemrate)d items/min)")
            log_args = {'pages': pages, 'pagerate': prate,
                        'items': items, 'itemrate': irate}
            logger.info(msg, log_args, extra={'spider': spider})

        def spider_closed(self, spider, reason):
            if self.task and self.task.running:
                self.task.stop()