def updateInfo(self, item, newlinks, oldlinks):
		'''爬虫爬完之后对数据库内容进行更新'''
		cur = self.conn.cursor()
		cur.execute("SELECT wid,did FROM Websites WHERE url=?", (item['url'],))
		wid, did = cur.fetchone()
		# website记录更新
		cur.execute("UPDATE Websites SET title=?,visited=1 WHERE wid=?", (item['title'], wid,))
		# 对应的domain记录中出度也需要更新
		cur.execute("UPDATE Domains SET outdegree=outdegree+? WHERE did=?", (len(item['links']), did,))

		# 对该网页中所有链接涉及的记录进行更新
		# 外部判断未出现过的链接
		for link,domain in newlinks:
			self.insertWebsite(link, domain)

		# 外部判断出现过的链接
		for link,domain in oldlinks:
			# 对对应的domain记录入度增加
			cur.execute("UPDATE Domains SET outdegree=outdegree+1 WHERE domain=?", (domain,))
		# 写入到文件
		self.conn.commit()
def _should_fetch(cls, dest, rev):
        """
        Return true if rev is a ref or is a commit that we don't have locally.

        Branches and tags are not considered in this method because they are
        assumed to be always available locally (which is a normal outcome of
        ``git clone`` and ``git fetch --tags``).
        """
        if rev.startswith("refs/"):
            # Always fetch remote refs.
            return True

        if not looks_like_hash(rev):
            # Git fetch would fail with abbreviated commits.
            return False

        if cls.has_commit(dest, rev):
            # Don't fetch if we have the commit locally.
            return False

        return True