def insertWebsite(self, url, domain):
		'''增加一个网页,标记为未访问,并对相应的domain增加其入度'''
		cur = self.conn.cursor()
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		result = cur.fetchone()
		if not result:
			# 未有对应domain记录, 先创建domain, 把入度设为1
			if VERBOSE:
				print 'Spot Domain:',domain
			self.insertDomain(domain, indegree=1)
			cur.execute("SELECT did FROM Domains WHERE domain=?", (domain,))
			did = cur.fetchone()[0]
		else:
			did = result[0]
			# 对应的domain记录已经存在, 对其入度+1
			cur.execute("UPDATE Domains SET outdegree=outdegree+1 WHERE domain=?", (domain,))

		cur.execute("INSERT INTO Websites VALUES (NULL,?,?,NULL,0)", (did, url,))
		# 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