def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def _add_implementor(rpc_code, blocking, fn):

    # Validate the argument types.
    if type(rpc_code) is not int:
        raise TypeError("Expected int, got %r instead" % type(rpc_code))
    if type(blocking) is not bool:
        raise TypeError("Expected bool, got %r instead" % type(blocking))
    if not callable(fn):
        raise TypeError("Expected callable, got %r instead" % type(fn))

    # Validate the RPC code.
    if rpc_code in rpcMap:
        try:
            msg = "Duplicated RPC implementors for code %d: %s and %s"
            msg %= (rpc_code, rpcMap[rpc_code][0].__name__, fn.__name__)
        except Exception:
            msg = "Duplicated RPC implementors for code: %d" % rpc_code
        raise SyntaxError(msg)

    # TODO: use introspection to validate the function signature

    # Register the implementor.
    rpcMap[rpc_code] = (fn, blocking)

    # Return the implementor. No wrapping is needed! :)
    return fn