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 init(num_players):
	global MAP_WIDTH,MAP_HEIGHT,N_ITERATIONS,H_RATIO,W_RATIO,MIN_ROOM_SIDE,CENTER_HUB_HOLE,CENTER_HUB_RADIO,MAP_NAME
	MAP_WIDTH=int(500*sqrt(num_players))
	MAP_HEIGHT=MAP_WIDTH
	N_ITERATIONS=log(MAP_WIDTH*100,2)
	H_RATIO=0.49
	W_RATIO=H_RATIO
	MIN_ROOM_SIDE = 32
	CENTER_HUB_HOLE = 32
	CENTER_HUB_RADIO = CENTER_HUB_HOLE-MIN_ROOM_SIDE/2
	MAP_NAME="result%s.png"%MAP_WIDTH