豆瓣API限制次数

API限制为每分钟40次，一不小心就超了，马上KEY就被封了，等了半个多小时居然还没有解封，只能用不带KEY的API，每分钟只有可怜的10次。
马上写了一个限制类，还挺好用的
用法：
1.
client = Limit(DoubanService(server=SERVER), 60, 9)
调用client.some_services_function()的时候，如果超过了访问限制，就会自动sleep，到指定的时刻再继续干活
2.
用来限制函数也可以
urlopen = Limit(urllib2.urlopen, 60, 40)
$ cat limit.py
import time
import unittest
import logging
logger = logging.getLogger('Limit')
class Limit(object):
    def __init__(self, obj_or_func, seconds=None, maxn=None):
        self.obj_or_func = obj_or_func
        self.seconds = seconds
        self.maxn = maxn
        self.hist = []
    def check(self):
        now = time.time()
        hist = [ i for i in self.hist if i>=now-self.seconds ]
        if len(hist) >= self.maxn:
            t = hist[0]+self.seconds-now
            logger.debug('exceed limit, go to sleep for %.1f seconds'%t)
            time.sleep(t)
        self.hist = hist+[time.time()]
    def __getattr__(self, name):
        if self.seconds and self.maxn:
            self.check()
        return object.__getattribute__(self.obj_or_func, name)
    def __call__(self, *args, **kw):
        if self.seconds and self.maxn:
            self.check()
        return self.obj_or_func(*args, **kw)
class LimitTest(unittest.TestCase):
    def setUp(self):
        self.obj = {}
        self.func = lambda:0
    def test_obj1(self):
        l = Limit(self.obj, .1, 2)
        t1 = time.time()
        for i in range(1):
            l.keys
        self.assertTrue(time.time()-t1<.1)
    def test_obj2(self):
        l = Limit(self.obj, .1, 2)
        t1 = time.time()
        for i in range(3):
            l.keys
        self.assertTrue(time.time()-t1>.1)
    def test_obj3(self):
        l = Limit(self.obj, .1, 2)
        t1 = time.time()
        for i in range(5):
            l.keys
        self.assertTrue(time.time()-t1>.2)
    def test_func(self):
        l = Limit(self.func, .1, 2)
        t1 = time.time()
        for i in range(3):
            l()
        self.assertTrue(time.time()-t1>.1)