频率组件
一:自定义频率类
仿源码自定义频率规则:
class MyThrottles(): VISIT_RECORD = {} def __init__(self): self.history=None def allow_request(self,request, view): #(1)取出访问者ip ip=request.META.get('REMOTE_ADDR') import time ctime=time.time() # (2)判断当前ip不在访问字典里,添加进去,并且直接返回True,表示第一次访问 if ip not in self.VISIT_RECORD: self.VISIT_RECORD[ip]=[ctime,] return True self.history=self.VISIT_RECORD.get(ip) # (3)循环判断当前ip的列表,有值,并且当前时间减去列表的最后一个时间大于60s,把这种数据pop掉,这样列表中只有60s以内的访问时间, while self.history and ctime-self.history[-1]>60: self.history.pop() # (4)判断,当列表小于3,说明一分钟以内访问不足三次,把当前时间插入到列表第一个位置,返回True,顺利通过 # (5)当大于等于3,说明一分钟内访问超过三次,返回False验证失败 if len(self.history)<3: self.history.insert(0,ctime) return True else: return False def wait(self): import time ctime=time.time() return 60-(ctime-self.history[-1])
二:内置频率类的使用
定义频率类,必须继承SimpleRateThrottle类:
from rest_framework.throttling import SimpleRateThrottle class VisitThrottle(SimpleRateThrottle):
# 必须配置scope参数 通过scope参数去settings中找频率限定的规则 scope = 'throttle'
# 必须定义 get_cache_key函数 返回用户标识的key 这里借用源码中BaseThrottle类(SimpleRateThrottle的父类)中的get_ident函数返回用户ip地址 def get_cache_key(self, request, view): return self.get_ident(request)
局部使用:
视图函数中加上
throttle_classes = [VisitThrottle,]
全局使用:settings中配置
REST_FRAMEWORK={ 'DEFAULT_THROTTLE_CLASSES':['utils.common.VisitThrottle'],
# 局部使用也要在settings中配置上 DEFAULT_THROTTLE_RATES 通过self.scope取频率规则 (一分钟访问3次) 'DEFAULT_THROTTLE_RATES':{'throttle':'3/m',} }
设置错误信息为中文:
class Course(APIView): authentication_classes = [TokenAuth, ] permission_classes = [UserPermission, ] throttle_classes = [MyThrottles,] def get(self, request): return HttpResponse('get') def post(self, request): return HttpResponse('post')
# 函数名为throttled 重写Throttled类中默认的错误信息 def throttled(self, request, wait): from rest_framework.exceptions import Throttled class MyThrottled(Throttled): default_detail = '访问频繁' extra_detail_singular = '等待 {wait} second.' extra_detail_plural = '等待 {wait} seconds.' raise MyThrottled(wait)
三:源码分析
源码查看流程:
APIView的dispatch方法() ---- self.initial(request, *args, **kwargs) --- self.check_throttles(request)
SimpleRateThrottle类详解:
class SimpleRateThrottle(BaseThrottle): # 字典 {ip1:[time1,time2],ip2:[time1,time2]} 放在缓存中 cache = default_cache # 获取当前时间 timer = time.time # 做了一个字符串格式化,为登录用户ip限制,配合auth模块使用 cache_format = 'throttle_%(scope)s_%(ident)s' scope = None # 从配置文件中取DEFAULT_THROTTLE_RATES THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES def __init__(self): if not getattr(self, 'rate', None): # 从配置文件中找出scope配置的名字对应的值 self.rate = self.get_rate() self.num_requests, self.duration = self.parse_rate(self.rate) # 这个方法需要重写,否则直接抛异常 def get_cache_key(self, request, view): """ Should return a unique cache-key which can be used for throttling. Must be overridden. May return `None` if the request should not be throttled. """ raise NotImplementedError('.get_cache_key() must be overridden') def get_rate(self): if not getattr(self, 'scope', None): msg = ("You must set either `.scope` or `.rate` for '%s' throttle" % self.__class__.__name__) raise ImproperlyConfigured(msg) try: # 获取在setting里配置的字典中的值 return self.THROTTLE_RATES[self.scope] except KeyError: msg = "No default throttle rate set for '%s' scope" % self.scope raise ImproperlyConfigured(msg) # 解析 3/m这种传参 def parse_rate(self, rate): """ Given the request rate string, return a two tuple of: <allowed number of requests>, <period of time in seconds> """ if rate is None: return (None, None) num, period = rate.split('/') num_requests = int(num) # 只取了第一位,也就是 3/mimmmmmmm也是代表一分钟 duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]] return (num_requests, duration) # 频率验证逻辑 def allow_request(self, request, view): """ Implement the check to see if the request should be throttled. On success calls `throttle_success`. On failure calls `throttle_failure`. """ if self.rate is None: return True self.key = self.get_cache_key(request, view) if self.key is None: return True self.history = self.cache.get(self.key, []) self.now = self.timer() # Drop any requests from the history which have now passed the # throttle duration while self.history and self.history[-1] <= self.now - self.duration: self.history.pop() if len(self.history) >= self.num_requests: return self.throttle_failure() return self.throttle_success() # 成功返回true,并且插入到缓存中 def throttle_success(self): """ Inserts the current request's timestamp along with the key into the cache. """ self.history.insert(0, self.now) self.cache.set(self.key, self.history, self.duration) return True # 失败返回false def throttle_failure(self): """ Called when a request to the API has failed due to throttling. """ return False # 计算返回还需等待多长时间 def wait(self): """ Returns the recommended next request time in seconds. """ if self.history: remaining_duration = self.duration - (self.now - self.history[-1]) else: remaining_duration = self.duration available_requests = self.num_requests - len(self.history) + 1 if available_requests <= 0: return None return remaining_duration / float(available_requests)