Django:RestFramework之-------频率控制

5.频率控制

5.1频率监控代码实现

import time
VISIT_RECORD = {}
class VisitThrottle(object):
    def __init__(self):
        #定义历史记录，生产环境上，应该将其保存在redis
        self.history = []

    def allow_request(self,request,view):

        #1.获取用户IP
        remote_addr = request._request.META.get("REMOTE_ADDR")
        print(remote_addr)
        #记录访问时的时间
        ctime = time.time()
        #判断当前IP是否在访问记录中
        if remote_addr not in VISIT_RECORD:
            VISIT_RECORD[remote_addr] = [ctime,]
            return True
        #拿取当前访问IP记录
        history = VISIT_RECORD.get(remote_addr)

        #将历史访问时间记录，复制给self.history,以方便wait方法调用，通过wait方法告诉用户一些信息
        self.history = history

        #逻辑判断只记录1分钟内访问记录。
        while history and history[-1] < ctime-60:
            history.pop()
		#访问历史列表中时间记录不能大于3
        if len(history) < 3:
            history.insert(0,ctime)
            return True
    def wait(self):
        """用于提示多少秒后才可以重新访问"""
        #记录当前时间
        ctime = time.time()
        #返回告知用户还有多长时间可以再次访问
        return 60-(ctime - self.history[-1])

class AuthView(APIView):
    #用于频率限制
    throttle_classes = [VisitThrottle,]

    def post(self,request,*args,**kwargs):
        ret = {"code":1000,"msg":None}
        return JsonResponse(ret)

• 效果：

  当发送请求在监测频率范围内：

  

  当发送请求超出监测频率范围：返回信息提示，此信息提示为wait定义的。

  

5.2频率表权限源码解析

def dispatch(self, request, *args, **kwargs):
    ...
	try:
		#执行initial方法
		self.initial(request, *args, **kwargs)
	...

#---------------------------------------------------------
def initial(self, request, *args, **kwargs):
    ...
    self.check_throttles(request)#用于限制频率
    ...
#---------------------------------------------------------

    def check_throttles(self, request):
        throttle_durations = []
        #遍历 循环get_throttles
        for throttle in self.get_throttles():
            #如果allow_request返回False，则拒绝访问，并执行wait方法，抛出提示用户信息
            if not throttle.allow_request(request, self):
                throttle_durations.append(throttle.wait())
        if throttle_durations:
            self.throttled(request, max(throttle_durations))
#---------------------------------------------------------  
            
    def get_throttles(self):
        #实例化返回一个列表，当用户定义throttle_classes，则返回用户定义的[对象，对象...]
        #如果用户没有定义，将使用django内置配置：throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
        return [throttle() for throttle in self.throttle_classes]

5.3全局和局部配置权限：

#全局配置settings.py
REST_FRAMEWORK={
    'DEFAULT_THROTTLE_CLASSES':['app.utils.throttle.VisitThrottle']
}
#局部配置
类下面定义throttle_classes =[频率监测类,]

5.4内置频率类

class BaseThrottle:
	def allow_request(self, request, view):
        """
        如果应该允许请求，则返回True，否则返回False。
        """
        raise NotImplementedError('.allow_request() must be overridden')

    def get_ident(self, request):
        """
        通过解析HTTP_X_FORWARDED_FOR（如果存在且代理数> 0）来识别发出请求的机器。如果不可用，则使用所有HTTP_X_FORWARDED_FOR（如果可用），如果不使用，则不使用REMOTE_ADDR
        """
        xff = request.META.get('HTTP_X_FORWARDED_FOR')
        remote_addr = request.META.get('REMOTE_ADDR')
        num_proxies = api_settings.NUM_PROXIES

        if num_proxies is not None:
            if num_proxies == 0 or xff is None:
                return remote_addr
            addrs = xff.split(',')
            client_addr = addrs[-min(num_proxies, len(addrs))]
            return client_addr.strip()

        return ''.join(xff.split()) if xff else remote_addr

    def wait(self):
        """
        (可选）返回建议的秒数，以等待下一个请求
        """
        return None
#BaseThrottle定义了get_ident用于获取访问用户ID，这样可以自定义频率监测类继承BaseThrottle，通过调用父类方法，获取访问用户ID
	remote_addr = self.get_ident(request)
    
#------------------------------------------------------------------------------------------------
class SimpleRateThrottle(BaseThrottle):
	"""一个简单的缓存实现，只需要覆盖.get_cache_key（）即可。速率（请求/秒）由View类的“ rate”属性设置。该属性是形式为'number_of_requests / period'的字符串。周期应为以下之一：（'s'，'sec'，'m'，'min'，'h'，'hour'，'d'，'day'）用于限制的先前请求信息存储在缓存中"""
    
	cache = default_cache
    timer = time.time
    cache_format = 'throttle_%(scope)s_%(ident)s'
    scope = None
    THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES

    def __init__(self):
        if not getattr(self, 'rate', None):
            self.rate = self.get_rate()
            #num_requests表示次数，duration表示秒/分数
        self.num_requests, self.duration = self.parse_rate(self.rate)

    def get_cache_key(self, request, view):
        """
        应该返回一个唯一的可用于节流的缓存键。必须重写。如果不应该限制请求，则可能会返回“无”
        """
        raise NotImplementedError('.get_cache_key() must be overridden')

    def get_rate(self):
        """
        确定允许请求速率
        """
        if not getattr(self, 'scope', None):
            msg = ("You must set either `.scope` or `.rate` for '%s' throttle" %
                   self.__class__.__name__)
            raise ImproperlyConfigured(msg)

        try:
            return self.THROTTLE_RATES[self.scope]
        except KeyError:
            msg = "No default throttle rate set for '%s' scope" % self.scope
            raise ImproperlyConfigured(msg)

    def parse_rate(self, rate):
        """
        给定请求速率字符串
        """
        if rate is None:
            return (None, None)
        num, period = rate.split('/')
        num_requests = int(num)
        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
        return (num_requests, duration)

    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
        # 将访问者信息放在缓存中
        self.key = self.get_cache_key(request, view)
        if self.key is None:
            return True
        #从缓存拿历史记录， cache = default_cache为Django内置缓存
        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()

    def throttle_success(self):
        #成功返回
        """
        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

    def throttle_failure(self):
        #失败返回
        """
        Called when a request to the API has failed due to throttling.
        """
        return False

    def wait(self):
        """
        返回建议的下一个请求时间（以秒为单位）。
        """
        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)
#SimpleRateThrottle 内置分装好了监测频率各种（成功返回，错误返回，定义访问频次，返回下一次请求时间，确定速率等）方法。这样我们自己定义类继承SimpleRateThrottle

#更改自定义频率监测：
class VisitThrottle(SimpleRateThrottle):
    scope = "key"#根据scope的值，去配置文件找频率设置
    def get_cache_key(self, request, view):
        return self.get_ident(request)
#settings.py配置

REST_FRAMEWORK={
    'DEFAULT_THROTTLE_CLASSES':['app.utils.throttle.VisitThrottle'],
    "DEFAULT_THROTTLE_RATES":{
        #设置频率3/m表示每分钟最多访问3次，并给予标识
        'key':'3/m'
    }

}

5.5对当前登录用户进行操作

#settings.py配置
REST_FRAMEWORK={
    'DEFAULT_THROTTLE_CLASSES':['app.utils.throttle.VisitThrottle'],
    "DEFAULT_THROTTLE_RATES":{
        'key':'3/m',
        #用于登录用户频率监测配置设置
        'vipkey':'10/m',
    }
}
#throttle.py
#定义登录用户频次监测类
class UserThrottle(SimpleRateThrottle):
    scope = "vipkey"
    def get_cache_key(self, request, view):
        #返回登录用户名
        return request.user.username
#因定义登录用户检测的类，不能放入settings配置,应予以局部添加
class OrderView(APIView):
	throttle_classes = [UserThrottle, ]

5.6小总结：

基本使用：
	类    继承：BaseThrottle 实现:allow_request,wait 方法
	类    继承：SimpleRateThrottle 实现：get_cache_key ,scope (配置文件中的key，去找频率设置)