Django REST_framework 频率类

频率类

APIView -> dispatch -> self.initial -> self.check_throttles

 def check_throttles(self, request):
        """
        Check if request should be throttled.
        Raises an appropriate exception if the request is throttled.
        """
        throttle_durations = []
        # 循环取出数据
        for throttle in self.get_throttles():
            # 判断是否存在, 因此能够重写allow_request方法, 自定义频率限制
            if not throttle.allow_request(request, self):
                throttle_durations.append(throttle.wait())

        if throttle_durations:
            self.throttled(request, max(throttle_durations))

 

频率类的简单使用

from rest_framework.views import APIView
from rest_framework.throttling import SimpleRateThrottle


class Throttle(SimpleRateThrottle):
    # 必须使用scope设定一个名词
    scope = 'lxx'

    # 重写get_cache_key方法
    def get_cache_key(self, request, view):
        return self.get_ident(request)


class Books(APIView):
    throttle_classes = [Throttle, ]
    def get(self, request):
        return Response('')

settings.py文件
REST_FRAMEWORK = {
    # 频率
    'DEFAULT_THROTTLE_RATES':{
        # 经过设定的名词
        'lxx': '3/m'   # 因为源码中只取day, hour, minute, second的第一个字母, 因此能够不用写全, 只写首字母就能够
    }
}

 

自定义频率限制的使用

from rest_framework.throttling import BaseThrottle


class MyThrottle(BaseThrottle):
    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，而且直接返回True,表示第一次访问，在字典里，继续往下走
        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，而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之内的访问时间，
        while self.history and ctime - self.history[-1] > 60:
            self.history.pop()
        # （4）判断，当列表小于3，说明一分钟之内访问不足三次，把当前时间插入到列表第一个位置，返回True，顺利经过
        if len(self.history) < 3:
            self.history.insert(0, ctime)
            return True
        # （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
        else:
            return False

    def wait(self):
        import time
        ctime = time.time()
        return 60 - (ctime - self.history[-1])


class Books(APIView):
    throttle_classes = [Throttle, ]

    def get(self, request):
        return Response('')

 

 

认证类的使用

局部使用

class Index(APIView):
    throttle_classes = [Throttle,]

全局使用

settings文件
REST_FRAMEWORK = {
    "DEFAULT_THROTTLE_RATES": {
　　　　'lxx': '3/m'
　　}
}

局部不使用

class Index(APIView):
    throttle_classes = []

 

内置频率限制类：

BaseThrottle是全部类的基类：方法：def get_ident(self, request)获取标识，其实就是获取ip，自定义的须要继承它

AnonRateThrottle：未登陆用户ip限制，须要配合auth模块用

SimpleRateThrottle：重写此方法，能够实现频率如今，不须要我们手写上面自定义的逻辑

UserRateThrottle:登陆用户频率限制，这个得配合auth模块来用

ScopedRateThrottle：应用在局部视图上的（忽略）

 

SimpleRateThrottle源码分析

class SimpleRateThrottle(BaseThrottle):
    # 咱本身写的放在了全局变量，他的在django的缓存中
    cache = default_cache
    # 获取当前时间，跟咱写的同样
    timer = time.time
    # 作了一个字符串格式化，
    cache_format = 'throttle_%(scope)s_%(ident)s'
    scope = None
    # 从配置文件中取DEFAULT_THROTTLE_RATES，因此咱配置文件中应该配置，不然报错
    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，好比咱写的‘3/m’,他取出来
            self.rate = self.get_rate()
        #     解析'3/m',解析成 3      m
        self.num_requests, self.duration = self.parse_rate(self.rate)
    # 这个方法须要重写
    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里配置的字典中的之，self.scope是 咱写的lxx
            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也是表明一分钟
        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
        return (num_requests, duration)
    # 逻辑跟咱自定义的相同
    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，而且插入到缓存中
    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

    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)

SimpleRateThrottle源码分析