Django REST_framework 頻率類

頻率類

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 = []
        # 循環取出數據
        for throttle in self.get_throttles():
            # 判斷是否存在, 因此能夠重寫allow_request方法, 自定義頻率限制
            if not throttle.allow_request(request, self):
                throttle_durations.append(throttle.wait())

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

 

頻率類的簡單使用

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


class Throttle(SimpleRateThrottle):
    # 必須使用scope設定一個名詞
    scope = 'lxx'

    # 重寫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 = {
    # 頻率
    'DEFAULT_THROTTLE_RATES':{
        # 經過設定的名詞
        'lxx': '3/m'   # 因爲源碼中只取day, hour, minute, second的第一個字母, 因此能夠不用寫全, 只寫首字母就能夠
    }
}

 

自定義頻率限制的使用

from rest_framework.throttling import BaseThrottle


class MyThrottle(BaseThrottle):
    VISIT_RECORD = {}

    def __init__(self):
        self.history = None

    def allow_request(self, request, view):
        # （1）取出訪問者ip
        ip = request.META.get('REMOTE_ADDR')
        import time
        ctime = time.time()
        # （2）判斷當前ip不在訪問字典裏，添加進去，而且直接返回True,表示第一次訪問，在字典裏，繼續往下走
        if ip not in self.VISIT_RECORD:
            self.VISIT_RECORD[ip] = [ctime, ]
            return True
        self.history = self.VISIT_RECORD.get(ip)
        # （3）循環判斷當前ip的列表，有值，而且當前時間減去列表的最後一個時間大於60s，把這種數據pop掉，這樣列表中只有60s之內的訪問時間，
        while self.history and ctime - self.history[-1] > 60:
            self.history.pop()
        # （4）判斷，當列表小於3，說明一分鐘之內訪問不足三次，把當前時間插入到列表第一個位置，返回True，順利經過
        if len(self.history) < 3:
            self.history.insert(0, ctime)
            return True
        # （5）當大於等於3，說明一分鐘內訪問超過三次，返回False驗證失敗
        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('')

 

 

認證類的使用

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 = []

 

內置頻率限制類：

BaseThrottle是全部類的基類：方法：def get_ident(self, request)獲取標識，其實就是獲取ip，自定義的須要繼承它

AnonRateThrottle：未登陸用戶ip限制，須要配合auth模塊用

SimpleRateThrottle：重寫此方法，能夠實現頻率如今，不須要我們手寫上面自定義的邏輯

UserRateThrottle:登陸用戶頻率限制，這個得配合auth模塊來用

ScopedRateThrottle：應用在局部視圖上的（忽略）

 

SimpleRateThrottle源碼分析

class SimpleRateThrottle(BaseThrottle):
    # 咱本身寫的放在了全局變量，他的在django的緩存中
    cache = default_cache
    # 獲取當前時間，跟咱寫的同樣
    timer = time.time
    # 作了一個字符串格式化，
    cache_format = 'throttle_%(scope)s_%(ident)s'
    scope = None
    # 從配置文件中取DEFAULT_THROTTLE_RATES，因此咱配置文件中應該配置，不然報錯
    THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES

    def __init__(self):
        if not getattr(self, 'rate', None):
            # 從配置文件中找出scope配置的名字對應的值，好比咱寫的‘3/m’,他取出來
            self.rate = self.get_rate()
        #     解析'3/m',解析成 3      m
        self.num_requests, self.duration = self.parse_rate(self.rate)
    # 這個方法須要重寫
    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:
            # 獲取在setting裏配置的字典中的之，self.scope是 咱寫的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這種傳參
    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也是表明一分鐘
        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
        return (num_requests, duration)
    # 邏輯跟咱自定義的相同
    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，而且插入到緩存中
    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
    # 失敗返回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源碼分析