django之访问频率

频率组件

-使用：
　　-第一步，写一个频率类，继承SimpleRateThrottle
　　　　#重写get_cache_key，返回self.get_ident(request)
　　　　#一定要记住配置一个scop=字符串

class Throttle(SimpleRateThrottle):
　　scope = 'lxx'
　　def get_cache_key(self, request, view):
　　return self.get_ident(request)

　　-第二步：在setting中配置
　　　　

REST_FRAMEWORK = {
'DEFAULT_THROTTLE_RATES':{
'lxx':'3/m'
}}

-局部使用
　　-在视图类中配置：
　　-throttle_classes=[Throttle,]
-全局使用
　　-在setting中配置
　　'DEFAULT_THROTTLE_CLASSES':['自己定义的频率类'],
-局部禁用
　　throttle_classes=[]
频率组件分析：
-核心源代码：

def check_throttles(self, request):
　　for throttle in self.get_throttles():
　　　　if not throttle.allow_request(request, self):
　　　　　　self.throttled(request, throttle.wait())

-自定义的频率类：详解代码views.py 25行开始

#自定义频率类
class MyThrottle(BaseThrottle):
    VISIT_RECORD = {}
    def __init__(self):
        self.history=None
    def allow_request(self,request,view):  #  校验是否可以访问
        #自定义控制每分钟访问多少次，运行访问返回true，不允许访问返回false
        # （1）取出访问者ip{ip1:[第二次访问时间，第一次访问时间],ip2:[]}
        # （2）判断当前ip不在访问字典里，如果不在添加进去，并且直接返回True,表示第一次访问，在字典里，继续往下走
        # （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，
        # （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
        # （1）取出访问者ip
        # print(request.META)
        #取出访问者ip
        ip = request.META.get('REMOTE_ADDR')
        import time
        #拿到当前时间
        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
        #是个当前访问者ip对应的时间列表 [第一次访问的时间，]
        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()
　　　　 #  返回多少秒之后可以再次访问　　
        return 60 - (ctime - self.history[-1])

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

-SimpleRateThrottle源码

class SimpleRateThrottle(BaseThrottle):
    """
    A simple cache implementation, that only requires `.get_cache_key()`
    to be overridden.

    The rate (requests / seconds) is set by a `rate` attribute on the View
    class.  The attribute is a string of the form 'number_of_requests/period'.

    Period should be one of: ('s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day')

    Previous request information used for throttling is stored in the cache.
    """
    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()
        self.num_requests, self.duration = self.parse_rate(self.rate)

    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):
        """
        Determine the string representation of the allowed request rate.
        """
        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):
        """
        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)
        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

        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()

    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

    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)