12.DRF-节流

Posted 2020-12-11 yanadoude

Django rest framework源码分析（3）----节流

添加节流

自定义节流的方法

• 限制60s内只能访问3次

（1）API文件夹下面新建throttle.py，代码如下：

# utils/throttle.py

from rest_framework.throttling import BaseThrottle
import time
VISIT_RECORD = {}   #保存访问记录

class VisitThrottle(BaseThrottle):
    ‘‘‘60s内只能访问3次‘‘‘
    def __init__(self):
        self.history = None   #初始化访问记录

    def allow_request(self,request,view):
        #获取用户ip (get_ident)
        remote_addr = self.get_ident(request)
        ctime = time.time()
        #如果当前IP不在访问记录里面，就添加到记录
        if remote_addr not in VISIT_RECORD:
            VISIT_RECORD[remote_addr] = [ctime,]     #键值对的形式保存
            return True    #True表示可以访问
        #获取当前ip的历史访问记录
        history = VISIT_RECORD.get(remote_addr)
        #初始化访问记录
        self.history = history

        #如果有历史访问记录，并且最早一次的访问记录离当前时间超过60s，就删除最早的那个访问记录，
        #只要为True，就一直循环删除最早的一次访问记录
        while history and history[-1] < ctime - 60:
            history.pop()
        #如果访问记录不超过三次，就把当前的访问记录插到第一个位置（pop删除最后一个）
        if len(history) < 3:
            history.insert(0,ctime)
            return True

    def wait(self):
        ‘‘‘还需要等多久才能访问‘‘‘
        ctime = time.time()
        return 60 - (ctime - self.history[-1])

（2）settings中全局配置节流

#全局
REST_FRAMEWORK = {
    #节流
    "DEFAULT_THROTTLE_CLASSES":[‘API.utils.throttle.VisitThrottle‘],
}

（3）现在访问auth看看结果：

• 60s内访问次数超过三次，会限制访问
• 提示剩余多少时间可以访问

接着访问

节流源码分析

（1）dispatch

def dispatch(self, request, *args, **kwargs):
    """
    `.dispatch()` is pretty much the same as Django‘s regular dispatch,
    but with extra hooks for startup, finalize, and exception handling.
    """
    self.args = args
    self.kwargs = kwargs
    #对原始request进行加工，丰富了一些功能
    #Request(
    #     request,
    #     parsers=self.get_parsers(),
    #     authenticators=self.get_authenticators(),
    #     negotiator=self.get_content_negotiator(),
    #     parser_context=parser_context
    # )
    #request(原始request,[BasicAuthentications对象，])
    #获取原生request,request._request
    #获取认证类的对象，request.authticators
    #1.封装request
    request = self.initialize_request(request, *args, **kwargs)
    self.request = request
    self.headers = self.default_response_headers  # deprecate?

    try:
        #2.认证
        self.initial(request, *args, **kwargs)

        # Get the appropriate handler method
        if request.method.lower() in self.http_method_names:
            handler = getattr(self, request.method.lower(),
                                  self.http_method_not_allowed)
        else:
            handler = self.http_method_not_allowed

        response = handler(request, *args, **kwargs)

    except Exception as exc:
        response = self.handle_exception(exc)

    self.response = self.finalize_response(request, response, *args, **kwargs)
    return self.response

（2）initial

def initial(self, request, *args, **kwargs):
    """
    Runs anything that needs to occur prior to calling the method handler.
    """
    self.format_kwarg = self.get_format_suffix(**kwargs)

    # Perform content negotiation and store the accepted info on the request
    neg = self.perform_content_negotiation(request)
    request.accepted_renderer, request.accepted_media_type = neg

    # Determine the API version, if versioning is in use.
    version, scheme = self.determine_version(request, *args, **kwargs)
    request.version, request.versioning_scheme = version, scheme

    # Ensure that the incoming request is permitted
    #4.实现认证
    self.perform_authentication(request)
    #5.权限判断
    self.check_permissions(request)
    #6.控制访问频率
    self.check_throttles(request)

（3）check_throttles

里面有个allow_request

def check_throttles(self, request):
    """
    Check if request should be throttled.
    Raises an appropriate exception if the request is throttled.
    """
    for throttle in self.get_throttles():
        if not throttle.allow_request(request, self):
            self.throttled(request, throttle.wait())

（4）get_throttles

def get_throttles(self):
    """
    Instantiates and returns the list of throttles that this view uses.
    """
    return [throttle() for throttle in self.throttle_classes]

（5）thtottle_classes

内置节流类

上面是写的自定义节流，drf内置了很多节流的类，用起来比较方便。

（1）BaseThrottle

• 自己要写allow_request和wait方法
• get_ident就是获取ip

class BaseThrottle(object):
    """
    Rate throttling of requests.
    """

    def allow_request(self, request, view):
        """
        Return `True` if the request should be allowed, `False` otherwise.
        """
        raise NotImplementedError(‘.allow_request() must be overridden‘)

    def get_ident(self, request):
        """
        Identify the machine making the request by parsing HTTP_X_FORWARDED_FOR
        if present and number of proxies is > 0. If not use all of
        HTTP_X_FORWARDED_FOR if it is available, if not use 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):
        """
        Optionally, return a recommended number of seconds to wait before
        the next request.
        """
        return None

（2）SimpleRateThrottle

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   #这个值自定义，写什么都可以
    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)

我们可以通过继承SimpleRateThrottle类，来实现节流，会更加的简单，因为SimpleRateThrottle里面都帮我们写好了

（1）throttle.py

from rest_framework.throttling import SimpleRateThrottle

class VisitThrottle(SimpleRateThrottle):
    ‘‘‘匿名用户60s只能访问三次（根据ip）‘‘‘
    scope = ‘NBA‘   #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        #通过ip限制节流
        return self.get_ident(request)

class UserThrottle(SimpleRateThrottle):
    ‘‘‘登录用户60s可以访问10次‘‘‘
    scope = ‘NBAUser‘    #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        return request.user.username

（2）settings.py

#全局
REST_FRAMEWORK = {
    #节流
    "DEFAULT_THROTTLE_CLASSES":[‘API.utils.throttle.UserThrottle‘],   #全局配置，登录用户节流限制（10/m）
    "DEFAULT_THROTTLE_RATES":{
        ‘NBA‘:‘3/m‘,         #没登录用户3/m，NBA就是scope定义的值
        ‘NBAUser‘:‘10/m‘,    #登录用户10/m，NBAUser就是scope定义的值
    }
}

（3）views.py

局部配置方法

class AuthView(APIView):
    .
    .    
    .
    # 默认的节流是登录用户（10/m）,AuthView不需要登录，这里用匿名用户的节流（3/m）
    throttle_classes = [VisitThrottle,]　 　.    .

# views.py
from django.shortcuts import render,HttpResponse
from django.http import JsonResponse
from rest_framework.views import APIView
from API import models
from rest_framework.request import Request
from rest_framework import exceptions
from rest_framework.authentication import BaseAuthentication
from API.utils.permission import SVIPPremission,MyPremission
from API.utils.throttle import  VisitThrottle

ORDER_DICT = {
    1:{
        ‘name‘:‘apple‘,
        ‘price‘:15
    },
    2:{
        ‘name‘:‘dog‘,
        ‘price‘:100
    }
}

def md5(user):
    import hashlib
    import time
    #当前时间，相当于生成一个随机的字符串
    ctime = str(time.time())
    m = hashlib.md5(bytes(user,encoding=‘utf-8‘))
    m.update(bytes(ctime,encoding=‘utf-8‘))
    return m.hexdigest()


class AuthView(APIView):
    ‘‘‘用于用户登录验证‘‘‘

    authentication_classes = []      #里面为空，代表不需要认证
    permission_classes = []          #不里面为空，代表不需要权限
    # 默认的节流是登录用户（10/m）,AuthView不需要登录，这里用匿名用户的节流（3/m）
    throttle_classes = [VisitThrottle,]

    def post(self,request,*args,**kwargs):
        ret = {‘code‘:1000,‘msg‘:None}
        try:
            user = request._request.POST.get(‘username‘)
            pwd = request._request.POST.get(‘password‘)
            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()
            if not obj:
                ret[‘code‘] = 1001
                ret[‘msg‘] = ‘用户名或密码错误‘
            #为用户创建token
            token = md5(user)
            #存在就更新，不存在就创建
            models.UserToken.objects.update_or_create(user=obj,defaults={‘token‘:token})
            ret[‘token‘] = token
        except Exception as e:
            ret[‘code‘] = 1002
            ret[‘msg‘] = ‘请求异常‘
        return JsonResponse(ret)


class OrderView(APIView):
    ‘‘‘
    订单相关业务(只有SVIP用户才能看)
    ‘‘‘

    def get(self,request,*args,**kwargs):
        self.dispatch
        #request.user
        #request.auth
        ret = {‘code‘:1000,‘msg‘:None,‘data‘:None}
        try:
            ret[‘data‘] = ORDER_DICT
        except Exception as e:
            pass
        return JsonResponse(ret)


class UserInfoView(APIView):
    ‘‘‘
       订单相关业务(普通用户和VIP用户可以看)
       ‘‘‘
    permission_classes = [MyPremission,]    #不用全局的权限配置的话，这里就要写自己的局部权限
    def get(self,request,*args,**kwargs):

        print(request.user)
        return HttpResponse(‘用户信息‘)

说明：

• API.utils.throttle.UserThrottle 这个是全局配置（根据ip限制，10/m）
• DEFAULT_THROTTLE_RATES --->>>设置访问频率的
• throttle_classes = [VisitThrottle,] --->>>局部配置（不适用settings里面默认的全局配置）

总结

基本使用

• 创建类，继承BaseThrottle, 实现：allow_request ，wait
• 创建类，继承SimpleRateThrottle, 实现： get_cache_key， scope=‘NBA‘ (配置文件中的key)

全局

   #节流
    "DEFAULT_THROTTLE_CLASSES":[‘API.utils.throttle.UserThrottle‘],   #全局配置，登录用户节流限制（10/m）
    "DEFAULT_THROTTLE_RATES":{
        ‘NBA‘:‘3/m‘,         #没登录用户3/m，NBA就是scope定义的值
        ‘NBAUser‘:‘10/m‘,    #登录用户10/m，NBAUser就是scope定义的值
    }
}

局部

throttle_classes = [VisitThrottle,]

所有代码

认证、权限和节流

# MyProject/urls.py

from django.contrib import admin
from django.urls import path
from API.views import AuthView,OrderView,UserInfoView

urlpatterns = [
    path(‘admin/‘, admin.site.urls),
    path(‘api/v1/auth/‘,AuthView.as_view()),
    path(‘api/v1/order/‘,OrderView.as_view()),
    path(‘api/v1/info/‘,UserInfoView.as_view()),
]

#全局 settings.py
REST_FRAMEWORK = {
    #认证
    "DEFAULT_AUTHENTICATION_CLASSES":[‘API.utils.auth.Authentication‘,],
    #权限
    "DEFAULT_PERMISSION_CLASSES":[‘API.utils.permission.SVIPPermission‘],
    #节流
    "DEFAULT_THROTTLE_CLASSES":[‘API.utils.throttle.UserThrottle‘],   #全局配置，登录用户节流限制（10/m）
    "DEFAULT_THROTTLE_RATES":{
        ‘NBA‘:‘3/m‘,         #没登录用户3/m，NBA就是scope定义的值
        ‘NBAUser‘:‘10/m‘,    #登录用户10/m，NBAUser就是scope定义的值
    }
}

# API/models.py


from django.db import models

class UserInfo(models.Model):
    USER_TYPE = (
        (1,‘普通用户‘),
        (2,‘VIP‘),
        (3,‘SVIP‘)
    )

    user_type = models.IntegerField(choices=USER_TYPE)
    username = models.CharField(max_length=32)
    password = models.CharField(max_length=64)

class UserToken(models.Model):
    user = models.OneToOneField(UserInfo,on_delete=models.CASCADE)
    token = models.CharField(max_length=64)

# API/views.py

from django.shortcuts import render,HttpResponse
from django.http import JsonResponse
from rest_framework.views import APIView
from API import models
from rest_framework.request import Request
from rest_framework import exceptions
from rest_framework.authentication import BaseAuthentication
from API.utils.permission import SVIPPermission,MyPermission
from API.utils.throttle import  VisitThrottle

ORDER_DICT = {
    1:{
        ‘name‘:‘apple‘,
        ‘price‘:15
    },
    2:{
        ‘name‘:‘dog‘,
        ‘price‘:100
    }
}

def md5(user):
    import hashlib
    import time
    #当前时间，相当于生成一个随机的字符串
    ctime = str(time.time())
    m = hashlib.md5(bytes(user,encoding=‘utf-8‘))
    m.update(bytes(ctime,encoding=‘utf-8‘))
    return m.hexdigest()


class AuthView(APIView):
    ‘‘‘用于用户登录验证‘‘‘

    authentication_classes = []      #里面为空，代表不需要认证
    permission_classes = []          #不里面为空，代表不需要权限
    # 默认的节流是登录用户（10/m）,AuthView不需要登录，这里用匿名用户的节流（3/m）
    throttle_classes = [VisitThrottle,]

    def post(self,request,*args,**kwargs):
        ret = {‘code‘:1000,‘msg‘:None}
        try:
            user = request._request.POST.get(‘username‘)
            pwd = request._request.POST.get(‘password‘)
            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()
            if not obj:
                ret[‘code‘] = 1001
                ret[‘msg‘] = ‘用户名或密码错误‘
            #为用户创建token
            token = md5(user)
            #存在就更新，不存在就创建
            models.UserToken.objects.update_or_create(user=obj,defaults={‘token‘:token})
            ret[‘token‘] = token
        except Exception as e:
            ret[‘code‘] = 1002
            ret[‘msg‘] = ‘请求异常‘
        return JsonResponse(ret)


class OrderView(APIView):
    ‘‘‘
    订单相关业务(只有SVIP用户才能看)
    ‘‘‘

    def get(self,request,*args,**kwargs):
        self.dispatch
        #request.user
        #request.auth
        ret = {‘code‘:1000,‘msg‘:None,‘data‘:None}
        try:
            ret[‘data‘] = ORDER_DICT
        except Exception as e:
            pass
        return JsonResponse(ret)


class UserInfoView(APIView):
    ‘‘‘
       订单相关业务(普通用户和VIP用户可以看)
       ‘‘‘
    permission_classes = [MyPermission,]    #不用全局的权限配置的话，这里就要写自己的局部权限
    def get(self,request,*args,**kwargs):

        print(request.user)
        return HttpResponse(‘用户信息‘)

# API/utils/auth/py

from rest_framework import exceptions
from API import models
from rest_framework.authentication import BaseAuthentication


class Authentication(BaseAuthentication):
    ‘‘‘用于用户登录验证‘‘‘
    def authenticate(self,request):
        token = request._request.GET.get(‘token‘)
        token_obj = models.UserToken.objects.filter(token=token).first()
        if not token_obj:
            raise exceptions.AuthenticationFailed(‘用户认证失败‘)
        #在rest framework内部会将这两个字段赋值给request，以供后续操作使用
        return (token_obj.user,token_obj)

    def authenticate_header(self, request):
        pass

# utils/permission.py

from rest_framework.permissions import BasePermission

class SVIPPermission(BasePermission):
    message = "必须是SVIP才能访问"
    def has_permission(self,request,view):
        if request.user.user_type != 3:
            return False
        return True


class MyPermission(BasePermission):
    def has_permission(self,request,view):
        if request.user.user_type == 3:
            return False
        return True

# utils/throttle.py
#
# from rest_framework.throttling import BaseThrottle
# import time
# VISIT_RECORD = {}   #保存访问记录
#
# class VisitThrottle(BaseThrottle):
#     ‘‘‘60s内只能访问3次‘‘‘
#     def __init__(self):
#         self.history = None   #初始化访问记录
#
#     def allow_request(self,request,view):
#         #获取用户ip (get_ident)
#         remote_addr = self.get_ident(request)
#         ctime = time.time()
#         #如果当前IP不在访问记录里面，就添加到记录
#         if remote_addr not in VISIT_RECORD:
#             VISIT_RECORD[remote_addr] = [ctime,]     #键值对的形式保存
#             return True    #True表示可以访问
#         #获取当前ip的历史访问记录
#         history = VISIT_RECORD.get(remote_addr)
#         #初始化访问记录
#         self.history = history
#
#         #如果有历史访问记录，并且最早一次的访问记录离当前时间超过60s，就删除最早的那个访问记录，
#         #只要为True，就一直循环删除最早的一次访问记录
#         while history and history[-1] < ctime - 60:
#             history.pop()
#         #如果访问记录不超过三次，就把当前的访问记录插到第一个位置（pop删除最后一个）
#         if len(history) < 3:
#             history.insert(0,ctime)
#             return True
#
#     def wait(self):
#         ‘‘‘还需要等多久才能访问‘‘‘
#         ctime = time.time()
#         return 60 - (ctime - self.history[-1])

from rest_framework.throttling import SimpleRateThrottle

class VisitThrottle(SimpleRateThrottle):
    ‘‘‘匿名用户60s只能访问三次（根据ip）‘‘‘
    scope = ‘NBA‘   #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        #通过ip限制节流
        return self.get_ident(request)

class UserThrottle(SimpleRateThrottle):
    ‘‘‘登录用户60s可以访问10次‘‘‘
    scope = ‘NBAUser‘    #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        return request.user.username