核心源码
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())
class SimpleRateThrottle(BaseThrottle):
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):
# 这里需要我们在定义 频率类的时候 重写该方法，返回的是访问者的ip，并放在缓存中
"""
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.
确认允许请求的频率的字符串表达形式
"""
# 去继承SimpleRateThrottle的类的对象中 反射 scope ，如果存在，则不执行，如果不存在执行if
if not getattr(self, 'scope', None):
msg = ("You must set either `.scope` or `.rate` for '%s' throttle" %
self.__class__.__name__)
raise ImproperlyConfigured(msg)
try:
# 根据我配置的scope 去 settings.py 中的 REST_FRAMEWORK 中去获取DEFAULT_THROTTLE_RATES 中的值 这里我配置的是 "qzk":"3/m"
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)
# 通过"/" 做切分，解压赋值给 num,period
num, period = rate.split('/')
# 将num 转成数字类型的整型
num_requests = int(num)
# 此时 period = 字符串 “m” 或 “minute”
# duration 是在 下面的 字典中的映射关系中取第{...}["m"]
# period[0] 表示 在字符串中取第一个字符（索引0）
duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
# 此时返回的 num_reuqets=3 duration=60
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`.
验证通过 调用 throttle_success
On failure calls `throttle_failure`.
验证失败 调用 `throttle_failure`
"""
if self.rate is None:
return True
# 这里的self.key 获取的值是 访问者的 ip（存在缓存中），我们在自己写的频率类中重写了该方法，这个方法返回时很么我们就以什么做过滤的 key
self.key = self.get_cache_key(request, view)
# 如果获取不到ip 则返回none
if self.key is None:
return True
# 根据ip 获取 self.cache缓存中的 value---> [ctime2,ctime1]
self.history = self.cache.get(self.key, []) # self.history 就是当前访客的访问时间列表
# 获取当前时间
self.now = self.timer()
# Drop any requests from the history which have now passed the
# throttle duration
# 如果 当前访客的时间列表不为空（有值） 并且 最后一个值 <= 当前时间-你设定的时间范围（60）
while self.history and self.history[-1] <= self.now - self.duration:
self.history.pop() # 将时间列表中的最后一个pop弹栈出去（删除）
if len(self.history) >= self.num_requests: # 如果列表的长度 >= 你设置的次数（3）
return self.throttle_failure() # 返回 False
return self.throttle_success() # 返回True
def throttle_success(self):
"""
Inserts the current request's timestamp along with the key
into the cache.
"""
self.history.insert(0, self.now) # 将当前时间 插入到时间列表的头部
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)
BaseThrottle 类
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.
"""
# 获取 请求头中的扩展头
xff = request.META.get('HTTP_X_FORWARDED_FOR')
# 获取 ip地址
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
"""频率部分源码执行流程"""
'''
先写一个频率校验的类（继承SimpleRateThrottle） ---> 在该类中 配置 scope参数---> 重写 get_cache_key 方法 并返回self.get_ident(request)---->在需要校验的类中配置 该校验类
执行步骤：
1.APIView
2.---->dispatch
3.---->self.initial(request, *args, **kwargs)
4.---->self.check_throttles(request)
5.---->throttle.allow_request(request, self)
6.---->self.get_cache_key(request, view)(自己重写的)（返回的是ip）
7.---->self.cache.get(self.key, []) 根据ip获取当前ip的 时间列表
8.---->需要用到参数（self.rate，self.num_requests，self.duration）在类实例化的时已经执行了如下代码（__init__）：
8.1--> self.rate = self.get_rate()-->self.THROTTLE_RATES[self.scope]
-->api_settings.DEFAULT_THROTTLE_RATES(配置文件中找)
这里 self.rate ---> 是前面配置的 'qzk':'3/m'
8.2-->self.num_requests, self.duration = self.parse_rate(self.rate)
这里 self.num_requests 是设定的访问限制次数（3）
self.duration 是访问的时间限制（60）
9.----> 通过如上数据，并进行一通逻辑判断， 返回
True：——> 执行throttle_success：
self.history.insert(0, self.now) # 把当前访问时间添加到时间列表
# 再将 key,history,duration 在 {} 中更新
self.cache.set(self.key, self.history, self.duration)
False ：---> 执行throttle_failure ，返回 Ture
'''