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一、内置频率控制类
DRF内置了多种频率控制类提供我们使用，其核心原理都是通过判断request_allow方法返回值来判断频率是否通过，通过wait方法返回等待时间。
1. BaseThrottle:最基本的频率控制需要重写allow_request方法和wait方法
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
class BaseThrottle(object)
2. SimpleRateThrottle:示例中已经使用，并对源码和原理进行了分析。
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)
3. AnonRateThrottle：匿名用户频率控制
class AnonRateThrottle(SimpleRateThrottle):
"""
Limits the rate of API calls that may be made by a anonymous users.
The IP address of the request will be used as the unique cache key.
"""
scope = 'anon'
def get_cache_key(self, request, view):
if request.user.is_authenticated:
return None # Only throttle unauthenticated requests.
return self.cache_format % {
'scope': self.scope,
'ident': self.get_ident(request)
}
AnonRateThrottle
4.UserRateThrottle:基于SimpleRateThrottle，对用户的频率控
class UserRateThrottle(SimpleRateThrottle):
"""
Limits the rate of API calls that may be made by a given user.
The user id will be used as a unique cache key if the user is
authenticated. For anonymous requests, the IP address of the request will
be used.
"""
scope = 'user'
def get_cache_key(self, request, view):
if request.user.is_authenticated:
ident = request.user.pk
else:
ident = self.get_ident(request)
return self.cache_format % {
'scope': self.scope,
'ident': ident
}
UserRateThrottle
二、自定义频率控制
自定义频率控制无非实现request_allow方法和wait方法，你可以根据实际需求来定制你的频率控制，下面是示例：
from rest_framework.throttling import BaseThrottle
import time
REQUEST_RECORD = {} # 访问记录，可使用nosql数据库class VisitThrottle(BaseThrottle):
'''60s内最多能访问5次'''def __init__(self):
self.history = None
def allow_request(self, request, view):
# 获取用户ip (get_ident)
remote_addr = self.get_ident(request)
ctime = time.time()
if remote_addr not in REQUEST_RECORD:
REQUEST_RECORD[remote_addr] = [ctime, ] # 保持请求的时间，形式{ip:[时间,]}return True # True表示可以访问# 获取当前ip的历史访问记录
history = REQUEST_RECORD.get(remote_addr)
self.history = history
while history and history[-1] < ctime - 60:
# while循环确保每列表中是最新的60秒内的请求
history.pop()
# 访问记录小于5次，将本次请求插入到最前面，作为最新的请求if len(history) < 5:
history.insert(0, ctime)
return True
def wait(self):
'''返回等待时间'''
ctime = time.time()
return 60 - (ctime - self.history[-1])
三、总结
1.使用方法：
- 继承BaseThrottle类
- 重写request_allow方法和wait方法，request_allow方法返回true代表通过，否则拒绝，wait返回等待的时间
2.配置
###全局使用
REST_FRAMEWORK = {
#频率控制配置"DEFAULT_THROTTLE_CLASSES":['utils.throttle.VisitThrottle'], #全局配置，"DEFAULT_THROTTLE_RATES":{
'WD':'5/m', #速率配置每分钟不能超过5次访问，WD是scope定义的值
}
}
##单一视图使用
throttle_classes = [VisitThrottle,]
##优先级
单一视图>全局
