memcache rate limiter

rate_limit.py

import webapp2
from functools import wraps
from google.appengine.api import memcache
 
 
def rate_limit(seconds_per_request=1):
  def rate_limiter(function):
    @wraps(function)
    def wrapper(self, *args, **kwargs):
      added = memcache.add('%s:%s' % (self.__class__.__name__, self.request.remote_addr or ''), 1,
                           time=seconds_per_request, namespace='rate_limiting')
      if not added:
        self.response.write('Rate limit exceeded.')
        self.response.set_status(429)
        return
      return function(self, *args, **kwargs)
    return wrapper
  return rate_limiter
 
 
class ExampleHandler(webapp2.RequestHandler):
  @rate_limit(seconds_per_request=2)
  def get(self):
    self.response.write('Hello, webapp2!')