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# Derived from Django snippets: http://djangosnippets.org/snippets/2242/
from collections import OrderedDict
from datetime import datetime, timedelta
from hashlib import md5
import traceback
from pytz import utc
class LimitedSizeDict(OrderedDict):
def __init__(self, *args, **kwargs):
self.size_limit = kwargs.pop('size', None)
if self.size_limit == 0:
self.size_limit = None
if self.size_limit and self.size_limit < 0:
raise Exception('Invalid size specified')
super(LimitedSizeDict, self).__init__(*args, **kwargs)
self.check_item_limits()
def __setitem__(self, key, value):
# delete and add to ensure it ends up at the end of the linked list
if key in self:
super(LimitedSizeDict, self).__delitem__(key)
super(LimitedSizeDict, self).__setitem__(key, value)
self.check_item_limits()
def check_item_limits(self):
if self.size_limit is None:
return
while len(self) > self.size_limit:
self.popitem(last=False)
class RateLimitFilter(object):
def __init__(self, name='', rate=10, prefix='error_rate', max_keys=100):
# delayed import otherwise we have a circular dep when setting up
# the logging config: settings -> logging -> cache -> settings
self.cache_module = __import__('django.core.cache', fromlist=['cache'])
self.errors = LimitedSizeDict(size=max_keys)
self.rate = rate
self.prefix = prefix
def filter(self, record):
if self.rate == 0:
# rate == 0 means totally unfiltered
return True
trace = '\n'.join(traceback.format_exception(*record.exc_info))
key = md5(trace).hexdigest()
cache = self.cache_module.cache
# Test if the cache works
try:
cache.set(self.prefix, 1, 300)
use_cache = (cache.get(self.prefix) == 1)
except:
use_cache = False
if use_cache:
cache_key = '%s_%s' % (self.prefix, key)
duplicate = (cache.get(cache_key) == 1)
cache.set(cache_key, 1, self.rate)
else:
now = datetime.utcnow().replace(tzinfo=utc)
min_date = now - timedelta(seconds=self.rate)
duplicate = (key in self.errors and self.errors[key] >= min_date)
self.errors[key] = now
return not duplicate
# vim: set ts=4 sw=4 et:
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