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#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import time
import eventlet
from webob import Request, Response
from swift.common.utils import split_path, cache_from_env, get_logger
from swift.proxy.controllers.base import get_container_memcache_key
from swift.common.memcached import MemcacheConnectionError
class MaxSleepTimeHitError(Exception):
pass
class RateLimitMiddleware(object):
"""
Rate limiting middleware
Rate limits requests on both an Account and Container level. Limits are
configurable.
"""
BLACK_LIST_SLEEP = 1
def __init__(self, app, conf, logger=None):
self.app = app
if logger:
self.logger = logger
else:
self.logger = get_logger(conf, log_route='ratelimit')
self.account_ratelimit = float(conf.get('account_ratelimit', 0))
self.max_sleep_time_seconds = \
float(conf.get('max_sleep_time_seconds', 60))
self.log_sleep_time_seconds = \
float(conf.get('log_sleep_time_seconds', 0))
self.clock_accuracy = int(conf.get('clock_accuracy', 1000))
self.rate_buffer_seconds = int(conf.get('rate_buffer_seconds', 5))
self.ratelimit_whitelist = [acc.strip() for acc in
conf.get('account_whitelist', '').split(',') if acc.strip()]
self.ratelimit_blacklist = [acc.strip() for acc in
conf.get('account_blacklist', '').split(',') if acc.strip()]
self.memcache_client = None
conf_limits = []
for conf_key in conf.keys():
if conf_key.startswith('container_ratelimit_'):
cont_size = int(conf_key[len('container_ratelimit_'):])
rate = float(conf[conf_key])
conf_limits.append((cont_size, rate))
conf_limits.sort()
self.container_ratelimits = []
while conf_limits:
cur_size, cur_rate = conf_limits.pop(0)
if conf_limits:
next_size, next_rate = conf_limits[0]
slope = (float(next_rate) - float(cur_rate)) \
/ (next_size - cur_size)
def new_scope(cur_size, slope, cur_rate):
# making new scope for variables
return lambda x: (x - cur_size) * slope + cur_rate
line_func = new_scope(cur_size, slope, cur_rate)
else:
line_func = lambda x: cur_rate
self.container_ratelimits.append((cur_size, cur_rate, line_func))
def get_container_maxrate(self, container_size):
"""
Returns number of requests allowed per second for given container size.
"""
last_func = None
if container_size:
container_size = int(container_size)
for size, rate, func in self.container_ratelimits:
if container_size < size:
break
last_func = func
if last_func:
return last_func(container_size)
return None
def get_ratelimitable_key_tuples(self, req_method, account_name,
container_name=None, obj_name=None):
"""
Returns a list of key (used in memcache), ratelimit tuples. Keys
should be checked in order.
:param req_method: HTTP method
:param account_name: account name from path
:param container_name: container name from path
:param obj_name: object name from path
"""
keys = []
# COPYs are not limited
if self.account_ratelimit and \
account_name and container_name and not obj_name and \
req_method in ('PUT', 'DELETE'):
keys.append(("ratelimit/%s" % account_name,
self.account_ratelimit))
if account_name and container_name and obj_name and \
req_method in ('PUT', 'DELETE', 'POST'):
container_size = None
memcache_key = get_container_memcache_key(account_name,
container_name)
container_info = self.memcache_client.get(memcache_key)
if isinstance(container_info, dict):
container_size = container_info.get('container_size', 0)
container_rate = self.get_container_maxrate(container_size)
if container_rate:
keys.append(("ratelimit/%s/%s" % (account_name,
container_name),
container_rate))
return keys
def _get_sleep_time(self, key, max_rate):
'''
Returns the amount of time (a float in seconds) that the app
should sleep.
:param key: a memcache key
:param max_rate: maximum rate allowed in requests per second
:raises: MaxSleepTimeHitError if max sleep time is exceeded.
'''
try:
now_m = int(round(time.time() * self.clock_accuracy))
time_per_request_m = int(round(self.clock_accuracy / max_rate))
running_time_m = self.memcache_client.incr(key,
delta=time_per_request_m)
need_to_sleep_m = 0
if (now_m - running_time_m >
self.rate_buffer_seconds * self.clock_accuracy):
next_avail_time = int(now_m + time_per_request_m)
self.memcache_client.set(key, str(next_avail_time),
serialize=False)
else:
need_to_sleep_m = \
max(running_time_m - now_m - time_per_request_m, 0)
max_sleep_m = self.max_sleep_time_seconds * self.clock_accuracy
if max_sleep_m - need_to_sleep_m <= self.clock_accuracy * 0.01:
# treat as no-op decrement time
self.memcache_client.decr(key, delta=time_per_request_m)
raise MaxSleepTimeHitError("Max Sleep Time Exceeded: %.2f" %
(float(need_to_sleep_m) / self.clock_accuracy))
return float(need_to_sleep_m) / self.clock_accuracy
except MemcacheConnectionError:
return 0
def handle_ratelimit(self, req, account_name, container_name, obj_name):
'''
Performs rate limiting and account white/black listing. Sleeps
if necessary.
:param account_name: account name from path
:param container_name: container name from path
:param obj_name: object name from path
'''
if account_name in self.ratelimit_blacklist:
self.logger.error(_('Returning 497 because of blacklisting: %s'),
account_name)
eventlet.sleep(self.BLACK_LIST_SLEEP)
return Response(status='497 Blacklisted',
body='Your account has been blacklisted', request=req)
if account_name in self.ratelimit_whitelist:
return None
for key, max_rate in self.get_ratelimitable_key_tuples(
req.method, account_name, container_name=container_name,
obj_name=obj_name):
try:
need_to_sleep = self._get_sleep_time(key, max_rate)
if self.log_sleep_time_seconds and \
need_to_sleep > self.log_sleep_time_seconds:
self.logger.warning(_("Ratelimit sleep log: %(sleep)s for "
"%(account)s/%(container)s/%(object)s"),
{'sleep': need_to_sleep, 'account': account_name,
'container': container_name, 'object': obj_name})
if need_to_sleep > 0:
eventlet.sleep(need_to_sleep)
except MaxSleepTimeHitError, e:
self.logger.error(_('Returning 498 for %(meth)s to '
'%(acc)s/%(cont)s/%(obj)s . Ratelimit (Max Sleep) %(e)s'),
{'meth': req.method, 'acc': account_name,
'cont': container_name, 'obj': obj_name, 'e': str(e)})
error_resp = Response(status='498 Rate Limited',
body='Slow down', request=req)
return error_resp
return None
def __call__(self, env, start_response):
"""
WSGI entry point.
Wraps env in webob.Request object and passes it down.
:param env: WSGI environment dictionary
:param start_response: WSGI callable
"""
req = Request(env)
if self.memcache_client is None:
self.memcache_client = cache_from_env(env)
if not self.memcache_client:
self.logger.warning(
_('Warning: Cannot ratelimit without a memcached client'))
return self.app(env, start_response)
try:
version, account, container, obj = split_path(req.path, 1, 4, True)
except ValueError:
return self.app(env, start_response)
ratelimit_resp = self.handle_ratelimit(req, account, container, obj)
if ratelimit_resp is None:
return self.app(env, start_response)
else:
return ratelimit_resp(env, start_response)
def filter_factory(global_conf, **local_conf):
"""
paste.deploy app factory for creating WSGI proxy apps.
"""
conf = global_conf.copy()
conf.update(local_conf)
def limit_filter(app):
return RateLimitMiddleware(app, conf)
return limit_filter
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