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- # -*- coding: utf-8 -*-
- # Copyright 2015, 2016 OpenMarket Ltd
- #
- # 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.
- from twisted.internet import defer
- from synapse.api.errors import LimitExceededError
- from synapse.util.async import sleep
- from synapse.util.logcontext import run_in_background
- import collections
- import contextlib
- import logging
- logger = logging.getLogger(__name__)
- class FederationRateLimiter(object):
- def __init__(self, clock, window_size, sleep_limit, sleep_msec,
- reject_limit, concurrent_requests):
- """
- Args:
- clock (Clock)
- window_size (int): The window size in milliseconds.
- sleep_limit (int): The number of requests received in the last
- `window_size` milliseconds before we artificially start
- delaying processing of requests.
- sleep_msec (int): The number of milliseconds to delay processing
- of incoming requests by.
- reject_limit (int): The maximum number of requests that are can be
- queued for processing before we start rejecting requests with
- a 429 Too Many Requests response.
- concurrent_requests (int): The number of concurrent requests to
- process.
- """
- self.clock = clock
- self.window_size = window_size
- self.sleep_limit = sleep_limit
- self.sleep_msec = sleep_msec
- self.reject_limit = reject_limit
- self.concurrent_requests = concurrent_requests
- self.ratelimiters = {}
- def ratelimit(self, host):
- """Used to ratelimit an incoming request from given host
- Example usage:
- with rate_limiter.ratelimit(origin) as wait_deferred:
- yield wait_deferred
- # Handle request ...
- Args:
- host (str): Origin of incoming request.
- Returns:
- _PerHostRatelimiter
- """
- return self.ratelimiters.setdefault(
- host,
- _PerHostRatelimiter(
- clock=self.clock,
- window_size=self.window_size,
- sleep_limit=self.sleep_limit,
- sleep_msec=self.sleep_msec,
- reject_limit=self.reject_limit,
- concurrent_requests=self.concurrent_requests,
- )
- ).ratelimit()
- class _PerHostRatelimiter(object):
- def __init__(self, clock, window_size, sleep_limit, sleep_msec,
- reject_limit, concurrent_requests):
- self.clock = clock
- self.window_size = window_size
- self.sleep_limit = sleep_limit
- self.sleep_msec = sleep_msec
- self.reject_limit = reject_limit
- self.concurrent_requests = concurrent_requests
- self.sleeping_requests = set()
- self.ready_request_queue = collections.OrderedDict()
- self.current_processing = set()
- self.request_times = []
- @contextlib.contextmanager
- def ratelimit(self):
- # `contextlib.contextmanager` takes a generator and turns it into a
- # context manager. The generator should only yield once with a value
- # to be returned by manager.
- # Exceptions will be reraised at the yield.
- request_id = object()
- ret = self._on_enter(request_id)
- try:
- yield ret
- finally:
- self._on_exit(request_id)
- def _on_enter(self, request_id):
- time_now = self.clock.time_msec()
- self.request_times[:] = [
- r for r in self.request_times
- if time_now - r < self.window_size
- ]
- queue_size = len(self.ready_request_queue) + len(self.sleeping_requests)
- if queue_size > self.reject_limit:
- raise LimitExceededError(
- retry_after_ms=int(
- self.window_size / self.sleep_limit
- ),
- )
- self.request_times.append(time_now)
- def queue_request():
- if len(self.current_processing) > self.concurrent_requests:
- logger.debug("Ratelimit [%s]: Queue req", id(request_id))
- queue_defer = defer.Deferred()
- self.ready_request_queue[request_id] = queue_defer
- return queue_defer
- else:
- return defer.succeed(None)
- logger.debug(
- "Ratelimit [%s]: len(self.request_times)=%d",
- id(request_id), len(self.request_times),
- )
- if len(self.request_times) > self.sleep_limit:
- logger.debug(
- "Ratelimit [%s]: sleeping req",
- id(request_id),
- )
- ret_defer = run_in_background(sleep, self.sleep_msec / 1000.0)
- self.sleeping_requests.add(request_id)
- def on_wait_finished(_):
- logger.debug(
- "Ratelimit [%s]: Finished sleeping",
- id(request_id),
- )
- self.sleeping_requests.discard(request_id)
- queue_defer = queue_request()
- return queue_defer
- ret_defer.addBoth(on_wait_finished)
- else:
- ret_defer = queue_request()
- def on_start(r):
- logger.debug(
- "Ratelimit [%s]: Processing req",
- id(request_id),
- )
- self.current_processing.add(request_id)
- return r
- def on_err(r):
- self.current_processing.discard(request_id)
- return r
- def on_both(r):
- # Ensure that we've properly cleaned up.
- self.sleeping_requests.discard(request_id)
- self.ready_request_queue.pop(request_id, None)
- return r
- ret_defer.addCallbacks(on_start, on_err)
- ret_defer.addBoth(on_both)
- return ret_defer
- def _on_exit(self, request_id):
- logger.debug(
- "Ratelimit [%s]: Processed req",
- id(request_id),
- )
- self.current_processing.discard(request_id)
- try:
- request_id, deferred = self.ready_request_queue.popitem()
- self.current_processing.add(request_id)
- deferred.callback(None)
- except KeyError:
- pass
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