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- # Copyright 2014-2016 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.
- import collections
- class Ratelimiter(object):
- """
- Ratelimit message sending by user.
- """
- def __init__(self):
- self.message_counts = collections.OrderedDict()
- def send_message(self, user_id, time_now_s, msg_rate_hz, burst_count, update=True):
- """Can the user send a message?
- Args:
- user_id: The user sending a message.
- time_now_s: The time now.
- msg_rate_hz: The long term number of messages a user can send in a
- second.
- burst_count: How many messages the user can send before being
- limited.
- update (bool): Whether to update the message rates or not. This is
- useful to check if a message would be allowed to be sent before
- its ready to be actually sent.
- Returns:
- A pair of a bool indicating if they can send a message now and a
- time in seconds of when they can next send a message.
- """
- self.prune_message_counts(time_now_s)
- message_count, time_start, _ignored = self.message_counts.get(
- user_id, (0., time_now_s, None),
- )
- time_delta = time_now_s - time_start
- sent_count = message_count - time_delta * msg_rate_hz
- if sent_count < 0:
- allowed = True
- time_start = time_now_s
- message_count = 1.
- elif sent_count > burst_count - 1.:
- allowed = False
- else:
- allowed = True
- message_count += 1
- if update:
- self.message_counts[user_id] = (
- message_count, time_start, msg_rate_hz
- )
- if msg_rate_hz > 0:
- time_allowed = (
- time_start + (message_count - burst_count + 1) / msg_rate_hz
- )
- if time_allowed < time_now_s:
- time_allowed = time_now_s
- else:
- time_allowed = -1
- return allowed, time_allowed
- def prune_message_counts(self, time_now_s):
- for user_id in list(self.message_counts.keys()):
- message_count, time_start, msg_rate_hz = (
- self.message_counts[user_id]
- )
- time_delta = time_now_s - time_start
- if message_count - time_delta * msg_rate_hz > 0:
- break
- else:
- del self.message_counts[user_id]
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