80 lines
2.7 KiB
Python
80 lines
2.7 KiB
Python
# Copyright 2014 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import collections
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class Ratelimiter(object):
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"""
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Ratelimit message sending by user.
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"""
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def __init__(self):
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self.message_counts = collections.OrderedDict()
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def send_message(self, user_id, time_now_s, msg_rate_hz, burst_count):
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"""Can the user send a message?
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Args:
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user_id: The user sending a message.
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time_now_s: The time now.
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msg_rate_hz: The long term number of messages a user can send in a
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second.
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burst_count: How many messages the user can send before being
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limited.
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Returns:
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A pair of a bool indicating if they can send a message now and a
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time in seconds of when they can next send a message.
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"""
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self.prune_message_counts(time_now_s)
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message_count, time_start, _ignored = self.message_counts.pop(
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user_id, (0., time_now_s, None),
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)
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time_delta = time_now_s - time_start
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sent_count = message_count - time_delta * msg_rate_hz
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if sent_count < 0:
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allowed = True
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time_start = time_now_s
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message_count = 1.
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elif sent_count > burst_count - 1.:
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allowed = False
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else:
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allowed = True
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message_count += 1
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self.message_counts[user_id] = (
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message_count, time_start, msg_rate_hz
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)
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if msg_rate_hz > 0:
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time_allowed = (
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time_start + (message_count - burst_count + 1) / msg_rate_hz
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)
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if time_allowed < time_now_s:
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time_allowed = time_now_s
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else:
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time_allowed = -1
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return allowed, time_allowed
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def prune_message_counts(self, time_now_s):
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for user_id in self.message_counts.keys():
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message_count, time_start, msg_rate_hz = (
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self.message_counts[user_id]
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)
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time_delta = time_now_s - time_start
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if message_count - time_delta * msg_rate_hz > 0:
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break
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else:
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del self.message_counts[user_id]
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