prosody
148075532021
util/throttle.lua

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util/throttle.lua @ 11665:148075532021

net.server_epoll: Prevent stack overflow of opportunistic writes net.http.files serving a big enough file on a fast enough connection with opportunistic_writes enabled could trigger a stack overflow through repeatedly serving more data that immediately gets sent, draining the buffer and triggering more data to be sent. This also blocked the server on a single task until completion or an error. This change prevents nested opportunistic writes, which should prevent the stack overflow, at the cost of reduced download speed, but this is unlikely to be noticeable outside of Gbit networks. Speed at the cost of blocking other processing is not worth it, especially with the risk of stack overflow.
author Kim Alvefur <zash@zash.se>
date Sun, 11 Jul 2021 09:39:21 +0200
parent 8555:4f0f5b49bb03
child 12975:d10957394a3c
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851885cb332d util.throttle: Generic module by waqas to limit something over some time
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1
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2 local gettime = require "util.time".now
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3 local setmetatable = setmetatable;
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5 local _ENV = nil;
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6 -- luacheck: std none
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8 local throttle = {};
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9 local throttle_mt = { __index = throttle };
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11 function throttle:update()
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12 local newt = gettime();
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13 local elapsed = newt - self.t;
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14 self.t = newt;
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15 local balance = (self.rate * elapsed) + self.balance;
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16 if balance > self.max then
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17 self.balance = self.max;
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18 else
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19 self.balance = balance;
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20 end
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21 return self.balance;
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22 end
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24 function throttle:peek(cost)
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25 cost = cost or 1;
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26 return self.balance >= cost or self:update() >= cost;
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27 end
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29 function throttle:poll(cost, split)
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30 if self:peek(cost) then
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31 self.balance = self.balance - cost;
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32 return true;
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33 else
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34 local balance = self.balance;
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35 if split then
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36 self.balance = 0;
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37 end
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38 return false, balance, (cost-balance);
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39 end
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40 end
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42 local function create(max, period)
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43 return setmetatable({ rate = max / period, max = max, t = gettime(), balance = max }, throttle_mt);
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44 end
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45
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46 return {
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47 create = create;
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48 };