prosody
1c410b4f3a58
util/throttle.lua

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util/throttle.lua @ 7696:1c410b4f3a58

util.pubsub: Factor item storage cache into a per service configurable option
author Kim Alvefur <zash@zash.se>
date Sun, 16 Oct 2016 00:36:05 +0200
parent 6777:5de6b93d0190
child 7988:dc758422d896
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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 "socket".gettime;
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3 local setmetatable = setmetatable;
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4 local floor = math.floor;
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5
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6 local _ENV = nil;
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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 = floor(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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41
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42 local function create(max, period)
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43 return setmetatable({ rate = max / period, max = max, t = 0, 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 };