prosody
851885cb332d
util/throttle.lua

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util/throttle.lua @ 4362:851885cb332d

util.throttle: Generic module by waqas to limit something over some time
author Matthew Wild <mwild1@gmail.com>
date Mon, 29 Aug 2011 13:00:33 -0400
child 4466:28e0bf9cf0f5
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1
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2 local gettime = require "socket".gettime;
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3
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4 module "throttle"
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5
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6 local throttle = {};
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7 local throttle_mt = { __index = throttle };
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8
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9 function throttle:update()
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10 local newt = gettime();
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11 local elapsed = newt - self.t;
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12 self.t = newt;
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13 local balance = self.rate * elapsed + self.balance;
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14 if balance > self.max then
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15 self.balance = self.max;
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16 else
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17 self.balance = balance;
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18 end
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19 return self.balance;
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20 end
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21
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22 function throttle:peek(cost)
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23 cost = cost or 1;
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24 return self.balance >= cost or self:update() >= cost;
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25 end
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26
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27 function throttle:poll(cost, split)
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28 if self:peek(cost) then
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29 self.balance = self.balance - cost;
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30 return true;
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31 else
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32 local balance = self.balance;
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33 if split then
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34 self.balance = 0;
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35 end
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36 return false, balance, (cost-self.balance);
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37 end
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38 end
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39
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40 function create(max, period)
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41 return setmetatable({ rate = max / period, max = max, t = 0, balance = max }, throttle_mt);
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42 end
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43
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44 return _M;