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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> |
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date | Mon, 29 Aug 2011 13:00:33 -0400 |
child | 4466:28e0bf9cf0f5 |
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4361:605045b77bc6 | 4362:851885cb332d |
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1 | |
2 local gettime = require "socket".gettime; | |
3 | |
4 module "throttle" | |
5 | |
6 local throttle = {}; | |
7 local throttle_mt = { __index = throttle }; | |
8 | |
9 function throttle:update() | |
10 local newt = gettime(); | |
11 local elapsed = newt - self.t; | |
12 self.t = newt; | |
13 local balance = self.rate * elapsed + self.balance; | |
14 if balance > self.max then | |
15 self.balance = self.max; | |
16 else | |
17 self.balance = balance; | |
18 end | |
19 return self.balance; | |
20 end | |
21 | |
22 function throttle:peek(cost) | |
23 cost = cost or 1; | |
24 return self.balance >= cost or self:update() >= cost; | |
25 end | |
26 | |
27 function throttle:poll(cost, split) | |
28 if self:peek(cost) then | |
29 self.balance = self.balance - cost; | |
30 return true; | |
31 else | |
32 local balance = self.balance; | |
33 if split then | |
34 self.balance = 0; | |
35 end | |
36 return false, balance, (cost-self.balance); | |
37 end | |
38 end | |
39 | |
40 function create(max, period) | |
41 return setmetatable({ rate = max / period, max = max, t = 0, balance = max }, throttle_mt); | |
42 end | |
43 | |
44 return _M; |