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comparison util/throttle.lua @ 4362:851885cb332d

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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
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children 28e0bf9cf0f5
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4361:605045b77bc6 4362:851885cb332d
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;