util/throttle.lua
author Matthew Wild <mwild1@gmail.com>
Mon, 31 Oct 2022 14:32:02 +0000
branch0.12
changeset 12794 24b55f0e2db9
parent 8558 4f0f5b49bb03
child 12979 d10957394a3c
permissions -rw-r--r--
mod_http: Allow disabling CORS in the http_cors_override option and by default Fixes #1779. Due to an oversight in the logic, if the user set 'enabled' to false in an override, it would disable the item's requested CORS settings, but still apply Prosody's default CORS policy. This change ensures that 'enabled = false' will now disable CORS entirely for the requested item. Due to the new structure of the code, it was necessary to have a flag to say whether CORS is to be applied at all. Rather than hard-coding 'true' here, I chose to add a new option: 'http_default_cors_enabled'. This is a boolean that allows the operator to disable Prosody's default CORS policy entirely (the one that is used when a module or config does not override it). This makes it easier to disable CORS and then selectively enable it only on services you want it on.


local gettime = require "util.time".now
local setmetatable = setmetatable;

local _ENV = nil;
-- luacheck: std none

local throttle = {};
local throttle_mt = { __index = throttle };

function throttle:update()
	local newt = gettime();
	local elapsed = newt - self.t;
	self.t = newt;
	local balance = (self.rate * elapsed) + self.balance;
	if balance > self.max then
		self.balance = self.max;
	else
		self.balance = balance;
	end
	return self.balance;
end

function throttle:peek(cost)
	cost = cost or 1;
	return self.balance >= cost or self:update() >= cost;
end

function throttle:poll(cost, split)
	if self:peek(cost) then
		self.balance = self.balance - cost;
		return true;
	else
		local balance = self.balance;
		if split then
			self.balance = 0;
		end
		return false, balance, (cost-balance);
	end
end

local function create(max, period)
	return setmetatable({ rate = max / period, max = max, t = gettime(), balance = max }, throttle_mt);
end

return {
	create = create;
};