util/throttle.lua
author Matthew Wild <mwild1@gmail.com>
Mon, 20 Feb 2023 18:10:15 +0000
branch0.12
changeset 12898 0598d822614f
parent 8558 4f0f5b49bb03
child 12979 d10957394a3c
permissions -rw-r--r--
mod_websocket: Fire pre-session-close event (fixes #1800) This event was added in a7c183bb4e64 and is required to make mod_smacks know that a session was intentionally closed and shouldn't be hibernated (see fcea4d9e7502). Because this was missing from mod_websocket's session.close(), mod_smacks would always attempt to hibernate websocket sessions even if they closed cleanly. That mod_websocket has its own copy of session.close() is something to fix another day (probably not in the stable branch). So for now this commit makes the minimal change to get things working again. Thanks to Damian and the Jitsi team for reporting.


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;
};