File

util/statistics.lua @ 12828:f33887f925e1

net.server_epoll: Remove delay on last main loop iteration when quitting Main difference is that timers are not checked unconditionally before each poll, only when running out of previous poll results (hidden by util.poll). This removes a final poll at shutdown that usually delays the 'not quitting' condition check by one second.
author Kim Alvefur <zash@zash.se>
date Fri, 06 Jan 2023 04:38:39 +0100
parent 12124:7d985e5bc1fb
child 12975:d10957394a3c
line wrap: on
line source

local time = require "util.time".now;
local new_metric_registry = require "util.openmetrics".new_metric_registry;
local render_histogram_le = require "util.openmetrics".render_histogram_le;

-- BEGIN of Metric implementations

-- Gauges
local gauge_metric_mt = {}
gauge_metric_mt.__index = gauge_metric_mt

local function new_gauge_metric()
	local metric = { value = 0 }
	setmetatable(metric, gauge_metric_mt)
	return metric
end

function gauge_metric_mt:set(value)
	self.value = value
end

function gauge_metric_mt:add(delta)
	self.value = self.value + delta
end

function gauge_metric_mt:reset()
	self.value = 0
end

function gauge_metric_mt:iter_samples()
	local done = false
	return function(_s)
		if done then
			return nil, true
		end
		done = true
		return "", nil, _s.value
	end, self
end

-- Counters
local counter_metric_mt = {}
counter_metric_mt.__index = counter_metric_mt

local function new_counter_metric()
	local metric = {
		_created = time(),
		value = 0,
	}
	setmetatable(metric, counter_metric_mt)
	return metric
end

function counter_metric_mt:set(value)
	self.value = value
end

function counter_metric_mt:add(value)
	self.value = (self.value or 0) + value
end

function counter_metric_mt:iter_samples()
	local step = 0
	return function(_s)
		step = step + 1
		if step == 1 then
			return "_created", nil, _s._created
		elseif step == 2 then
			return "_total", nil, _s.value
		else
			return nil, nil, true
		end
	end, self
end

function counter_metric_mt:reset()
	self.value = 0
end

-- Histograms
local histogram_metric_mt = {}
histogram_metric_mt.__index = histogram_metric_mt

local function new_histogram_metric(buckets)
	local metric = {
		_created = time(),
		_sum = 0,
		_count = 0,
	}
	-- the order of buckets matters unfortunately, so we cannot directly use
	-- the thresholds as table keys
	for i, threshold in ipairs(buckets) do
		metric[i] = {
			threshold = threshold,
			threshold_s = render_histogram_le(threshold),
			count = 0
		}
	end
	setmetatable(metric, histogram_metric_mt)
	return metric
end

function histogram_metric_mt:sample(value)
	-- According to the I-D, values must be part of all buckets
	for i, bucket in pairs(self) do
		if "number" == type(i) and value <= bucket.threshold then
			bucket.count = bucket.count + 1
		end
	end
	self._sum = self._sum + value
	self._count = self._count + 1
end

function histogram_metric_mt:iter_samples()
	local key = nil
	return function (_s)
		local data
		key, data = next(_s, key)
		if key == "_created" or key == "_sum" or key == "_count" then
			return key, nil, data
		elseif key ~= nil then
			return "_bucket", {["le"] = data.threshold_s}, data.count
		else
			return nil, nil, nil
		end
	end, self
end

function histogram_metric_mt:reset()
	self._created = time()
	self._count = 0
	self._sum = 0
	for i, bucket in pairs(self) do
		if "number" == type(i) then
			bucket.count = 0
		end
	end
end

-- Summary
local summary_metric_mt = {}
summary_metric_mt.__index = summary_metric_mt

local function new_summary_metric()
	-- quantiles are not supported yet
	local metric = {
		_created = time(),
		_sum = 0,
		_count = 0,
	}
	setmetatable(metric, summary_metric_mt)
	return metric
end

function summary_metric_mt:sample(value)
	self._sum = self._sum + value
	self._count = self._count + 1
end

function summary_metric_mt:iter_samples()
	local key = nil
	return function (_s)
		local data
		key, data = next(_s, key)
		return key, nil, data
	end, self
end

function summary_metric_mt:reset()
	self._created = time()
	self._count = 0
	self._sum = 0
end

local pull_backend = {
	gauge = new_gauge_metric,
	counter = new_counter_metric,
	histogram = new_histogram_metric,
	summary = new_summary_metric,
}

-- END of Metric implementations

local function new()
	return {
		metric_registry = new_metric_registry(pull_backend),
	}
end

return {
	new = new;
}