File

util/statistics.lua @ 10688:83668e16b9a3

MUC: Switch to new storage format by default Changing the default setting of `new_muc_storage_format` from false to true. The code supports reading both formats since 0.11, but servers with MUCs stored using the new format will not be able to downgrade to 0.10 or earlier. The new format is clearer (less nesting for the most commonly-accessed data), and combined with the new map-store methods, allows for some operations to become more efficient (such as finding out which MUCs on a service a given user is affiliated with).
author Matthew Wild <mwild1@gmail.com>
date Thu, 12 Mar 2020 16:10:44 +0000
parent 10314:bbc879eab1bf
child 10883:d75d805c852f
line wrap: on
line source

local t_sort = table.sort
local m_floor = math.floor;
local time = require "util.time".now;

local function nop_function() end

local function percentile(arr, length, pc)
	local n = pc/100 * (length + 1);
	local k, d = m_floor(n), n%1;
	if k == 0 then
		return arr[1] or 0;
	elseif k >= length then
		return arr[length];
	end
	return arr[k] + d*(arr[k+1] - arr[k]);
end

local function new_registry(config)
	config = config or {};
	local duration_sample_interval = config.duration_sample_interval or 5;
	local duration_max_samples = config.duration_max_stored_samples or 5000;

	local function get_distribution_stats(events, n_actual_events, since, new_time, units)
		local n_stored_events = #events;
		t_sort(events);
		local sum = 0;
		for i = 1, n_stored_events do
			sum = sum + events[i];
		end

		return {
			samples = events;
			sample_count = n_stored_events;
			count = n_actual_events,
			rate = n_actual_events/(new_time-since);
			average = n_stored_events > 0 and sum/n_stored_events or 0,
			min = events[1] or 0,
			max = events[n_stored_events] or 0,
			units = units,
		};
	end


	local registry = {};
	local methods;
	methods = {
		amount = function (name, initial)
			local v = initial or 0;
			registry[name..":amount"] = function () return "amount", v; end
			return function (new_v) v = new_v; end
		end;
		counter = function (name, initial)
			local v = initial or 0;
			registry[name..":amount"] = function () return "amount", v; end
			return function (delta)
				v = v + delta;
			end;
		end;
		rate = function (name)
			local since, n, total = time(), 0, 0;
			registry[name..":rate"] = function ()
				total = total + n;
				local t = time();
				local stats = {
					rate = n/(t-since);
					count = n;
					total = total;
				};
				since, n = t, 0;
				return "rate", stats.rate, stats;
			end;
			return function ()
				n = n + 1;
			end;
		end;
		distribution = function (name, unit, type)
			type = type or "distribution";
			local events, last_event = {}, 0;
			local n_actual_events = 0;
			local since = time();

			registry[name..":"..type] = function ()
				local new_time = time();
				local stats = get_distribution_stats(events, n_actual_events, since, new_time, unit);
				events, last_event = {}, 0;
				n_actual_events = 0;
				since = new_time;
				return type, stats.average, stats;
			end;

			return function (value)
				n_actual_events = n_actual_events + 1;
				if n_actual_events%duration_sample_interval == 1 then
					last_event = (last_event%duration_max_samples) + 1;
					events[last_event] = value;
				end
			end;
		end;
		sizes = function (name)
			return methods.distribution(name, "bytes", "size");
		end;
		times = function (name)
			local events, last_event = {}, 0;
			local n_actual_events = 0;
			local since = time();

			registry[name..":duration"] = function ()
				local new_time = time();
				local stats = get_distribution_stats(events, n_actual_events, since, new_time, "seconds");
				events, last_event = {}, 0;
				n_actual_events = 0;
				since = new_time;
				return "duration", stats.average, stats;
			end;

			return function ()
				n_actual_events = n_actual_events + 1;
				if n_actual_events%duration_sample_interval ~= 1 then
					return nop_function;
				end

				local start_time = time();
				return function ()
					local end_time = time();
					local duration = end_time - start_time;
					last_event = (last_event%duration_max_samples) + 1;
					events[last_event] = duration;
				end
			end;
		end;

		get_stats = function ()
			return registry;
		end;
	};
	return methods;
end

return {
	new = new_registry;
	get_histogram = function (duration, n_buckets)
		n_buckets = n_buckets or 100;
		local events, n_events = duration.samples, duration.sample_count;
		if not (events and n_events) then
			return nil, "not a valid distribution stat";
		end
		local histogram = {};

		for i = 1, 100, 100/n_buckets do
			histogram[i] = percentile(events, n_events, i);
		end
		return histogram;
	end;

	get_percentile = function (duration, pc)
		local events, n_events = duration.samples, duration.sample_count;
		if not (events and n_events) then
			return nil, "not a valid distribution stat";
		end
		return percentile(events, n_events, pc);
	end;
}