File

util/helpers.lua @ 11523:5f15ab7c6ae5

Statistics: Rewrite statistics backends to use OpenMetrics The metric subsystem of Prosody has had some shortcomings from the perspective of the current state-of-the-art in metric observability. The OpenMetrics standard [0] is a formalization of the data model (and serialization format) of the well-known and widely-used Prometheus [1] software stack. The previous stats subsystem of Prosody did not map well to that format (see e.g. [2] and [3]); the key reason is that it was trying to do too much math on its own ([2]) while lacking first-class support for "families" of metrics ([3]) and structured metric metadata (despite the `extra` argument to metrics, there was no standard way of representing common things like "tags" or "labels"). Even though OpenMetrics has grown from the Prometheus world of monitoring, it maps well to other popular monitoring stacks such as: - InfluxDB (labels can be mapped to tags and fields as necessary) - Carbon/Graphite (labels can be attached to the metric name with dot-separation) - StatsD (see graphite when assuming that graphite is used as backend, which is the default) The util.statsd module has been ported to use the OpenMetrics model as a proof of concept. An implementation which exposes the util.statistics backend data as Prometheus metrics is ready for publishing in prosody-modules (most likely as mod_openmetrics_prometheus to avoid breaking existing 0.11 deployments). At the same time, the previous measure()-based API had one major advantage: It is really simple and easy to use without requiring lots of knowledge about OpenMetrics or similar concepts. For that reason as well as compatibility with existing code, it is preserved and may even be extended in the future. However, code relying on the `stats-updated` event as well as `get_stats` from `statsmanager` will break because the data model has changed completely; in case of `stats-updated`, the code will simply not run (as the event was renamed in order to avoid conflicts); the `get_stats` function has been removed completely (so it will cause a traceback when it is attempted to be used). Note that the measure_*_event methods have been removed from the module API. I was unable to find any uses or documentation and thus deemed they should not be ported. Re-implementation is possible when necessary. [0]: https://openmetrics.io/ [1]: https://prometheus.io/ [2]: #959 [3]: #960
author Jonas Schäfer <jonas@wielicki.name>
date Sun, 18 Apr 2021 11:47:41 +0200 (2021-04-18)
parent 11059:ad89e3cc67b6
child 12975:d10957394a3c
line wrap: on
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-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local debug = require "util.debug";

-- Helper functions for debugging

local log = require "util.logger".init("util.debug");

local function log_events(events, name, logger)
	local f = events.fire_event;
	if not f then
		error("Object does not appear to be a util.events object");
	end
	logger = logger or log;
	name = name or tostring(events);
	function events.fire_event(event, ...)
		logger("debug", "%s firing event: %s", name, event);
		return f(event, ...);
	end

	local function event_handler_hook(handler, event_name, event_data)
		logger("debug", "calling handler for %s: %s", event_name, handler);
		local ok, ret = pcall(handler, event_data);
		if not ok then
			logger("error", "error in event handler %s: %s", handler, ret);
			error(ret);
		end
		if ret ~= nil then
			logger("debug", "event chain ended for %s by %s with result: %s", event_name, handler, ret);
		end
		return ret;
	end
	events.set_debug_hook(event_handler_hook);
	events[events.fire_event] = f;
	return events;
end

local function revert_log_events(events)
	events.fire_event, events[events.fire_event] = events[events.fire_event], nil; -- :))
	events.set_debug_hook(nil);
end

local function log_host_events(host)
	return log_events(prosody.hosts[host].events, host);
end

local function revert_log_host_events(host)
	return revert_log_events(prosody.hosts[host].events);
end

local function show_events(events, specific_event)
	local event_handlers = events._handlers;
	local events_array = {};
	local event_handler_arrays = {};
	for event, priorities in pairs(events._event_map) do
		local handlers = event_handlers[event];
		if handlers and (event == specific_event or not specific_event) then
			table.insert(events_array, event);
			local handler_strings = {};
			for i, handler in ipairs(handlers) do
				local upvals = debug.string_from_var_table(debug.get_upvalues_table(handler));
				handler_strings[i] = "  "..(priorities[handler] or "?")..": "..tostring(handler)..(upvals and ("\n        "..upvals) or "");
			end
			event_handler_arrays[event] = handler_strings;
		end
	end
	table.sort(events_array);
	local i = 1;
	while i <= #events_array do
		local handlers = event_handler_arrays[events_array[i]];
		for j=#handlers, 1, -1 do
			table.insert(events_array, i+1, handlers[j]);
		end
		if i > 1 then events_array[i] = "\n"..events_array[i]; end
		i = i + #handlers + 1
	end
	return table.concat(events_array, "\n");
end

local function get_upvalue(f, get_name)
	local i, name, value = 0;
	repeat
		i = i + 1;
		name, value = debug.getupvalue(f, i);
	until name == get_name or name == nil;
	return value;
end

return {
	log_host_events = log_host_events;
	revert_log_host_events = revert_log_host_events;
	log_events = log_events;
	revert_log_events = revert_log_events;
	show_events = show_events;
	get_upvalue = get_upvalue;
};