File

plugins/mod_csi_simple.lua @ 11913:75d69e4c54a2

mod_csi_simple: Unlock writes after event, to allow things to be queued E.g. mod_smacks could queue an <r>, which would be more likely to be included in the same write and TCP segment as the previously buffered data, reducing syscalls and network packets needing to be sent.
author Kim Alvefur <zash@zash.se>
date Tue, 16 Nov 2021 13:37:18 +0100
parent 11834:f54d9abc4e14
child 11914:8f7946ce7d66
line wrap: on
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-- Copyright (C) 2016-2020 Kim Alvefur
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

module:depends"csi"

local jid = require "util.jid";
local st = require "util.stanza";
local dt = require "util.datetime";
local filters = require "util.filters";

local queue_size = module:get_option_number("csi_queue_size", 256);

local important_payloads = module:get_option_set("csi_important_payloads", { });

function is_important(stanza) --> boolean, reason: string
	if stanza == " " then
		return true, "whitespace keepalive";
	elseif type(stanza) == "string" then
		return true, "raw data";
	elseif not st.is_stanza(stanza) then
		-- This should probably never happen
		return true, type(stanza);
	end
	if stanza.attr.xmlns ~= nil then
		-- stream errors, stream management etc
		return true, "nonza";
	end
	local st_name = stanza.name;
	if not st_name then return false; end
	local st_type = stanza.attr.type;
	if st_name == "presence" then
		if st_type == nil or st_type == "unavailable" or st_type == "error" then
			return false, "presence update";
		end
		-- TODO Some MUC awareness, e.g. check for the 'this relates to you' status code
		return true, "subscription request";
	elseif st_name == "message" then
		if st_type == "headline" then
			-- Headline messages are ephemeral by definition
			return false, "headline";
		end
		if st_type == "error" then
			return true, "delivery failure";
		end
		if stanza:get_child("sent", "urn:xmpp:carbons:2") then
			return true, "carbon";
		end
		local forwarded = stanza:find("{urn:xmpp:carbons:2}received/{urn:xmpp:forward:0}/{jabber:client}message");
		if forwarded then
			stanza = forwarded;
		end
		if stanza:get_child("body") then
			return true, "body";
		end
		if stanza:get_child("subject") then
			-- Last step of a MUC join
			return true, "subject";
		end
		if stanza:get_child("encryption", "urn:xmpp:eme:0") then
			-- Since we can't know what an encrypted message contains, we assume it's important
			-- XXX Experimental XEP
			return true, "encrypted";
		end
		if stanza:get_child("x", "jabber:x:conference") or stanza:find("{http://jabber.org/protocol/muc#user}x/invite") then
			return true, "invite";
		end
		if stanza:get_child(nil, "urn:xmpp:jingle-message:0") then
			-- XXX Experimental XEP
			return true, "jingle call";
		end
		for important in important_payloads do
			if stanza:find(important) then
				return true;
			end
		end
		return false;
	elseif st_name == "iq" then
		return true;
	end
end

module:hook("csi-is-stanza-important", function (event)
	local important, why = is_important(event.stanza);
	event.reason = why;
	return important;
end, -1);

local function should_flush(stanza, session, ctr) --> boolean, reason: string
	if ctr >= queue_size then
		return true, "queue size limit reached";
	end
	local event = { stanza = stanza, session = session };
	local ret = module:fire_event("csi-is-stanza-important", event)
	return ret, event.reason;
end

local function with_timestamp(stanza, from)
	if st.is_stanza(stanza) and stanza.attr.xmlns == nil and stanza.name ~= "iq" then
		stanza = st.clone(stanza);
		stanza:add_direct_child(st.stanza("delay", {xmlns = "urn:xmpp:delay", from = from, stamp = dt.datetime()}));
	end
	return stanza;
end

local measure_buffer_hold = module:measure("buffer_hold", "times",
	{ buckets = { 0.1; 1; 5; 10; 15; 30; 60; 120; 180; 300; 600; 900 } });

local flush_reasons = module:metric(
	"counter", "flushes", "",
	"CSI queue flushes",
	{ "reason" }
);

local function manage_buffer(stanza, session)
	local ctr = session.csi_counter or 0;
	local flush, why = should_flush(stanza, session, ctr);
	if flush then
		if session.csi_measure_buffer_hold then
			session.csi_measure_buffer_hold();
			session.csi_measure_buffer_hold = nil;
		end
		flush_reasons:with_labels(why or "important"):add(1);
		session.log("debug", "Flushing buffer (%s; queue size is %d)", why or "important", session.csi_counter);
		session.state = "flushing";
		module:fire_event("csi-flushing", { session = session });
		session.conn:resume_writes();
	else
		session.log("debug", "Holding buffer (%s; queue size is %d)", why or "unimportant", session.csi_counter);
		stanza = with_timestamp(stanza, jid.join(session.username, session.host))
	end
	session.csi_counter = ctr + 1;
	return stanza;
end

local function flush_buffer(data, session)
	session.log("debug", "Flushing buffer (%s; queue size is %d)", "client activity", session.csi_counter);
	flush_reasons:with_labels("client activity"):add(1);
	if session.csi_measure_buffer_hold then
		session.csi_measure_buffer_hold();
		session.csi_measure_buffer_hold = nil;
	end
	session.conn:resume_writes();
	return data;
end

function enable_optimizations(session)
	if session.conn and session.conn.pause_writes then
		session.conn:pause_writes();
		session.csi_measure_buffer_hold = measure_buffer_hold();
		session.csi_counter = 0;
		filters.add_filter(session, "stanzas/out", manage_buffer);
		filters.add_filter(session, "bytes/in", flush_buffer);
	else
		session.log("warn", "Session connection does not support write pausing");
	end
end

function disable_optimizations(session)
	filters.remove_filter(session, "stanzas/out", manage_buffer);
	filters.remove_filter(session, "bytes/in", flush_buffer);
	session.csi_counter = nil;
	if session.csi_measure_buffer_hold then
		session.csi_measure_buffer_hold();
		session.csi_measure_buffer_hold = nil;
	end
	if session.conn and session.conn.resume_writes then
		session.conn:resume_writes();
	end
end

module:hook("csi-client-inactive", function (event)
	local session = event.origin;
	enable_optimizations(session);
end);

module:hook("csi-client-active", function (event)
	local session = event.origin;
	disable_optimizations(session);
end);

module:hook("pre-resource-unbind", function (event)
	local session = event.session;
	disable_optimizations(session);
end, 1);

module:hook("c2s-ondrain", function (event)
	local session = event.session;
	if (session.state == "flushing" or session.state == "inactive") and session.conn and session.conn.pause_writes then
		session.state = "inactive";
		session.conn:pause_writes();
		session.csi_measure_buffer_hold = measure_buffer_hold();
		session.log("debug", "Buffer flushed, resuming inactive mode (queue size was %d)", session.csi_counter);
		session.csi_counter = 0;
	end
end);

function module.load()
	for _, user_session in pairs(prosody.hosts[module.host].sessions) do
		for _, session in pairs(user_session.sessions) do
			if session.state == "inactive" then
				enable_optimizations(session);
			end
		end
	end
end

function module.unload()
	for _, user_session in pairs(prosody.hosts[module.host].sessions) do
		for _, session in pairs(user_session.sessions) do
			if session.state == "inactive" then
				disable_optimizations(session);
			end
		end
	end
end

function module.command(arg)
	if arg[1] ~= "test" then
		print("Usage: "..module.name.." test < test-stream.xml")
		print("");
		print("Provide a series of stanzas to test against importance algorithm");
		return 1;
	end
	-- luacheck: ignore 212/self
	local xmppstream = require "util.xmppstream";
	local input_session = { notopen = true }
	local stream_callbacks = { stream_ns = "jabber:client", default_ns = "jabber:client" };
	function stream_callbacks:handlestanza(stanza)
		local important, because = is_important(stanza);
		print("--");
		print(stanza:indent(nil, "  "));
		-- :pretty_print() maybe?
		if important then
			print((because or "unspecified reason").. " -> important");
		else
			print((because or "unspecified reason").. " -> unimportant");
		end
	end
	local input_stream = xmppstream.new(input_session, stream_callbacks);
	input_stream:reset();
	input_stream:feed(st.stanza("stream", { xmlns = "jabber:client" }):top_tag());
	input_session.notopen = nil;

	for line in io.lines() do
		input_stream:feed(line);
	end
end