File

util/promise.lua @ 11749:83d6d6a70edf

net.http: fail open if surrounding code does not configure TLS Previously, if surrounding code was not configuring the TLS context used default in net.http, it would not validate certificates at all. This is not a security issue with prosody, because prosody updates the context with `verify = "peer"` as well as paths to CA certificates in util.startup.init_http_client. Nevertheless... Let's not leave this pitfall out there in the open.
author Jonas Schäfer <jonas@wielicki.name>
date Sun, 29 Aug 2021 15:04:47 +0200
parent 11486:78d843faaffc
child 11947:073e53b72792
line wrap: on
line source

local promise_methods = {};
local promise_mt = { __name = "promise", __index = promise_methods };

local xpcall = require "util.xpcall".xpcall;
local unpack = table.unpack or unpack; --luacheck: ignore 113

function promise_mt:__tostring()
	return  "promise (" .. (self._state or "invalid") .. ")";
end

local function is_promise(o)
	local mt = getmetatable(o);
	return mt == promise_mt;
end

local function wrap_handler(f, resolve, reject, default)
	if not f then
		return default;
	end
	return function (param)
		local ok, ret = xpcall(f, debug.traceback, param);
		if ok then
			resolve(ret);
		else
			reject(ret);
		end
		return true;
	end;
end

local function next_pending(self, on_fulfilled, on_rejected, resolve, reject)
	table.insert(self._pending_on_fulfilled, wrap_handler(on_fulfilled, resolve, reject, resolve));
	table.insert(self._pending_on_rejected, wrap_handler(on_rejected, resolve, reject, reject));
end

local function next_fulfilled(promise, on_fulfilled, on_rejected, resolve, reject) -- luacheck: ignore 212/on_rejected
	wrap_handler(on_fulfilled, resolve, reject, resolve)(promise.value);
end

local function next_rejected(promise, on_fulfilled, on_rejected, resolve, reject) -- luacheck: ignore 212/on_fulfilled
	wrap_handler(on_rejected, resolve, reject, reject)(promise.reason);
end

local function promise_settle(promise, new_state, new_next, cbs, value)
	if promise._state ~= "pending" then
		return;
	end
	promise._state = new_state;
	promise._next = new_next;
	for _, cb in ipairs(cbs) do
		cb(value);
	end
	-- No need to keep references to callbacks
	promise._pending_on_fulfilled = nil;
	promise._pending_on_rejected = nil;
	return true;
end

local function new_resolve_functions(p)
	local resolved = false;
	local function _resolve(v)
		if resolved then return; end
		resolved = true;
		if is_promise(v) then
			v:next(new_resolve_functions(p));
		elseif promise_settle(p, "fulfilled", next_fulfilled, p._pending_on_fulfilled, v) then
			p.value = v;
		end

	end
	local function _reject(e)
		if resolved then return; end
		resolved = true;
		if promise_settle(p, "rejected", next_rejected, p._pending_on_rejected, e) then
			p.reason = e;
		end
	end
	return _resolve, _reject;
end

local function new(f)
	local p = setmetatable({ _state = "pending", _next = next_pending, _pending_on_fulfilled = {}, _pending_on_rejected = {} }, promise_mt);
	if f then
		local resolve, reject = new_resolve_functions(p);
		local ok, ret = xpcall(f, debug.traceback, resolve, reject);
		if not ok and p._state == "pending" then
			reject(ret);
		end
	end
	return p;
end

local function all(promises)
	return new(function (resolve, reject)
		local settled, results, loop_finished = 0, {}, false;
		local total = 0;
		for k, v in pairs(promises) do
			if is_promise(v) then
				total = total + 1;
				v:next(function (value)
					results[k] = value;
					settled = settled + 1;
					if settled == total and loop_finished then
						resolve(results);
					end
				end, reject);
			else
				results[k] = v;
			end
		end
		loop_finished = true;
		if settled == total then
			resolve(results);
		end
	end);
end

local function all_settled(promises)
	return new(function (resolve)
		local settled, results, loop_finished = 0, {}, false;
		local total = 0;
		for k, v in pairs(promises) do
			if is_promise(v) then
				total = total + 1;
				v:next(function (value)
					results[k] = { status = "fulfilled", value = value };
					settled = settled + 1;
					if settled == total and loop_finished then
						resolve(results);
					end
				end, function (e)
					results[k] = { status = "rejected", reason = e };
					settled = settled + 1;
					if settled == total and loop_finished then
						resolve(results);
					end
				end);
			else
				results[k] = v;
			end
		end
		loop_finished = true;
		if settled == total then
			resolve(results);
		end
	end);
end

local function join(handler, ...)
	local promises, n = { ... }, select("#", ...);
	return all(promises):next(function (results)
		return handler(unpack(results, 1, n));
	end);
end

local function race(promises)
	return new(function (resolve, reject)
		for i = 1, #promises do
			promises[i]:next(resolve, reject);
		end
	end);
end

local function resolve(v)
	return new(function (_resolve)
		_resolve(v);
	end);
end

local function reject(v)
	return new(function (_, _reject)
		_reject(v);
	end);
end

local function try(f)
	return resolve():next(function () return f(); end);
end

function promise_methods:next(on_fulfilled, on_rejected)
	return new(function (resolve, reject) --luacheck: ignore 431/resolve 431/reject
		self:_next(on_fulfilled, on_rejected, resolve, reject);
	end);
end

function promise_methods:catch(on_rejected)
	return self:next(nil, on_rejected);
end

function promise_methods:finally(on_finally)
	local function _on_finally(value) on_finally(); return value; end
	local function _on_catch_finally(err) on_finally(); return reject(err); end
	return self:next(_on_finally, _on_catch_finally);
end

return {
	new = new;
	resolve = resolve;
	join = join;
	reject = reject;
	all = all;
	all_settled = all_settled;
	race = race;
	try = try;
	is_promise = is_promise;
}