Untested example code for reusing lanes in luajit to bypass thread creation time

luajit_lanes_reuse.lua

local retired_lanes = {}

local function thread_func(controller)
	while true do
		local key, func_args = controller:receive(10, "func_args")
		if key == lanes.cancel_error then
			break
		end
		if func_args then
			local func = func_args.func
			local args = func_args.args
			local results = {func(unpack(args))}
			controller:send("results", results)
		end
	end
end

local function run_lane(func, ...)
	-- get a lane
	local lane_info
	if #retired_lanes > 0 then
		-- use an existing one that isn't running anything
		lane_info = retired_lanes[#retired_lanes]
		retired_lanes[#retired_lanes] = nil
	else
		-- there are no existing ones; make a new one
		local controller = lanes.linda("threads_controller")
		local lane = lanes.gen(thread_func, controller)
		lane_info = {
			lane = lane,
			controller = controller
		}
	end
	-- set up last_results
	local run_results = {
		results = nil,
		controller = lane_info.controller,
		lane_info = lane_info
	}
	function run_results:receive(timeout)
		if self.results then
			return true, unpack(self.results)
		end
		local key, results = self.controller:receive(timeout, "results")
		if key == lanes.cancel_error then
			return false, nil
		elseif not results then
			return nil, nil
		end
		-- save the results, then make the lane re-usable by putting it in retired_lanes
		self.results = results
		retired_lanes[#retired_lanes + 1] = self.lane_info
		return true, unpack(results)
	end
	function run_results:get()
		if self.results then
			return true, unpack(self.results)
		end
		local results = self.controller:get("results")
		if results == lanes.cancel_error then
			return false, nil
		elseif not results then
			return nil, nil
		end
		-- save the results, then make the lane re-usable by putting it in retired_lanes
		self.results = results
		retired_lanes[#retired_lanes + 1] = self.lane_info
		return true, unpack(results)
	end
	lane_info.last_results = run_results
	-- run the lane
	local success = lane_info.controller:send("func_args", {func = func, args = {...}})
	if success == lanes.cancel_error then
		-- if it's cancelled, we need to not use it again and get a new lane
		return false
	else
		return true, run_results
	end
end

local function run_thread(func, ...)
	local success, results
	while not success do
		success, results = run_lane(func, ...)
	end
	return results
end

---

-- example:

local results = run_thread(function(...)
	print(...)
	local a = 5
	for _ = 1, 100000000 do
		a = a + 2
	end
	return a, "hello!"
end, 1, 2, 3)

local success, computation_result, message = results:receive(5)

if success == false then
	print("thread run failed! (cancelled?)")
elseif success == nil then
	print("thread is not finished yet!")
else
	print("thread finished! result: "..tostring(computation_result).." "..tostring(message))
end