Main.lua

-- Main.lua

--[[
Starts a TCP server; then launches self again with the server port as param, which creates a client that connects to the server.
The server uses socket timeouts to report time, the client doesn't send any response to trigger the timeout.

In ZeroBraneStudio on Linux, the :settimeout() call seems to succeed, but the timeout is ignored and pretty much
every :receive() call then returns immediately with a "timeout" error.
--]]





local socket = require("socket")

local args = arg or {...}





-- Outputs the specified text with a prepended timestamp
local function log(aText)
	assert(type(aText) == "string")
	local d = os.date("%H:%M:%S")
	print(d, aText)
end





-- Runs the server process part:
local function doServer(aSelfFileName)
	assert(type(aSelfFileName) == "string")
	
	local port = 32000
	local server = assert(socket.bind("localhost", port, 0))
	log("S: Listening on port " .. tostring(port))
	-- while (true) do
	do
		-- Launch the client process:
		local childProcess = io.popen("lua " .. aSelfFileName .. " " .. tostring(port), "w")
		
		-- Accept the client:
		local client = assert(server:accept())
		log("S: Client connected: " .. tostring(client:getpeername()))
		
		-- Wait for 10 consecutive (timeouting) reads from the client, log each one with timestamp:
		client:settimeout(1)
		for i = 1, 10 do
			local data, msg = client:receive(1)
			if not(data) then
				log("S: Failed to receive client data: " .. tostring(msg))
			end
			client:send('a')
		end
		client:close()
		childProcess:close()
	end
end





-- Runs the client process part:
local function doClient(aPort)
	assert(type(aPort) == "number")
	
	log("Client: Connecting to port " .. tostring(aPort))
	local client = assert(socket.connect("localhost", aPort))
	print(client:receive("100"))
end





-- Main:
if (args[1]) then
	doClient(tonumber(args[1]))
else
	doServer(args[0])
end