How to implement independent execution of two or more functions in PHP?

Question

PHP

Kind.
I'm doing a little automation for myself on a few simple controllers. Controllers can send and receive data (in my case from a php script).
Simple tasks - "pressed the button => turned on / off the light" - are implemented trivially and simply

//код утрирован и упрощен
$click = $_GET["click"];

if ( $click == "1" )
{
  switchOver();
}

function switchOver()
{
  file_get_contents("http://192.168.0.201/?lamp=01&cmd=off");
}

Reading an RFID key is written in approximately the same way - we got the key ID => "done something"; polling by cron from the server side of some sensors, and so on.
And how to implement, for example, "blinking" more correctly. There is a relay, there is a light bulb, turn it on for 2 seconds, turn it off for 2 seconds ...
In a simple and rough design, this is an endless loop with a delay

while (true)
{
  file_get_contents("http://192.168.0.201/?out=1&cmd=on");
  sleep(2000);

  file_get_contents("http://192.168.0.201/?out=1&cmd=off");
  sleep(2000);
}

Let's say there should be a "flashing" after the sensor is triggered. Yes, you can put break on a certain condition, but while "sleep" is being executed, everything will be idle.
Does it make sense to run such tasks in separate threads, and then, if necessary, kill them by a certain id? Or is there a classic solution to such problems?
While considering exec("command &") as one of the potential solutions

Answer 1

Asynchronous requests (ajax), in order to do it all faster, I think you can use sockets.

Answer 2

Two options immediately come to mind:
1. run the flasher as a separate process via system()
2. implement a task queue and select a task from this queue in an endless loop and execute it. For example, add a task:
2017-12-04 9:00:00 Turn on the light bulb
in the switchOver() function write code that adds a task: 2017-12-04 9:00:02 Turn off the light bulb
in the turn off function - add code: 2017-12 -04 09:00:04 Turn on the light bulb
And so on.
At the beginning of the infinite loop, tasks are selected for the current time and processed.

Answer 3

Each new http request will automatically create a new PHP stream anyway. So sleep() in one will not affect the second in any way (although it will create a small load, keep the connection, take up memory, etc.).
If there are not so many requests, you can leave it like that. But it is better to at least redo it on the queue.
If there are a lot of requests, it is better to rewrite in asynchronous Node.JS

Answer 4

install rabbitmq, then throw tasks there for execution, and take it somewhere in other processes
Or the fork / pthreads option

Answer 5

via Command Bus or process symphony that run scripts via proc_open
It is important to remember when running in asynchronous mode each command: if the parent of the script terminates before the buses that were fired, then all buses will die in place with the parent,
this is the peculiarity of the proc * functions in windows / unix