Question

Ok I know the title doesn’t really tell you what my problem is but I’ll try it now.
I am developing a game. People can subscribe their animals for a race. That race starts at a specific time. It is a race for which ALL users can subscribe. So the calculation of which animal is first, second etc. happens in an php file that is executed, every 2mins there is a new calculation for about 1h. So there are 30 calculations. But ofc. this code is not connected to the logged in user. The logged in user can click on the LIVE button to see the current result.

Example: There is a race at 17.00 later today. 15 animals subscribed, from 4 players and they can all check how their animals are doing.

I do not want someone to post me the full code but I want to know how I should let a php code run for about 1 hour (so execute code, sleep 2min, new calculation, sleep 2min and so on) on my server or so. So it is not connected to the user.

I thought about cron jobs but that is really not the solution for this I believe.
Thank you for reading :p

Answer 1

Two approaches:

1. You use an algorithm which will always come to the same conclusion, regardless of when it is run and who runs it. You just define the starting parameters, then at any time you can calculate the result (or the intermediate result at any point in time between start and finish) when needed. So any user can at any time visit your site and the algorithm will calculate the current standings on the fly from some fixed starting condition.
2. Alternatively, you keep all data in a central data store and actually update the data in certain intervals; any user can request the current standings at any time and the latest data from the datastore will be used. You will still need an algorithm that has traits of the one described above, since you’re likely explicitly not actually running the simulation in real time. Just every x seconds, you run your calculations again, calculating what is supposed to have changed from the last time you ran them.

In essence, any algorithm you use needs this approach. Even a “realtime” program simply keeps looping, changing values little by little from their previous state. The interval between theses changes can be arbitrarily stretched out, to the point where you calculate nothing until it becomes necessary. In the meantime, you just store all the data you need in a database.