Possible file_put_contents conflict?

Question

I am posting this not about code error but about possible conflict using this piece of code:

$logFile = 'data.log';
$result = (int) file_get_contents($logFile) + 1;
file_put_contents($logFile, $result);

This will read a file called data.log and get it's number and write this number +1. But, I will run this application with many users calling this in realtime (like 100 users per second).

So, I want to know if this will create some conflict, get outupdated number and store wrong data or something like this. Is it possible? Are there an way to I avoid it?

Thank you.

score 0 · Accepted Answer · answered Jun 08 '21 at 01:24

It will not work correctly because the data is not changed "atomically".

You can solve it by locking the file before accessing it - read about the flock function. But this could affect performance and possibly seriously limit your throughput - so you should benchmark it.

Generally speaking, this is not considered a "good" way to implement a counter. Look into using a proper database like MySQL or a NoSQL like MongoDB.

Possible file_put_contents conflict?

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