Saving High Scores to A Text File - Multiple Requests

[serdar]

Hi,

I've built a Flash game and using PHP to save scores to a text file. Everything works fine so far.

My potential problem is that I'm not sure what happens when there are multiple requests to write to the file simultaneously. The file might be corrupted, or the request(s) might fail?

I'm not good at file system functions so I need your help. This is the basic structure of my script:

<?php 
    $handle=fopen("theScores.txt", "r+");
    $data=fread($handle, filesize("theScores.txt"));
 
        //prepare the output here
 
    ftruncate($handle, 0);
    fseek ($handle, 0);
    fwrite($handle, $output);
    fclose($handle);
?>
 

Now, I know about the flock function. Is it the right solution to queue the requests and prevent data loss/corruption.

How should I proceed?

Thanks.

[dlite922]

Yes, if PHP doesn't get a lock with flock() it waits until it does. (you can test this with a short script) unless your provide LOCK_EX | LOCK_NB. But you don't want this, unless writing to the file takes a long time and you don't want the user to wait.

How are you planning on doing the queues?


Dan

[serdar]

Thanks for the answer.

Still not clear what happens when a user tries to save a score while another is already submitting score.

Suppose I locked the file with flock while processing the first request.

Does this mean the second user will simply wait (most probably for a very short time in my case) and this request will be processed successfully after the first?

Or does it mean, the second request will be ignored or worse cause data loss/corruption?

This is what I called a queue in my first post. I mean, do I need to take care of anything else to maintain the queue the way I described?

[serdar]

I've made a few tests; sending multiple requests to read/write the file and it worked perfectly.

As I'm told here and at some other forum, the queue is handled by the server and you don't need anything else than using flock().

Thanks.