[RESOLVED] trigger an action 30 seconds later

blackhorse

say I have a script
http://www.mysite.com/trigger30.php

<?php
   sleep(30);

   //trigger some action here ...

So http request to http://www.mysite.com/trigger30.php, the page will hung there as loading, wait for 30 seconds and then trigger some action.

But what I want is http request to http://www.mysite.com/trigger30.php, the session will close immediately, NOT hung there as loading for 30 seconds as the above case. but STILL 30 seconds later, trigger some action.

I was thinking like http request to http://www.mysite.com/trigger30.php, it will change some value, saved that value to a text. And I will also run cron every minute to check that value, if that values is changed, then trigger some action. But that was ugly. And still technically it will sleep 60 seconds to trigger instead of 30 seconds.

NogDog

You could use one of the [man]exec[/man] commands to launch another script in the background, and have that script do its own sleep.

blackhorse

I tried like this

call_ruby.php

<?php

   shell_execute('php ruby.php');
   exit;

ruby.php

<?php
   sleep(30);

   //trigger some action here ...
   //ruby script in this case

But when I run call_ruby.php, it still sleep 30 seconds.

I have been thinking launch a script in the background, like in the web page design, I can submit the form to two urls, one is in the background. But in this shell_execute, how can I launch a script in the background?

Thanks!

johanafm

Just have your script update the value instantly so the user doesn't have to wait.

Use a daemon to continously check for a value change every second. When the value changes you append an array element with the time of change.
Every second you also
1. check if your array contains any elements.
1a. if not, you're done
2. check first array element to see if the value is older than 30 seconds ago
2a. if not, you're done
3. pop the element off the array to get rid of it
4. do whatever you are supposed to do 30 seconds after the value changed
5. go to 1.

blackhorse

I found this thread,

"Forking" a Process and Sending it to Background – in PHP

http://www.welldonesoft.com/technology/articles/php/forking/

exec("/usr/bin/php ./child_script.php > /dev/null 2>&1 &");

the "&", Will do the trick.

It is exactly what I want. Thanks!