Making variable readable from multiple scripts?

KendersPlace

I have done lots of reading on globals, but what I'm seeing seems restricted to a single script.

I have a script that runs constantly on a linux box. The script is executed on box boot up (rc.local kicks it off) then it just loops forever... something to this effect:


while (!$myvar){
    sleep 1;
    }

Then I want a separate script, actually executed as a web page from apache to occasionally change $myvar to "true", and have the script running on the server to break out of its sleep loop and execute some commands before eventually returning to the sleep loop.

I am able to do this by writing $myvar to mysql or a text file, but the looping / sleeping script needs to query the DB or text file after each second to determine if $myvar has changed or not. This leads to lots of un-necessary queries on the DB.

Does php maintain a "super global" variable array that is readable by all scripts running on the server? The kind of thing where I could use it in a while() loop efficiently. Checking a global like this is probably more efficient than constant file reads or DB queries.

Thanks!

ScubaKing22

Try using sessions to carry it across pages.

KendersPlace

Originally posted by ScubaKing22
Try using sessions to carry it across pages.

In this case sessions will not work, as the value is not user specific, and it doesn't really cross pages either.

I'll try to cliarify...

The server runs a script at boot up, and that script ramains sleeping in the background, it is always active, even if there are no current web users. The script wakes up every few seconds and checks a variable, based on it's status, the script may proceed to do some operations then go back to sleep again.

The page viewed by the actual web user will change this variable from time to time, depending on what the user has requested.

I need to set a variable that can be read by this other script. I don't think it can be done though. I will probably just record the value in SQL and query it.

Thanks.

benpaul

make the script update tha variable in mysql and then get the sleeping ( or croned ) script to read it from the mysql server.

Thats pretty much the best way to do it.

Regards

ben

Mucello

You could create a new php file and have that variable set in that new file. Then, any page that needs to know what the variable is or change it can just do a include 'newfile.php'

HalfaBee

Couldn't you have the web pages execute the extra commands when needed?

Other wise have them write to a file with a different value and have the sleeping script read the file and modify $myvar according to the value in the file.

HalfaBee

benpaul

Originally posted by HalfaBee
Couldn't you have the web pages execute the extra commands when needed?

Other wise have them write to a file with a different value and have the sleeping script read the file and modify $myvar according to the value in the file.

HalfaBee

saving variables in text files is very messy and extremly heavy on the server, manipulating data storage etc is exactly what the database was created for.

Your best bet so far is to use mysql to save the value, its quick and very easy for other scripts to connect to.

Regards

Ben

HalfaBee

How could a save to a file be more load than a database update?

A DB update / query is a lot more load than any file open / read.

If you want the full description you can have it, but I am not going to waste my time now.

HalfaBee