On 7/8/2011 4:58 PM, Kenneth Porter wrote:
> I have a Bash script, currently run a couple times an hour from cron, that
> pulls data from an old Windows DB by rsync, converts it to SQL, and injects
> it into a MySQL DB for display in a LAMP-based app. (Make and Perl are also
> involved to minimize the number of tables touched and to clean up the SQL
> generated by Pxlib.)
>
> I'd like to add the ability to refresh the data immediately from the web
> app, but I don't want it to trample on the periodic script and corrupt the
> data.
>
> I figure the ideal way to do this is to run the script in a loop in its own
> process, waiting on a semaphore that times out at the refresh period, and
> poke the semaphore from the web app to have it run before the next periodic
> cycle.
>
> Are there existing frameworks to wrap this kind of thing in? Something that
> handles starting the loop at server startup, shutting it down at server
> halt, and handles the IPC between the web server and the service script.
You already have a DB connection in common - can't the update script
itself lock something in the DB while it works? Or just make the web
script wait for the cron job to complete if you are anywhere near the
time for it to run.
--
Les Mikesell
lesmikesell at gmail.com