Saving application state

[Celso Barriga]

Hello, it's me again :)

I have a POE-based application that queries a web app for some data filtered on some time range, say, "send me any changes from time x to now".

The application will be running 24/7, and will query for more changes since the last time it asked for changes. I have a tick handler that keeps the heartbeat going every second so I can do the query repeatedly.

I need to save the last time it made the query in some persistent fashion so I can pass it in my next query. I can't just save it to my heap in case the application quits, I need to be able to resume the query since the last successful query.

What is the best way of doing this, the "POE way". Can I just save it to a file and read it back every tick count, which is 1 sec, using a regular file handle?

Thanks in advance!

Celso

[Rocco Caputo]

Hi, Celso.

This isn't a job for POE.

Use File::AtomicWrite, or something like it, to safely write the time stamp as frequently as necessary. It's a trivial amount of data, so you probably don't need it written asynchronously.

Reload the time stamp when the program restarts.

--
Rocco Caputo <rca...@pobox.com>

[Celso Barriga]

Thanks guys.

I think I'll go with Rocco's suggestion. Since I'll be reading and writing probably only 7 to 10 characters, should be no worries about call being blocked. Besides, I probably want the previous data already in the file before the next iteration, now that I think about it. And I also like your suggestion about using File::AtomicWrite.