[Backgroundrb-devel] Scheduling one-off tasks

Ed W lists at wildgooses.com
Tue Jul 29 10:21:03 EDT 2008

Joost Baaij wrote:
> I am building a Rails website which has content that expires at some 
> time in the future.
> Since this content is cached, by the time it expires I would like a 
> method to sweep the cache at that time. Since it's based on a date, I 
> cannot use the Rails app itself. I could use polling or sweep the 
> cache every 5 minutes, but maybe there's a better approach?
> I would like to know if I can use backgroundrb's at/cron-like features 
> to schedule one-off execution of a piece of code at a date/time in the 
> future. This would be a sweeper that runs at the expires_at time of my 
> content.
> I realise I can build a worker that goes into a sleep/wait loop until 
> the desired time, but that's not really better than polling.

I think one issue is that the backgroundb will loose it's pending tasks 
if it's rebooted?  Does this cause your app a problem?

Have you considered memcached caching which has time based expiry (could 
integrate better).  Or I think it's not so hard to wrap the builtin 
partial caching to include time based expiration (see some of the 
plugins for inspiration, just need to choose a good place to store your 

Anyway, feels like although bdrb can do this it might not be the best 

Good luck

Ed W

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