Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/18618

Log:
commit 0b41fa99eec900a24a95e9ac3456428ac7d98c77
Author: Michael Still <mikal at stillhq.com>
Date:   Mon Dec 24 15:00:52 2012 +1100

    Refactor periodic tasks.
    
    This review allows periodic tasks to be enabled or disabled in the
    decorator, as well as by specifying an interval which is negative.
    
    The spacing between runs of a periodic task is now specified in
    seconds, with zero meaning the default spacing which is currently 60
    seconds.
    
    I also remove the periodic_interval flag to services, as the interval
    between runs is now dynamic based on the number of seconds that a
    periodic task wants to wait for its next run. For callers who want to
    twiddle the sleep period (for example unit tests), there is a
    create() argument periodic_interval_max which lets the period
    periodic_tasks() specifies be overridden. This is not exposed as a
    flag because I cannot see a use case for that. It is needed for unit
    testing however.
    
    DocImpact. Resolves bug 939087.
    
    Change-Id: I7f245a88b8d229a481c1b65a4c0f1e2769bf3901