Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/18718

Log:
commit c6ca69501c8d8d86ca07275d13832bd350c1b1a6
Author: Zhiteng Huang <zhiteng.huang at intel.com>
Date:   Sat Dec 22 17:08:52 2012 +0800

    Convert Nova to use common scheduler filter/weight
    
    Filter scheduler is being used for more than one core projects (Nova
    and Cinder as of writing), the implementation shared a lot of common
    code. Efforts has been spent on porting scheduler filters and weighing
    functions to Oslo.
    
    This patch will convert Nova to use common scheduler filters and
    weights. And the common filters/weights are managed/exposed via entry
    points, therefore this patch removes loadables module (since it is not
    necessary anymore) and related tests as well.  Besides filters/weights,
    the rest of Nova remains almost untouched, only a few lines of code
    change is needed for Host Manager().
    
    The implications for this patch to end users are:
    1) Users who don't add custom filters or weighers
    
       * If a user has set the scheduler_default_filters config option to
         enable or disable some filters, this should keep working without
         the user having to update their config files. The current patch
         renames ComputeCapabilitiesFilter to CapabilitiesFilter which
         results a deprecated warning log message but the expected behavior
         is unchanged.
    
       * The behaviour of the filters should not change at all. For example,
         they operate on the same set of filter_properties provided to
         run_instance() so you should be able to update the scheduler before
         updating the API server.
    
       * The scheduler_available_filters config option is removed in favor of
         the default "all_filters" behaviour. It's safe to assume this class
         of users wouldn't have changed this option.  Even if end users who had
         this config explictly set in config file (a.k.a change default), simply
         remove this config option will solve the problem (NoSuchOptError).
    
       * The scheduler_weight_classes config option is replaced by
         scheduler_default_weigher option.  This class of users should not
         notice any difference at all.
    
    2) Users who have added their own custom filters or weighers.
    
       * There were previously two ways of adding new code - drop a file
         into the right directory Nova's codebase or install it elsewhere
         and update the available_filters or weight_classes options. Neither
         of these methods will work anymore. Instead, they need to register
         their filter as an entry point.
    
       * The code needs to be updated to use the new Oslo filter/weigher
         base classes.
    
       * To use custom weighers or to disable the RAM weigher, simple place
         the desired weighers in new scheduler_default_weigher options will
         do the trick.
    
    DocImpact
    
    Change-Id: Ib0b3eb580072633be4367f22959d5ebed0bc86d6