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From Michal Fojtik <mfoj...@redhat.com>
Subject Re: Openstack check buckets capability v2
Date Fri, 14 Sep 2012 15:10:15 GMT

On Sep 14, 2012, at 5:07 PM, Michal Fojtik <mi@mifo.sk> wrote:

> 
> On Sep 14, 2012, at 4:48 PM, marios@redhat.com wrote:
> 
>> 
>> notes:
>> 
>> 1) moved supported_collection to base_driver and given it a credentials parameter
>> 
>> 2) This means we can get rid of the Thread.current["credentials"] business 
>> altogether since the credentials are passed from the GET /api request so 
>> LazyAuth works as intended.
>> 
>> 3) I kept the actual definition of 'supported_collections' as in the original 
>> - I don't see the benefit of changing this. The way I understand it currently:
>> 
>> => each collection defines a lambda like : 
>> 
>>       set :capability, lambda { |m| driver.respond_to? m }$
>> 
>> => the supported_collections method calls this lamba:
>> 
>>       m.settings.capability(index_operation_capability)
>>       (where 'index_operation_capability' is :buckets, in this case)
> 
> This is correct.
> 
>> So the result is supported_collections checks if a driver supports a given 
>> collection by calling respond_to?(collection_name) on the driver. Is this bad?
> 
> I did it using lambda{} because it was the only way how to make it work with
> the driver switching. The 'driver' method returns the 'current' driver and since
> the 'lambda' is evaluated in each request we can be sure we always check the
> right (current) driver for the capability.
> 
> Also this can lead to nice extensions, like using something more complicated
> than just checking if method exists.
> 
>> With these additions, each driver can just override supported_collections as
>> David suggests anyway.
> 
> Be careful about what happen when you switch the driver. It should always return
> to its original state. Mean you do a request for OpenStack which overrides this method,
> but then request to EC2 but the method will stay overridden.

Never mind this last comment, it is Friday and after I spend few more seconds on thinking
about this patch I don't think this can happen ;-)

  -- Michal

Michal Fojtik
http://deltacloud.org
mfojtik@redhat.com




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