[sheepdog] [PATCH] sheep: add simple_store driver again

[Liu Yuan]

On 08/24/2012 03:15 PM, MORITA Kazutaka wrote:
> At Fri, 24 Aug 2012 15:04:56 +0800,
> Liu Yuan wrote:
>>
>> On 08/24/2012 01:37 PM, MORITA Kazutaka wrote:
>>> It is a good idea to refine the farm backend store too, but simple
>>> store should be added as another driver, I think.  The simple driver
>>> would become a good tutorial to introduce new drivers.
>>
>> Okay, I'd suggest use default_xxx as prefix instead of simple_store_xxx,
>> because 1) more concise 2) won't cause confusion when people read the
>> farm code.
> 
> The driver name should be 'default', too?  I think we shouldn't use a
> name 'simple_store' to avoid confusion.
> 

I think simple_store.c itself won't cause confusion. 'default store'
will instead cause greater confusion.

>>
>> I'll go to update the farm's io path to use defaul_xxx functions, I
>> think this simple store implementation can be nicely applied to farm.
> 
> The update will change the data layout of farm.  How about introducing
> 'farm2'?  I guess farm and farm2 can share all files other than
> farm.c.

No, this won't change the data layout of farm at all. Just adding
another .stale file directory, which is useless after cluster becomes
stable. With .stale, old .farm directory will be solely used for storing
snapshot objects, which is also relevant to ordinary data objects in
working directory.

Thanks,
Yuan