Re: [PATCH 0/5] Suggested for PU: revision caching system to significantly speed up packing/walking

[A Large Angry SCM <gitzilla@gmail.com>]

Shawn O. Pearce wrote:
> Nick Edelen <sirnot@gmail.com> wrote:
>> Hrmm, I just realized that it dosn't actually cache paths/names...
>> This obviously has no bearing on its use in packing, but I should
>> either add that in or restrict usage in non-packing-related walks.
>> Weird how things like that escape you.
>>
>> I think I may go ahead and add support for this tomorrow.  It should
>> have no effect on performance and very little impact on cache slice
>> size.
> 
> You may not need the path name, but instead the hash value that
> pack-objects computes from the path name.  All that matters is
> the hash, so pack-objects can schedule the objects into the right
> buckets when its doing delta computation for objects which are not
> yet delta compressed, or whose delta cannot be suitably reused.
> 

Please do NOT expose the hash values. The hash used by pack-objects is 
an implementation detail of the heuristics used by the _current_ object 
packing code. It would be a real shame to have to maintain backward 
compatibility with it at some future date after the packing machinery 
has changed.