Thoughts on file ids

[John Arbash Meinel]

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On 5/8/2011 1:56 PM, Jelmer Vernooij wrote:
> On Fri, 2011-05-06 at 16:06 +0200, John Arbash Meinel wrote:
>> On 05/06/2011 03:42 PM, Martin Pool wrote:
>>> Yeah, I was thinking of wt access possibly being simpler and faster by
>>> name, but you're right this will need testing and may well be a problem
>>> for committed trees.
>>>
>>
>> I think right now any api which is performance sensitive takes a "path"
>> hint. And I know we make use of it in many places. dirstate itself
>> prefers to lookup by path, because it stores things by path. If you pass
>> a file-id it reads all entries and creates a file_id => path mapping.
>>
>> We do this because WT level operations are, indeed, generally done by
>> path (status path, commit path, etc.) but repository level operations
>> are generally done by file-id (log over history of a file, diff, etc.)
> The one thing I've always wondered about this API is that while it
> allows you to pass in the path, it also requires you to have (possibly
> lookup) the file id. Is that never an issue in terms of performance?
> 
> Cheers,
> 
> Jelmer
> 

I don't know about all of them. The underlying dirstate code would
rather you *didn't* pass a file_id, but will validate it if it is
passed. (It looks by path, and gives an exception if the file_id doesn't
match.)

John
=:->

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