Re: [PATCH 1/1] Bypass expensive content comparsion during rename detection.

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Hi,

On Thu, 14 Dec 2006, Shawn Pearce wrote:

> My first version of the patch had the hash comparsion right after we 
> called diff_populate_filespec to get the size data.  But then I realized 
> that very often the sizes will be different and the src->size != 
> dst->size comparsion will tend to be true most of the time, thus saving 
> us a (relatively) expensive hash comparsion, which we know must fail 
> anyway if the sizes differed.

Ah! I misunderstood. Since the call to diff_populate_filespec was not 
visible in the hunk, I erroneously assumed that you meant to _check_ the 
sizes before checking the hashes.

But your explanation makes lots of sense to me. May I request a short 
comment above the new code, like "let diff_populate_filespec() do its 
thing since we need the filesize later on anyway, and having that, do the 
cheaper filesize check before the more expensive hashcmp()"?

Ciao,
Dscho

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