Re: [RFC/PATCH v2] fetch: Speed up fetch by rewriting find_non_local_tags

From: Julian Phillips <julian@quantumfyre.co.uk>
Date: Sep 16, 2009, 23:46 UTC
Message-ID: <alpine.LNX.2.00.0909170039410.14993@reaper.quantumfyre.co.uk>
In-Reply-To: <7veiq6wkfu.fsf@alter.siamese.dyndns.org>

On Wed, 16 Sep 2009, Junio C Hamano wrote:

Show 19 quoted lines

> Julian Phillips <julian@quantumfyre.co.uk> writes:
>
>> When trying to get a list of remote tags to see if we need to fetch
>> any we were doing a linear search for the matching tag ref for the
>> tag^{} commit entries.  This proves to be incredibly slow for large
>> numbers of tags.  Rewrite the function so that we can do lookup in
>> string_lists instead.
>>
>> For a repository with 50000 tags (and just a single commit on a single
>> branch), a fetch that does nothing goes from ~ 1m50s to ~4.2s.
>>
>> Signed-off-by: Julian Phillips <julian@quantumfyre.co.uk>
>> ---
>>
>> Not only does this not require a custom hash table, it is also slightly
>> faster than the last version (~4.2s vs ~4.5s).
>
> I am just curious.  How would a "just one item lookbehind" code perform
> compared to this one?

The code you wrote ealier is almost the same as the string_list version, ~4.3s, so very marginally slower but a lot less code change. Personally I'd be happy with any of the three, so long as I don't have to wait 30s to find out that nothing's happened at $dayjob anymore ;)

-- 
Julian

  ---
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