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Re: Index files autocompletion too slow in big repositories (w / suggestion for improvement)




On Sat, Apr 15, 2017 at 4:59 AM, Johannes Sixt <j6t@xxxxxxxx> wrote:
> Cc Gábor.
>
> Am 15.04.2017 um 00:33 schrieb Ævar Arnfjörð Bjarmason:
>>
>> On Sat, Apr 15, 2017 at 12:08 AM, Carlos Pita <carlosjosepita@xxxxxxxxx>
>> wrote:
>>>
>>> This is much faster (below 0.1s):
>>>
>>> __git_index_files ()
>>> {
>>>     local dir="$(__gitdir)" root="${2-.}" file;
>>>     if [ -d "$dir" ]; then
>>>         __git_ls_files_helper "$root" "$1" | \
>>>             sed -r 's@/.*@@' | uniq | sort | uniq
>>>     fi
>>> }
>>>
>>> time __git_index_files
>>>
>>> real    0m0.075s
>>> user    0m0.083s
>>> sys    0m0.010s
>>>
>>> Most of the improvement is due to the simpler, non-grouping, regex.
>>> Since I expect most of the common prefixes to arrive consecutively,
>>> running uniq before sort also improves things a bit. I'm not removing
>>> leading double quotes anymore (this isn't being done by the current
>>> version, anyway) but this doesn't seem to hurt.
>>>
>>> Despite the dependence on sed this is ten times faster than the
>>> original, maybe an option to enable fast index completion or something
>>> like that might be desirable.
>>
>>
>> It's fine to depend on sed, these shell-scripts are POSIX compatible,
>> and so is sed, we use sed in a lot of the built-in shellscripts.
>
>
> This is about command line completion. We go a long way to avoid forking
> processes there. What is 10x faster on Linux despite of forking a process
> may not be so on Windows.
>
> (I'm not using bash command line completion on Windows, so I can't tell what
> the effect of your suggested change is on Windows. I hope Gábor can comment
> on it.)
>
> -- Hannes
>

In cases like this, might it be worth somehow splitting it so Linux
can use the best thing, and Windows can continue using what's best for
it, since it is a pretty significant advantage on Linux.

Thanks,
Jake