From: Johannes Sixt <j6t@kdbg.org>
Date: Sat, 15 Apr 2017 12:30:39 GMT
Subject: Re: Index files autocompletion too slow in big repositories (w / suggestion for improvement)
Message-ID: <3711baf1-af54-b5c9-25e8-9613312c536a@kdbg.org>
In-Reply-To: <CACBZZX7Ajf1c9YKP=MO0T9SV7d0-XZsT=RthJocqZw4_TcCcQw@mail.gmail.com>

Cc Gábor, resent with working email (hopefully); please follow-up on 
this mail.

Am 15.04.2017 um 00:33 schrieb Ævar Arnfjörð Bjarmason:
> On Sat, Apr 15, 2017 at 12:08 AM, Carlos Pita <carlosjosepita@gmail.com> 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