completion: optimize refs completion
After a unique command or option is completed, in most cases it is a
good thing to add a trailing a space, but sometimes it doesn't make
sense, e.g. when the completed word is an option taking an argument
('--option=') or a configuration section ('core.'). Therefore the
completion script uses the '-o nospace' option to prevent bash from
automatically appending a space to unique completions, and it has the
__gitcomp() function to add that trailing space only when necessary.
See
72e5e989 (bash: Add space after unique command name is completed.,
2007-02-04),
78d4d6a2 (bash: Support unique completion on git-config.,
2007-02-04), and
b3391775 (bash: Support unique completion when
possible., 2007-02-04).
__gitcomp() therefore iterates over all possible completion words it
got as argument, and checks each word whether a trailing space is
necessary or not. This is ok for commands, options, etc., i.e. when
the number of words is relatively small, but can be noticeably slow
for large number of refs. However, while options might or might not
need that trailing space, refs are always handled uniformly and always
get that trailing space (or a trailing '.' for 'git config
branch.<head>.'). Since refs listed by __git_refs() & co. are
separated by newline, this allows us some optimizations with
'compgen'.
So, add a specialized variant of __gitcomp() that only deals with
possible completion words separated by a newline and uniformly appends
the trailing space to all words using 'compgen -S " "' (or any other
suffix, if specified), so no iteration over all words is needed. But
we need to fiddle with IFS, because the default IFS containing a space
would cause the added space suffix to be stripped off when compgen's
output is stored in the COMPREPLY array. Therefore we use only
newline as IFS, hence the requirement for the newline-separated
possible completion words.
Convert all callsites of __gitcomp() where it's called with refs, i.e.
when it gets the output of either __git_refs(), __git_heads(),
__git_tags(), __git_refs2(), __git_refs_remotes(), or the odd 'git
for-each-ref' somewhere in _git_config(). Also convert callsites
where it gets other uniformly handled newline separated word lists,
i.e. either remotes from __git_remotes(), names of set configuration
variables from __git_config_get_set_variables(), stashes, or commands.
Here are some timing results for dealing with 10000 refs.
Before:
$ refs="$(__git_refs ~/tmp/git/repo-with-10k-refs/)"
$ time __gitcomp "$refs"
real 0m1.134s
user 0m1.060s
sys 0m0.130s
After:
$ time __gitcomp_nl "$refs"
real 0m0.373s
user 0m0.360s
sys 0m0.020s
Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
projects / git.git / commit