Re: [PATCH] Speed up bash completion loading
- From
Jonathan Nieder <jrnieder@gmail.com>
- Date
- Nov 13, 2009, 09:03 UTC
- Message-ID
- <20091113090343.GA5355@progeny.tock>
- In-Reply-To
- <20091113085028.GA4804@progeny.tock>
On my slow laptop (P3 600MHz), system-wide bash completions take too much time to load (> 2s), and a significant fraction of this time is spent loading git-completion.bash:
$ time bash -c ". ./git-completion.bash" # hot cache, before this patch
real 0m0.509s user 0m0.310s sys 0m0.180s
Kirill noticed that most of the time is spent warming up merge_strategy, all_command & porcelain_command caches.
Since git is not used in each and every interactive xterm, it seems best to load completion support with cold caches, and then load each needed thing lazily. This has most of the speed advantage of pre-generating everything at build time, without the complication of figuring out at build time what commands will be available at run time.
The result is that loading completion is significantly faster now:
$ time bash -c ". ./git-completion.bash" # cold cache, after this patch
real 0m0.171s user 0m0.060s sys 0m0.040s
Suggested-by: Kirill Smelkov <kirr@mns.spb.ru> Cc: Shawn O. Pearce <spearce@spearce.org> Cc: Stephen Boyd <bebarino@gmail.com> Cc: Sverre Rabbelier <srabbelier@gmail.com> Cc: Junio C Hamano <junio@pobox.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> --- Jonathan Nieder wrote:
> Stephen Boyd wrote:
Show 6 quoted lines
>> Ah ok. I think this proves even more that pregenerating the >> completion is a bad idea. With dynamic population we don't have >> these problems and it only takes 250ms more to load on a P3 >> 700Mhz. > > Hmm, 250 ms is a lot.
Here’s the real patch. Sorry about that.
Jonathan
contrib/completion/git-completion.bash | 67 +++++++++++++++---------------- 1 files changed, 32 insertions(+), 35 deletions(-)
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash index e3ddecc..7088ec7 100755 --- a/contrib/completion/git-completion.bash +++ b/contrib/completion/git-completion.bash @@ -21,13 +21,7 @@ # 2) Added the following line to your .bashrc: # source ~/.git-completion.sh # -# 3) You may want to make sure the git executable is available -# in your PATH before this script is sourced, as some caching -# is performed while the script loads. If git isn't found -# at source time then all lookups will be done on demand, -# which may be slightly slower. -# -# 4) Consider changing your PS1 to also show the current branch: +# 3) Consider changing your PS1 to also show the current branch: # PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ ' # # The argument to __git_ps1 will be displayed only if you @@ -324,12 +318,8 @@ __git_remotes () done } -__git_merge_strategies () +__git_list_merge_strategies () { - if [ -n "${__git_merge_strategylist-}" ]; then - echo "$__git_merge_strategylist" - return - fi git merge -s help 2>&1 | sed -n -e '/[Aa]vailable strategies are: /,/^$/{ s/\.$// @@ -339,8 +329,11 @@ __git_merge_strategies () p }' } -__git_merge_strategylist= -__git_merge_strategylist=$(__git_merge_strategies 2>/dev/null) + +__git_compute_merge_strategies () +{ + : ${__git_merge_strategies=$(__git_list_merge_strategies)} +} __git_complete_file () { @@ -474,27 +467,24 @@ __git_complete_remote_or_refspec () __git_complete_strategy () { + __git_compute_merge_strategies case "${COMP_WORDS[COMP_CWORD-1]}" in -s|--strategy) - __gitcomp "$(__git_merge_strategies)" + __gitcomp "$__git_merge_strategies" return 0 esac local cur="${COMP_WORDS[COMP_CWORD]}" case "$cur" in --strategy=*) - __gitcomp "$(__git_merge_strategies)" "" "${cur##--strategy=}" + __gitcomp "$__git_merge_strategies" "" "${cur##--strategy=}" return 0 ;; esac return 1 } -__git_all_commands () +__git_list_all_commands () { - if [ -n "${__git_all_commandlist-}" ]; then - echo "$__git_all_commandlist" - return - fi local i IFS=" "$'\n' for i in $(git help -a|egrep '^ [a-zA-Z0-9]') do @@ -504,17 +494,17 @@ __git_all_commands () esac done } -__git_all_commandlist= -__git_all_commandlist="$(__git_all_commands 2>/dev/null)" -__git_porcelain_commands () +__git_compute_all_commands () +{ + : ${__git_all_commands=$(__git_list_all_commands)} +} + +__git_list_porcelain_commands () { - if [ -n "${__git_porcelain_commandlist-}" ]; then - echo "$__git_porcelain_commandlist" - return - fi local i IFS=" "$'\n' - for i in "help" $(__git_all_commands) + __git_compute_all_commands + for i in "help" $__git_all_commands do case $i in *--*) : helper pattern;; @@ -595,8 +585,11 @@ __git_porcelain_commands () esac done } -__git_porcelain_commandlist= -__git_porcelain_commandlist="$(__git_porcelain_commands 2>/dev/null)" + +__git_compute_porcelain_commands () +{ + : ${__git_porcelain_commands=$(__git_list_porcelain_commands)} +} __git_aliases () { @@ -1088,7 +1081,8 @@ _git_help () return ;; esac - __gitcomp "$(__git_all_commands) + __git_compute_all_commands + __gitcomp "__git_all_commands attributes cli core-tutorial cvs-migration diffcore gitk glossary hooks ignore modules repository-layout tutorial tutorial-2 @@ -1444,7 +1438,8 @@ _git_config () return ;; pull.twohead|pull.octopus) - __gitcomp "$(__git_merge_strategies)" + __git_compute_merge_strategies + __gitcomp "$__git_merge_strategies" return ;; color.branch|color.diff|color.interactive|\ @@ -1545,7 +1540,8 @@ _git_config () pager.*) local pfx="${cur%.*}." cur="${cur#*.}" - __gitcomp "$(__git_all_commands)" "$pfx" "$cur" + __git_compute_all_commands + __gitcomp "__git_all_commands" "$pfx" "$cur" return ;; remote.*.*) @@ -2142,7 +2138,8 @@ _git () --help " ;; - *) __gitcomp "$(__git_porcelain_commands) $(__git_aliases)" ;; + *) __git_compute_porcelain_commands + __gitcomp "$__git_porcelain_commands $(__git_aliases)" ;; esac return fi
-- 1.6.5.2