[PATCH] Speed up bash completion loading
From: Jonathan Nieder <hidden>
Date: 2016-06-15 22:47:43
Subsystem:
the rest · Maintainer:
Linus Torvalds
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 tracked down that the most 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 <redacted> Cc: Shawn O. Pearce <redacted> Cc: Stephen Boyd <redacted> Cc: Sverre Rabbelier <redacted> Cc: Junio C Hamano <redacted> Signed-off-by: Jonathan Nieder <redacted> --- Stephen Boyd wrote:
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.
Strictly speaking, even with the existing completion script, it might
be nice to provide a "hash -r"-like command to bring the caches up to
date. Such a function could be:
git-completion-rehash ()
{
__git_compute_all_commands
__git_compute_merge_strategies
__git_compute_porcelain_commands
}
But that is a separate topic.
contrib/completion/git-completion.bash | 35 +++++++++++++++++--------------
1 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 9e8b607..7088ec7 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash@@ -330,10 +330,9 @@ __git_list_merge_strategies () }' } -__git_merge_strategies () +__git_compute_merge_strategies () { - : ${__git_merge_strategylist:=$(__git_list_merge_strategies)} - echo "$__git_merge_strategylist" + : ${__git_merge_strategies=$(__git_list_merge_strategies)} } __git_complete_file ()
@@ -468,15 +467,16 @@ __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
@@ -495,16 +495,16 @@ __git_list_all_commands () done } -__git_all_commands () +__git_compute_all_commands () { - : ${__git_all_commandlist:=$(__git_list_all_commands)} - echo "$__git_all_commandlist" + : ${__git_all_commands=$(__git_list_all_commands)} } __git_list_porcelain_commands () { 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;;
@@ -586,10 +586,9 @@ __git_list_porcelain_commands () done } -__git_porcelain_commands () +__git_compute_porcelain_commands () { - : ${__git_porcelain_commandlist:=$(__git_list_porcelain_commands)} - echo "$__git_porcelain_commandlist" + : ${__git_porcelain_commands=$(__git_list_porcelain_commands)} } __git_aliases ()
@@ -1082,7 +1081,8 @@ _git_help () return ;; esac - __gitcomp "$(__git_all_commands) + __git_compute_all_commands + __gitcomp "__git_all_commands attributes cli core-tutorial cvs-migration diffcore gitk glossary hooks ignore modules repository-layout tutorial tutorial-2
@@ -1438,7 +1438,8 @@ _git_config () return ;; pull.twohead|pull.octopus) - __gitcomp "$(__git_merge_strategies)" + __git_compute_merge_strategies + __gitcomp "$__git_merge_strategies" return ;; color.branch|color.diff|color.interactive|\
@@ -1539,7 +1540,8 @@ _git_config () pager.*) local pfx="${cur%.*}." cur="${cur#*.}" - __gitcomp "$(__git_all_commands)" "$pfx" "$cur" + __git_compute_all_commands + __gitcomp "__git_all_commands" "$pfx" "$cur" return ;; remote.*.*)
@@ -2136,7 +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