Re: Bash-specific performance by avoiding sed
Pavel Raiskup <[email protected]>
| Newsgroups | gmane.comp.gnu.libtool.general |
|---|---|
| Message-ID | <[email protected]> |
forcemerge 20006 20005
thanks
On Monday 09 of March 2015 18:04:34 Mike Frysinger wrote:
> On 09 Mar 2015 14:48, Eric Blake wrote:
> > On 03/09/2015 01:50 PM, Bob Friesenhahn wrote:
> > > On Mon, 9 Mar 2015, Mike Gran wrote:
> > >> I don't know if y'all saw this blogpost where a guy pushed
> > >> the sed regular expression handling into bash-specific
> > >> regular expressions when bash was available. He claims
> > >> there's a significant performance improvement because of
> > >> reduced forking.
> > >>
> > >> http://harald.hoyer.xyz/2015/03/05/libtool-getting-rid-of-180000-sed-forks/
> > >
> > > There is an issue in the libtool bug tracker regarding this.
> > >
> > > This solution only works with GNU bash. It would be good if volunteers
> > > could research to see if there are similar solutions which can work with
> > > other common shells (e.g. dash, ksh, zsh).
> >
> > For context, we're trying to speed up:
> >
> > sed_quote_subst='s|\([`"$\\]\)|\\\1|g'
> > _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"`
> >
> > How about this, which should be completely portable to XSI shells (alas,
> > it still uses ${a#b} and ${a%b} at the end, so it is not portable to
> > ancient Solaris /bin/sh):
> >
> > # func_quote STRING
> > # Escapes all \`"$ in STRING with another \, and stores that in $quoted
> > func_quote () {
> > case $1 in
> > *[\\\`\"\$]*)
> > save_IFS=$IFS pre=.$1.
> > for char in '\' '`' '"' '$'; do
> > post= IFS=$char
> > for part in $pre; do
> > post=${post:+$post\\$char}$part
> > done
> > pre=$post
> > done
>
> should we test the size of the string first ? i've written such raw shell
> string parsing functions before, and once you hit a certain size (like 1k+
> iirc), forking out to sed is way faster, especially when running in multibyte
> locales (like UTF8) which most people are doing nowadays.
> -mike
Well, that optimization would require (fast) strlen()-like construct.
Anyway, the vast majority of calls to func_quote () function will have
short ARG, and its complexity is still "just" linear. We could optimize
later if that was a real issue.
I would like to propose solution based on Eric's one, without using of
'${VAR%.}' and '${VAR#.}' constructs -- sounds like this could be even
more portable while it keeps almost the same speed (if we can use += its
even faster).
I have yet a another patch trying to minimize option-parser overhead
(that is focused on the POV of Richard, but that needs to be cleaned up a
bit, I'll post hopefully tomorrow).
Any comment is welcome!
Pave
_______________________________________________
https://lists.gnu.org/mailman/listinfo/libtool
0001-libtool-mitigate-the-sed_quote_subst-slowdown.patch
(text/x-patch, 6.6 KB)
From aa988d0a49f2d2b419519b09fef62fc993a6169f Mon Sep 17 00:00:00 2001 From: Pavel Raiskup <[email protected]> Date: Sun, 4 Oct 2015 21:55:03 +0200 Subject: [PATCH] libtool: mitigate the $sed_quote_subst slowdown References: http://lists.gnu.org/archive/html/libtool/2015-03/msg00005.html http://lists.gnu.org/archive/html/libtool/2015-02/msg00000.html https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20006 * gl/build-aux/funclib.sh (func_quote): New function that can be used as substition for '$SED $sed_quote_subst' call. * build-aux/ltmain.in (func_emit_wrapper): Use func_quote instead of '$SED $sed_quote_subst'. (func_mode_link): Likewise. * NEWS: Document. * bootstrap: Sync with funclib.sh. --- NEWS | 3 +++ bootstrap | 49 +++++++++++++++++++++++++++++++++++++++++++++++-- build-aux/ltmain.in | 10 ++++++---- gl/build-aux/funclib.sh | 49 +++++++++++++++++++++++++++++++++++++++++++++++-- 4 files changed, 103 insertions(+), 8 deletions(-) diff --git a/NEWS b/NEWS index a3c5b12..7c23d03 100644 --- a/NEWS +++ b/NEWS @@ -17,6 +17,9 @@ NEWS - list of user-visible changes between releases of GNU Libtool - Fix significant slowdown of libtoolize for certain projects (regression introduced in 2.4.3 release) caused by infinite m4 macro recursion. + - Mitigate the slowdown of libtool script (introduced in v2.4.3) caused by + increased number of calls to '$SED $sed_quote_subst' (bug#20006). + * Noteworthy changes in release 2.4.6 (2015-02-15) [stable] ** New features: diff --git a/bootstrap b/bootstrap index c179f51..0c73a49 100755 --- a/bootstrap +++ b/bootstrap @@ -230,7 +230,7 @@ vc_ignore= # Source required external libraries: # Set a version string for this script. -scriptversion=2015-01-20.17; # UTC +scriptversion=2015-10-04.22; # UTC # General shell script boiler plate, and helper functions. # Written by Gary V. Vaughan, 2004 @@ -1257,6 +1257,50 @@ func_relative_path () } +# func_quote ARG +# -------------- +# Aesthetically quote one ARG, store the result into $func_quote_result. Note +# that we keep attention to performance here (so far O(N) complexity as long as +# func_append is O(N) too). +func_quote () +{ + $debug_cmd + + func_quote_result=$1 + func_quote_old_IFS=$IFS + + case $func_quote_result in + *[\\\`\"\$]*) + for _G_char in '\' '`' '"' '$' + do + # STATE($1) PREV($2) SEPARATOR($3) + set start "" "" + func_quote_result="dummy${_G_char}${func_quote_result}${_G_char}dummy" + IFS=$_G_char + for _G_part in $func_quote_result + do + case $1 in + quote) + func_append func_quote_result "$3$2" + set quote "$_G_part" "\\${_G_char}" + ;; + start) + set first "" "" + func_quote_result="" + ;; + first) + set quote "$_G_part" "" + ;; + esac + done + IFS=$func_quote_old_IFS + done + ;; + *) ;; + esac +} + + # func_quote_for_eval ARG... # -------------------------- # Aesthetically quote ARGs to be evaled later. @@ -1275,7 +1319,8 @@ func_quote_for_eval () while test 0 -lt $#; do case $1 in *[\\\`\"\$]*) - _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;; + func_quote "$1" + _G_unquoted_arg=$func_quote_result ;; *) _G_unquoted_arg=$1 ;; esac diff --git a/build-aux/ltmain.in b/build-aux/ltmain.in index 0c40da0..24acefd 100644 --- a/build-aux/ltmain.in +++ b/build-aux/ltmain.in @@ -3346,7 +3346,8 @@ else if test \"\$libtool_execute_magic\" != \"$magic\"; then file=\"\$0\"" - qECHO=`$ECHO "$ECHO" | $SED "$sed_quote_subst"` + func_quote "$ECHO" + qECHO=$func_quote_result $ECHO "\ # A function that is used when there is no print builtin or printf. @@ -8596,8 +8597,8 @@ EOF relink_command="$var=$func_quote_for_eval_result; export $var; $relink_command" fi done - relink_command="(cd `pwd`; $relink_command)" - relink_command=`$ECHO "$relink_command" | $SED "$sed_quote_subst"` + func_quote "(cd `pwd`; $relink_command)" + relink_command=$func_quote_result fi # Only actually do things if not in dry run mode. @@ -8843,7 +8844,8 @@ EOF done # Quote the link command for shipping. relink_command="(cd `pwd`; $SHELL \"$progpath\" $preserve_args --mode=relink $libtool_args @inst_prefix_dir@)" - relink_command=`$ECHO "$relink_command" | $SED "$sed_quote_subst"` + func_quote "$relink_command" + relink_command=$func_quote_result if test yes = "$hardcode_automatic"; then relink_command= fi diff --git a/gl/build-aux/funclib.sh b/gl/build-aux/funclib.sh index 39d972e..d2f2bff 100644 --- a/gl/build-aux/funclib.sh +++ b/gl/build-aux/funclib.sh @@ -1,5 +1,5 @@ # Set a version string for this script. -scriptversion=2015-01-20.17; # UTC +scriptversion=2015-10-04.22; # UTC # General shell script boiler plate, and helper functions. # Written by Gary V. Vaughan, 2004 @@ -1026,6 +1026,50 @@ func_relative_path () } +# func_quote ARG +# -------------- +# Aesthetically quote one ARG, store the result into $func_quote_result. Note +# that we keep attention to performance here (so far O(N) complexity as long as +# func_append is O(N) too). +func_quote () +{ + $debug_cmd + + func_quote_result=$1 + func_quote_old_IFS=$IFS + + case $func_quote_result in + *[\\\`\"\$]*) + for _G_char in '\' '`' '"' '$' + do + # STATE($1) PREV($2) SEPARATOR($3) + set start "" "" + func_quote_result="dummy${_G_char}${func_quote_result}${_G_char}dummy" + IFS=$_G_char + for _G_part in $func_quote_result + do + case $1 in + quote) + func_append func_quote_result "$3$2" + set quote "$_G_part" "\\${_G_char}" + ;; + start) + set first "" "" + func_quote_result="" + ;; + first) + set quote "$_G_part" "" + ;; + esac + done + IFS=$func_quote_old_IFS + done + ;; + *) ;; + esac +} + + # func_quote_for_eval ARG... # -------------------------- # Aesthetically quote ARGs to be evaled later. @@ -1044,7 +1088,8 @@ func_quote_for_eval () while test 0 -lt $#; do case $1 in *[\\\`\"\$]*) - _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;; + func_quote "$1" + _G_unquoted_arg=$func_quote_result ;; *) _G_unquoted_arg=$1 ;; esac -- 2.5.0