prepstrip/ecompressdir: parallelize operations

Stealing some ideas from ferringb, add a new API for doing parallel
processing in bash, and then deploy this with the stripping and
compressing stages.

For stripping coreutils which has about 100 ELFs, this brings time
to strip down from ~7 seconds to ~0.7 seconds on my system.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2 files changed, 42 insertions, 8 deletions

diff --git a/bin/ebuild-helpers/ecompressdir b/bin/ebuild-helpers/ecompressdir
index 17ecd8082..a2c9e52a0 100755
--- a/bin/ebuild-helpers/ecompressdir
+++ b/bin/ebuild-helpers/ecompressdir
@@ -2,7 +2,7 @@
 # Copyright 1999-2011 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
-source "${PORTAGE_BIN_PATH:-/usr/lib/portage/bin}"/isolated-functions.sh
+source "${PORTAGE_BIN_PATH:-/usr/lib/portage/bin}"/helper-functions.sh
 
 if [[ -z $1 ]] ; then
 	helpers_die "${0##*/}: at least one argument needed"
@@ -116,6 +116,16 @@ ret=0
 
 rm -rf "${T}"/ecompress-skip
 
+decompressors=(
+	".Z"    "gunzip -f"
+	".gz"   "gunzip -f"
+	".bz2"  "bunzip2 -f"
+	".xz"   "unxz -f"
+	".lzma" "unxz -f"
+)
+
+multijob_init
+
 for dir in "$@" ; do
 	dir=${dir#/}
 	dir="${ED}${dir}"
@@ -136,14 +146,26 @@ for dir in "$@" ; do
 	find "${dir}" -type f -name '*.ecompress.file' -print0 | ${XARGS} -0 rm -f
 
 	# not uncommon for packages to compress doc files themselves
-	funk_up_dir "decompress" ".Z" "gunzip -f"
-	funk_up_dir "decompress" ".gz" "gunzip -f"
-	funk_up_dir "decompress" ".bz2" "bunzip2 -f"
+	for (( d = 0; d < ${#decompressors[@]}; d += 2 )) ; do
+		# It's faster to parallelize at this stage than to try to
+		# parallelize the compressors.  This is because the find|xargs
+		# ends up launching less compressors overall, so the overhead
+		# of forking children ends up dominating.
+		(
+		multijob_child_init
+		funk_up_dir "decompress" "${decompressors[i]}" "${decompressors[i+1]}"
+		) &
+		multijob_post_fork
+		: $(( ret |= $? ))
+	done
 
 	# forcibly break all hard links as some compressors whine about it
 	find "${dir}" -type f -links +1 -exec env file="{}" sh -c \
 		'cp -p "${file}" "${file}.ecompress.break" ; mv -f "${file}.ecompress.break" "${file}"' \;
 
+	multijob_finish
+	: $(( ret |= $? ))
+
 	# now lets do our work
 	if [[ -n ${suffix} ]] ; then
 		vecho "${0##*/}: $(ecompress --bin) /${actual_dir#${ED}}"
diff --git a/bin/ebuild-helpers/prepstrip b/bin/ebuild-helpers/prepstrip
index daaa25250..09b0333d9 100755
--- a/bin/ebuild-helpers/prepstrip
+++ b/bin/ebuild-helpers/prepstrip
@@ -1,8 +1,8 @@
 #!/bin/bash
-# Copyright 1999-2011 Gentoo Foundation
+# Copyright 1999-2012 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
-source "${PORTAGE_BIN_PATH:-/usr/lib/portage/bin}"/isolated-functions.sh
+source "${PORTAGE_BIN_PATH:-/usr/lib/portage/bin}"/helper-functions.sh
 
 # avoid multiple calls to `has`.  this creates things like:
 #   FEATURES_foo=false
@@ -62,6 +62,8 @@ prepstrip_sources_dir=${EPREFIX}/usr/src/debug/${CATEGORY}/${PF}
 type -P debugedit >/dev/null && debugedit_found=true || debugedit_found=false
 debugedit_warned=false
 
+multijob_init
+
 unset ${!INODE_*}
 
 inode_var_name() {
@@ -171,6 +173,8 @@ process_elf() {
 # We want to log already stripped binaries, as this may be a QA violation.
 # They prevent us from getting the splitdebug data.
 if ! ${RESTRICT_binchecks} && ! ${RESTRICT_strip} ; then
+	(
+	multijob_child_init
 	log=$T/scanelf-already-stripped.log
 	qa_var="QA_PRESTRIPPED_${ARCH/-/_}"
 	[[ -n ${!qa_var} ]] && QA_PRESTRIPPED="${!qa_var}"
@@ -193,6 +197,8 @@ if ! ${RESTRICT_binchecks} && ! ${RESTRICT_strip} ; then
 	else
 		rm -f "$log"
 	fi
+	) &
+	multijob_post_fork
 fi
 
 # Now we look for unstripped binaries.
@@ -205,8 +211,10 @@ do
 		banner=true
 	fi
 
-	f=$(file "${x}") || continue
-	[[ -z ${f} ]] && continue
+	(
+	multijob_child_init
+	f=$(file "${x}") || exit 0
+	[[ -z ${f} ]] && exit 0
 
 	if ! ${SKIP_STRIP} ; then
 		# The noglob funk is to support STRIP_MASK="/*/booga" and to keep
@@ -253,6 +261,8 @@ do
 	if ${was_not_writable} ; then
 		chmod u-w "${x}"
 	fi
+	) &
+	multijob_post_fork
 done
 
 if [[ -s ${T}/debug.sources ]] && \
@@ -274,3 +284,5 @@ then
 		>> "$emptydir"/.keepdir
 	done < <(find "${D}${prepstrip_sources_dir}/" -type d -empty -print0)
 fi
+
+multijob_finish