[gentoo-dev] [PATCH 1/2] Introduce multibuild_merge_root() to merge interim installs.

[Michał Górny]

This is mostly a copy from distutils-r1. The function does copy all the
files from one location onto another, preserving whatever possible. It
can be run in parallel too without the risk of race conditions.
---
 gx86/eclass/distutils-r1.eclass | 41 +------------------------------------
 gx86/eclass/multibuild.eclass   | 45 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 40 deletions(-)

diff --git a/gx86/eclass/distutils-r1.eclass b/gx86/eclass/distutils-r1.eclass
index 0982e6c..3c21741 100644
--- a/gx86/eclass/distutils-r1.eclass
+++ b/gx86/eclass/distutils-r1.eclass
@@ -449,49 +449,10 @@ distutils-r1_python_install() {
 
 	if [[ ! ${DISTUTILS_SINGLE_IMPL} ]]; then
 		_distutils-r1_rename_scripts "${root}"
-		_distutils-r1_merge_root "${root}" "${D}"
+		multibuild_merge_root "${root}" "${D}"
 	fi
 }
 
-# @FUNCTION: distutils-r1_merge_root
-# @USAGE: <src-root> <dest-root>
-# @INTERNAL
-# @DESCRIPTION:
-# Merge the directory tree from <src-root> to <dest-root>, removing
-# the <src-root> in the process.
-_distutils-r1_merge_root() {
-	local src=${1}
-	local dest=${2}
-
-	local lockfile=${T}/distutils-r1-merge-lock
-
-	if type -P lockf &>/dev/null; then
-		# On BSD, we have 'lockf' wrapper.
-		tar -C "${src}" -f - -c . \
-			| lockf "${lockfile}" tar -x -f - -C "${dest}"
-	else
-		local lock_fd
-		if type -P flock &>/dev/null; then
-			# On Linux, we have 'flock' which can lock fd.
-			redirect_alloc_fd lock_fd "${lockfile}" '>>'
-			flock ${lock_fd}
-		else
-			ewarn "distutils-r1: no locking service found, please report."
-		fi
-
-		cp -a -l -n "${src}"/. "${dest}"/
-
-		if [[ ${lock_fd} ]]; then
-			# Close the lock file when we are done with it.
-			# Prevents deadlock if we aren't in a subshell.
-			eval "exec ${lock_fd}>&-"
-		fi
-	fi
-	[[ ${?} == 0 ]] || die "Merging ${EPYTHON} image failed."
-
-	rm -rf "${src}"
-}
-
 # @FUNCTION: distutils-r1_python_install_all
 # @DESCRIPTION:
 # The default python_install_all(). It installs the documentation.
diff --git a/gx86/eclass/multibuild.eclass b/gx86/eclass/multibuild.eclass
index a3f1402..ed837d3 100644
--- a/gx86/eclass/multibuild.eclass
+++ b/gx86/eclass/multibuild.eclass
@@ -238,5 +238,50 @@ run_in_build_dir() {
 	return ${ret}
 }
 
+# @FUNCTION: multibuild_merge_root
+# @USAGE: <src-root> <dest-root>
+# @DESCRIPTION:
+# Merge the directory tree (fake root) from <src-root> to <dest-root>
+# (the real root). Both directories have to be real, absolute paths
+# (i.e. including ${D}). Source root will be removed.
+#
+# This functions uses locking to support merging during parallel
+# installs.
+multibuild_merge_root() {
+	local src=${1}
+	local dest=${2}
+
+	local lockfile=${T}/multibuild_merge_lock
+
+	if type -P lockf &>/dev/null; then
+		# On BSD, we have 'lockf' wrapper.
+		tar -C "${src}" -f - -c . \
+			| lockf "${lockfile}" tar -x -f - -C "${dest}"
+	else
+		local lock_fd
+		if type -P flock &>/dev/null; then
+			# On Linux, we have 'flock' which can lock fd.
+			redirect_alloc_fd lock_fd "${lockfile}" '>>'
+			flock ${lock_fd}
+		else
+			ewarn "multibuild: no locking service found, please report."
+		fi
+
+		cp -a -l -n "${src}"/. "${dest}"/
+
+		if [[ ${lock_fd} ]]; then
+			# Close the lock file when we are done with it.
+			# Prevents deadlock if we aren't in a subshell.
+			eval "exec ${lock_fd}>&-"
+		fi
+	fi
+
+	if [[ ${?} -ne 0 ]]; then
+		die "${MULTIBUILD_VARIANT:-(unknown)}: merging image failed."
+	fi
+
+	rm -rf "${src}"
+}
+
 _MULTIBUILD=1
 fi
-- 
1.8.1.5