[Buildroot] [PATCH v4] support/scripts/fix-rpath: parallelize patching files

[Victor Dumas]

Using "xargs" instead of "while read" loop allows for the patching of files to be parallelized.
This significantly reduces the amount of time it takes to fix all the paths.
On a larger RFS(~300MB) this script was taking 5 minutes, it now only takes about 30s on a 12 core machine

Signed-off-by: Victor Dumas <dumasv.dev at gmail.com>
---
 support/scripts/fix-rpath | 66 ++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/support/scripts/fix-rpath b/support/scripts/fix-rpath
index 3e67e770e5..7ed1851aac 100755
--- a/support/scripts/fix-rpath
+++ b/support/scripts/fix-rpath
@@ -58,6 +58,40 @@ HOST_EXCLUDEPATHS="/share/terminfo"
 STAGING_EXCLUDEPATHS="/usr/include /usr/share/terminfo"
 TARGET_EXCLUDEPATHS="/lib/firmware"
 
+patch_file() {
+    PATCHELF="${1}"
+    rootdir="${2}"
+    sanitize_extra_args="${3}"
+    file="${4}"
+
+    # check if it's an ELF file
+    rpath=$(${PATCHELF} --print-rpath "${file}" 2>&1)
+    if test $? -ne 0 ; then
+        return 0
+    fi
+
+    # make files writable if necessary
+    changed=$(chmod -c u+w "${file}")
+
+    # With per-package directory support, most RPATH of host
+    # binaries will point to per-package directories. This won't
+    # work with the --make-rpath-relative ${rootdir} invocation as
+    # the per-package host directory is not within ${rootdir}. So,
+    # we rewrite all RPATHs pointing to per-package directories so
+    # that they point to the global host directry.
+    changed_rpath=$(echo ${rpath} | sed "s@${PER_PACKAGE_DIR}/[^/]\+/host@${HOST_DIR}@")
+    if test "${rpath}" != "${changed_rpath}" ; then
+        ${PATCHELF} --set-rpath ${changed_rpath} "${file}"
+    fi
+
+    # call patchelf to sanitize the rpath
+    ${PATCHELF} --make-rpath-relative "${rootdir}" ${sanitize_extra_args[@]} "${file}"
+    # restore the original permission
+    test "${changed}" != "" && chmod u-w "${file}"
+}
+
 main() {
     local rootdir
     local tree="${1}"
@@ -123,34 +157,10 @@ main() {
             ;;
     esac
 
-    find_args+=( "-type" "f" "-print" )
-
-    while read file ; do
-        # check if it's an ELF file
-        rpath=$(${PATCHELF} --print-rpath "${file}" 2>&1)
-        if test $? -ne 0 ; then
-            continue
-        fi
-
-        # make files writable if necessary
-        changed=$(chmod -c u+w "${file}")
-
-        # With per-package directory support, most RPATH of host
-        # binaries will point to per-package directories. This won't
-        # work with the --make-rpath-relative ${rootdir} invocation as
-        # the per-package host directory is not within ${rootdir}. So,
-        # we rewrite all RPATHs pointing to per-package directories so
-        # that they point to the global host directry.
-        changed_rpath=$(echo ${rpath} | sed "s@${PER_PACKAGE_DIR}/[^/]\+/host@${HOST_DIR}@")
-        if test "${rpath}" != "${changed_rpath}" ; then
-            ${PATCHELF} --set-rpath ${changed_rpath} "${file}"
-        fi
-
-        # call patchelf to sanitize the rpath
-        ${PATCHELF} --make-rpath-relative "${rootdir}" ${sanitize_extra_args[@]} "${file}"
-        # restore the original permission
-        test "${changed}" != "" && chmod u-w "${file}"
-    done < <(find "${rootdir}" ${find_args[@]})
+    find_args+=( "-type" "f" "-print0" )
+
+    export -f patch_file
+    # Limit the number of cores used
+    procs=$(echo -e "$(($(nproc)-2)) \n 1" | sort -n | tail -n1)
+    find "${rootdir}" ${find_args[@]} | xargs -0 -r -P ${procs} -I {} bash -c "patch_file '${PATCHELF}' '${rootdir}' '${sanitize_extra_args}' $@" _ {}
 
     # Restore patched patchelf utility
     test "${tree}" = "host" && mv "${PATCHELF}.__to_be_patched" "${PATCHELF}"
-- 
2.30.2