format-cpp: run clang-format in parallel

Use the -P option of GNU xargs to run multiple instances of clang-format
in parallel, which speeds up the execution quite a bit (depending on the
number of cores, of course).

Inspired by this babeltrace commit:

  http://git.efficios.com/?p=babeltrace.git;a=commit;h=66c3bce11973e6e96a3791c378a9e5f98ddaa280

Change-Id: I201535244ef4c3614dfd742ae6f1c427994e6147
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/format-cpp b/format-cpp
index d7155b21dd329a39a1dc53ea8e8e7715ca0d9185..17275de77c7f4ee7f0d004cab9f94558e9f2c511 100755 (executable)
--- a/format-cpp
+++ b/format-cpp
@@ -38,7 +38,7 @@ format_cpp() {
        # shellcheck disable=SC2086
        find "$root_dir" -path './src/vendor' -prune \
                -o -type f \( -name '*\.h' -o -name '*\.hpp' -o -name '*\.c' -o -name '*\.cpp' \) \
-               -not -path '*/\.*' -print0 | xargs -n1 -0 $formatter -i --style=file --fallback-style=none
+               -not -path '*/\.*' -print0 | xargs -P$(nproc) -n1 -0 $formatter -i --style=file --fallback-style=none
 }
 
 if [[ -n "$FORMATTER" ]]; then