perf/run: add --subsection option

This new option makes it possible to run perf tests as defined
in only one subsection of a config file.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/run

@@ -1,21 +1,34 @@
 #!/bin/sh
 
-case "$1" in
+die () {
+	echo >&2 "error: $*"
+	exit 1
+}
+
+while [ $# -gt 0 ]; do
+	arg="$1"
+	case "$arg" in
+	--)
+		break ;;
 	--help)
-		echo "usage: $0 [--config file] [other_git_tree...] [--] [test_scripts]"
-		exit 0
-		;;
+		echo "usage: $0 [--config file] [--subsection subsec] [other_git_tree...] [--] [test_scripts]"
+		exit 0 ;;
 	--config)
 		shift
 		GIT_PERF_CONFIG_FILE=$(cd "$(dirname "$1")"; pwd)/$(basename "$1")
 		export GIT_PERF_CONFIG_FILE
 		shift ;;
-esac
-
-die () {
-	echo >&2 "error: $*"
-	exit 1
-}
+	--subsection)
+		shift
+		GIT_PERF_SUBSECTION="$1"
+		export GIT_PERF_SUBSECTION
+		shift ;;
+	--*)
+		die "unrecognised option: '$arg'" ;;
+	*)
+		break ;;
+	esac
+done
 
 run_one_dir () {
 	if test $# -eq 0; then
@@ -172,9 +185,32 @@ get_subsections "perf" >test-results/run_subsections.names
 
 if test $(wc -l <test-results/run_subsections.names) -eq 0
 then
+	if test -n "$GIT_PERF_SUBSECTION"
+	then
+		if test -n "$GIT_PERF_CONFIG_FILE"
+		then
+			die "no subsections are defined in config file '$GIT_PERF_CONFIG_FILE'"
+		else
+			die "subsection '$GIT_PERF_SUBSECTION' defined without a config file"
+		fi
+	fi
 	(
 		run_subsection "$@"
 	)
+elif test -n "$GIT_PERF_SUBSECTION"
+then
+	egrep "^$GIT_PERF_SUBSECTION\$" test-results/run_subsections.names >/dev/null ||
+		die "subsection '$GIT_PERF_SUBSECTION' not found in '$GIT_PERF_CONFIG_FILE'"
+
+	egrep "^$GIT_PERF_SUBSECTION\$" test-results/run_subsections.names | while read -r subsec
+	do
+		(
+			GIT_PERF_SUBSECTION="$subsec"
+			export GIT_PERF_SUBSECTION
+			echo "======== Run for subsection '$GIT_PERF_SUBSECTION' ========"
+			run_subsection "$@"
+		)
+	done
 else
 	while read -r subsec
 	do