[PATCH v5 3/5] t/perf: fix benchmarks with out-of-tree builds

[Patrick Steinhardt <ps@pks.im>]

The "perf-lib.sh" script is sourced by all of our benchmarking suites to
make available common infrastructure. The script assumes that build and
source directory are the same, which works for our Makefile. But the
assumption breaks with both CMake and Meson, where the build directory
can be located in an arbitrary place.

Adapt the script so that it works with out-of-tree builds. Most
importantly, this requires us to figure out the location of the build
directory:

  - When running benchmarks via our Makefile the build directory is the
    same as the source directory. We already know to derive the test
    directory ("t/") via `$(pwd)/..`, which works because we chdir into
    "t/perf" before executing benchmarks. We can thus derive the build
    directory by appending another "/.." to that path.

  - When running benchmarks via Meson the build directory is located at
    an arbitrary location. The build system thus has to make the path
    known by exporting the `GIT_BUILD_DIR` environment variable.

This change prepares us for wiring up benchmarks in Meson.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 t/perf/perf-lib.sh | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index 4173eee4def..5406557b7ca 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -25,7 +25,29 @@ TEST_OUTPUT_DIRECTORY=$(pwd)
 TEST_NO_CREATE_REPO=t
 TEST_NO_MALLOC_CHECK=t
 
-. ../test-lib.sh
+# While test-lib.sh computes the build directory for us, we also have to do the
+# same thing in order to locate the script via GIT-BUILD-OPTIONS in the first
+# place.
+GIT_BUILD_DIR="${GIT_BUILD_DIR:-$TEST_DIRECTORY/..}"
+if test -f "$GIT_BUILD_DIR/GIT-BUILD-DIR"
+then
+	GIT_BUILD_DIR="$(cat "$GIT_BUILD_DIR/GIT-BUILD-DIR")" || exit 1
+	# On Windows, we must convert Windows paths lest they contain a colon
+	case "$(uname -s)" in
+	*MINGW*)
+		GIT_BUILD_DIR="$(cygpath -au "$GIT_BUILD_DIR")"
+		;;
+	esac
+fi
+
+if test ! -f "$GIT_BUILD_DIR"/GIT-BUILD-OPTIONS
+then
+	echo >&2 'error: GIT-BUILD-OPTIONS missing (has Git been built?).'
+	exit 1
+fi
+
+. "$GIT_BUILD_DIR"/GIT-BUILD-OPTIONS
+. "$GIT_SOURCE_DIR"/t/test-lib.sh
 
 unset GIT_CONFIG_NOSYSTEM
 GIT_CONFIG_SYSTEM="$TEST_DIRECTORY/perf/config"
@@ -324,7 +346,7 @@ test_at_end_hook_ () {
 	if test -z "$GIT_PERF_AGGREGATING_LATER"; then
 		(
 			cd "$TEST_DIRECTORY"/perf &&
-			"$PERL_PATH" ./aggregate.perl --results-dir="$TEST_RESULTS_DIR" $(basename "$0")
+			"$PERL_PATH" "$GIT_SOURCE_DIR"/t/perf/aggregate.perl --results-dir="$TEST_RESULTS_DIR" $(basename "$0")
 		)
 	fi
 }

-- 
2.49.0.967.g6a0df3ecc3.dirty