Introduce a performance testing framework

This introduces a performance testing framework under t/perf/.  It
tries to be as close to the test-lib.sh infrastructure as possible,
and thus should be easy to get used to for git developers.

The following points were considered for the implementation:

1. You usually want to compare arbitrary revisions/build trees against
   each other.  They may not have the performance test under
   consideration, or even the perf-lib.sh infrastructure.

   To cope with this, the 'run' script lets you specify arbitrary
   build dirs and revisions.  It even automatically builds the revisions
   if it doesn't have them at hand yet.

2. Usually you would not want to run all tests.  It would take too
   long anyway.  The 'run' script lets you specify which tests to run;
   or you can also do it manually.  There is a Makefile for
   discoverability and 'make clean', but it is not meant for
   real-world use.

3. Creating test repos from scratch in every test is extremely
   time-consuming, and shipping or downloading such large/weird repos
   is out of the question.

   We leave this decision to the user.  Two different sizes of test
   repos can be configured, and the scripts just copy one or more of
   those (using hardlinks for the object store).  By default it tries
   to use the build tree's git.git repository.

   This is fairly fast and versatile.  Using a copy instead of a clone
   preserves many properties that the user may want to test for, such
   as lots of loose objects, unpacked refs, etc.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 23 insertions, 3 deletions

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 1da3f40..d75766a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -55,6 +55,7 @@ unset $(perl -e '
 		.*_TEST
 		PROVE
 		VALGRIND
+		PERF_AGGREGATING_LATER
 	));
 	my @vars = grep(/^GIT_/ && !/^GIT_($ok)/o, @env);
 	print join("\n", @vars);
@@ -98,6 +99,8 @@ _z40=0000000000000000000000000000000000000000
 LF='
 '
 
+export _x05 _x40 _z40 LF
+
 # Each test should start with something like this, after copyright notices:
 #
 # test_description='Description of this test...
@@ -313,11 +316,16 @@ test_skip () {
 	esac
 }
 
+# stub; perf-lib overrides it
+test_at_end_hook_ () {
+	:
+}
+
 test_done () {
 	GIT_EXIT_OK=t
 
 	if test -z "$HARNESS_ACTIVE"; then
-		test_results_dir="$TEST_DIRECTORY/test-results"
+		test_results_dir="$TEST_OUTPUT_DIRECTORY/test-results"
 		mkdir -p "$test_results_dir"
 		test_results_path="$test_results_dir/${0%.sh}-$$.counts"
 
@@ -356,6 +364,8 @@ test_done () {
 		cd "$(dirname "$remove_trash")" &&
 		rm -rf "$(basename "$remove_trash")"
 
+		test_at_end_hook_
+
 		exit 0 ;;
 
 	*)
@@ -378,6 +388,12 @@ then
 	# itself.
 	TEST_DIRECTORY=$(pwd)
 fi
+if test -z "$TEST_OUTPUT_DIRECTORY"
+then
+	# Similarly, override this to store the test-results subdir
+	# elsewhere
+	TEST_OUTPUT_DIRECTORY=$TEST_DIRECTORY
+fi
 GIT_BUILD_DIR="$TEST_DIRECTORY"/..
 
 if test -n "$valgrind"
@@ -513,7 +529,7 @@ test="trash directory.$(basename "$0" .sh)"
 test -n "$root" && test="$root/$test"
 case "$test" in
 /*) TRASH_DIRECTORY="$test" ;;
- *) TRASH_DIRECTORY="$TEST_DIRECTORY/$test" ;;
+ *) TRASH_DIRECTORY="$TEST_OUTPUT_DIRECTORY/$test" ;;
 esac
 test ! -z "$debug" || remove_trash=$TRASH_DIRECTORY
 rm -fr "$test" || {
@@ -525,7 +541,11 @@ rm -fr "$test" || {
 HOME="$TRASH_DIRECTORY"
 export HOME
 
-test_create_repo "$test"
+if test -z "$TEST_NO_CREATE_REPO"; then
+	test_create_repo "$test"
+else
+	mkdir -p "$test"
+fi
 # Use -P to resolve symlinks in our working directory so that the cwd
 # in subprocesses like git equals our $PWD (for pathname comparisons).
 cd -P "$test" || exit 1