hook API: fix v2.36.0 regression: hooks should be connected to a TTY

Fix a regression reported[1] against f443246 (commit: convert {pre-commit,prepare-commit-msg} hook to hook.h, 2021-12-22): Due to using the run_process_parallel() API in the earlier 96e7225 (hook: add 'run' subcommand, 2021-12-22) we'd capture the hook's stderr and stdout, and thus lose the connection to the TTY in the case of e.g. the "pre-commit" hook. As a preceding commit notes GNU parallel's similar --ungroup option also has it emit output faster. While we're unlikely to have hooks that emit truly massive amounts of output (or where the performance thereof matters) it's still informative to measure the overhead. In a similar "seq" test we're now ~30% faster: $ cat .git/hooks/seq-hook; git hyperfine -L rev origin/master,HEAD~0 -s 'make CFLAGS=-O3' './git hook run seq-hook' #!/bin/sh seq 100000000 Benchmark 1: ./git hook run seq-hook' in 'origin/master Time (mean ± σ): 787.1 ms ± 13.6 ms [User: 701.6 ms, System: 534.4 ms] Range (min … max): 773.2 ms … 806.3 ms 10 runs Benchmark 2: ./git hook run seq-hook' in 'HEAD~0 Time (mean ± σ): 603.4 ms ± 1.6 ms [User: 573.1 ms, System: 30.3 ms] Range (min … max): 601.0 ms … 606.2 ms 10 runs Summary './git hook run seq-hook' in 'HEAD~0' ran 1.30 ± 0.02 times faster than './git hook run seq-hook' in 'origin/master' 1. https://lore.kernel.org/git/CA+dzEBn108QoMA28f0nC8K21XT+Afua0V2Qv8XkR8rAeqUCCZw@mail.gmail.com/ Reported-by: Anthony Sottile <[email protected]> Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]> [jc: minor fix-up to tests for consistency] Signed-off-by: Junio C Hamano <[email protected]>
git · Jun 7, 2022 · a082345 · a082345
1 parent fd3aaf5
commit a082345
Show file tree

Hide file tree

Showing 2 changed files with 32 additions and 0 deletions.
diff --git a/hook.c b/hook.c
@@ -144,6 +144,7 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 		cb_data.hook_path = abs_path.buf;
 	}
 
+	run_processes_parallel_ungroup = 1;
 	run_processes_parallel_tr2(jobs,
 				   pick_next_hook,
 				   notify_start_failure,

diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
@@ -4,6 +4,7 @@ test_description='git-hook command'
 
 TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-terminal.sh
 
 test_expect_success 'git hook usage' '
 	test_expect_code 129 git hook &&
@@ -120,4 +121,34 @@ test_expect_success 'git -c core.hooksPath=<PATH> hook run' '
 	test_cmp expect actual
 '
 
+test_hook_tty () {
+	cat >expect <<-\EOF
+	STDOUT TTY
+	STDERR TTY
+	EOF
+
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+
+	test_commit -C repo A &&
+	test_commit -C repo B &&
+	git -C repo reset --soft HEAD^ &&
+
+	test_hook -C repo pre-commit <<-EOF &&
+	test -t 1 && echo STDOUT TTY >>actual || echo STDOUT NO TTY >>actual &&
+	test -t 2 && echo STDERR TTY >>actual || echo STDERR NO TTY >>actual
+	EOF
+
+	test_terminal git -C repo "$@" &&
+	test_cmp expect repo/actual
+}
+
+test_expect_success TTY 'git hook run: stdout and stderr are connected to a TTY' '
+	test_hook_tty hook run pre-commit
+'
+
+test_expect_success TTY 'git commit: stdout and stderr are connected to a TTY' '
+	test_hook_tty commit -m"B.new"
+'
+
 test_done