[PATCH 1/6] run-command API: replace run_processes_parallel_tr2() with opts struct

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Add a new "struct run_process_parallel_opts" to cover the trace2
use-case added in ee4512ed481 (trace2: create new combined trace
facility, 2019-02-22). A subsequent commit will add more options, and
having a proliferation of new functions or extra parameters would
result in needless churn.

It makes for a smaller change to make run_processes_parallel() and
run_processes_parallel_tr2() wrapper functions for the new "static"
run_processes_parallel_1(), which contains the main logic. We pass
down "opts" to the *_1() function even though it isn't used there
yet (only in the *_tr2() function), a subsequent commit will make more
use of it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/fetch.c             | 15 ++++++++------
 builtin/submodule--helper.c | 12 +++++++----
 hook.c                      | 13 ++++++------
 run-command.c               | 40 +++++++++++++++++++++++++++----------
 run-command.h               | 26 ++++++++++++++++--------
 submodule.c                 | 13 ++++++------
 t/helper/test-run-command.c | 13 ++++++------
 7 files changed, 84 insertions(+), 48 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index e3791f09ed5..9bc99183191 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1948,14 +1948,17 @@ static int fetch_multiple(struct string_list *list, int max_children)
 
 	if (max_children != 1 && list->nr != 1) {
 		struct parallel_fetch_state state = { argv.v, list, 0, 0 };
+		struct run_process_parallel_opts run_opts = {
+			.tr2_category = "fetch",
+			.tr2_label = "parallel/fetch",
+		};
 
 		strvec_push(&argv, "--end-of-options");
-		result = run_processes_parallel_tr2(max_children,
-						    &fetch_next_remote,
-						    &fetch_failed_to_start,
-						    &fetch_finished,
-						    &state,
-						    "fetch", "parallel/fetch");
+		result = run_processes_parallel(max_children,
+						&fetch_next_remote,
+						&fetch_failed_to_start,
+						&fetch_finished, &state,
+						&run_opts);
 
 		if (!result)
 			result = state.result;
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 2c87ef9364f..c3d1aace546 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2652,12 +2652,16 @@ static int update_submodules(struct update_data *update_data)
 {
 	int i, res = 0;
 	struct submodule_update_clone suc = SUBMODULE_UPDATE_CLONE_INIT;
+	struct run_process_parallel_opts run_opts = {
+		.tr2_category = "submodule",
+		.tr2_label = "parallel/update",
+	};
 
 	suc.update_data = update_data;
-	run_processes_parallel_tr2(suc.update_data->max_jobs, update_clone_get_next_task,
-				   update_clone_start_failure,
-				   update_clone_task_finished, &suc, "submodule",
-				   "parallel/update");
+	run_processes_parallel(suc.update_data->max_jobs,
+			       update_clone_get_next_task,
+			       update_clone_start_failure,
+			       update_clone_task_finished, &suc, &run_opts);
 
 	/*
 	 * We saved the output and put it out all at once now.
diff --git a/hook.c b/hook.c
index 1d51be3b77a..eadb2d58a7b 100644
--- a/hook.c
+++ b/hook.c
@@ -123,6 +123,10 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 	const char *const hook_path = find_hook(hook_name);
 	int jobs = 1;
 	int ret = 0;
+	struct run_process_parallel_opts run_opts = {
+		.tr2_category = "hook",
+		.tr2_label = hook_name,
+	};
 
 	if (!options)
 		BUG("a struct run_hooks_opt must be provided to run_hooks");
@@ -144,13 +148,8 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 		cb_data.hook_path = abs_path.buf;
 	}
 
-	run_processes_parallel_tr2(jobs,
-				   pick_next_hook,
-				   notify_start_failure,
-				   notify_hook_finished,
-				   &cb_data,
-				   "hook",
-				   hook_name);
+	run_processes_parallel(jobs, pick_next_hook, notify_start_failure,
+			       notify_hook_finished, &cb_data, &run_opts);
 	ret = cb_data.rc;
 cleanup:
 	strbuf_release(&abs_path);
diff --git a/run-command.c b/run-command.c
index a8501e38ceb..7b8159aa235 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1738,11 +1738,11 @@ static int pp_collect_finished(struct parallel_processes *pp)
 	return result;
 }
 
-int run_processes_parallel(int n,
-			   get_next_task_fn get_next_task,
-			   start_failure_fn start_failure,
-			   task_finished_fn task_finished,
-			   void *pp_cb)
+static int run_processes_parallel_1(int n, get_next_task_fn get_next_task,
+				    start_failure_fn start_failure,
+				    task_finished_fn task_finished,
+				    void *pp_cb,
+				    struct run_process_parallel_opts *opts)
 {
 	int i, code;
 	int output_timeout = 100;
@@ -1780,24 +1780,42 @@ int run_processes_parallel(int n,
 	return 0;
 }
 
-int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
-			       start_failure_fn start_failure,
-			       task_finished_fn task_finished, void *pp_cb,
-			       const char *tr2_category, const char *tr2_label)
+static int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
+				      start_failure_fn start_failure,
+				      task_finished_fn task_finished,
+				      void *pp_cb,
+				      struct run_process_parallel_opts *opts)
 {
+	const char *tr2_category = opts->tr2_category;
+	const char *tr2_label = opts->tr2_label;
 	int result;
 
 	trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
 				   ((n < 1) ? online_cpus() : n));
 
-	result = run_processes_parallel(n, get_next_task, start_failure,
-					task_finished, pp_cb);
+	result = run_processes_parallel_1(n, get_next_task, start_failure,
+					  task_finished, pp_cb, opts);
 
 	trace2_region_leave(tr2_category, tr2_label, NULL);
 
 	return result;
 }
 
+int run_processes_parallel(int n, get_next_task_fn get_next_task,
+			   start_failure_fn start_failure,
+			   task_finished_fn task_finished, void *pp_cb,
+			   struct run_process_parallel_opts *opts)
+{
+	if (opts->tr2_category && opts->tr2_label)
+		return run_processes_parallel_tr2(n, get_next_task,
+						  start_failure, task_finished,
+						  pp_cb, opts);
+
+	return run_processes_parallel_1(n, get_next_task, start_failure,
+					task_finished, pp_cb, opts);
+}
+
+
 int run_auto_maintenance(int quiet)
 {
 	int enabled;
diff --git a/run-command.h b/run-command.h
index 07bed6c31b4..66e7bebd88a 100644
--- a/run-command.h
+++ b/run-command.h
@@ -458,6 +458,19 @@ typedef int (*task_finished_fn)(int result,
 				void *pp_cb,
 				void *pp_task_cb);
 
+/**
+ * Options to pass to run_processes_parallel(), { 0 }-initialized
+ * means no options. Fields:
+ *
+ * tr2_category & tr2_label: sets the trace2 category and label for
+ * logging. These must either be unset, or both of them must be set.
+ */
+struct run_process_parallel_opts
+{
+	const char *tr2_category;
+	const char *tr2_label;
+};
+
 /**
  * Runs up to n processes at the same time. Whenever a process can be
  * started, the callback get_next_task_fn is called to obtain the data
@@ -469,15 +482,12 @@ typedef int (*task_finished_fn)(int result,
  *
  * start_failure_fn and task_finished_fn can be NULL to omit any
  * special handling.
+ *
+ * Options are passed via a "struct run_process_parallel_opts".
  */
-int run_processes_parallel(int n,
-			   get_next_task_fn,
-			   start_failure_fn,
-			   task_finished_fn,
-			   void *pp_cb);
-int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn,
-			       task_finished_fn, void *pp_cb,
-			       const char *tr2_category, const char *tr2_label);
+int run_processes_parallel(int n, get_next_task_fn, start_failure_fn,
+			   task_finished_fn, void *pp_cb,
+			   struct run_process_parallel_opts *opts);
 
 /**
  * Convenience function which prepares env_array for a command to be run in a
diff --git a/submodule.c b/submodule.c
index 86c8f0f89db..256c6bb4b8f 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1817,6 +1817,10 @@ int fetch_submodules(struct repository *r,
 {
 	int i;
 	struct submodule_parallel_fetch spf = SPF_INIT;
+	struct run_process_parallel_opts run_opts = {
+		.tr2_category = "submodule",
+		.tr2_label = "parallel/fetch",
+	};
 
 	spf.r = r;
 	spf.command_line_option = command_line_option;
@@ -1838,12 +1842,9 @@ int fetch_submodules(struct repository *r,
 
 	calculate_changed_submodule_paths(r, &spf.changed_submodule_names);
 	string_list_sort(&spf.changed_submodule_names);
-	run_processes_parallel_tr2(max_parallel_jobs,
-				   get_next_submodule,
-				   fetch_start_failure,
-				   fetch_finish,
-				   &spf,
-				   "submodule", "parallel/fetch");
+	run_processes_parallel(max_parallel_jobs, get_next_submodule,
+			       fetch_start_failure, fetch_finish, &spf,
+			       &run_opts);
 
 	if (spf.submodules_with_errors.len > 0)
 		fprintf(stderr, _("Errors during submodule fetch:\n%s"),
diff --git a/t/helper/test-run-command.c b/t/helper/test-run-command.c
index f3b90aa834a..9b21f2f9f83 100644
--- a/t/helper/test-run-command.c
+++ b/t/helper/test-run-command.c
@@ -183,7 +183,7 @@ static int testsuite(int argc, const char **argv)
 		(uintmax_t)suite.tests.nr, max_jobs);
 
 	ret = run_processes_parallel(max_jobs, next_test, test_failed,
-				     test_finished, &suite);
+				     test_finished, &suite, NULL);
 
 	if (suite.failed.nr > 0) {
 		ret = 1;
@@ -371,6 +371,7 @@ int cmd__run_command(int argc, const char **argv)
 {
 	struct child_process proc = CHILD_PROCESS_INIT;
 	int jobs;
+	struct run_process_parallel_opts opts = { 0 };
 
 	if (argc > 1 && !strcmp(argv[1], "testsuite"))
 		exit(testsuite(argc - 1, argv + 1));
@@ -413,15 +414,15 @@ int cmd__run_command(int argc, const char **argv)
 
 	if (!strcmp(argv[1], "run-command-parallel"))
 		exit(run_processes_parallel(jobs, parallel_next,
-					    NULL, NULL, &proc));
+					    NULL, NULL, &proc, &opts));
 
 	if (!strcmp(argv[1], "run-command-abort"))
-		exit(run_processes_parallel(jobs, parallel_next,
-					    NULL, task_finished, &proc));
+		exit(run_processes_parallel(jobs, parallel_next, NULL,
+					    task_finished, &proc, &opts));
 
 	if (!strcmp(argv[1], "run-command-no-jobs"))
-		exit(run_processes_parallel(jobs, no_job,
-					    NULL, task_finished, &proc));
+		exit(run_processes_parallel(jobs, no_job, NULL, task_finished,
+					    &proc, &opts));
 
 	fprintf(stderr, "check usage\n");
 	return 1;
-- 
2.36.0.893.g80a51c675f6