maintenance: create basic maintenance runner

The 'gc' builtin is our current entrypoint for automatically maintaining
a repository. This one tool does many operations, such as repacking the
repository, packing refs, and rewriting the commit-graph file. The name
implies it performs "garbage collection" which means several different
things, and some users may not want to use this operation that rewrites
the entire object database.

Create a new 'maintenance' builtin that will become a more general-
purpose command. To start, it will only support the 'run' subcommand,
but will later expand to add subcommands for scheduling maintenance in
the background.

For now, the 'maintenance' builtin is a thin shim over the 'gc' builtin.
In fact, the only option is the '--auto' toggle, which is handed
directly to the 'gc' builtin. The current change is isolated to this
simple operation to prevent more interesting logic from being lost in
all of the boilerplate of adding a new builtin.

Use existing builtin/gc.c file because we want to share code between the
two builtins. It is possible that we will have 'maintenance' replace the
'gc' builtin entirely at some point, leaving 'git gc' as an alias for
some specific arguments to 'git maintenance run'.

Create a new test_subcommand helper that allows us to test if a certain
subcommand was run. It requires storing the GIT_TRACE2_EVENT logs in a
file. A negation mode is available that will be used in later tests.

Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/builtin/gc.c b/builtin/gc.c
index aafa0946f52..ec064e86867 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -699,3 +699,61 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 
 	return 0;
 }
+
+static const char * const builtin_maintenance_run_usage[] = {
+	N_("git maintenance run [--auto]"),
+	NULL
+};
+
+struct maintenance_run_opts {
+	int auto_flag;
+};
+
+static int maintenance_task_gc(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_push(&child.args, "gc");
+
+	if (opts->auto_flag)
+		strvec_push(&child.args, "--auto");
+
+	close_object_store(the_repository->objects);
+	return run_command(&child);
+}
+
+static int maintenance_run(int argc, const char **argv, const char *prefix)
+{
+	struct maintenance_run_opts opts;
+	struct option builtin_maintenance_run_options[] = {
+		OPT_BOOL(0, "auto", &opts.auto_flag,
+			 N_("run tasks based on the state of the repository")),
+		OPT_END()
+	};
+	memset(&opts, 0, sizeof(opts));
+
+	argc = parse_options(argc, argv, prefix,
+			     builtin_maintenance_run_options,
+			     builtin_maintenance_run_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+
+	if (argc != 0)
+		usage_with_options(builtin_maintenance_run_usage,
+				   builtin_maintenance_run_options);
+	return maintenance_task_gc(&opts);
+}
+
+static const char builtin_maintenance_usage[] = N_("git maintenance run [<options>]");
+
+int cmd_maintenance(int argc, const char **argv, const char *prefix)
+{
+	if (argc < 2 ||
+	    (argc == 2 && !strcmp(argv[1], "-h")))
+		usage(builtin_maintenance_usage);
+
+	if (!strcmp(argv[1], "run"))
+		return maintenance_run(argc - 1, argv + 1, prefix);
+
+	die(_("invalid subcommand: %s"), argv[1]);
+}