scalar: implement the `run` command

Note: this subcommand is provided primarily for backwards-compatibility,
for existing Scalar uses. It is mostly just a shim for `git
maintenance`, mapping task names from the way Scalar called them to the
way Git calls them.

The reason why those names differ? The background maintenance was first
implemented in Scalar, and when it was contributed as a patch series
implementing the `git maintenance` command, reviewers suggested better
names, those suggestions were accepted before the patches were
integrated into core Git.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 83 insertions, 0 deletions

diff --git a/contrib/scalar/scalar.c b/contrib/scalar/scalar.c
index 61b66e48aa..fa900e4373 100644
--- a/contrib/scalar/scalar.c
+++ b/contrib/scalar/scalar.c
@@ -484,6 +484,69 @@ static int cmd_register(int argc, const char **argv)
 	return register_dir();
 }
 
+static int cmd_run(int argc, const char **argv)
+{
+	struct option options[] = {
+		OPT_END(),
+	};
+	struct {
+		const char *arg, *task;
+	} tasks[] = {
+		{ "config", NULL },
+		{ "commit-graph", "commit-graph" },
+		{ "fetch", "prefetch" },
+		{ "loose-objects", "loose-objects" },
+		{ "pack-files", "incremental-repack" },
+		{ NULL, NULL }
+	};
+	struct strbuf buf = STRBUF_INIT;
+	const char *usagestr[] = { NULL, NULL };
+	int i;
+
+	strbuf_addstr(&buf, N_("scalar run <task> [<enlistment>]\nTasks:\n"));
+	for (i = 0; tasks[i].arg; i++)
+		strbuf_addf(&buf, "\t%s\n", tasks[i].arg);
+	usagestr[0] = buf.buf;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usagestr, 0);
+
+	if (!argc)
+		usage_with_options(usagestr, options);
+
+	if (!strcmp("all", argv[0])) {
+		i = -1;
+	} else {
+		for (i = 0; tasks[i].arg && strcmp(tasks[i].arg, argv[0]); i++)
+			; /* keep looking for the task */
+
+		if (i > 0 && !tasks[i].arg) {
+			error(_("no such task: '%s'"), argv[0]);
+			usage_with_options(usagestr, options);
+		}
+	}
+
+	argc--;
+	argv++;
+	setup_enlistment_directory(argc, argv, usagestr, options, NULL);
+	strbuf_release(&buf);
+
+	if (i == 0)
+		return register_dir();
+
+	if (i > 0)
+		return run_git("maintenance", "run",
+			       "--task", tasks[i].task, NULL);
+
+	if (register_dir())
+		return -1;
+	for (i = 1; tasks[i].arg; i++)
+		if (run_git("maintenance", "run",
+			    "--task", tasks[i].task, NULL))
+			return -1;
+	return 0;
+}
+
 static int remove_deleted_enlistment(struct strbuf *path)
 {
 	int res = 0;
@@ -556,6 +619,7 @@ static struct {
 	{ "list", cmd_list },
 	{ "register", cmd_register },
 	{ "unregister", cmd_unregister },
+	{ "run", cmd_run },
 	{ NULL, NULL},
 };
 
diff --git a/contrib/scalar/scalar.txt b/contrib/scalar/scalar.txt
index 56f744a4aa..39143b0832 100644
--- a/contrib/scalar/scalar.txt
+++ b/contrib/scalar/scalar.txt
@@ -12,6 +12,7 @@ scalar clone [--single-branch] [--branch <main-branch>] [--full-clone] <url> [<e
 scalar list
 scalar register [<enlistment>]
 scalar unregister [<enlistment>]
+scalar run ( all | config | commit-graph | fetch | loose-objects | pack-files ) [<enlistment>]
 
 DESCRIPTION
 -----------
@@ -98,6 +99,24 @@ unregister [<enlistment>]::
 	Remove the specified repository from the list of repositories
 	registered with Scalar and stop the scheduled background maintenance.
 
+Run
+~~~
+
+scalar run ( all | config | commit-graph | fetch | loose-objects | pack-files ) [<enlistment>]::
+	Run the given maintenance task (or all tasks, if `all` was specified).
+	Except for `all` and `config`, this subcommand simply hands off to
+	linkgit:git-maintenance[1] (mapping `fetch` to `prefetch` and
+	`pack-files` to `incremental-repack`).
++
+These tasks are run automatically as part of the scheduled maintenance,
+as soon as the repository is registered with Scalar. It should therefore
+not be necessary to run this subcommand manually.
++
+The `config` task is specific to Scalar and configures all those
+opinionated default settings that make Git work more efficiently with
+large repositories. As this task is run as part of `scalar clone`
+automatically, explicit invocations of this task are rarely needed.
+
 SEE ALSO
 --------
 linkgit:git-clone[1], linkgit:git-maintenance[1].