1 files changed, 977 insertions, 43 deletions

diff --git a/builtin/gc.c b/builtin/gc.c
index 8e0b9cf41b..b57fda4924 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -18,7 +18,7 @@
 #include "parse-options.h"
 #include "run-command.h"
 #include "sigchain.h"
-#include "argv-array.h"
+#include "strvec.h"
 #include "commit.h"
 #include "commit-graph.h"
 #include "packfile.h"
@@ -28,6 +28,10 @@
 #include "blob.h"
 #include "tree.h"
 #include "promisor-remote.h"
+#include "refs.h"
+#include "remote.h"
+#include "object-store.h"
+#include "exec-cmd.h"
 
 #define FAILED_RUN "failed to run %s"
 
@@ -50,12 +54,12 @@ static const char *prune_worktrees_expire = "3.months.ago";
 static unsigned long big_pack_threshold;
 static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
 
-static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
-static struct argv_array reflog = ARGV_ARRAY_INIT;
-static struct argv_array repack = ARGV_ARRAY_INIT;
-static struct argv_array prune = ARGV_ARRAY_INIT;
-static struct argv_array prune_worktrees = ARGV_ARRAY_INIT;
-static struct argv_array rerere = ARGV_ARRAY_INIT;
+static struct strvec pack_refs_cmd = STRVEC_INIT;
+static struct strvec reflog = STRVEC_INIT;
+static struct strvec repack = STRVEC_INIT;
+static struct strvec prune = STRVEC_INIT;
+static struct strvec prune_worktrees = STRVEC_INIT;
+static struct strvec rerere = STRVEC_INIT;
 
 static struct tempfile *pidfile;
 static struct lock_file log_lock;
@@ -311,18 +315,18 @@ static uint64_t estimate_repack_memory(struct packed_git *pack)
 
 static int keep_one_pack(struct string_list_item *item, void *data)
 {
-	argv_array_pushf(&repack, "--keep-pack=%s", basename(item->string));
+	strvec_pushf(&repack, "--keep-pack=%s", basename(item->string));
 	return 0;
 }
 
 static void add_repack_all_option(struct string_list *keep_pack)
 {
 	if (prune_expire && !strcmp(prune_expire, "now"))
-		argv_array_push(&repack, "-a");
+		strvec_push(&repack, "-a");
 	else {
-		argv_array_push(&repack, "-A");
+		strvec_push(&repack, "-A");
 		if (prune_expire)
-			argv_array_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
+			strvec_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
 	}
 
 	if (keep_pack)
@@ -331,7 +335,7 @@ static void add_repack_all_option(struct string_list *keep_pack)
 
 static void add_repack_incremental_option(void)
 {
-	argv_array_push(&repack, "--no-write-bitmap-index");
+	strvec_push(&repack, "--no-write-bitmap-index");
 }
 
 static int need_to_gc(void)
@@ -514,11 +518,11 @@ static void gc_before_repack(void)
 	if (done++)
 		return;
 
-	if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
-		die(FAILED_RUN, pack_refs_cmd.argv[0]);
+	if (pack_refs && run_command_v_opt(pack_refs_cmd.v, RUN_GIT_CMD))
+		die(FAILED_RUN, pack_refs_cmd.v[0]);
 
-	if (prune_reflogs && run_command_v_opt(reflog.argv, RUN_GIT_CMD))
-		die(FAILED_RUN, reflog.argv[0]);
+	if (prune_reflogs && run_command_v_opt(reflog.v, RUN_GIT_CMD))
+		die(FAILED_RUN, reflog.v[0]);
 }
 
 int cmd_gc(int argc, const char **argv, const char *prefix)
@@ -530,7 +534,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	const char *name;
 	pid_t pid;
 	int daemonized = 0;
-	int keep_base_pack = -1;
+	int keep_largest_pack = -1;
 	timestamp_t dummy;
 
 	struct option builtin_gc_options[] = {
@@ -544,7 +548,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		OPT_BOOL_F(0, "force", &force,
 			   N_("force running gc even if there may be another gc running"),
 			   PARSE_OPT_NOCOMPLETE),
-		OPT_BOOL(0, "keep-largest-pack", &keep_base_pack,
+		OPT_BOOL(0, "keep-largest-pack", &keep_largest_pack,
 			 N_("repack all other packs except the largest pack")),
 		OPT_END()
 	};
@@ -552,12 +556,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(builtin_gc_usage, builtin_gc_options);
 
-	argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
-	argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
-	argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
-	argv_array_pushl(&prune, "prune", "--expire", NULL);
-	argv_array_pushl(&prune_worktrees, "worktree", "prune", "--expire", NULL);
-	argv_array_pushl(&rerere, "rerere", "gc", NULL);
+	strvec_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
+	strvec_pushl(&reflog, "reflog", "expire", "--all", NULL);
+	strvec_pushl(&repack, "repack", "-d", "-l", NULL);
+	strvec_pushl(&prune, "prune", "--expire", NULL);
+	strvec_pushl(&prune_worktrees, "worktree", "prune", "--expire", NULL);
+	strvec_pushl(&rerere, "rerere", "gc", NULL);
 
 	/* default expiry time, overwritten in gc_config */
 	gc_config();
@@ -576,14 +580,14 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		die(_("failed to parse prune expiry value %s"), prune_expire);
 
 	if (aggressive) {
-		argv_array_push(&repack, "-f");
+		strvec_push(&repack, "-f");
 		if (aggressive_depth > 0)
-			argv_array_pushf(&repack, "--depth=%d", aggressive_depth);
+			strvec_pushf(&repack, "--depth=%d", aggressive_depth);
 		if (aggressive_window > 0)
-			argv_array_pushf(&repack, "--window=%d", aggressive_window);
+			strvec_pushf(&repack, "--window=%d", aggressive_window);
 	}
 	if (quiet)
-		argv_array_push(&repack, "-q");
+		strvec_push(&repack, "-q");
 
 	if (auto_gc) {
 		/*
@@ -621,8 +625,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	} else {
 		struct string_list keep_pack = STRING_LIST_INIT_NODUP;
 
-		if (keep_base_pack != -1) {
-			if (keep_base_pack)
+		if (keep_largest_pack != -1) {
+			if (keep_largest_pack)
 				find_base_packs(&keep_pack, 0);
 		} else if (big_pack_threshold) {
 			find_base_packs(&keep_pack, big_pack_threshold);
@@ -653,29 +657,29 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 
 	if (!repository_format_precious_objects) {
 		close_object_store(the_repository->objects);
-		if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
-			die(FAILED_RUN, repack.argv[0]);
+		if (run_command_v_opt(repack.v, RUN_GIT_CMD))
+			die(FAILED_RUN, repack.v[0]);
 
 		if (prune_expire) {
-			argv_array_push(&prune, prune_expire);
+			strvec_push(&prune, prune_expire);
 			if (quiet)
-				argv_array_push(&prune, "--no-progress");
+				strvec_push(&prune, "--no-progress");
 			if (has_promisor_remote())
-				argv_array_push(&prune,
-						"--exclude-promisor-objects");
-			if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
-				die(FAILED_RUN, prune.argv[0]);
+				strvec_push(&prune,
+					    "--exclude-promisor-objects");
+			if (run_command_v_opt(prune.v, RUN_GIT_CMD))
+				die(FAILED_RUN, prune.v[0]);
 		}
 	}
 
 	if (prune_worktrees_expire) {
-		argv_array_push(&prune_worktrees, prune_worktrees_expire);
-		if (run_command_v_opt(prune_worktrees.argv, RUN_GIT_CMD))
-			die(FAILED_RUN, prune_worktrees.argv[0]);
+		strvec_push(&prune_worktrees, prune_worktrees_expire);
+		if (run_command_v_opt(prune_worktrees.v, RUN_GIT_CMD))
+			die(FAILED_RUN, prune_worktrees.v[0]);
 	}
 
-	if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
-		die(FAILED_RUN, rerere.argv[0]);
+	if (run_command_v_opt(rerere.v, RUN_GIT_CMD))
+		die(FAILED_RUN, rerere.v[0]);
 
 	report_garbage = report_pack_garbage;
 	reprepare_packed_git(the_repository);
@@ -699,3 +703,933 @@ 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] [--[no-]quiet] [--task=<task>] [--schedule]"),
+	NULL
+};
+
+enum schedule_priority {
+	SCHEDULE_NONE = 0,
+	SCHEDULE_WEEKLY = 1,
+	SCHEDULE_DAILY = 2,
+	SCHEDULE_HOURLY = 3,
+};
+
+static enum schedule_priority parse_schedule(const char *value)
+{
+	if (!value)
+		return SCHEDULE_NONE;
+	if (!strcasecmp(value, "hourly"))
+		return SCHEDULE_HOURLY;
+	if (!strcasecmp(value, "daily"))
+		return SCHEDULE_DAILY;
+	if (!strcasecmp(value, "weekly"))
+		return SCHEDULE_WEEKLY;
+	return SCHEDULE_NONE;
+}
+
+static int maintenance_opt_schedule(const struct option *opt, const char *arg,
+				    int unset)
+{
+	enum schedule_priority *priority = opt->value;
+
+	if (unset)
+		die(_("--no-schedule is not allowed"));
+
+	*priority = parse_schedule(arg);
+
+	if (!*priority)
+		die(_("unrecognized --schedule argument '%s'"), arg);
+
+	return 0;
+}
+
+struct maintenance_run_opts {
+	int auto_flag;
+	int quiet;
+	enum schedule_priority schedule;
+};
+
+/* Remember to update object flag allocation in object.h */
+#define SEEN		(1u<<0)
+
+struct cg_auto_data {
+	int num_not_in_graph;
+	int limit;
+};
+
+static int dfs_on_ref(const char *refname,
+		      const struct object_id *oid, int flags,
+		      void *cb_data)
+{
+	struct cg_auto_data *data = (struct cg_auto_data *)cb_data;
+	int result = 0;
+	struct object_id peeled;
+	struct commit_list *stack = NULL;
+	struct commit *commit;
+
+	if (!peel_ref(refname, &peeled))
+		oid = &peeled;
+	if (oid_object_info(the_repository, oid, NULL) != OBJ_COMMIT)
+		return 0;
+
+	commit = lookup_commit(the_repository, oid);
+	if (!commit)
+		return 0;
+	if (parse_commit(commit) ||
+	    commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
+		return 0;
+
+	data->num_not_in_graph++;
+
+	if (data->num_not_in_graph >= data->limit)
+		return 1;
+
+	commit_list_append(commit, &stack);
+
+	while (!result && stack) {
+		struct commit_list *parent;
+
+		commit = pop_commit(&stack);
+
+		for (parent = commit->parents; parent; parent = parent->next) {
+			if (parse_commit(parent->item) ||
+			    commit_graph_position(parent->item) != COMMIT_NOT_FROM_GRAPH ||
+			    parent->item->object.flags & SEEN)
+				continue;
+
+			parent->item->object.flags |= SEEN;
+			data->num_not_in_graph++;
+
+			if (data->num_not_in_graph >= data->limit) {
+				result = 1;
+				break;
+			}
+
+			commit_list_append(parent->item, &stack);
+		}
+	}
+
+	free_commit_list(stack);
+	return result;
+}
+
+static int should_write_commit_graph(void)
+{
+	int result;
+	struct cg_auto_data data;
+
+	data.num_not_in_graph = 0;
+	data.limit = 100;
+	git_config_get_int("maintenance.commit-graph.auto",
+			   &data.limit);
+
+	if (!data.limit)
+		return 0;
+	if (data.limit < 0)
+		return 1;
+
+	result = for_each_ref(dfs_on_ref, &data);
+
+	repo_clear_commit_marks(the_repository, SEEN);
+
+	return result;
+}
+
+static int run_write_commit_graph(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_pushl(&child.args, "commit-graph", "write",
+		     "--split", "--reachable", NULL);
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--no-progress");
+
+	return !!run_command(&child);
+}
+
+static int maintenance_task_commit_graph(struct maintenance_run_opts *opts)
+{
+	prepare_repo_settings(the_repository);
+	if (!the_repository->settings.core_commit_graph)
+		return 0;
+
+	close_object_store(the_repository->objects);
+	if (run_write_commit_graph(opts)) {
+		error(_("failed to write commit-graph"));
+		return 1;
+	}
+
+	return 0;
+}
+
+static int fetch_remote(const char *remote, struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_pushl(&child.args, "fetch", remote, "--prune", "--no-tags",
+		     "--no-write-fetch-head", "--recurse-submodules=no",
+		     "--refmap=", NULL);
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--quiet");
+
+	strvec_pushf(&child.args, "+refs/heads/*:refs/prefetch/%s/*", remote);
+
+	return !!run_command(&child);
+}
+
+static int append_remote(struct remote *remote, void *cbdata)
+{
+	struct string_list *remotes = (struct string_list *)cbdata;
+
+	string_list_append(remotes, remote->name);
+	return 0;
+}
+
+static int maintenance_task_prefetch(struct maintenance_run_opts *opts)
+{
+	int result = 0;
+	struct string_list_item *item;
+	struct string_list remotes = STRING_LIST_INIT_DUP;
+
+	if (for_each_remote(append_remote, &remotes)) {
+		error(_("failed to fill remotes"));
+		result = 1;
+		goto cleanup;
+	}
+
+	for_each_string_list_item(item, &remotes)
+		result |= fetch_remote(item->string, opts);
+
+cleanup:
+	string_list_clear(&remotes, 0);
+	return result;
+}
+
+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");
+	if (opts->quiet)
+		strvec_push(&child.args, "--quiet");
+	else
+		strvec_push(&child.args, "--no-quiet");
+
+	close_object_store(the_repository->objects);
+	return run_command(&child);
+}
+
+static int prune_packed(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_push(&child.args, "prune-packed");
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--quiet");
+
+	return !!run_command(&child);
+}
+
+struct write_loose_object_data {
+	FILE *in;
+	int count;
+	int batch_size;
+};
+
+static int loose_object_auto_limit = 100;
+
+static int loose_object_count(const struct object_id *oid,
+			       const char *path,
+			       void *data)
+{
+	int *count = (int*)data;
+	if (++(*count) >= loose_object_auto_limit)
+		return 1;
+	return 0;
+}
+
+static int loose_object_auto_condition(void)
+{
+	int count = 0;
+
+	git_config_get_int("maintenance.loose-objects.auto",
+			   &loose_object_auto_limit);
+
+	if (!loose_object_auto_limit)
+		return 0;
+	if (loose_object_auto_limit < 0)
+		return 1;
+
+	return for_each_loose_file_in_objdir(the_repository->objects->odb->path,
+					     loose_object_count,
+					     NULL, NULL, &count);
+}
+
+static int bail_on_loose(const struct object_id *oid,
+			 const char *path,
+			 void *data)
+{
+	return 1;
+}
+
+static int write_loose_object_to_stdin(const struct object_id *oid,
+				       const char *path,
+				       void *data)
+{
+	struct write_loose_object_data *d = (struct write_loose_object_data *)data;
+
+	fprintf(d->in, "%s\n", oid_to_hex(oid));
+
+	return ++(d->count) > d->batch_size;
+}
+
+static int pack_loose(struct maintenance_run_opts *opts)
+{
+	struct repository *r = the_repository;
+	int result = 0;
+	struct write_loose_object_data data;
+	struct child_process pack_proc = CHILD_PROCESS_INIT;
+
+	/*
+	 * Do not start pack-objects process
+	 * if there are no loose objects.
+	 */
+	if (!for_each_loose_file_in_objdir(r->objects->odb->path,
+					   bail_on_loose,
+					   NULL, NULL, NULL))
+		return 0;
+
+	pack_proc.git_cmd = 1;
+
+	strvec_push(&pack_proc.args, "pack-objects");
+	if (opts->quiet)
+		strvec_push(&pack_proc.args, "--quiet");
+	strvec_pushf(&pack_proc.args, "%s/pack/loose", r->objects->odb->path);
+
+	pack_proc.in = -1;
+
+	if (start_command(&pack_proc)) {
+		error(_("failed to start 'git pack-objects' process"));
+		return 1;
+	}
+
+	data.in = xfdopen(pack_proc.in, "w");
+	data.count = 0;
+	data.batch_size = 50000;
+
+	for_each_loose_file_in_objdir(r->objects->odb->path,
+				      write_loose_object_to_stdin,
+				      NULL,
+				      NULL,
+				      &data);
+
+	fclose(data.in);
+
+	if (finish_command(&pack_proc)) {
+		error(_("failed to finish 'git pack-objects' process"));
+		result = 1;
+	}
+
+	return result;
+}
+
+static int maintenance_task_loose_objects(struct maintenance_run_opts *opts)
+{
+	return prune_packed(opts) || pack_loose(opts);
+}
+
+static int incremental_repack_auto_condition(void)
+{
+	struct packed_git *p;
+	int enabled;
+	int incremental_repack_auto_limit = 10;
+	int count = 0;
+
+	if (git_config_get_bool("core.multiPackIndex", &enabled) ||
+	    !enabled)
+		return 0;
+
+	git_config_get_int("maintenance.incremental-repack.auto",
+			   &incremental_repack_auto_limit);
+
+	if (!incremental_repack_auto_limit)
+		return 0;
+	if (incremental_repack_auto_limit < 0)
+		return 1;
+
+	for (p = get_packed_git(the_repository);
+	     count < incremental_repack_auto_limit && p;
+	     p = p->next) {
+		if (!p->multi_pack_index)
+			count++;
+	}
+
+	return count >= incremental_repack_auto_limit;
+}
+
+static int multi_pack_index_write(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_pushl(&child.args, "multi-pack-index", "write", NULL);
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--no-progress");
+
+	if (run_command(&child))
+		return error(_("failed to write multi-pack-index"));
+
+	return 0;
+}
+
+static int multi_pack_index_expire(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_pushl(&child.args, "multi-pack-index", "expire", NULL);
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--no-progress");
+
+	close_object_store(the_repository->objects);
+
+	if (run_command(&child))
+		return error(_("'git multi-pack-index expire' failed"));
+
+	return 0;
+}
+
+#define TWO_GIGABYTES (INT32_MAX)
+
+static off_t get_auto_pack_size(void)
+{
+	/*
+	 * The "auto" value is special: we optimize for
+	 * one large pack-file (i.e. from a clone) and
+	 * expect the rest to be small and they can be
+	 * repacked quickly.
+	 *
+	 * The strategy we select here is to select a
+	 * size that is one more than the second largest
+	 * pack-file. This ensures that we will repack
+	 * at least two packs if there are three or more
+	 * packs.
+	 */
+	off_t max_size = 0;
+	off_t second_largest_size = 0;
+	off_t result_size;
+	struct packed_git *p;
+	struct repository *r = the_repository;
+
+	reprepare_packed_git(r);
+	for (p = get_all_packs(r); p; p = p->next) {
+		if (p->pack_size > max_size) {
+			second_largest_size = max_size;
+			max_size = p->pack_size;
+		} else if (p->pack_size > second_largest_size)
+			second_largest_size = p->pack_size;
+	}
+
+	result_size = second_largest_size + 1;
+
+	/* But limit ourselves to a batch size of 2g */
+	if (result_size > TWO_GIGABYTES)
+		result_size = TWO_GIGABYTES;
+
+	return result_size;
+}
+
+static int multi_pack_index_repack(struct maintenance_run_opts *opts)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+
+	child.git_cmd = 1;
+	strvec_pushl(&child.args, "multi-pack-index", "repack", NULL);
+
+	if (opts->quiet)
+		strvec_push(&child.args, "--no-progress");
+
+	strvec_pushf(&child.args, "--batch-size=%"PRIuMAX,
+				  (uintmax_t)get_auto_pack_size());
+
+	close_object_store(the_repository->objects);
+
+	if (run_command(&child))
+		return error(_("'git multi-pack-index repack' failed"));
+
+	return 0;
+}
+
+static int maintenance_task_incremental_repack(struct maintenance_run_opts *opts)
+{
+	prepare_repo_settings(the_repository);
+	if (!the_repository->settings.core_multi_pack_index) {
+		warning(_("skipping incremental-repack task because core.multiPackIndex is disabled"));
+		return 0;
+	}
+
+	if (multi_pack_index_write(opts))
+		return 1;
+	if (multi_pack_index_expire(opts))
+		return 1;
+	if (multi_pack_index_repack(opts))
+		return 1;
+	return 0;
+}
+
+typedef int maintenance_task_fn(struct maintenance_run_opts *opts);
+
+/*
+ * An auto condition function returns 1 if the task should run
+ * and 0 if the task should NOT run. See needs_to_gc() for an
+ * example.
+ */
+typedef int maintenance_auto_fn(void);
+
+struct maintenance_task {
+	const char *name;
+	maintenance_task_fn *fn;
+	maintenance_auto_fn *auto_condition;
+	unsigned enabled:1;
+
+	enum schedule_priority schedule;
+
+	/* -1 if not selected. */
+	int selected_order;
+};
+
+enum maintenance_task_label {
+	TASK_PREFETCH,
+	TASK_LOOSE_OBJECTS,
+	TASK_INCREMENTAL_REPACK,
+	TASK_GC,
+	TASK_COMMIT_GRAPH,
+
+	/* Leave as final value */
+	TASK__COUNT
+};
+
+static struct maintenance_task tasks[] = {
+	[TASK_PREFETCH] = {
+		"prefetch",
+		maintenance_task_prefetch,
+	},
+	[TASK_LOOSE_OBJECTS] = {
+		"loose-objects",
+		maintenance_task_loose_objects,
+		loose_object_auto_condition,
+	},
+	[TASK_INCREMENTAL_REPACK] = {
+		"incremental-repack",
+		maintenance_task_incremental_repack,
+		incremental_repack_auto_condition,
+	},
+	[TASK_GC] = {
+		"gc",
+		maintenance_task_gc,
+		need_to_gc,
+		1,
+	},
+	[TASK_COMMIT_GRAPH] = {
+		"commit-graph",
+		maintenance_task_commit_graph,
+		should_write_commit_graph,
+	},
+};
+
+static int compare_tasks_by_selection(const void *a_, const void *b_)
+{
+	const struct maintenance_task *a = a_;
+	const struct maintenance_task *b = b_;
+
+	return b->selected_order - a->selected_order;
+}
+
+static int maintenance_run_tasks(struct maintenance_run_opts *opts)
+{
+	int i, found_selected = 0;
+	int result = 0;
+	struct lock_file lk;
+	struct repository *r = the_repository;
+	char *lock_path = xstrfmt("%s/maintenance", r->objects->odb->path);
+
+	if (hold_lock_file_for_update(&lk, lock_path, LOCK_NO_DEREF) < 0) {
+		/*
+		 * Another maintenance command is running.
+		 *
+		 * If --auto was provided, then it is likely due to a
+		 * recursive process stack. Do not report an error in
+		 * that case.
+		 */
+		if (!opts->auto_flag && !opts->quiet)
+			warning(_("lock file '%s' exists, skipping maintenance"),
+				lock_path);
+		free(lock_path);
+		return 0;
+	}
+	free(lock_path);
+
+	for (i = 0; !found_selected && i < TASK__COUNT; i++)
+		found_selected = tasks[i].selected_order >= 0;
+
+	if (found_selected)
+		QSORT(tasks, TASK__COUNT, compare_tasks_by_selection);
+
+	for (i = 0; i < TASK__COUNT; i++) {
+		if (found_selected && tasks[i].selected_order < 0)
+			continue;
+
+		if (!found_selected && !tasks[i].enabled)
+			continue;
+
+		if (opts->auto_flag &&
+		    (!tasks[i].auto_condition ||
+		     !tasks[i].auto_condition()))
+			continue;
+
+		if (opts->schedule && tasks[i].schedule < opts->schedule)
+			continue;
+
+		trace2_region_enter("maintenance", tasks[i].name, r);
+		if (tasks[i].fn(opts)) {
+			error(_("task '%s' failed"), tasks[i].name);
+			result = 1;
+		}
+		trace2_region_leave("maintenance", tasks[i].name, r);
+	}
+
+	rollback_lock_file(&lk);
+	return result;
+}
+
+static void initialize_maintenance_strategy(void)
+{
+	char *config_str;
+
+	if (git_config_get_string("maintenance.strategy", &config_str))
+		return;
+
+	if (!strcasecmp(config_str, "incremental")) {
+		tasks[TASK_GC].schedule = SCHEDULE_NONE;
+		tasks[TASK_COMMIT_GRAPH].enabled = 1;
+		tasks[TASK_COMMIT_GRAPH].schedule = SCHEDULE_HOURLY;
+		tasks[TASK_PREFETCH].enabled = 1;
+		tasks[TASK_PREFETCH].schedule = SCHEDULE_HOURLY;
+		tasks[TASK_INCREMENTAL_REPACK].enabled = 1;
+		tasks[TASK_INCREMENTAL_REPACK].schedule = SCHEDULE_DAILY;
+		tasks[TASK_LOOSE_OBJECTS].enabled = 1;
+		tasks[TASK_LOOSE_OBJECTS].schedule = SCHEDULE_DAILY;
+	}
+}
+
+static void initialize_task_config(int schedule)
+{
+	int i;
+	struct strbuf config_name = STRBUF_INIT;
+	gc_config();
+
+	if (schedule)
+		initialize_maintenance_strategy();
+
+	for (i = 0; i < TASK__COUNT; i++) {
+		int config_value;
+		char *config_str;
+
+		strbuf_reset(&config_name);
+		strbuf_addf(&config_name, "maintenance.%s.enabled",
+			    tasks[i].name);
+
+		if (!git_config_get_bool(config_name.buf, &config_value))
+			tasks[i].enabled = config_value;
+
+		strbuf_reset(&config_name);
+		strbuf_addf(&config_name, "maintenance.%s.schedule",
+			    tasks[i].name);
+
+		if (!git_config_get_string(config_name.buf, &config_str)) {
+			tasks[i].schedule = parse_schedule(config_str);
+			free(config_str);
+		}
+	}
+
+	strbuf_release(&config_name);
+}
+
+static int task_option_parse(const struct option *opt,
+			     const char *arg, int unset)
+{
+	int i, num_selected = 0;
+	struct maintenance_task *task = NULL;
+
+	BUG_ON_OPT_NEG(unset);
+
+	for (i = 0; i < TASK__COUNT; i++) {
+		if (tasks[i].selected_order >= 0)
+			num_selected++;
+		if (!strcasecmp(tasks[i].name, arg)) {
+			task = &tasks[i];
+		}
+	}
+
+	if (!task) {
+		error(_("'%s' is not a valid task"), arg);
+		return 1;
+	}
+
+	if (task->selected_order >= 0) {
+		error(_("task '%s' cannot be selected multiple times"), arg);
+		return 1;
+	}
+
+	task->selected_order = num_selected + 1;
+
+	return 0;
+}
+
+static int maintenance_run(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	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_CALLBACK(0, "schedule", &opts.schedule, N_("frequency"),
+			     N_("run tasks based on frequency"),
+			     maintenance_opt_schedule),
+		OPT_BOOL(0, "quiet", &opts.quiet,
+			 N_("do not report progress or other information over stderr")),
+		OPT_CALLBACK_F(0, "task", NULL, N_("task"),
+			N_("run a specific task"),
+			PARSE_OPT_NONEG, task_option_parse),
+		OPT_END()
+	};
+	memset(&opts, 0, sizeof(opts));
+
+	opts.quiet = !isatty(2);
+
+	for (i = 0; i < TASK__COUNT; i++)
+		tasks[i].selected_order = -1;
+
+	argc = parse_options(argc, argv, prefix,
+			     builtin_maintenance_run_options,
+			     builtin_maintenance_run_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+
+	if (opts.auto_flag && opts.schedule)
+		die(_("use at most one of --auto and --schedule=<frequency>"));
+
+	initialize_task_config(opts.schedule);
+
+	if (argc != 0)
+		usage_with_options(builtin_maintenance_run_usage,
+				   builtin_maintenance_run_options);
+	return maintenance_run_tasks(&opts);
+}
+
+static int maintenance_register(void)
+{
+	char *config_value;
+	struct child_process config_set = CHILD_PROCESS_INIT;
+	struct child_process config_get = CHILD_PROCESS_INIT;
+
+	/* Disable foreground maintenance */
+	git_config_set("maintenance.auto", "false");
+
+	/* Set maintenance strategy, if unset */
+	if (!git_config_get_string("maintenance.strategy", &config_value))
+		free(config_value);
+	else
+		git_config_set("maintenance.strategy", "incremental");
+
+	config_get.git_cmd = 1;
+	strvec_pushl(&config_get.args, "config", "--global", "--get",
+		     "--fixed-value", "maintenance.repo",
+		     the_repository->worktree ? the_repository->worktree
+					      : the_repository->gitdir,
+			 NULL);
+	config_get.out = -1;
+
+	if (start_command(&config_get))
+		return error(_("failed to run 'git config'"));
+
+	/* We already have this value in our config! */
+	if (!finish_command(&config_get))
+		return 0;
+
+	config_set.git_cmd = 1;
+	strvec_pushl(&config_set.args, "config", "--add", "--global", "maintenance.repo",
+		     the_repository->worktree ? the_repository->worktree
+					      : the_repository->gitdir,
+		     NULL);
+
+	return run_command(&config_set);
+}
+
+static int maintenance_unregister(void)
+{
+	struct child_process config_unset = CHILD_PROCESS_INIT;
+
+	config_unset.git_cmd = 1;
+	strvec_pushl(&config_unset.args, "config", "--global", "--unset",
+		     "--fixed-value", "maintenance.repo",
+		     the_repository->worktree ? the_repository->worktree
+					      : the_repository->gitdir,
+		     NULL);
+
+	return run_command(&config_unset);
+}
+
+#define BEGIN_LINE "# BEGIN GIT MAINTENANCE SCHEDULE"
+#define END_LINE "# END GIT MAINTENANCE SCHEDULE"
+
+static int update_background_schedule(int run_maintenance)
+{
+	int result = 0;
+	int in_old_region = 0;
+	struct child_process crontab_list = CHILD_PROCESS_INIT;
+	struct child_process crontab_edit = CHILD_PROCESS_INIT;
+	FILE *cron_list, *cron_in;
+	const char *crontab_name;
+	struct strbuf line = STRBUF_INIT;
+	struct lock_file lk;
+	char *lock_path = xstrfmt("%s/schedule", the_repository->objects->odb->path);
+
+	if (hold_lock_file_for_update(&lk, lock_path, LOCK_NO_DEREF) < 0)
+		return error(_("another process is scheduling background maintenance"));
+
+	crontab_name = getenv("GIT_TEST_CRONTAB");
+	if (!crontab_name)
+		crontab_name = "crontab";
+
+	strvec_split(&crontab_list.args, crontab_name);
+	strvec_push(&crontab_list.args, "-l");
+	crontab_list.in = -1;
+	crontab_list.out = dup(lk.tempfile->fd);
+	crontab_list.git_cmd = 0;
+
+	if (start_command(&crontab_list)) {
+		result = error(_("failed to run 'crontab -l'; your system might not support 'cron'"));
+		goto cleanup;
+	}
+
+	/* Ignore exit code, as an empty crontab will return error. */
+	finish_command(&crontab_list);
+
+	/*
+	 * Read from the .lock file, filtering out the old
+	 * schedule while appending the new schedule.
+	 */
+	cron_list = fdopen(lk.tempfile->fd, "r");
+	rewind(cron_list);
+
+	strvec_split(&crontab_edit.args, crontab_name);
+	crontab_edit.in = -1;
+	crontab_edit.git_cmd = 0;
+
+	if (start_command(&crontab_edit)) {
+		result = error(_("failed to run 'crontab'; your system might not support 'cron'"));
+		goto cleanup;
+	}
+
+	cron_in = fdopen(crontab_edit.in, "w");
+	if (!cron_in) {
+		result = error(_("failed to open stdin of 'crontab'"));
+		goto done_editing;
+	}
+
+	while (!strbuf_getline_lf(&line, cron_list)) {
+		if (!in_old_region && !strcmp(line.buf, BEGIN_LINE))
+			in_old_region = 1;
+		if (in_old_region)
+			continue;
+		fprintf(cron_in, "%s\n", line.buf);
+		if (in_old_region && !strcmp(line.buf, END_LINE))
+			in_old_region = 0;
+	}
+
+	if (run_maintenance) {
+		struct strbuf line_format = STRBUF_INIT;
+		const char *exec_path = git_exec_path();
+
+		fprintf(cron_in, "%s\n", BEGIN_LINE);
+		fprintf(cron_in,
+			"# The following schedule was created by Git\n");
+		fprintf(cron_in, "# Any edits made in this region might be\n");
+		fprintf(cron_in,
+			"# replaced in the future by a Git command.\n\n");
+
+		strbuf_addf(&line_format,
+			    "%%s %%s * * %%s \"%s/git\" --exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%%s\n",
+			    exec_path, exec_path);
+		fprintf(cron_in, line_format.buf, "0", "1-23", "*", "hourly");
+		fprintf(cron_in, line_format.buf, "0", "0", "1-6", "daily");
+		fprintf(cron_in, line_format.buf, "0", "0", "0", "weekly");
+		strbuf_release(&line_format);
+
+		fprintf(cron_in, "\n%s\n", END_LINE);
+	}
+
+	fflush(cron_in);
+	fclose(cron_in);
+	close(crontab_edit.in);
+
+done_editing:
+	if (finish_command(&crontab_edit)) {
+		result = error(_("'crontab' died"));
+		goto cleanup;
+	}
+	fclose(cron_list);
+
+cleanup:
+	rollback_lock_file(&lk);
+	return result;
+}
+
+static int maintenance_start(void)
+{
+	if (maintenance_register())
+		warning(_("failed to add repo to global config"));
+
+	return update_background_schedule(1);
+}
+
+static int maintenance_stop(void)
+{
+	return update_background_schedule(0);
+}
+
+static const char builtin_maintenance_usage[] =	N_("git maintenance <subcommand> [<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);
+	if (!strcmp(argv[1], "start"))
+		return maintenance_start();
+	if (!strcmp(argv[1], "stop"))
+		return maintenance_stop();
+	if (!strcmp(argv[1], "register"))
+		return maintenance_register();
+	if (!strcmp(argv[1], "unregister"))
+		return maintenance_unregister();
+
+	die(_("invalid subcommand: %s"), argv[1]);
+}