gc.c

/*
 * git gc builtin command
 *
 * Cleanup unreachable files and optimize the repository.
 *
 * Copyright (c) 2007 James Bowes
 *
 * Based on git-gc.sh, which is
 *
 * Copyright (c) 2006 Shawn O. Pearce
 */

#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "builtin.h"
#include "abspath.h"
#include "date.h"
#include "environment.h"
#include "hex.h"
#include "config.h"
#include "tempfile.h"
#include "lockfile.h"
#include "parse-options.h"
#include "run-command.h"
#include "sigchain.h"
#include "strvec.h"
#include "commit.h"
#include "commit-graph.h"
#include "packfile.h"
#include "object-store.h"
#include "pack.h"
#include "pack-objects.h"
#include "path.h"
#include "reflog.h"
#include "blob.h"
#include "tree.h"
#include "promisor-remote.h"
#include "refs.h"
#include "remote.h"
#include "exec-cmd.h"
#include "gettext.h"
#include "hook.h"
#include "setup.h"
#include "trace2.h"

#define FAILED_RUN "failed to run %s"

static const char * const builtin_gc_usage[] = {
	N_("git gc [<options>]"),
	NULL
};

static timestamp_t gc_log_expire_time;

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;

static struct string_list pack_garbage = STRING_LIST_INIT_DUP;

static void clean_pack_garbage(void)
{
	int i;
	for (i = 0; i < pack_garbage.nr; i++)
		unlink_or_warn(pack_garbage.items[i].string);
	string_list_clear(&pack_garbage, 0);
}

static void report_pack_garbage(unsigned seen_bits, const char *path)
{
	if (seen_bits == PACKDIR_FILE_IDX)
		string_list_append(&pack_garbage, path);
}

static void process_log_file(void)
{
	struct stat st;
	if (fstat(get_lock_file_fd(&log_lock), &st)) {
		/*
		 * Perhaps there was an i/o error or another
		 * unlikely situation.  Try to make a note of
		 * this in gc.log along with any existing
		 * messages.
		 */
		int saved_errno = errno;
		fprintf(stderr, _("Failed to fstat %s: %s"),
			get_lock_file_path(&log_lock),
			strerror(saved_errno));
		fflush(stderr);
		commit_lock_file(&log_lock);
		errno = saved_errno;
	} else if (st.st_size) {
		/* There was some error recorded in the lock file */
		commit_lock_file(&log_lock);
	} else {
		char *path = repo_git_path(the_repository, "gc.log");
		/* No error, clean up any old gc.log */
		unlink(path);
		rollback_lock_file(&log_lock);
		free(path);
	}
}

static void process_log_file_at_exit(void)
{
	fflush(stderr);
	process_log_file();
}

static int gc_config_is_timestamp_never(const char *var)
{
	const char *value;
	timestamp_t expire;

	if (!git_config_get_value(var, &value) && value) {
		if (parse_expiry_date(value, &expire))
			die(_("failed to parse '%s' value '%s'"), var, value);
		return expire == 0;
	}
	return 0;
}

struct gc_config {
	int pack_refs;
	int prune_reflogs;
	int cruft_packs;
	unsigned long max_cruft_size;
	int aggressive_depth;
	int aggressive_window;
	int gc_auto_threshold;
	int gc_auto_pack_limit;
	int detach_auto;
	char *gc_log_expire;
	char *prune_expire;
	char *prune_worktrees_expire;
	char *repack_filter;
	char *repack_filter_to;
	char *repack_expire_to;
	unsigned long big_pack_threshold;
	unsigned long max_delta_cache_size;
	/*
	 * Remove this member from gc_config once repo_settings is passed
	 * through the callchain.
	 */
	size_t delta_base_cache_limit;
};

#define GC_CONFIG_INIT { \
	.pack_refs = 1, \
	.prune_reflogs = 1, \
	.cruft_packs = 1, \
	.aggressive_depth = 50, \
	.aggressive_window = 250, \
	.gc_auto_threshold = 6700, \
	.gc_auto_pack_limit = 50, \
	.detach_auto = 1, \
	.gc_log_expire = xstrdup("1.day.ago"), \
	.prune_expire = xstrdup("2.weeks.ago"), \
	.prune_worktrees_expire = xstrdup("3.months.ago"), \
	.max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE, \
	.delta_base_cache_limit = DEFAULT_DELTA_BASE_CACHE_LIMIT, \
}

static void gc_config_release(struct gc_config *cfg)
{
	free(cfg->gc_log_expire);
	free(cfg->prune_expire);
	free(cfg->prune_worktrees_expire);
	free(cfg->repack_filter);
	free(cfg->repack_filter_to);
}

static void gc_config(struct gc_config *cfg)
{
	const char *value;
	char *owned = NULL;
	unsigned long ulongval;

	if (!git_config_get_value("gc.packrefs", &value)) {
		if (value && !strcmp(value, "notbare"))
			cfg->pack_refs = -1;
		else
			cfg->pack_refs = git_config_bool("gc.packrefs", value);
	}

	if (gc_config_is_timestamp_never("gc.reflogexpire") &&
	    gc_config_is_timestamp_never("gc.reflogexpireunreachable"))
		cfg->prune_reflogs = 0;

	git_config_get_int("gc.aggressivewindow", &cfg->aggressive_window);
	git_config_get_int("gc.aggressivedepth", &cfg->aggressive_depth);
	git_config_get_int("gc.auto", &cfg->gc_auto_threshold);
	git_config_get_int("gc.autopacklimit", &cfg->gc_auto_pack_limit);
	git_config_get_bool("gc.autodetach", &cfg->detach_auto);
	git_config_get_bool("gc.cruftpacks", &cfg->cruft_packs);
	git_config_get_ulong("gc.maxcruftsize", &cfg->max_cruft_size);

	if (!repo_config_get_expiry(the_repository, "gc.pruneexpire", &owned)) {
		free(cfg->prune_expire);
		cfg->prune_expire = owned;
	}

	if (!repo_config_get_expiry(the_repository, "gc.worktreepruneexpire", &owned)) {
		free(cfg->prune_worktrees_expire);
		cfg->prune_worktrees_expire = owned;
	}

	if (!repo_config_get_expiry(the_repository, "gc.logexpiry", &owned)) {
		free(cfg->gc_log_expire);
		cfg->gc_log_expire = owned;
	}

	git_config_get_ulong("gc.bigpackthreshold", &cfg->big_pack_threshold);
	git_config_get_ulong("pack.deltacachesize", &cfg->max_delta_cache_size);

	if (!git_config_get_ulong("core.deltabasecachelimit", &ulongval))
		cfg->delta_base_cache_limit = ulongval;

	if (!git_config_get_string("gc.repackfilter", &owned)) {
		free(cfg->repack_filter);
		cfg->repack_filter = owned;
	}

	if (!git_config_get_string("gc.repackfilterto", &owned)) {
		free(cfg->repack_filter_to);
		cfg->repack_filter_to = owned;
	}

	git_config(git_default_config, 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;
}

struct maintenance_run_opts {
	int auto_flag;
	int detach;
	int quiet;
	enum schedule_priority schedule;
};
#define MAINTENANCE_RUN_OPTS_INIT { \
	.detach = -1, \
}

static int pack_refs_condition(UNUSED struct gc_config *cfg)
{
	/*
	 * The auto-repacking logic for refs is handled by the ref backends and
	 * exposed via `git pack-refs --auto`. We thus always return truish
	 * here and let the backend decide for us.
	 */
	return 1;
}

static int maintenance_task_pack_refs(struct maintenance_run_opts *opts,
				      UNUSED struct gc_config *cfg)
{
	struct child_process cmd = CHILD_PROCESS_INIT;

	cmd.git_cmd = 1;
	strvec_pushl(&cmd.args, "pack-refs", "--all", "--prune", NULL);
	if (opts->auto_flag)
		strvec_push(&cmd.args, "--auto");

	return run_command(&cmd);
}

struct count_reflog_entries_data {
	struct expire_reflog_policy_cb policy;
	size_t count;
	size_t limit;
};

static int count_reflog_entries(struct object_id *old_oid, struct object_id *new_oid,
				const char *committer, timestamp_t timestamp,
				int tz, const char *msg, void *cb_data)
{
	struct count_reflog_entries_data *data = cb_data;
	if (should_expire_reflog_ent(old_oid, new_oid, committer, timestamp, tz, msg, &data->policy))
		data->count++;
	return data->count >= data->limit;
}

static int reflog_expire_condition(struct gc_config *cfg UNUSED)
{
	timestamp_t now = time(NULL);
	struct count_reflog_entries_data data = {
		.policy = {
			.opts = REFLOG_EXPIRE_OPTIONS_INIT(now),
		},
	};
	int limit = 100;

	git_config_get_int("maintenance.reflog-expire.auto", &limit);
	if (!limit)
		return 0;
	if (limit < 0)
		return 1;
	data.limit = limit;

	repo_config(the_repository, reflog_expire_config, &data.policy.opts);

	reflog_expire_options_set_refname(&data.policy.opts, "HEAD");
	refs_for_each_reflog_ent(get_main_ref_store(the_repository), "HEAD",
				 count_reflog_entries, &data);

	reflog_expiry_cleanup(&data.policy);
	return data.count >= data.limit;
}

static int maintenance_task_reflog_expire(struct maintenance_run_opts *opts UNUSED,
					  struct gc_config *cfg UNUSED)
{
	struct child_process cmd = CHILD_PROCESS_INIT;
	cmd.git_cmd = 1;
	strvec_pushl(&cmd.args, "reflog", "expire", "--all", NULL);
	return run_command(&cmd);
}

static int too_many_loose_objects(struct gc_config *cfg)
{
	/*
	 * Quickly check if a "gc" is needed, by estimating how
	 * many loose objects there are.  Because SHA-1 is evenly
	 * distributed, we can check only one and get a reasonable
	 * estimate.
	 */
	DIR *dir;
	struct dirent *ent;
	int auto_threshold;
	int num_loose = 0;
	int needed = 0;
	const unsigned hexsz_loose = the_hash_algo->hexsz - 2;
	char *path;

	path = repo_git_path(the_repository, "objects/17");
	dir = opendir(path);
	free(path);
	if (!dir)
		return 0;

	auto_threshold = DIV_ROUND_UP(cfg->gc_auto_threshold, 256);
	while ((ent = readdir(dir)) != NULL) {
		if (strspn(ent->d_name, "0123456789abcdef") != hexsz_loose ||
		    ent->d_name[hexsz_loose] != '\0')
			continue;
		if (++num_loose > auto_threshold) {
			needed = 1;
			break;
		}
	}
	closedir(dir);
	return needed;
}

static struct packed_git *find_base_packs(struct string_list *packs,
					  unsigned long limit)
{
	struct packed_git *p, *base = NULL;

	for (p = get_all_packs(the_repository); p; p = p->next) {
		if (!p->pack_local || p->is_cruft)
			continue;
		if (limit) {
			if (p->pack_size >= limit)
				string_list_append(packs, p->pack_name);
		} else if (!base || base->pack_size < p->pack_size) {
			base = p;
		}
	}

	if (base)
		string_list_append(packs, base->pack_name);

	return base;
}

static int too_many_packs(struct gc_config *cfg)
{
	struct packed_git *p;
	int cnt;

	if (cfg->gc_auto_pack_limit <= 0)
		return 0;

	for (cnt = 0, p = get_all_packs(the_repository); p; p = p->next) {
		if (!p->pack_local)
			continue;
		if (p->pack_keep)
			continue;
		/*
		 * Perhaps check the size of the pack and count only
		 * very small ones here?
		 */
		cnt++;
	}
	return cfg->gc_auto_pack_limit < cnt;
}

static uint64_t total_ram(void)
{
#if defined(HAVE_SYSINFO)
	struct sysinfo si;

	if (!sysinfo(&si)) {
		uint64_t total = si.totalram;

		if (si.mem_unit > 1)
			total *= (uint64_t)si.mem_unit;
		return total;
	}
#elif defined(HAVE_BSD_SYSCTL) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM))
	int64_t physical_memory;
	int mib[2];
	size_t length;

	mib[0] = CTL_HW;
# if defined(HW_MEMSIZE)
	mib[1] = HW_MEMSIZE;
# else
	mib[1] = HW_PHYSMEM;
# endif
	length = sizeof(int64_t);
	if (!sysctl(mib, 2, &physical_memory, &length, NULL, 0))
		return physical_memory;
#elif defined(GIT_WINDOWS_NATIVE)
	MEMORYSTATUSEX memInfo;

	memInfo.dwLength = sizeof(MEMORYSTATUSEX);
	if (GlobalMemoryStatusEx(&memInfo))
		return memInfo.ullTotalPhys;
#endif
	return 0;
}

static uint64_t estimate_repack_memory(struct gc_config *cfg,
				       struct packed_git *pack)
{
	unsigned long nr_objects = repo_approximate_object_count(the_repository);
	size_t os_cache, heap;

	if (!pack || !nr_objects)
		return 0;

	/*
	 * First we have to scan through at least one pack.
	 * Assume enough room in OS file cache to keep the entire pack
	 * or we may accidentally evict data of other processes from
	 * the cache.
	 */
	os_cache = pack->pack_size + pack->index_size;
	/* then pack-objects needs lots more for book keeping */
	heap = sizeof(struct object_entry) * nr_objects;
	/*
	 * internal rev-list --all --objects takes up some memory too,
	 * let's say half of it is for blobs
	 */
	heap += sizeof(struct blob) * nr_objects / 2;
	/*
	 * and the other half is for trees (commits and tags are
	 * usually insignificant)
	 */
	heap += sizeof(struct tree) * nr_objects / 2;
	/* and then obj_hash[], underestimated in fact */
	heap += sizeof(struct object *) * nr_objects;
	/* revindex is used also */
	heap += (sizeof(off_t) + sizeof(uint32_t)) * nr_objects;
	/*
	 * read_sha1_file() (either at delta calculation phase, or
	 * writing phase) also fills up the delta base cache
	 */
	heap += cfg->delta_base_cache_limit;
	/* and of course pack-objects has its own delta cache */
	heap += cfg->max_delta_cache_size;

	return os_cache + heap;
}

static int keep_one_pack(struct string_list_item *item, void *data UNUSED)
{
	strvec_pushf(&repack, "--keep-pack=%s", basename(item->string));
	return 0;
}

static void add_repack_all_option(struct gc_config *cfg,
				  struct string_list *keep_pack)
{
	if (cfg->prune_expire && !strcmp(cfg->prune_expire, "now")
		&& !(cfg->cruft_packs && cfg->repack_expire_to))
		strvec_push(&repack, "-a");
	else if (cfg->cruft_packs) {
		strvec_push(&repack, "--cruft");
		if (cfg->prune_expire)
			strvec_pushf(&repack, "--cruft-expiration=%s", cfg->prune_expire);
		if (cfg->max_cruft_size)
			strvec_pushf(&repack, "--max-cruft-size=%lu",
				     cfg->max_cruft_size);
		if (cfg->repack_expire_to)
			strvec_pushf(&repack, "--expire-to=%s", cfg->repack_expire_to);
	} else {
		strvec_push(&repack, "-A");
		if (cfg->prune_expire)
			strvec_pushf(&repack, "--unpack-unreachable=%s", cfg->prune_expire);
	}

	if (keep_pack)
		for_each_string_list(keep_pack, keep_one_pack, NULL);

	if (cfg->repack_filter && *cfg->repack_filter)
		strvec_pushf(&repack, "--filter=%s", cfg->repack_filter);
	if (cfg->repack_filter_to && *cfg->repack_filter_to)
		strvec_pushf(&repack, "--filter-to=%s", cfg->repack_filter_to);
}

static void add_repack_incremental_option(void)
{
	strvec_push(&repack, "--no-write-bitmap-index");
}

static int need_to_gc(struct gc_config *cfg)
{
	/*
	 * Setting gc.auto to 0 or negative can disable the
	 * automatic gc.
	 */
	if (cfg->gc_auto_threshold <= 0)
		return 0;

	/*
	 * If there are too many loose objects, but not too many
	 * packs, we run "repack -d -l".  If there are too many packs,
	 * we run "repack -A -d -l".  Otherwise we tell the caller
	 * there is no need.
	 */
	if (too_many_packs(cfg)) {
		struct string_list keep_pack = STRING_LIST_INIT_NODUP;

		if (cfg->big_pack_threshold) {
			find_base_packs(&keep_pack, cfg->big_pack_threshold);
			if (keep_pack.nr >= cfg->gc_auto_pack_limit) {
				cfg->big_pack_threshold = 0;
				string_list_clear(&keep_pack, 0);
				find_base_packs(&keep_pack, 0);
			}
		} else {
			struct packed_git *p = find_base_packs(&keep_pack, 0);
			uint64_t mem_have, mem_want;

			mem_have = total_ram();
			mem_want = estimate_repack_memory(cfg, p);

			/*
			 * Only allow 1/2 of memory for pack-objects, leave
			 * the rest for the OS and other processes in the
			 * system.
			 */
			if (!mem_have || mem_want < mem_have / 2)
				string_list_clear(&keep_pack, 0);
		}

		add_repack_all_option(cfg, &keep_pack);
		string_list_clear(&keep_pack, 0);
	} else if (too_many_loose_objects(cfg))
		add_repack_incremental_option();
	else
		return 0;

	if (run_hooks(the_repository, "pre-auto-gc"))
		return 0;
	return 1;
}

/* return NULL on success, else hostname running the gc */
static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
{
	struct lock_file lock = LOCK_INIT;
	char my_host[HOST_NAME_MAX + 1];
	struct strbuf sb = STRBUF_INIT;
	struct stat st;
	uintmax_t pid;
	FILE *fp;
	int fd;
	char *pidfile_path;

	if (is_tempfile_active(pidfile))
		/* already locked */
		return NULL;

	if (xgethostname(my_host, sizeof(my_host)))
		xsnprintf(my_host, sizeof(my_host), "unknown");

	pidfile_path = repo_git_path(the_repository, "gc.pid");
	fd = hold_lock_file_for_update(&lock, pidfile_path,
				       LOCK_DIE_ON_ERROR);
	if (!force) {
		static char locking_host[HOST_NAME_MAX + 1];
		static char *scan_fmt;
		int should_exit;

		if (!scan_fmt)
			scan_fmt = xstrfmt("%s %%%ds", "%"SCNuMAX, HOST_NAME_MAX);
		fp = fopen(pidfile_path, "r");
		memset(locking_host, 0, sizeof(locking_host));
		should_exit =
			fp != NULL &&
			!fstat(fileno(fp), &st) &&
			/*
			 * 12 hour limit is very generous as gc should
			 * never take that long. On the other hand we
			 * don't really need a strict limit here,
			 * running gc --auto one day late is not a big
			 * problem. --force can be used in manual gc
			 * after the user verifies that no gc is
			 * running.
			 */
			time(NULL) - st.st_mtime <= 12 * 3600 &&
			fscanf(fp, scan_fmt, &pid, locking_host) == 2 &&
			/* be gentle to concurrent "gc" on remote hosts */
			(strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
		if (fp)
			fclose(fp);
		if (should_exit) {
			if (fd >= 0)
				rollback_lock_file(&lock);
			*ret_pid = pid;
			free(pidfile_path);
			return locking_host;
		}
	}

	strbuf_addf(&sb, "%"PRIuMAX" %s",
		    (uintmax_t) getpid(), my_host);
	write_in_full(fd, sb.buf, sb.len);
	strbuf_release(&sb);
	commit_lock_file(&lock);
	pidfile = register_tempfile(pidfile_path);
	free(pidfile_path);
	return NULL;
}

/*
 * Returns 0 if there was no previous error and gc can proceed, 1 if
 * gc should not proceed due to an error in the last run. Prints a
 * message and returns with a non-[01] status code if an error occurred
 * while reading gc.log
 */
static int report_last_gc_error(void)
{
	struct strbuf sb = STRBUF_INIT;
	int ret = 0;
	ssize_t len;
	struct stat st;
	char *gc_log_path = repo_git_path(the_repository, "gc.log");

	if (stat(gc_log_path, &st)) {
		if (errno == ENOENT)
			goto done;

		ret = die_message_errno(_("cannot stat '%s'"), gc_log_path);
		goto done;
	}

	if (st.st_mtime < gc_log_expire_time)
		goto done;

	len = strbuf_read_file(&sb, gc_log_path, 0);
	if (len < 0)
		ret = die_message_errno(_("cannot read '%s'"), gc_log_path);
	else if (len > 0) {
		/*
		 * A previous gc failed.  Report the error, and don't
		 * bother with an automatic gc run since it is likely
		 * to fail in the same way.
		 */
		warning(_("The last gc run reported the following. "
			       "Please correct the root cause\n"
			       "and remove %s\n"
			       "Automatic cleanup will not be performed "
			       "until the file is removed.\n\n"
			       "%s"),
			    gc_log_path, sb.buf);
		ret = 1;
	}
	strbuf_release(&sb);
done:
	free(gc_log_path);
	return ret;
}

static void gc_before_repack(struct maintenance_run_opts *opts,
			     struct gc_config *cfg)
{
	/*
	 * We may be called twice, as both the pre- and
	 * post-daemonized phases will call us, but running these
	 * commands more than once is pointless and wasteful.
	 */
	static int done = 0;
	if (done++)
		return;

	if (cfg->pack_refs && maintenance_task_pack_refs(opts, cfg))
		die(FAILED_RUN, "pack-refs");
	if (cfg->prune_reflogs && maintenance_task_reflog_expire(opts, cfg))
		die(FAILED_RUN, "reflog");
}

int cmd_gc(int argc,
const char **argv,
const char *prefix,
struct repository *repo UNUSED)
{
	int aggressive = 0;
	int quiet = 0;
	int force = 0;
	const char *name;
	pid_t pid;
	int daemonized = 0;
	int keep_largest_pack = -1;
	timestamp_t dummy;
	struct child_process rerere_cmd = CHILD_PROCESS_INIT;
	struct maintenance_run_opts opts = MAINTENANCE_RUN_OPTS_INIT;
	struct gc_config cfg = GC_CONFIG_INIT;
	const char *prune_expire_sentinel = "sentinel";
	const char *prune_expire_arg = prune_expire_sentinel;
	int ret;
	struct option builtin_gc_options[] = {
		OPT__QUIET(&quiet, N_("suppress progress reporting")),
		{
			.type = OPTION_STRING,
			.long_name = "prune",
			.value = &prune_expire_arg,
			.argh = N_("date"),
			.help = N_("prune unreferenced objects"),
			.flags = PARSE_OPT_OPTARG,
			.defval = (intptr_t)prune_expire_arg,
		},
		OPT_BOOL(0, "cruft", &cfg.cruft_packs, N_("pack unreferenced objects separately")),
		OPT_UNSIGNED(0, "max-cruft-size", &cfg.max_cruft_size,
			     N_("with --cruft, limit the size of new cruft packs")),
		OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
		OPT_BOOL_F(0, "auto", &opts.auto_flag, N_("enable auto-gc mode"),
			   PARSE_OPT_NOCOMPLETE),
		OPT_BOOL(0, "detach", &opts.detach,
			 N_("perform garbage collection in the background")),
		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_largest_pack,
			 N_("repack all other packs except the largest pack")),
		OPT_STRING(0, "expire-to", &cfg.repack_expire_to, N_("dir"),
			   N_("pack prefix to store a pack containing pruned objects")),
		OPT_END()
	};

	show_usage_with_options_if_asked(argc, argv,
					 builtin_gc_usage, builtin_gc_options);

	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);

	gc_config(&cfg);

	if (parse_expiry_date(cfg.gc_log_expire, &gc_log_expire_time))
		die(_("failed to parse gc.logExpiry value %s"), cfg.gc_log_expire);

	if (cfg.pack_refs < 0)
		cfg.pack_refs = !is_bare_repository();

	argc = parse_options(argc, argv, prefix, builtin_gc_options,
			     builtin_gc_usage, 0);
	if (argc > 0)
		usage_with_options(builtin_gc_usage, builtin_gc_options);

	if (prune_expire_arg != prune_expire_sentinel) {
		free(cfg.prune_expire);
		cfg.prune_expire = xstrdup_or_null(prune_expire_arg);
	}
	if (cfg.prune_expire && parse_expiry_date(cfg.prune_expire, &dummy))
		die(_("failed to parse prune expiry value %s"), cfg.prune_expire);

	if (aggressive) {
		strvec_push(&repack, "-f");
		if (cfg.aggressive_depth > 0)
			strvec_pushf(&repack, "--depth=%d", cfg.aggressive_depth);
		if (cfg.aggressive_window > 0)
			strvec_pushf(&repack, "--window=%d", cfg.aggressive_window);
	}
	if (quiet)
		strvec_push(&repack, "-q");

	if (opts.auto_flag) {
		if (cfg.detach_auto && opts.detach < 0)
			opts.detach = 1;

		/*
		 * Auto-gc should be least intrusive as possible.
		 */
		if (!need_to_gc(&cfg)) {
			ret = 0;
			goto out;
		}

		if (!quiet) {
			if (opts.detach > 0)
				fprintf(stderr, _("Auto packing the repository in background for optimum performance.\n"));
			else
				fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
			fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
		}
	} else {
		struct string_list keep_pack = STRING_LIST_INIT_NODUP;

		if (keep_largest_pack != -1) {
			if (keep_largest_pack)
				find_base_packs(&keep_pack, 0);
		} else if (cfg.big_pack_threshold) {
			find_base_packs(&keep_pack, cfg.big_pack_threshold);
		}

		add_repack_all_option(&cfg, &keep_pack);
		string_list_clear(&keep_pack, 0);
	}

	if (opts.detach > 0) {
		ret = report_last_gc_error();
		if (ret == 1) {
			/* Last gc --auto failed. Skip this one. */
			ret = 0;
			goto out;

		} else if (ret) {
			/* an I/O error occurred, already reported */
			goto out;
		}

		if (lock_repo_for_gc(force, &pid)) {
			ret = 0;
			goto out;
		}

		gc_before_repack(&opts, &cfg); /* dies on failure */
		delete_tempfile(&pidfile);

		/*
		 * failure to daemonize is ok, we'll continue
		 * in foreground
		 */
		daemonized = !daemonize();
	}

	name = lock_repo_for_gc(force, &pid);
	if (name) {
		if (opts.auto_flag) {
			ret = 0;
			goto out; /* be quiet on --auto */
		}

		die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
		    name, (uintmax_t)pid);
	}

	if (daemonized) {
		char *path = repo_git_path(the_repository, "gc.log");
		hold_lock_file_for_update(&log_lock, path,
					  LOCK_DIE_ON_ERROR);
		dup2(get_lock_file_fd(&log_lock), 2);
		atexit(process_log_file_at_exit);
		free(path);
	}

	gc_before_repack(&opts, &cfg);

	if (!repository_format_precious_objects) {
		struct child_process repack_cmd = CHILD_PROCESS_INIT;

		repack_cmd.git_cmd = 1;
		repack_cmd.close_object_store = 1;
		strvec_pushv(&repack_cmd.args, repack.v);
		if (run_command(&repack_cmd))
			die(FAILED_RUN, repack.v[0]);

		if (cfg.prune_expire) {
			struct child_process prune_cmd = CHILD_PROCESS_INIT;

			/* run `git prune` even if using cruft packs */
			strvec_push(&prune, cfg.prune_expire);
			if (quiet)
				strvec_push(&prune, "--no-progress");
			if (repo_has_promisor_remote(the_repository))
				strvec_push(&prune,
					    "--exclude-promisor-objects");
			prune_cmd.git_cmd = 1;
			strvec_pushv(&prune_cmd.args, prune.v);
			if (run_command(&prune_cmd))
				die(FAILED_RUN, prune.v[0]);
		}
	}

	if (cfg.prune_worktrees_expire) {
		struct child_process prune_worktrees_cmd = CHILD_PROCESS_INIT;

		strvec_push(&prune_worktrees, cfg.prune_worktrees_expire);
		prune_worktrees_cmd.git_cmd = 1;
		strvec_pushv(&prune_worktrees_cmd.args, prune_worktrees.v);
		if (run_command(&prune_worktrees_cmd))
			die(FAILED_RUN, prune_worktrees.v[0]);
	}

	rerere_cmd.git_cmd = 1;
	strvec_pushv(&rerere_cmd.args, rerere.v);
	if (run_command(&rerere_cmd))
		die(FAILED_RUN, rerere.v[0]);

	report_garbage = report_pack_garbage;
	reprepare_packed_git(the_repository);
	if (pack_garbage.nr > 0) {
		close_object_store(the_repository->objects);
		clean_pack_garbage();
	}

	if (the_repository->settings.gc_write_commit_graph == 1)
		write_commit_graph_reachable(the_repository->objects->odb,
					     !quiet && !daemonized ? COMMIT_GRAPH_WRITE_PROGRESS : 0,
					     NULL);

	if (opts.auto_flag && too_many_loose_objects(&cfg))
		warning(_("There are too many unreachable loose objects; "
			"run 'git prune' to remove them."));

	if (!daemonized) {
		char *path = repo_git_path(the_repository, "gc.log");
		unlink(path);
		free(path);
	}

out:
	gc_config_release(&cfg);
	return 0;
}

static const char *const builtin_maintenance_run_usage[] = {
	N_("git maintenance run [--auto] [--[no-]quiet] [--task=<task>] [--schedule]"),
	NULL
};

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;
}

/* 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 UNUSED,
		      const char *referent UNUSED,
		      const struct object_id *oid,
		      int flags UNUSED,
		      void *cb_data)
{