Merge branch 'js/cmake-extra-built-ins-fix'

[thirdparty/git.git] / builtin / 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
 */

#include "builtin.h"
#include "repository.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 "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"

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

static int pack_refs = 1;
static int prune_reflogs = 1;
static int aggressive_depth = 50;
static int aggressive_window = 250;
static int gc_auto_threshold = 6700;
static int gc_auto_pack_limit = 50;
static int detach_auto = 1;
static timestamp_t gc_log_expire_time;
static const char *gc_log_expire = "1.day.ago";
static const char *prune_expire = "2.weeks.ago";
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 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;

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_tempfile_path(log_lock.tempfile),
                        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 {
                /* No error, clean up any old gc.log */
                unlink(git_path("gc.log"));
                rollback_lock_file(&log_lock);
        }
}

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

static void process_log_file_on_signal(int signo)
{
        process_log_file();
        sigchain_pop(signo);
        raise(signo);
}

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;
}

static void gc_config(void)
{
        const char *value;

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

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

        git_config_get_int("gc.aggressivewindow", &aggressive_window);
        git_config_get_int("gc.aggressivedepth", &aggressive_depth);
        git_config_get_int("gc.auto", &gc_auto_threshold);
        git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
        git_config_get_bool("gc.autodetach", &detach_auto);
        git_config_get_expiry("gc.pruneexpire", &prune_expire);
        git_config_get_expiry("gc.worktreepruneexpire", &prune_worktrees_expire);
        git_config_get_expiry("gc.logexpiry", &gc_log_expire);

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

        git_config(git_default_config, NULL);
}

static int too_many_loose_objects(void)
{
        /*
         * 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;

        dir = opendir(git_path("objects/17"));
        if (!dir)
                return 0;

        auto_threshold = DIV_ROUND_UP(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)
                        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(void)
{
        struct packed_git *p;
        int cnt;

        if (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 gc_auto_pack_limit < cnt;
}

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

        if (!sysinfo(&si))
                return si.totalram;
#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 packed_git *pack)
{
        unsigned long nr_objects = approximate_object_count();
        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(struct revindex_entry) * nr_objects;
        /*
         * read_sha1_file() (either at delta calculation phase, or
         * writing phase) also fills up the delta base cache
         */
        heap += delta_base_cache_limit;
        /* and of course pack-objects has its own delta cache */
        heap += max_delta_cache_size;

        return os_cache + heap;
}

static int keep_one_pack(struct string_list_item *item, void *data)
{
        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"))
                strvec_push(&repack, "-a");
        else {
                strvec_push(&repack, "-A");
                if (prune_expire)
                        strvec_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
        }

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

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

static int need_to_gc(void)
{
        /*
         * Setting gc.auto to 0 or negative can disable the
         * automatic gc.
         */
        if (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()) {
                struct string_list keep_pack = STRING_LIST_INIT_NODUP;

                if (big_pack_threshold) {
                        find_base_packs(&keep_pack, big_pack_threshold);
                        if (keep_pack.nr >= gc_auto_pack_limit) {
                                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(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(&keep_pack);
                string_list_clear(&keep_pack, 0);
        } else if (too_many_loose_objects())
                add_repack_incremental_option();
        else
                return 0;

        if (run_hook_le(NULL, "pre-auto-gc", NULL))
                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 = git_pathdup("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 != NULL)
                        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 -1 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 = git_pathdup("gc.log");

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

                ret = error_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 = error_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(void)
{
        /*
         * 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 (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.v, RUN_GIT_CMD))
                die(FAILED_RUN, reflog.v[0]);
}

int cmd_gc(int argc, const char **argv, const char *prefix)
{
        int aggressive = 0;
        int auto_gc = 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 option builtin_gc_options[] = {
                OPT__QUIET(&quiet, N_("suppress progress reporting")),
                { OPTION_STRING, 0, "prune", &prune_expire, N_("date"),
                        N_("prune unreferenced objects"),
                        PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
                OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
                OPT_BOOL_F(0, "auto", &auto_gc, N_("enable auto-gc mode"),
                           PARSE_OPT_NOCOMPLETE),
                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_END()
        };

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(builtin_gc_usage, builtin_gc_options);

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

        if (pack_refs < 0)
                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 && parse_expiry_date(prune_expire, &dummy))
                die(_("failed to parse prune expiry value %s"), prune_expire);

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

        if (auto_gc) {
                /*
                 * Auto-gc should be least intrusive as possible.
                 */
                if (!need_to_gc())
                        return 0;
                if (!quiet) {
                        if (detach_auto)
                                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"));
                }
                if (detach_auto) {
                        int ret = report_last_gc_error();
                        if (ret < 0)
                                /* an I/O error occurred, already reported */
                                exit(128);
                        if (ret == 1)
                                /* Last gc --auto failed. Skip this one. */
                                return 0;

                        if (lock_repo_for_gc(force, &pid))
                                return 0;
                        gc_before_repack(); /* dies on failure */
                        delete_tempfile(&pidfile);

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

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

        name = lock_repo_for_gc(force, &pid);
        if (name) {
                if (auto_gc)
                        return 0; /* be quiet on --auto */
                die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
                    name, (uintmax_t)pid);
        }

        if (daemonized) {
                hold_lock_file_for_update(&log_lock,
                                          git_path("gc.log"),
                                          LOCK_DIE_ON_ERROR);
                dup2(get_lock_file_fd(&log_lock), 2);
                sigchain_push_common(process_log_file_on_signal);
                atexit(process_log_file_at_exit);
        }

        gc_before_repack();

        if (!repository_format_precious_objects) {
                close_object_store(the_repository->objects);
                if (run_command_v_opt(repack.v, RUN_GIT_CMD))
                        die(FAILED_RUN, repack.v[0]);

                if (prune_expire) {
                        strvec_push(&prune, prune_expire);
                        if (quiet)
                                strvec_push(&prune, "--no-progress");
                        if (has_promisor_remote())
                                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) {
                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.v, RUN_GIT_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();
        }

        prepare_repo_settings(the_repository);
        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 (auto_gc && too_many_loose_objects())
                warning(_("There are too many unreachable loose objects; "
                        "run 'git prune' to remove them."));

        if (!daemonized)
                unlink(git_path("gc.log"));

        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]);
}