builtin/gc.c

   1 /*
   2  * git gc builtin command
   3  *
   4  * Cleanup unreachable files and optimize the repository.
   5  *
   6  * Copyright (c) 2007 James Bowes
   7  *
   8  * Based on git-gc.sh, which is
   9  *
  10  * Copyright (c) 2006 Shawn O. Pearce
  11  */
  12
  13 #include "builtin.h"
  14 #include "cache.h"
  15 #include "parse-options.h"
  16 #include "run-command.h"
  17 #include "sigchain.h"
  18 #include "argv-array.h"
  19 #include "commit.h"
  20
  21 #define FAILED_RUN "failed to run %s"
  22
  23 static const char * const builtin_gc_usage[] = {
  24         N_("git gc [options]"),
  25         NULL
  26 };
  27
  28 static int pack_refs = 1;
  29 static int aggressive_window = 250;
  30 static int gc_auto_threshold = 6700;
  31 static int gc_auto_pack_limit = 50;
  32 static int detach_auto = 1;
  33 static const char *prune_expire = "2.weeks.ago";
  34
  35 static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
  36 static struct argv_array reflog = ARGV_ARRAY_INIT;
  37 static struct argv_array repack = ARGV_ARRAY_INIT;
  38 static struct argv_array prune = ARGV_ARRAY_INIT;
  39 static struct argv_array rerere = ARGV_ARRAY_INIT;
  40
  41 static char *pidfile;
  42
  43 static void remove_pidfile(void)
  44 {
  45         if (pidfile)
  46                 unlink(pidfile);
  47 }
  48
  49 static void remove_pidfile_on_signal(int signo)
  50 {
  51         remove_pidfile();
  52         sigchain_pop(signo);
  53         raise(signo);
  54 }
  55
  56 static int gc_config(const char *var, const char *value, void *cb)
  57 {
  58         if (!strcmp(var, "gc.packrefs")) {
  59                 if (value && !strcmp(value, "notbare"))
  60                         pack_refs = -1;
  61                 else
  62                         pack_refs = git_config_bool(var, value);
  63                 return 0;
  64         }
  65         if (!strcmp(var, "gc.aggressivewindow")) {
  66                 aggressive_window = git_config_int(var, value);
  67                 return 0;
  68         }
  69         if (!strcmp(var, "gc.auto")) {
  70                 gc_auto_threshold = git_config_int(var, value);
  71                 return 0;
  72         }
  73         if (!strcmp(var, "gc.autopacklimit")) {
  74                 gc_auto_pack_limit = git_config_int(var, value);
  75                 return 0;
  76         }
  77         if (!strcmp(var, "gc.autodetach")) {
  78                 detach_auto = git_config_bool(var, value);
  79                 return 0;
  80         }
  81         if (!strcmp(var, "gc.pruneexpire")) {
  82                 if (value && strcmp(value, "now")) {
  83                         unsigned long now = approxidate("now");
  84                         if (approxidate(value) >= now)
  85                                 return error(_("Invalid %s: '%s'"), var, value);
  86                 }
  87                 return git_config_string(&prune_expire, var, value);
  88         }
  89         return git_default_config(var, value, cb);
  90 }
  91
  92 static int too_many_loose_objects(void)
  93 {
  94         /*
  95          * Quickly check if a "gc" is needed, by estimating how
  96          * many loose objects there are.  Because SHA-1 is evenly
  97          * distributed, we can check only one and get a reasonable
  98          * estimate.
  99          */
 100         char path[PATH_MAX];
 101         const char *objdir = get_object_directory();
 102         DIR *dir;
 103         struct dirent *ent;
 104         int auto_threshold;
 105         int num_loose = 0;
 106         int needed = 0;
 107
 108         if (gc_auto_threshold <= 0)
 109                 return 0;
 110
 111         if (sizeof(path) <= snprintf(path, sizeof(path), "%s/17", objdir)) {
 112                 warning(_("insanely long object directory %.*s"), 50, objdir);
 113                 return 0;
 114         }
 115         dir = opendir(path);
 116         if (!dir)
 117                 return 0;
 118
 119         auto_threshold = (gc_auto_threshold + 255) / 256;
 120         while ((ent = readdir(dir)) != NULL) {
 121                 if (strspn(ent->d_name, "0123456789abcdef") != 38 ||
 122                     ent->d_name[38] != '\0')
 123                         continue;
 124                 if (++num_loose > auto_threshold) {
 125                         needed = 1;
 126                         break;
 127                 }
 128         }
 129         closedir(dir);
 130         return needed;
 131 }
 132
 133 static int too_many_packs(void)
 134 {
 135         struct packed_git *p;
 136         int cnt;
 137
 138         if (gc_auto_pack_limit <= 0)
 139                 return 0;
 140
 141         prepare_packed_git();
 142         for (cnt = 0, p = packed_git; p; p = p->next) {
 143                 if (!p->pack_local)
 144                         continue;
 145                 if (p->pack_keep)
 146                         continue;
 147                 /*
 148                  * Perhaps check the size of the pack and count only
 149                  * very small ones here?
 150                  */
 151                 cnt++;
 152         }
 153         return gc_auto_pack_limit <= cnt;
 154 }
 155
 156 static void add_repack_all_option(void)
 157 {
 158         if (prune_expire && !strcmp(prune_expire, "now"))
 159                 argv_array_push(&repack, "-a");
 160         else {
 161                 argv_array_push(&repack, "-A");
 162                 if (prune_expire)
 163                         argv_array_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
 164         }
 165 }
 166
 167 static int need_to_gc(void)
 168 {
 169         /*
 170          * Setting gc.auto to 0 or negative can disable the
 171          * automatic gc.
 172          */
 173         if (gc_auto_threshold <= 0)
 174                 return 0;
 175
 176         /*
 177          * If there are too many loose objects, but not too many
 178          * packs, we run "repack -d -l".  If there are too many packs,
 179          * we run "repack -A -d -l".  Otherwise we tell the caller
 180          * there is no need.
 181          */
 182         if (too_many_packs())
 183                 add_repack_all_option();
 184         else if (!too_many_loose_objects())
 185                 return 0;
 186
 187         if (run_hook(NULL, "pre-auto-gc", NULL))
 188                 return 0;
 189         return 1;
 190 }
 191
 192 /* return NULL on success, else hostname running the gc */
 193 static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 194 {
 195         static struct lock_file lock;
 196         char my_host[128];
 197         struct strbuf sb = STRBUF_INIT;
 198         struct stat st;
 199         uintmax_t pid;
 200         FILE *fp;
 201         int fd;
 202
 203         if (pidfile)
 204                 /* already locked */
 205                 return NULL;
 206
 207         if (gethostname(my_host, sizeof(my_host)))
 208                 strcpy(my_host, "unknown");
 209
 210         fd = hold_lock_file_for_update(&lock, git_path("gc.pid"),
 211                                        LOCK_DIE_ON_ERROR);
 212         if (!force) {
 213                 static char locking_host[128];
 214                 int should_exit;
 215                 fp = fopen(git_path("gc.pid"), "r");
 216                 memset(locking_host, 0, sizeof(locking_host));
 217                 should_exit =
 218                         fp != NULL &&
 219                         !fstat(fileno(fp), &st) &&
 220                         /*
 221                          * 12 hour limit is very generous as gc should
 222                          * never take that long. On the other hand we
 223                          * don't really need a strict limit here,
 224                          * running gc --auto one day late is not a big
 225                          * problem. --force can be used in manual gc
 226                          * after the user verifies that no gc is
 227                          * running.
 228                          */
 229                         time(NULL) - st.st_mtime <= 12 * 3600 &&
 230                         fscanf(fp, "%"PRIuMAX" %127c", &pid, locking_host) == 2 &&
 231                         /* be gentle to concurrent "gc" on remote hosts */
 232                         (strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
 233                 if (fp != NULL)
 234                         fclose(fp);
 235                 if (should_exit) {
 236                         if (fd >= 0)
 237                                 rollback_lock_file(&lock);
 238                         *ret_pid = pid;
 239                         return locking_host;
 240                 }
 241         }
 242
 243         strbuf_addf(&sb, "%"PRIuMAX" %s",
 244                     (uintmax_t) getpid(), my_host);
 245         write_in_full(fd, sb.buf, sb.len);
 246         strbuf_release(&sb);
 247         commit_lock_file(&lock);
 248
 249         pidfile = git_pathdup("gc.pid");
 250         sigchain_push_common(remove_pidfile_on_signal);
 251         atexit(remove_pidfile);
 252
 253         return NULL;
 254 }
 255
 256 int cmd_gc(int argc, const char **argv, const char *prefix)
 257 {
 258         int aggressive = 0;
 259         int auto_gc = 0;
 260         int quiet = 0;
 261         int force = 0;
 262         const char *name;
 263         pid_t pid;
 264
 265         struct option builtin_gc_options[] = {
 266                 OPT__QUIET(&quiet, N_("suppress progress reporting")),
 267                 { OPTION_STRING, 0, "prune", &prune_expire, N_("date"),
 268                         N_("prune unreferenced objects"),
 269                         PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
 270                 OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
 271                 OPT_BOOL(0, "auto", &auto_gc, N_("enable auto-gc mode")),
 272                 OPT_BOOL(0, "force", &force, N_("force running gc even if there may be another gc running")),
 273                 OPT_END()
 274         };
 275
 276         if (argc == 2 && !strcmp(argv[1], "-h"))
 277                 usage_with_options(builtin_gc_usage, builtin_gc_options);
 278
 279         argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
 280         argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
 281         argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
 282         argv_array_pushl(&prune, "prune", "--expire", NULL );
 283         argv_array_pushl(&rerere, "rerere", "gc", NULL);
 284
 285         git_config(gc_config, NULL);
 286
 287         if (pack_refs < 0)
 288                 pack_refs = !is_bare_repository();
 289
 290         argc = parse_options(argc, argv, prefix, builtin_gc_options,
 291                              builtin_gc_usage, 0);
 292         if (argc > 0)
 293                 usage_with_options(builtin_gc_usage, builtin_gc_options);
 294
 295         if (aggressive) {
 296                 argv_array_push(&repack, "-f");
 297                 argv_array_push(&repack, "--depth=250");
 298                 if (aggressive_window > 0)
 299                         argv_array_pushf(&repack, "--window=%d", aggressive_window);
 300         }
 301         if (quiet)
 302                 argv_array_push(&repack, "-q");
 303
 304         if (auto_gc) {
 305                 /*
 306                  * Auto-gc should be least intrusive as possible.
 307                  */
 308                 if (!need_to_gc())
 309                         return 0;
 310                 if (!quiet) {
 311                         if (detach_auto)
 312                                 fprintf(stderr, _("Auto packing the repository in background for optimum performance.\n"));
 313                         else
 314                                 fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
 315                         fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
 316                 }
 317                 if (detach_auto)
 318                         /*
 319                          * failure to daemonize is ok, we'll continue
 320                          * in foreground
 321                          */
 322                         daemonize();
 323         } else
 324                 add_repack_all_option();
 325
 326         name = lock_repo_for_gc(force, &pid);
 327         if (name) {
 328                 if (auto_gc)
 329                         return 0; /* be quiet on --auto */
 330                 die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
 331                     name, (uintmax_t)pid);
 332         }
 333
 334         if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
 335                 return error(FAILED_RUN, pack_refs_cmd.argv[0]);
 336
 337         if (run_command_v_opt(reflog.argv, RUN_GIT_CMD))
 338                 return error(FAILED_RUN, reflog.argv[0]);
 339
 340         if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
 341                 return error(FAILED_RUN, repack.argv[0]);
 342
 343         if (prune_expire) {
 344                 argv_array_push(&prune, prune_expire);
 345                 if (quiet)
 346                         argv_array_push(&prune, "--no-progress");
 347                 if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
 348                         return error(FAILED_RUN, prune.argv[0]);
 349         }
 350
 351         if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
 352                 return error(FAILED_RUN, rerere.argv[0]);
 353
 354         if (auto_gc && too_many_loose_objects())
 355                 warning(_("There are too many unreachable loose objects; "
 356                         "run 'git prune' to remove them."));
 357
 358         return 0;
 359 }