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 prune_reflogs = 1;
  30 static int aggressive_depth = 250;
  31 static int aggressive_window = 250;
  32 static int gc_auto_threshold = 6700;
  33 static int gc_auto_pack_limit = 50;
  34 static int detach_auto = 1;
  35 static const char *prune_expire = "2.weeks.ago";
  36
  37 static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
  38 static struct argv_array reflog = ARGV_ARRAY_INIT;
  39 static struct argv_array repack = ARGV_ARRAY_INIT;
  40 static struct argv_array prune = ARGV_ARRAY_INIT;
  41 static struct argv_array rerere = ARGV_ARRAY_INIT;
  42
  43 static char *pidfile;
  44
  45 static void remove_pidfile(void)
  46 {
  47         if (pidfile)
  48                 unlink(pidfile);
  49 }
  50
  51 static void remove_pidfile_on_signal(int signo)
  52 {
  53         remove_pidfile();
  54         sigchain_pop(signo);
  55         raise(signo);
  56 }
  57
  58 static int gc_config(const char *var, const char *value, void *cb)
  59 {
  60         if (!strcmp(var, "gc.packrefs")) {
  61                 if (value && !strcmp(value, "notbare"))
  62                         pack_refs = -1;
  63                 else
  64                         pack_refs = git_config_bool(var, value);
  65                 return 0;
  66         }
  67         if (!strcmp(var, "gc.aggressivewindow")) {
  68                 aggressive_window = git_config_int(var, value);
  69                 return 0;
  70         }
  71         if (!strcmp(var, "gc.aggressivedepth")) {
  72                 aggressive_depth = git_config_int(var, value);
  73                 return 0;
  74         }
  75         if (!strcmp(var, "gc.auto")) {
  76                 gc_auto_threshold = git_config_int(var, value);
  77                 return 0;
  78         }
  79         if (!strcmp(var, "gc.autopacklimit")) {
  80                 gc_auto_pack_limit = git_config_int(var, value);
  81                 return 0;
  82         }
  83         if (!strcmp(var, "gc.autodetach")) {
  84                 detach_auto = git_config_bool(var, value);
  85                 return 0;
  86         }
  87         if (!strcmp(var, "gc.pruneexpire")) {
  88                 if (value && strcmp(value, "now")) {
  89                         unsigned long now = approxidate("now");
  90                         if (approxidate(value) >= now)
  91                                 return error(_("Invalid %s: '%s'"), var, value);
  92                 }
  93                 return git_config_string(&prune_expire, var, value);
  94         }
  95         return git_default_config(var, value, cb);
  96 }
  97
  98 static int too_many_loose_objects(void)
  99 {
 100         /*
 101          * Quickly check if a "gc" is needed, by estimating how
 102          * many loose objects there are.  Because SHA-1 is evenly
 103          * distributed, we can check only one and get a reasonable
 104          * estimate.
 105          */
 106         char path[PATH_MAX];
 107         const char *objdir = get_object_directory();
 108         DIR *dir;
 109         struct dirent *ent;
 110         int auto_threshold;
 111         int num_loose = 0;
 112         int needed = 0;
 113
 114         if (gc_auto_threshold <= 0)
 115                 return 0;
 116
 117         if (sizeof(path) <= snprintf(path, sizeof(path), "%s/17", objdir)) {
 118                 warning(_("insanely long object directory %.*s"), 50, objdir);
 119                 return 0;
 120         }
 121         dir = opendir(path);
 122         if (!dir)
 123                 return 0;
 124
 125         auto_threshold = (gc_auto_threshold + 255) / 256;
 126         while ((ent = readdir(dir)) != NULL) {
 127                 if (strspn(ent->d_name, "0123456789abcdef") != 38 ||
 128                     ent->d_name[38] != '\0')
 129                         continue;
 130                 if (++num_loose > auto_threshold) {
 131                         needed = 1;
 132                         break;
 133                 }
 134         }
 135         closedir(dir);
 136         return needed;
 137 }
 138
 139 static int too_many_packs(void)
 140 {
 141         struct packed_git *p;
 142         int cnt;
 143
 144         if (gc_auto_pack_limit <= 0)
 145                 return 0;
 146
 147         prepare_packed_git();
 148         for (cnt = 0, p = packed_git; p; p = p->next) {
 149                 if (!p->pack_local)
 150                         continue;
 151                 if (p->pack_keep)
 152                         continue;
 153                 /*
 154                  * Perhaps check the size of the pack and count only
 155                  * very small ones here?
 156                  */
 157                 cnt++;
 158         }
 159         return gc_auto_pack_limit <= cnt;
 160 }
 161
 162 static void add_repack_all_option(void)
 163 {
 164         if (prune_expire && !strcmp(prune_expire, "now"))
 165                 argv_array_push(&repack, "-a");
 166         else {
 167                 argv_array_push(&repack, "-A");
 168                 if (prune_expire)
 169                         argv_array_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
 170         }
 171 }
 172
 173 static int need_to_gc(void)
 174 {
 175         /*
 176          * Setting gc.auto to 0 or negative can disable the
 177          * automatic gc.
 178          */
 179         if (gc_auto_threshold <= 0)
 180                 return 0;
 181
 182         /*
 183          * If there are too many loose objects, but not too many
 184          * packs, we run "repack -d -l".  If there are too many packs,
 185          * we run "repack -A -d -l".  Otherwise we tell the caller
 186          * there is no need.
 187          */
 188         if (too_many_packs())
 189                 add_repack_all_option();
 190         else if (!too_many_loose_objects())
 191                 return 0;
 192
 193         if (run_hook_le(NULL, "pre-auto-gc", NULL))
 194                 return 0;
 195         return 1;
 196 }
 197
 198 /* return NULL on success, else hostname running the gc */
 199 static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 200 {
 201         static struct lock_file lock;
 202         char my_host[128];
 203         struct strbuf sb = STRBUF_INIT;
 204         struct stat st;
 205         uintmax_t pid;
 206         FILE *fp;
 207         int fd;
 208
 209         if (pidfile)
 210                 /* already locked */
 211                 return NULL;
 212
 213         if (gethostname(my_host, sizeof(my_host)))
 214                 strcpy(my_host, "unknown");
 215
 216         fd = hold_lock_file_for_update(&lock, git_path("gc.pid"),
 217                                        LOCK_DIE_ON_ERROR);
 218         if (!force) {
 219                 static char locking_host[128];
 220                 int should_exit;
 221                 fp = fopen(git_path("gc.pid"), "r");
 222                 memset(locking_host, 0, sizeof(locking_host));
 223                 should_exit =
 224                         fp != NULL &&
 225                         !fstat(fileno(fp), &st) &&
 226                         /*
 227                          * 12 hour limit is very generous as gc should
 228                          * never take that long. On the other hand we
 229                          * don't really need a strict limit here,
 230                          * running gc --auto one day late is not a big
 231                          * problem. --force can be used in manual gc
 232                          * after the user verifies that no gc is
 233                          * running.
 234                          */
 235                         time(NULL) - st.st_mtime <= 12 * 3600 &&
 236                         fscanf(fp, "%"PRIuMAX" %127c", &pid, locking_host) == 2 &&
 237                         /* be gentle to concurrent "gc" on remote hosts */
 238                         (strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
 239                 if (fp != NULL)
 240                         fclose(fp);
 241                 if (should_exit) {
 242                         if (fd >= 0)
 243                                 rollback_lock_file(&lock);
 244                         *ret_pid = pid;
 245                         return locking_host;
 246                 }
 247         }
 248
 249         strbuf_addf(&sb, "%"PRIuMAX" %s",
 250                     (uintmax_t) getpid(), my_host);
 251         write_in_full(fd, sb.buf, sb.len);
 252         strbuf_release(&sb);
 253         commit_lock_file(&lock);
 254
 255         pidfile = git_pathdup("gc.pid");
 256         sigchain_push_common(remove_pidfile_on_signal);
 257         atexit(remove_pidfile);
 258
 259         return NULL;
 260 }
 261
 262 static int gc_before_repack(void)
 263 {
 264         if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
 265                 return error(FAILED_RUN, pack_refs_cmd.argv[0]);
 266
 267         if (prune_reflogs && run_command_v_opt(reflog.argv, RUN_GIT_CMD))
 268                 return error(FAILED_RUN, reflog.argv[0]);
 269
 270         pack_refs = 0;
 271         prune_reflogs = 0;
 272         return 0;
 273 }
 274
 275 int cmd_gc(int argc, const char **argv, const char *prefix)
 276 {
 277         int aggressive = 0;
 278         int auto_gc = 0;
 279         int quiet = 0;
 280         int force = 0;
 281         const char *name;
 282         pid_t pid;
 283
 284         struct option builtin_gc_options[] = {
 285                 OPT__QUIET(&quiet, N_("suppress progress reporting")),
 286                 { OPTION_STRING, 0, "prune", &prune_expire, N_("date"),
 287                         N_("prune unreferenced objects"),
 288                         PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
 289                 OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
 290                 OPT_BOOL(0, "auto", &auto_gc, N_("enable auto-gc mode")),
 291                 OPT_BOOL(0, "force", &force, N_("force running gc even if there may be another gc running")),
 292                 OPT_END()
 293         };
 294
 295         if (argc == 2 && !strcmp(argv[1], "-h"))
 296                 usage_with_options(builtin_gc_usage, builtin_gc_options);
 297
 298         argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
 299         argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
 300         argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
 301         argv_array_pushl(&prune, "prune", "--expire", NULL );
 302         argv_array_pushl(&rerere, "rerere", "gc", NULL);
 303
 304         git_config(gc_config, NULL);
 305
 306         if (pack_refs < 0)
 307                 pack_refs = !is_bare_repository();
 308
 309         argc = parse_options(argc, argv, prefix, builtin_gc_options,
 310                              builtin_gc_usage, 0);
 311         if (argc > 0)
 312                 usage_with_options(builtin_gc_usage, builtin_gc_options);
 313
 314         if (aggressive) {
 315                 argv_array_push(&repack, "-f");
 316                 if (aggressive_depth > 0)
 317                         argv_array_pushf(&repack, "--depth=%d", aggressive_depth);
 318                 if (aggressive_window > 0)
 319                         argv_array_pushf(&repack, "--window=%d", aggressive_window);
 320         }
 321         if (quiet)
 322                 argv_array_push(&repack, "-q");
 323
 324         if (auto_gc) {
 325                 /*
 326                  * Auto-gc should be least intrusive as possible.
 327                  */
 328                 if (!need_to_gc())
 329                         return 0;
 330                 if (!quiet) {
 331                         if (detach_auto)
 332                                 fprintf(stderr, _("Auto packing the repository in background for optimum performance.\n"));
 333                         else
 334                                 fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
 335                         fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
 336                 }
 337                 if (detach_auto) {
 338                         if (gc_before_repack())
 339                                 return -1;
 340                         /*
 341                          * failure to daemonize is ok, we'll continue
 342                          * in foreground
 343                          */
 344                         daemonize();
 345                 }
 346         } else
 347                 add_repack_all_option();
 348
 349         name = lock_repo_for_gc(force, &pid);
 350         if (name) {
 351                 if (auto_gc)
 352                         return 0; /* be quiet on --auto */
 353                 die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
 354                     name, (uintmax_t)pid);
 355         }
 356
 357         if (gc_before_repack())
 358                 return -1;
 359
 360         if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
 361                 return error(FAILED_RUN, repack.argv[0]);
 362
 363         if (prune_expire) {
 364                 argv_array_push(&prune, prune_expire);
 365                 if (quiet)
 366                         argv_array_push(&prune, "--no-progress");
 367                 if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
 368                         return error(FAILED_RUN, prune.argv[0]);
 369         }
 370
 371         if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
 372                 return error(FAILED_RUN, rerere.argv[0]);
 373
 374         if (auto_gc && too_many_loose_objects())
 375                 warning(_("There are too many unreachable loose objects; "
 376                         "run 'git prune' to remove them."));
 377
 378         return 0;
 379 }