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
  18 #define FAILED_RUN "failed to run %s"
  19
  20 static const char * const builtin_gc_usage[] = {
  21         "git-gc [options]",
  22         NULL
  23 };
  24
  25 static int pack_refs = 1;
  26 static int aggressive_window = -1;
  27 static int gc_auto_threshold = 6700;
  28 static int gc_auto_pack_limit = 20;
  29
  30 #define MAX_ADD 10
  31 static const char *argv_pack_refs[] = {"pack-refs", "--all", "--prune", NULL};
  32 static const char *argv_reflog[] = {"reflog", "expire", "--all", NULL};
  33 static const char *argv_repack[MAX_ADD] = {"repack", "-d", "-l", NULL};
  34 static const char *argv_prune[] = {"prune", NULL};
  35 static const char *argv_rerere[] = {"rerere", "gc", NULL};
  36
  37 static int gc_config(const char *var, const char *value)
  38 {
  39         if (!strcmp(var, "gc.packrefs")) {
  40                 if (value && !strcmp(value, "notbare"))
  41                         pack_refs = -1;
  42                 else
  43                         pack_refs = git_config_bool(var, value);
  44                 return 0;
  45         }
  46         if (!strcmp(var, "gc.aggressivewindow")) {
  47                 aggressive_window = git_config_int(var, value);
  48                 return 0;
  49         }
  50         if (!strcmp(var, "gc.auto")) {
  51                 gc_auto_threshold = git_config_int(var, value);
  52                 return 0;
  53         }
  54         if (!strcmp(var, "gc.autopacklimit")) {
  55                 gc_auto_pack_limit = git_config_int(var, value);
  56                 return 0;
  57         }
  58         return git_default_config(var, value);
  59 }
  60
  61 static void append_option(const char **cmd, const char *opt, int max_length)
  62 {
  63         int i;
  64
  65         for (i = 0; cmd[i]; i++)
  66                 ;
  67
  68         if (i + 2 >= max_length)
  69                 die("Too many options specified");
  70         cmd[i++] = opt;
  71         cmd[i] = NULL;
  72 }
  73
  74 static int too_many_loose_objects(void)
  75 {
  76         /*
  77          * Quickly check if a "gc" is needed, by estimating how
  78          * many loose objects there are.  Because SHA-1 is evenly
  79          * distributed, we can check only one and get a reasonable
  80          * estimate.
  81          */
  82         char path[PATH_MAX];
  83         const char *objdir = get_object_directory();
  84         DIR *dir;
  85         struct dirent *ent;
  86         int auto_threshold;
  87         int num_loose = 0;
  88         int needed = 0;
  89
  90         if (gc_auto_threshold <= 0)
  91                 return 0;
  92
  93         if (sizeof(path) <= snprintf(path, sizeof(path), "%s/17", objdir)) {
  94                 warning("insanely long object directory %.*s", 50, objdir);
  95                 return 0;
  96         }
  97         dir = opendir(path);
  98         if (!dir)
  99                 return 0;
 100
 101         auto_threshold = (gc_auto_threshold + 255) / 256;
 102         while ((ent = readdir(dir)) != NULL) {
 103                 if (strspn(ent->d_name, "0123456789abcdef") != 38 ||
 104                     ent->d_name[38] != '\0')
 105                         continue;
 106                 if (++num_loose > auto_threshold) {
 107                         needed = 1;
 108                         break;
 109                 }
 110         }
 111         closedir(dir);
 112         return needed;
 113 }
 114
 115 static int too_many_packs(void)
 116 {
 117         struct packed_git *p;
 118         int cnt;
 119
 120         if (gc_auto_pack_limit <= 0)
 121                 return 0;
 122
 123         prepare_packed_git();
 124         for (cnt = 0, p = packed_git; p; p = p->next) {
 125                 char path[PATH_MAX];
 126                 size_t len;
 127                 int keep;
 128
 129                 if (!p->pack_local)
 130                         continue;
 131                 len = strlen(p->pack_name);
 132                 if (PATH_MAX <= len + 1)
 133                         continue; /* oops, give up */
 134                 memcpy(path, p->pack_name, len-5);
 135                 memcpy(path + len - 5, ".keep", 6);
 136                 keep = access(p->pack_name, F_OK) && (errno == ENOENT);
 137                 if (keep)
 138                         continue;
 139                 /*
 140                  * Perhaps check the size of the pack and count only
 141                  * very small ones here?
 142                  */
 143                 cnt++;
 144         }
 145         return gc_auto_pack_limit <= cnt;
 146 }
 147
 148 static int need_to_gc(void)
 149 {
 150         /*
 151          * Setting gc.auto and gc.autopacklimit to 0 or negative can
 152          * disable the automatic gc.
 153          */
 154         if (gc_auto_threshold <= 0 && gc_auto_pack_limit <= 0)
 155                 return 0;
 156
 157         /*
 158          * If there are too many loose objects, but not too many
 159          * packs, we run "repack -d -l".  If there are too many packs,
 160          * we run "repack -A -d -l".  Otherwise we tell the caller
 161          * there is no need.
 162          */
 163         if (too_many_packs())
 164                 append_option(argv_repack, "-A", MAX_ADD);
 165         else if (!too_many_loose_objects())
 166                 return 0;
 167         return 1;
 168 }
 169
 170 int cmd_gc(int argc, const char **argv, const char *prefix)
 171 {
 172         int prune = 0;
 173         int aggressive = 0;
 174         int auto_gc = 0;
 175         char buf[80];
 176
 177         struct option builtin_gc_options[] = {
 178                 OPT_BOOLEAN(0, "prune", &prune, "prune unreferenced objects"),
 179                 OPT_BOOLEAN(0, "aggressive", &aggressive, "be more thorough (increased runtime)"),
 180                 OPT_BOOLEAN(0, "auto", &auto_gc, "enable auto-gc mode"),
 181                 OPT_END()
 182         };
 183
 184         git_config(gc_config);
 185
 186         if (pack_refs < 0)
 187                 pack_refs = !is_bare_repository();
 188
 189         argc = parse_options(argc, argv, builtin_gc_options, builtin_gc_usage, 0);
 190         if (argc > 0)
 191                 usage_with_options(builtin_gc_usage, builtin_gc_options);
 192
 193         if (aggressive) {
 194                 append_option(argv_repack, "-f", MAX_ADD);
 195                 if (aggressive_window > 0) {
 196                         sprintf(buf, "--window=%d", aggressive_window);
 197                         append_option(argv_repack, buf, MAX_ADD);
 198                 }
 199         }
 200
 201         if (auto_gc) {
 202                 /*
 203                  * Auto-gc should be least intrusive as possible.
 204                  */
 205                 prune = 0;
 206                 if (!need_to_gc())
 207                         return 0;
 208                 fprintf(stderr, "Auto packing your repository for optimum "
 209                         "performance. You may also\n"
 210                         "run \"git gc\" manually. See "
 211                         "\"git help gc\" for more information.\n");
 212         } else {
 213                 /*
 214                  * Use safer (for shared repos) "-A" option to
 215                  * repack when not pruning. Auto-gc makes its
 216                  * own decision.
 217                  */
 218                 if (prune)
 219                         append_option(argv_repack, "-a", MAX_ADD);
 220                 else
 221                         append_option(argv_repack, "-A", MAX_ADD);
 222         }
 223
 224         if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
 225                 return error(FAILED_RUN, argv_pack_refs[0]);
 226
 227         if (run_command_v_opt(argv_reflog, RUN_GIT_CMD))
 228                 return error(FAILED_RUN, argv_reflog[0]);
 229
 230         if (run_command_v_opt(argv_repack, RUN_GIT_CMD))
 231                 return error(FAILED_RUN, argv_repack[0]);
 232
 233         if (prune && run_command_v_opt(argv_prune, RUN_GIT_CMD))
 234                 return error(FAILED_RUN, argv_prune[0]);
 235
 236         if (run_command_v_opt(argv_rerere, RUN_GIT_CMD))
 237                 return error(FAILED_RUN, argv_rerere[0]);
 238
 239         if (auto_gc && too_many_loose_objects())
 240                 warning("There are too many unreachable loose objects; "
 241                         "run 'git prune' to remove them.");
 242
 243         return 0;
 244 }