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#include "builtin.h"
14#include "repository.h"
15#include "config.h"
16#include "tempfile.h"
17#include "lockfile.h"
18#include "parse-options.h"
19#include "run-command.h"
20#include "sigchain.h"
21#include "argv-array.h"
22#include "commit.h"
23#include "commit-graph.h"
24#include "packfile.h"
25#include "object-store.h"
26#include "pack.h"
27#include "pack-objects.h"
28#include "blob.h"
29#include "tree.h"
30#include "promisor-remote.h"
31#define FAILED_RUN "failed to run %s"
33static const char * const builtin_gc_usage[] = {
35 N_("git gc [<options>]"),
36 NULL
37};
38static int pack_refs = 1;
40static int prune_reflogs = 1;
41static int aggressive_depth = 50;
42static int aggressive_window = 250;
43static int gc_auto_threshold = 6700;
44static int gc_auto_pack_limit = 50;
45static int detach_auto = 1;
46static timestamp_t gc_log_expire_time;
47static const char *gc_log_expire = "1.day.ago";
48static const char *prune_expire = "2.weeks.ago";
49static const char *prune_worktrees_expire = "3.months.ago";
50static unsigned long big_pack_threshold;
51static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
52static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
54static struct argv_array reflog = ARGV_ARRAY_INIT;
55static struct argv_array repack = ARGV_ARRAY_INIT;
56static struct argv_array prune = ARGV_ARRAY_INIT;
57static struct argv_array prune_worktrees = ARGV_ARRAY_INIT;
58static struct argv_array rerere = ARGV_ARRAY_INIT;
59static struct tempfile *pidfile;
61static struct lock_file log_lock;
62static struct string_list pack_garbage = STRING_LIST_INIT_DUP;
64static void clean_pack_garbage(void)
66{
67 int i;
68 for (i = 0; i < pack_garbage.nr; i++)
69 unlink_or_warn(pack_garbage.items[i].string);
70 string_list_clear(&pack_garbage, 0);
71}
72static void report_pack_garbage(unsigned seen_bits, const char *path)
74{
75 if (seen_bits == PACKDIR_FILE_IDX)
76 string_list_append(&pack_garbage, path);
77}
78static void process_log_file(void)
80{
81 struct stat st;
82 if (fstat(get_lock_file_fd(&log_lock), &st)) {
83 /*
84 * Perhaps there was an i/o error or another
85 * unlikely situation. Try to make a note of
86 * this in gc.log along with any existing
87 * messages.
88 */
89 int saved_errno = errno;
90 fprintf(stderr, _("Failed to fstat %s: %s"),
91 get_tempfile_path(log_lock.tempfile),
92 strerror(saved_errno));
93 fflush(stderr);
94 commit_lock_file(&log_lock);
95 errno = saved_errno;
96 } else if (st.st_size) {
97 /* There was some error recorded in the lock file */
98 commit_lock_file(&log_lock);
99 } else {
100 /* No error, clean up any old gc.log */
101 unlink(git_path("gc.log"));
102 rollback_lock_file(&log_lock);
103 }
104}
105static void process_log_file_at_exit(void)
107{
108 fflush(stderr);
109 process_log_file();
110}
111static void process_log_file_on_signal(int signo)
113{
114 process_log_file();
115 sigchain_pop(signo);
116 raise(signo);
117}
118static int gc_config_is_timestamp_never(const char *var)
120{
121 const char *value;
122 timestamp_t expire;
123 if (!git_config_get_value(var, &value) && value) {
125 if (parse_expiry_date(value, &expire))
126 die(_("failed to parse '%s' value '%s'"), var, value);
127 return expire == 0;
128 }
129 return 0;
130}
131static void gc_config(void)
133{
134 const char *value;
135 if (!git_config_get_value("gc.packrefs", &value)) {
137 if (value && !strcmp(value, "notbare"))
138 pack_refs = -1;
139 else
140 pack_refs = git_config_bool("gc.packrefs", value);
141 }
142 if (gc_config_is_timestamp_never("gc.reflogexpire") &&
144 gc_config_is_timestamp_never("gc.reflogexpireunreachable"))
145 prune_reflogs = 0;
146 git_config_get_int("gc.aggressivewindow", &aggressive_window);
148 git_config_get_int("gc.aggressivedepth", &aggressive_depth);
149 git_config_get_int("gc.auto", &gc_auto_threshold);
150 git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
151 git_config_get_bool("gc.autodetach", &detach_auto);
152 git_config_get_expiry("gc.pruneexpire", &prune_expire);
153 git_config_get_expiry("gc.worktreepruneexpire", &prune_worktrees_expire);
154 git_config_get_expiry("gc.logexpiry", &gc_log_expire);
155 git_config_get_ulong("gc.bigpackthreshold", &big_pack_threshold);
157 git_config_get_ulong("pack.deltacachesize", &max_delta_cache_size);
158 git_config(git_default_config, NULL);
160}
161static int too_many_loose_objects(void)
163{
164 /*
165 * Quickly check if a "gc" is needed, by estimating how
166 * many loose objects there are. Because SHA-1 is evenly
167 * distributed, we can check only one and get a reasonable
168 * estimate.
169 */
170 DIR *dir;
171 struct dirent *ent;
172 int auto_threshold;
173 int num_loose = 0;
174 int needed = 0;
175 const unsigned hexsz_loose = the_hash_algo->hexsz - 2;
176 dir = opendir(git_path("objects/17"));
178 if (!dir)
179 return 0;
180 auto_threshold = DIV_ROUND_UP(gc_auto_threshold, 256);
182 while ((ent = readdir(dir)) != NULL) {
183 if (strspn(ent->d_name, "0123456789abcdef") != hexsz_loose ||
184 ent->d_name[hexsz_loose] != '\0')
185 continue;
186 if (++num_loose > auto_threshold) {
187 needed = 1;
188 break;
189 }
190 }
191 closedir(dir);
192 return needed;
193}
194static struct packed_git *find_base_packs(struct string_list *packs,
196 unsigned long limit)
197{
198 struct packed_git *p, *base = NULL;
199 for (p = get_all_packs(the_repository); p; p = p->next) {
201 if (!p->pack_local)
202 continue;
203 if (limit) {
204 if (p->pack_size >= limit)
205 string_list_append(packs, p->pack_name);
206 } else if (!base || base->pack_size < p->pack_size) {
207 base = p;
208 }
209 }
210 if (base)
212 string_list_append(packs, base->pack_name);
213 return base;
215}
216static int too_many_packs(void)
218{
219 struct packed_git *p;
220 int cnt;
221 if (gc_auto_pack_limit <= 0)
223 return 0;
224 for (cnt = 0, p = get_all_packs(the_repository); p; p = p->next) {
226 if (!p->pack_local)
227 continue;
228 if (p->pack_keep)
229 continue;
230 /*
231 * Perhaps check the size of the pack and count only
232 * very small ones here?
233 */
234 cnt++;
235 }
236 return gc_auto_pack_limit < cnt;
237}
238static uint64_t total_ram(void)
240{
241#if defined(HAVE_SYSINFO)
242 struct sysinfo si;
243 if (!sysinfo(&si))
245 return si.totalram;
246#elif defined(HAVE_BSD_SYSCTL) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM))
247 int64_t physical_memory;
248 int mib[2];
249 size_t length;
250 mib[0] = CTL_HW;
252# if defined(HW_MEMSIZE)
253 mib[1] = HW_MEMSIZE;
254# else
255 mib[1] = HW_PHYSMEM;
256# endif
257 length = sizeof(int64_t);
258 if (!sysctl(mib, 2, &physical_memory, &length, NULL, 0))
259 return physical_memory;
260#elif defined(GIT_WINDOWS_NATIVE)
261 MEMORYSTATUSEX memInfo;
262 memInfo.dwLength = sizeof(MEMORYSTATUSEX);
264 if (GlobalMemoryStatusEx(&memInfo))
265 return memInfo.ullTotalPhys;
266#endif
267 return 0;
268}
269static uint64_t estimate_repack_memory(struct packed_git *pack)
271{
272 unsigned long nr_objects = approximate_object_count();
273 size_t os_cache, heap;
274 if (!pack || !nr_objects)
276 return 0;
277 /*
279 * First we have to scan through at least one pack.
280 * Assume enough room in OS file cache to keep the entire pack
281 * or we may accidentally evict data of other processes from
282 * the cache.
283 */
284 os_cache = pack->pack_size + pack->index_size;
285 /* then pack-objects needs lots more for book keeping */
286 heap = sizeof(struct object_entry) * nr_objects;
287 /*
288 * internal rev-list --all --objects takes up some memory too,
289 * let's say half of it is for blobs
290 */
291 heap += sizeof(struct blob) * nr_objects / 2;
292 /*
293 * and the other half is for trees (commits and tags are
294 * usually insignificant)
295 */
296 heap += sizeof(struct tree) * nr_objects / 2;
297 /* and then obj_hash[], underestimated in fact */
298 heap += sizeof(struct object *) * nr_objects;
299 /* revindex is used also */
300 heap += sizeof(struct revindex_entry) * nr_objects;
301 /*
302 * read_sha1_file() (either at delta calculation phase, or
303 * writing phase) also fills up the delta base cache
304 */
305 heap += delta_base_cache_limit;
306 /* and of course pack-objects has its own delta cache */
307 heap += max_delta_cache_size;
308 return os_cache + heap;
310}
311static int keep_one_pack(struct string_list_item *item, void *data)
313{
314 argv_array_pushf(&repack, "--keep-pack=%s", basename(item->string));
315 return 0;
316}
317static void add_repack_all_option(struct string_list *keep_pack)
319{
320 if (prune_expire && !strcmp(prune_expire, "now"))
321 argv_array_push(&repack, "-a");
322 else {
323 argv_array_push(&repack, "-A");
324 if (prune_expire)
325 argv_array_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
326 }
327 if (keep_pack)
329 for_each_string_list(keep_pack, keep_one_pack, NULL);
330}
331static void add_repack_incremental_option(void)
333{
334 argv_array_push(&repack, "--no-write-bitmap-index");
335}
336static int need_to_gc(void)
338{
339 /*
340 * Setting gc.auto to 0 or negative can disable the
341 * automatic gc.
342 */
343 if (gc_auto_threshold <= 0)
344 return 0;
345 /*
347 * If there are too many loose objects, but not too many
348 * packs, we run "repack -d -l". If there are too many packs,
349 * we run "repack -A -d -l". Otherwise we tell the caller
350 * there is no need.
351 */
352 if (too_many_packs()) {
353 struct string_list keep_pack = STRING_LIST_INIT_NODUP;
354 if (big_pack_threshold) {
356 find_base_packs(&keep_pack, big_pack_threshold);
357 if (keep_pack.nr >= gc_auto_pack_limit) {
358 big_pack_threshold = 0;
359 string_list_clear(&keep_pack, 0);
360 find_base_packs(&keep_pack, 0);
361 }
362 } else {
363 struct packed_git *p = find_base_packs(&keep_pack, 0);
364 uint64_t mem_have, mem_want;
365 mem_have = total_ram();
367 mem_want = estimate_repack_memory(p);
368 /*
370 * Only allow 1/2 of memory for pack-objects, leave
371 * the rest for the OS and other processes in the
372 * system.
373 */
374 if (!mem_have || mem_want < mem_have / 2)
375 string_list_clear(&keep_pack, 0);
376 }
377 add_repack_all_option(&keep_pack);
379 string_list_clear(&keep_pack, 0);
380 } else if (too_many_loose_objects())
381 add_repack_incremental_option();
382 else
383 return 0;
384 if (run_hook_le(NULL, "pre-auto-gc", NULL))
386 return 0;
387 return 1;
388}
389/* return NULL on success, else hostname running the gc */
391static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
392{
393 struct lock_file lock = LOCK_INIT;
394 char my_host[HOST_NAME_MAX + 1];
395 struct strbuf sb = STRBUF_INIT;
396 struct stat st;
397 uintmax_t pid;
398 FILE *fp;
399 int fd;
400 char *pidfile_path;
401 if (is_tempfile_active(pidfile))
403 /* already locked */
404 return NULL;
405 if (xgethostname(my_host, sizeof(my_host)))
407 xsnprintf(my_host, sizeof(my_host), "unknown");
408 pidfile_path = git_pathdup("gc.pid");
410 fd = hold_lock_file_for_update(&lock, pidfile_path,
411 LOCK_DIE_ON_ERROR);
412 if (!force) {
413 static char locking_host[HOST_NAME_MAX + 1];
414 static char *scan_fmt;
415 int should_exit;
416 if (!scan_fmt)
418 scan_fmt = xstrfmt("%s %%%ds", "%"SCNuMAX, HOST_NAME_MAX);
419 fp = fopen(pidfile_path, "r");
420 memset(locking_host, 0, sizeof(locking_host));
421 should_exit =
422 fp != NULL &&
423 !fstat(fileno(fp), &st) &&
424 /*
425 * 12 hour limit is very generous as gc should
426 * never take that long. On the other hand we
427 * don't really need a strict limit here,
428 * running gc --auto one day late is not a big
429 * problem. --force can be used in manual gc
430 * after the user verifies that no gc is
431 * running.
432 */
433 time(NULL) - st.st_mtime <= 12 * 3600 &&
434 fscanf(fp, scan_fmt, &pid, locking_host) == 2 &&
435 /* be gentle to concurrent "gc" on remote hosts */
436 (strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
437 if (fp != NULL)
438 fclose(fp);
439 if (should_exit) {
440 if (fd >= 0)
441 rollback_lock_file(&lock);
442 *ret_pid = pid;
443 free(pidfile_path);
444 return locking_host;
445 }
446 }
447 strbuf_addf(&sb, "%"PRIuMAX" %s",
449 (uintmax_t) getpid(), my_host);
450 write_in_full(fd, sb.buf, sb.len);
451 strbuf_release(&sb);
452 commit_lock_file(&lock);
453 pidfile = register_tempfile(pidfile_path);
454 free(pidfile_path);
455 return NULL;
456}
457/*
459 * Returns 0 if there was no previous error and gc can proceed, 1 if
460 * gc should not proceed due to an error in the last run. Prints a
461 * message and returns -1 if an error occured while reading gc.log
462 */
463static int report_last_gc_error(void)
464{
465 struct strbuf sb = STRBUF_INIT;
466 int ret = 0;
467 ssize_t len;
468 struct stat st;
469 char *gc_log_path = git_pathdup("gc.log");
470 if (stat(gc_log_path, &st)) {
472 if (errno == ENOENT)
473 goto done;
474 ret = error_errno(_("cannot stat '%s'"), gc_log_path);
476 goto done;
477 }
478 if (st.st_mtime < gc_log_expire_time)
480 goto done;
481 len = strbuf_read_file(&sb, gc_log_path, 0);
483 if (len < 0)
484 ret = error_errno(_("cannot read '%s'"), gc_log_path);
485 else if (len > 0) {
486 /*
487 * A previous gc failed. Report the error, and don't
488 * bother with an automatic gc run since it is likely
489 * to fail in the same way.
490 */
491 warning(_("The last gc run reported the following. "
492 "Please correct the root cause\n"
493 "and remove %s.\n"
494 "Automatic cleanup will not be performed "
495 "until the file is removed.\n\n"
496 "%s"),
497 gc_log_path, sb.buf);
498 ret = 1;
499 }
500 strbuf_release(&sb);
501done:
502 free(gc_log_path);
503 return ret;
504}
505static void gc_before_repack(void)
507{
508 /*
509 * We may be called twice, as both the pre- and
510 * post-daemonized phases will call us, but running these
511 * commands more than once is pointless and wasteful.
512 */
513 static int done = 0;
514 if (done++)
515 return;
516 if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
518 die(FAILED_RUN, pack_refs_cmd.argv[0]);
519 if (prune_reflogs && run_command_v_opt(reflog.argv, RUN_GIT_CMD))
521 die(FAILED_RUN, reflog.argv[0]);
522}
523int cmd_gc(int argc, const char **argv, const char *prefix)
525{
526 int aggressive = 0;
527 int auto_gc = 0;
528 int quiet = 0;
529 int force = 0;
530 const char *name;
531 pid_t pid;
532 int daemonized = 0;
533 int keep_base_pack = -1;
534 timestamp_t dummy;
535 struct option builtin_gc_options[] = {
537 OPT__QUIET(&quiet, N_("suppress progress reporting")),
538 { OPTION_STRING, 0, "prune", &prune_expire, N_("date"),
539 N_("prune unreferenced objects"),
540 PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
541 OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
542 OPT_BOOL_F(0, "auto", &auto_gc, N_("enable auto-gc mode"),
543 PARSE_OPT_NOCOMPLETE),
544 OPT_BOOL_F(0, "force", &force,
545 N_("force running gc even if there may be another gc running"),
546 PARSE_OPT_NOCOMPLETE),
547 OPT_BOOL(0, "keep-largest-pack", &keep_base_pack,
548 N_("repack all other packs except the largest pack")),
549 OPT_END()
550 };
551 if (argc == 2 && !strcmp(argv[1], "-h"))
553 usage_with_options(builtin_gc_usage, builtin_gc_options);
554 argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
556 argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
557 argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
558 argv_array_pushl(&prune, "prune", "--expire", NULL);
559 argv_array_pushl(&prune_worktrees, "worktree", "prune", "--expire", NULL);
560 argv_array_pushl(&rerere, "rerere", "gc", NULL);
561 /* default expiry time, overwritten in gc_config */
563 gc_config();
564 if (parse_expiry_date(gc_log_expire, &gc_log_expire_time))
565 die(_("failed to parse gc.logexpiry value %s"), gc_log_expire);
566 if (pack_refs < 0)
568 pack_refs = !is_bare_repository();
569 argc = parse_options(argc, argv, prefix, builtin_gc_options,
571 builtin_gc_usage, 0);
572 if (argc > 0)
573 usage_with_options(builtin_gc_usage, builtin_gc_options);
574 if (prune_expire && parse_expiry_date(prune_expire, &dummy))
576 die(_("failed to parse prune expiry value %s"), prune_expire);
577 if (aggressive) {
579 argv_array_push(&repack, "-f");
580 if (aggressive_depth > 0)
581 argv_array_pushf(&repack, "--depth=%d", aggressive_depth);
582 if (aggressive_window > 0)
583 argv_array_pushf(&repack, "--window=%d", aggressive_window);
584 }
585 if (quiet)
586 argv_array_push(&repack, "-q");
587 if (auto_gc) {
589 /*
590 * Auto-gc should be least intrusive as possible.
591 */
592 if (!need_to_gc())
593 return 0;
594 if (!quiet) {
595 if (detach_auto)
596 fprintf(stderr, _("Auto packing the repository in background for optimum performance.\n"));
597 else
598 fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
599 fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
600 }
601 if (detach_auto) {
602 int ret = report_last_gc_error();
603 if (ret < 0)
604 /* an I/O error occured, already reported */
605 exit(128);
606 if (ret == 1)
607 /* Last gc --auto failed. Skip this one. */
608 return 0;
609 if (lock_repo_for_gc(force, &pid))
611 return 0;
612 gc_before_repack(); /* dies on failure */
613 delete_tempfile(&pidfile);
614 /*
616 * failure to daemonize is ok, we'll continue
617 * in foreground
618 */
619 daemonized = !daemonize();
620 }
621 } else {
622 struct string_list keep_pack = STRING_LIST_INIT_NODUP;
623 if (keep_base_pack != -1) {
625 if (keep_base_pack)
626 find_base_packs(&keep_pack, 0);
627 } else if (big_pack_threshold) {
628 find_base_packs(&keep_pack, big_pack_threshold);
629 }
630 add_repack_all_option(&keep_pack);
632 string_list_clear(&keep_pack, 0);
633 }
634 name = lock_repo_for_gc(force, &pid);
636 if (name) {
637 if (auto_gc)
638 return 0; /* be quiet on --auto */
639 die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
640 name, (uintmax_t)pid);
641 }
642 if (daemonized) {
644 hold_lock_file_for_update(&log_lock,
645 git_path("gc.log"),
646 LOCK_DIE_ON_ERROR);
647 dup2(get_lock_file_fd(&log_lock), 2);
648 sigchain_push_common(process_log_file_on_signal);
649 atexit(process_log_file_at_exit);
650 }
651 gc_before_repack();
653 if (!repository_format_precious_objects) {
655 close_object_store(the_repository->objects);
656 if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
657 die(FAILED_RUN, repack.argv[0]);
658 if (prune_expire) {
660 argv_array_push(&prune, prune_expire);
661 if (quiet)
662 argv_array_push(&prune, "--no-progress");
663 if (has_promisor_remote())
664 argv_array_push(&prune,
665 "--exclude-promisor-objects");
666 if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
667 die(FAILED_RUN, prune.argv[0]);
668 }
669 }
670 if (prune_worktrees_expire) {
672 argv_array_push(&prune_worktrees, prune_worktrees_expire);
673 if (run_command_v_opt(prune_worktrees.argv, RUN_GIT_CMD))
674 die(FAILED_RUN, prune_worktrees.argv[0]);
675 }
676 if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
678 die(FAILED_RUN, rerere.argv[0]);
679 report_garbage = report_pack_garbage;
681 reprepare_packed_git(the_repository);
682 if (pack_garbage.nr > 0) {
683 close_object_store(the_repository->objects);
684 clean_pack_garbage();
685 }
686 prepare_repo_settings(the_repository);
688 if (the_repository->settings.gc_write_commit_graph == 1)
689 write_commit_graph_reachable(get_object_directory(),
690 !quiet && !daemonized ? COMMIT_GRAPH_WRITE_PROGRESS : 0,
691 NULL);
692 if (auto_gc && too_many_loose_objects())
694 warning(_("There are too many unreachable loose objects; "
695 "run 'git prune' to remove them."));
696 if (!daemonized)
698 unlink(git_path("gc.log"));
699 return 0;
701}