shallow.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "tag.h"
   4 #include "pkt-line.h"
   5 #include "remote.h"
   6 #include "refs.h"
   7 #include "sha1-array.h"
   8 #include "diff.h"
   9 #include "revision.h"
  10 #include "commit-slab.h"
  11
  12 static int is_shallow = -1;
  13 static struct stat shallow_stat;
  14 static char *alternate_shallow_file;
  15
  16 void set_alternate_shallow_file(const char *path)
  17 {
  18         if (is_shallow != -1)
  19                 die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
  20         free(alternate_shallow_file);
  21         alternate_shallow_file = path ? xstrdup(path) : NULL;
  22 }
  23
  24 int register_shallow(const unsigned char *sha1)
  25 {
  26         struct commit_graft *graft =
  27                 xmalloc(sizeof(struct commit_graft));
  28         struct commit *commit = lookup_commit(sha1);
  29
  30         hashcpy(graft->sha1, sha1);
  31         graft->nr_parent = -1;
  32         if (commit && commit->object.parsed)
  33                 commit->parents = NULL;
  34         return register_commit_graft(graft, 0);
  35 }
  36
  37 int is_repository_shallow(void)
  38 {
  39         FILE *fp;
  40         char buf[1024];
  41         const char *path = alternate_shallow_file;
  42
  43         if (is_shallow >= 0)
  44                 return is_shallow;
  45
  46         if (!path)
  47                 path = git_path("shallow");
  48         /*
  49          * fetch-pack sets '--shallow-file ""' as an indicator that no
  50          * shallow file should be used. We could just open it and it
  51          * will likely fail. But let's do an explicit check instead.
  52          */
  53         if (!*path ||
  54             stat(path, &shallow_stat) ||
  55             (fp = fopen(path, "r")) == NULL) {
  56                 is_shallow = 0;
  57                 return is_shallow;
  58         }
  59         is_shallow = 1;
  60
  61         while (fgets(buf, sizeof(buf), fp)) {
  62                 unsigned char sha1[20];
  63                 if (get_sha1_hex(buf, sha1))
  64                         die("bad shallow line: %s", buf);
  65                 register_shallow(sha1);
  66         }
  67         fclose(fp);
  68         return is_shallow;
  69 }
  70
  71 struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
  72                 int shallow_flag, int not_shallow_flag)
  73 {
  74         int i = 0, cur_depth = 0;
  75         struct commit_list *result = NULL;
  76         struct object_array stack = OBJECT_ARRAY_INIT;
  77         struct commit *commit = NULL;
  78         struct commit_graft *graft;
  79
  80         while (commit || i < heads->nr || stack.nr) {
  81                 struct commit_list *p;
  82                 if (!commit) {
  83                         if (i < heads->nr) {
  84                                 commit = (struct commit *)
  85                                         deref_tag(heads->objects[i++].item, NULL, 0);
  86                                 if (!commit || commit->object.type != OBJ_COMMIT) {
  87                                         commit = NULL;
  88                                         continue;
  89                                 }
  90                                 if (!commit->util)
  91                                         commit->util = xmalloc(sizeof(int));
  92                                 *(int *)commit->util = 0;
  93                                 cur_depth = 0;
  94                         } else {
  95                                 commit = (struct commit *)
  96                                         stack.objects[--stack.nr].item;
  97                                 cur_depth = *(int *)commit->util;
  98                         }
  99                 }
 100                 if (parse_commit(commit))
 101                         die("invalid commit");
 102                 cur_depth++;
 103                 if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
 104                     (is_repository_shallow() && !commit->parents &&
 105                      (graft = lookup_commit_graft(commit->object.sha1)) != NULL &&
 106                      graft->nr_parent < 0)) {
 107                         commit_list_insert(commit, &result);
 108                         commit->object.flags |= shallow_flag;
 109                         commit = NULL;
 110                         continue;
 111                 }
 112                 commit->object.flags |= not_shallow_flag;
 113                 for (p = commit->parents, commit = NULL; p; p = p->next) {
 114                         if (!p->item->util) {
 115                                 int *pointer = xmalloc(sizeof(int));
 116                                 p->item->util = pointer;
 117                                 *pointer =  cur_depth;
 118                         } else {
 119                                 int *pointer = p->item->util;
 120                                 if (cur_depth >= *pointer)
 121                                         continue;
 122                                 *pointer = cur_depth;
 123                         }
 124                         if (p->next)
 125                                 add_object_array(&p->item->object,
 126                                                 NULL, &stack);
 127                         else {
 128                                 commit = p->item;
 129                                 cur_depth = *(int *)commit->util;
 130                         }
 131                 }
 132         }
 133
 134         return result;
 135 }
 136
 137 void check_shallow_file_for_update(void)
 138 {
 139         struct stat st;
 140
 141         if (!is_shallow)
 142                 return;
 143         else if (is_shallow == -1)
 144                 die("BUG: shallow must be initialized by now");
 145
 146         if (stat(git_path("shallow"), &st))
 147                 die("shallow file was removed during fetch");
 148         else if (st.st_mtime != shallow_stat.st_mtime
 149 #ifdef USE_NSEC
 150                  || ST_MTIME_NSEC(st) != ST_MTIME_NSEC(shallow_stat)
 151 #endif
 152                    )
 153                 die("shallow file was changed during fetch");
 154 }
 155
 156 struct write_shallow_data {
 157         struct strbuf *out;
 158         int use_pack_protocol;
 159         int count;
 160 };
 161
 162 static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
 163 {
 164         struct write_shallow_data *data = cb_data;
 165         const char *hex = sha1_to_hex(graft->sha1);
 166         if (graft->nr_parent != -1)
 167                 return 0;
 168         data->count++;
 169         if (data->use_pack_protocol)
 170                 packet_buf_write(data->out, "shallow %s", hex);
 171         else {
 172                 strbuf_addstr(data->out, hex);
 173                 strbuf_addch(data->out, '\n');
 174         }
 175         return 0;
 176 }
 177
 178 int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
 179                           const struct sha1_array *extra)
 180 {
 181         struct write_shallow_data data;
 182         int i;
 183         data.out = out;
 184         data.use_pack_protocol = use_pack_protocol;
 185         data.count = 0;
 186         for_each_commit_graft(write_one_shallow, &data);
 187         if (!extra)
 188                 return data.count;
 189         for (i = 0; i < extra->nr; i++) {
 190                 strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
 191                 strbuf_addch(out, '\n');
 192                 data.count++;
 193         }
 194         return data.count;
 195 }
 196
 197 char *setup_temporary_shallow(const struct sha1_array *extra)
 198 {
 199         struct strbuf sb = STRBUF_INIT;
 200         int fd;
 201
 202         if (write_shallow_commits(&sb, 0, extra)) {
 203                 struct strbuf path = STRBUF_INIT;
 204                 strbuf_addstr(&path, git_path("shallow_XXXXXX"));
 205                 fd = xmkstemp(path.buf);
 206                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
 207                         die_errno("failed to write to %s",
 208                                   path.buf);
 209                 close(fd);
 210                 strbuf_release(&sb);
 211                 return strbuf_detach(&path, NULL);
 212         }
 213         /*
 214          * is_repository_shallow() sees empty string as "no shallow
 215          * file".
 216          */
 217         return xstrdup("");
 218 }
 219
 220 void setup_alternate_shallow(struct lock_file *shallow_lock,
 221                              const char **alternate_shallow_file,
 222                              const struct sha1_array *extra)
 223 {
 224         struct strbuf sb = STRBUF_INIT;
 225         int fd;
 226
 227         check_shallow_file_for_update();
 228         fd = hold_lock_file_for_update(shallow_lock, git_path("shallow"),
 229                                        LOCK_DIE_ON_ERROR);
 230         if (write_shallow_commits(&sb, 0, extra)) {
 231                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
 232                         die_errno("failed to write to %s",
 233                                   shallow_lock->filename);
 234                 *alternate_shallow_file = shallow_lock->filename;
 235         } else
 236                 /*
 237                  * is_repository_shallow() sees empty string as "no
 238                  * shallow file".
 239                  */
 240                 *alternate_shallow_file = "";
 241         strbuf_release(&sb);
 242 }
 243
 244 static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
 245 {
 246         int fd = *(int *)cb;
 247         if (graft->nr_parent == -1)
 248                 packet_write(fd, "shallow %s\n", sha1_to_hex(graft->sha1));
 249         return 0;
 250 }
 251
 252 void advertise_shallow_grafts(int fd)
 253 {
 254         if (!is_repository_shallow())
 255                 return;
 256         for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
 257 }
 258
 259 #define TRACE_KEY "GIT_TRACE_SHALLOW"
 260
 261 /*
 262  * Step 1, split sender shallow commits into "ours" and "theirs"
 263  * Step 2, clean "ours" based on .git/shallow
 264  */
 265 void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
 266 {
 267         int i;
 268         trace_printf_key(TRACE_KEY, "shallow: prepare_shallow_info\n");
 269         memset(info, 0, sizeof(*info));
 270         info->shallow = sa;
 271         if (!sa)
 272                 return;
 273         info->ours = xmalloc(sizeof(*info->ours) * sa->nr);
 274         info->theirs = xmalloc(sizeof(*info->theirs) * sa->nr);
 275         for (i = 0; i < sa->nr; i++) {
 276                 if (has_sha1_file(sa->sha1[i])) {
 277                         struct commit_graft *graft;
 278                         graft = lookup_commit_graft(sa->sha1[i]);
 279                         if (graft && graft->nr_parent < 0)
 280                                 continue;
 281                         info->ours[info->nr_ours++] = i;
 282                 } else
 283                         info->theirs[info->nr_theirs++] = i;
 284         }
 285 }
 286
 287 void clear_shallow_info(struct shallow_info *info)
 288 {
 289         free(info->ours);
 290         free(info->theirs);
 291 }
 292
 293 /* Step 4, remove non-existent ones in "theirs" after getting the pack */
 294
 295 void remove_nonexistent_theirs_shallow(struct shallow_info *info)
 296 {
 297         unsigned char (*sha1)[20] = info->shallow->sha1;
 298         int i, dst;
 299         trace_printf_key(TRACE_KEY, "shallow: remove_nonexistent_theirs_shallow\n");
 300         for (i = dst = 0; i < info->nr_theirs; i++) {
 301                 if (i != dst)
 302                         info->theirs[dst] = info->theirs[i];
 303                 if (has_sha1_file(sha1[info->theirs[i]]))
 304                         dst++;
 305         }
 306         info->nr_theirs = dst;
 307 }
 308
 309 /* Step 5, remove non-existent ones in "ours" in the pack */
 310 void remove_nonexistent_ours_in_pack(struct shallow_info *info,
 311                                      struct packed_git *p)
 312 {
 313         unsigned char (*sha1)[20] = info->shallow->sha1;
 314         int i, dst;
 315         trace_printf_key(TRACE_KEY, "shallow: remove_nonexistent_ours_in_pack\n");
 316         for (i = dst = 0; i < info->nr_ours; i++) {
 317                 if (i != dst)
 318                         info->ours[dst] = info->ours[i];
 319                 if (find_pack_entry_one(sha1[info->ours[i]], p))
 320                         dst++;
 321         }
 322         info->nr_ours = dst;
 323 }
 324
 325 define_commit_slab(ref_bitmap, uint32_t *);
 326
 327 struct paint_info {
 328         struct ref_bitmap ref_bitmap;
 329         unsigned nr_bits;
 330         char **slab;
 331         char *free, *end;
 332         unsigned slab_count;
 333 };
 334
 335 static uint32_t *paint_alloc(struct paint_info *info)
 336 {
 337         unsigned nr = (info->nr_bits + 31) / 32;
 338         unsigned size = nr * sizeof(uint32_t);
 339         void *p;
 340         if (!info->slab_count || info->free + size > info->end) {
 341                 info->slab_count++;
 342                 info->slab = xrealloc(info->slab,
 343                                       info->slab_count * sizeof(*info->slab));
 344                 info->free = xmalloc(COMMIT_SLAB_SIZE);
 345                 info->slab[info->slab_count - 1] = info->free;
 346                 info->end = info->free + COMMIT_SLAB_SIZE;
 347         }
 348         p = info->free;
 349         info->free += size;
 350         return p;
 351 }
 352
 353 /*
 354  * Given a commit SHA-1, walk down to parents until either SEEN,
 355  * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
 356  * all walked commits.
 357  */
 358 static void paint_down(struct paint_info *info, const unsigned char *sha1,
 359                        int id)
 360 {
 361         unsigned int i, nr;
 362         struct commit_list *head = NULL;
 363         int bitmap_nr = (info->nr_bits + 31) / 32;
 364         int bitmap_size = bitmap_nr * sizeof(uint32_t);
 365         uint32_t *tmp = xmalloc(bitmap_size); /* to be freed before return */
 366         uint32_t *bitmap = paint_alloc(info);
 367         struct commit *c = lookup_commit_reference_gently(sha1, 1);
 368         if (!c)
 369                 return;
 370         memset(bitmap, 0, bitmap_size);
 371         bitmap[id / 32] |= (1 << (id % 32));
 372         commit_list_insert(c, &head);
 373         while (head) {
 374                 struct commit_list *p;
 375                 struct commit *c = head->item;
 376                 uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);
 377
 378                 p = head;
 379                 head = head->next;
 380                 free(p);
 381
 382                 /* XXX check "UNINTERESTING" from pack bitmaps if available */
 383                 if (c->object.flags & (SEEN | UNINTERESTING))
 384                         continue;
 385                 else
 386                         c->object.flags |= SEEN;
 387
 388                 if (*refs == NULL)
 389                         *refs = bitmap;
 390                 else {
 391                         memcpy(tmp, *refs, bitmap_size);
 392                         for (i = 0; i < bitmap_nr; i++)
 393                                 tmp[i] |= bitmap[i];
 394                         if (memcmp(tmp, *refs, bitmap_size)) {
 395                                 *refs = paint_alloc(info);
 396                                 memcpy(*refs, tmp, bitmap_size);
 397                         }
 398                 }
 399
 400                 if (c->object.flags & BOTTOM)
 401                         continue;
 402
 403                 if (parse_commit(c))
 404                         die("unable to parse commit %s",
 405                             sha1_to_hex(c->object.sha1));
 406
 407                 for (p = c->parents; p; p = p->next) {
 408                         uint32_t **p_refs = ref_bitmap_at(&info->ref_bitmap,
 409                                                           p->item);
 410                         if (p->item->object.flags & SEEN)
 411                                 continue;
 412                         if (*p_refs == NULL || *p_refs == *refs)
 413                                 *p_refs = *refs;
 414                         commit_list_insert(p->item, &head);
 415                 }
 416         }
 417
 418         nr = get_max_object_index();
 419         for (i = 0; i < nr; i++) {
 420                 struct object *o = get_indexed_object(i);
 421                 if (o && o->type == OBJ_COMMIT)
 422                         o->flags &= ~SEEN;
 423         }
 424
 425         free(tmp);
 426 }
 427
 428 static int mark_uninteresting(const char *refname,
 429                               const unsigned char *sha1,
 430                               int flags, void *cb_data)
 431 {
 432         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
 433         if (!commit)
 434                 return 0;
 435         commit->object.flags |= UNINTERESTING;
 436         mark_parents_uninteresting(commit);
 437         return 0;
 438 }
 439
 440 static void post_assign_shallow(struct shallow_info *info,
 441                                 struct ref_bitmap *ref_bitmap,
 442                                 int *ref_status);
 443 /*
 444  * Step 6(+7), associate shallow commits with new refs
 445  *
 446  * info->ref must be initialized before calling this function.
 447  *
 448  * If used is not NULL, it's an array of info->shallow->nr
 449  * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
 450  * m-th shallow commit from info->shallow.
 451  *
 452  * If used is NULL, "ours" and "theirs" are updated. And if ref_status
 453  * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
 454  * the ref needs some shallow commits from either info->ours or
 455  * info->theirs.
 456  */
 457 void assign_shallow_commits_to_refs(struct shallow_info *info,
 458                                     uint32_t **used, int *ref_status)
 459 {
 460         unsigned char (*sha1)[20] = info->shallow->sha1;
 461         struct sha1_array *ref = info->ref;
 462         unsigned int i, nr;
 463         int *shallow, nr_shallow = 0;
 464         struct paint_info pi;
 465
 466         trace_printf_key(TRACE_KEY, "shallow: assign_shallow_commits_to_refs\n");
 467         shallow = xmalloc(sizeof(*shallow) * (info->nr_ours + info->nr_theirs));
 468         for (i = 0; i < info->nr_ours; i++)
 469                 shallow[nr_shallow++] = info->ours[i];
 470         for (i = 0; i < info->nr_theirs; i++)
 471                 shallow[nr_shallow++] = info->theirs[i];
 472
 473         /*
 474          * Prepare the commit graph to track what refs can reach what
 475          * (new) shallow commits.
 476          */
 477         nr = get_max_object_index();
 478         for (i = 0; i < nr; i++) {
 479                 struct object *o = get_indexed_object(i);
 480                 if (!o || o->type != OBJ_COMMIT)
 481                         continue;
 482
 483                 o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
 484         }
 485
 486         memset(&pi, 0, sizeof(pi));
 487         init_ref_bitmap(&pi.ref_bitmap);
 488         pi.nr_bits = ref->nr;
 489
 490         /*
 491          * "--not --all" to cut short the traversal if new refs
 492          * connect to old refs. If not (e.g. force ref updates) it'll
 493          * have to go down to the current shallow commits.
 494          */
 495         head_ref(mark_uninteresting, NULL);
 496         for_each_ref(mark_uninteresting, NULL);
 497
 498         /* Mark potential bottoms so we won't go out of bound */
 499         for (i = 0; i < nr_shallow; i++) {
 500                 struct commit *c = lookup_commit(sha1[shallow[i]]);
 501                 c->object.flags |= BOTTOM;
 502         }
 503
 504         for (i = 0; i < ref->nr; i++)
 505                 paint_down(&pi, ref->sha1[i], i);
 506
 507         if (used) {
 508                 int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
 509                 memset(used, 0, sizeof(*used) * info->shallow->nr);
 510                 for (i = 0; i < nr_shallow; i++) {
 511                         const struct commit *c = lookup_commit(sha1[shallow[i]]);
 512                         uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
 513                         if (*map)
 514                                 used[shallow[i]] = xmemdupz(*map, bitmap_size);
 515                 }
 516                 /*
 517                  * unreachable shallow commits are not removed from
 518                  * "ours" and "theirs". The user is supposed to run
 519                  * step 7 on every ref separately and not trust "ours"
 520                  * and "theirs" any more.
 521                  */
 522         } else
 523                 post_assign_shallow(info, &pi.ref_bitmap, ref_status);
 524
 525         clear_ref_bitmap(&pi.ref_bitmap);
 526         for (i = 0; i < pi.slab_count; i++)
 527                 free(pi.slab[i]);
 528         free(pi.slab);
 529         free(shallow);
 530 }
 531
 532 struct commit_array {
 533         struct commit **commits;
 534         int nr, alloc;
 535 };
 536
 537 static int add_ref(const char *refname,
 538                    const unsigned char *sha1, int flags, void *cb_data)
 539 {
 540         struct commit_array *ca = cb_data;
 541         ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
 542         ca->commits[ca->nr] = lookup_commit_reference_gently(sha1, 1);
 543         if (ca->commits[ca->nr])
 544                 ca->nr++;
 545         return 0;
 546 }
 547
 548 static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
 549 {
 550         int i;
 551         if (!ref_status)
 552                 return;
 553         for (i = 0; i < nr; i++)
 554                 if (bitmap[i / 32] & (1 << (i % 32)))
 555                         ref_status[i]++;
 556 }
 557
 558 /*
 559  * Step 7, reachability test on "ours" at commit level
 560  */
 561 static void post_assign_shallow(struct shallow_info *info,
 562                                 struct ref_bitmap *ref_bitmap,
 563                                 int *ref_status)
 564 {
 565         unsigned char (*sha1)[20] = info->shallow->sha1;
 566         struct commit *c;
 567         uint32_t **bitmap;
 568         int dst, i, j;
 569         int bitmap_nr = (info->ref->nr + 31) / 32;
 570         struct commit_array ca;
 571
 572         trace_printf_key(TRACE_KEY, "shallow: post_assign_shallow\n");
 573         if (ref_status)
 574                 memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);
 575
 576         /* Remove unreachable shallow commits from "theirs" */
 577         for (i = dst = 0; i < info->nr_theirs; i++) {
 578                 if (i != dst)
 579                         info->theirs[dst] = info->theirs[i];
 580                 c = lookup_commit(sha1[info->theirs[i]]);
 581                 bitmap = ref_bitmap_at(ref_bitmap, c);
 582                 if (!*bitmap)
 583                         continue;
 584                 for (j = 0; j < bitmap_nr; j++)
 585                         if (bitmap[0][j]) {
 586                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
 587                                 dst++;
 588                                 break;
 589                         }
 590         }
 591         info->nr_theirs = dst;
 592
 593         memset(&ca, 0, sizeof(ca));
 594         head_ref(add_ref, &ca);
 595         for_each_ref(add_ref, &ca);
 596
 597         /* Remove unreachable shallow commits from "ours" */
 598         for (i = dst = 0; i < info->nr_ours; i++) {
 599                 if (i != dst)
 600                         info->ours[dst] = info->ours[i];
 601                 c = lookup_commit(sha1[info->ours[i]]);
 602                 bitmap = ref_bitmap_at(ref_bitmap, c);
 603                 if (!*bitmap)
 604                         continue;
 605                 for (j = 0; j < bitmap_nr; j++)
 606                         if (bitmap[0][j] &&
 607                             /* Step 7, reachability test at commit level */
 608                             !in_merge_bases_many(c, ca.nr, ca.commits)) {
 609                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
 610                                 dst++;
 611                                 break;
 612                         }
 613         }
 614         info->nr_ours = dst;
 615
 616         free(ca.commits);
 617 }