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