shallow.con commit Merge git://ozlabs.org/~paulus/gitk (482456a)
   1#include "cache.h"
   2#include "tempfile.h"
   3#include "lockfile.h"
   4#include "commit.h"
   5#include "tag.h"
   6#include "pkt-line.h"
   7#include "remote.h"
   8#include "refs.h"
   9#include "sha1-array.h"
  10#include "diff.h"
  11#include "revision.h"
  12#include "commit-slab.h"
  13
  14static int is_shallow = -1;
  15static struct stat_validity shallow_stat;
  16static char *alternate_shallow_file;
  17
  18void set_alternate_shallow_file(const char *path, int override)
  19{
  20        if (is_shallow != -1)
  21                die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
  22        if (alternate_shallow_file && !override)
  23                return;
  24        free(alternate_shallow_file);
  25        alternate_shallow_file = xstrdup_or_null(path);
  26}
  27
  28int register_shallow(const unsigned char *sha1)
  29{
  30        struct commit_graft *graft =
  31                xmalloc(sizeof(struct commit_graft));
  32        struct commit *commit = lookup_commit(sha1);
  33
  34        hashcpy(graft->oid.hash, sha1);
  35        graft->nr_parent = -1;
  36        if (commit && commit->object.parsed)
  37                commit->parents = NULL;
  38        return register_commit_graft(graft, 0);
  39}
  40
  41int is_repository_shallow(void)
  42{
  43        FILE *fp;
  44        char buf[1024];
  45        const char *path = alternate_shallow_file;
  46
  47        if (is_shallow >= 0)
  48                return is_shallow;
  49
  50        if (!path)
  51                path = git_path_shallow();
  52        /*
  53         * fetch-pack sets '--shallow-file ""' as an indicator that no
  54         * shallow file should be used. We could just open it and it
  55         * will likely fail. But let's do an explicit check instead.
  56         */
  57        if (!*path || (fp = fopen(path, "r")) == NULL) {
  58                stat_validity_clear(&shallow_stat);
  59                is_shallow = 0;
  60                return is_shallow;
  61        }
  62        stat_validity_update(&shallow_stat, fileno(fp));
  63        is_shallow = 1;
  64
  65        while (fgets(buf, sizeof(buf), fp)) {
  66                unsigned char sha1[20];
  67                if (get_sha1_hex(buf, sha1))
  68                        die("bad shallow line: %s", buf);
  69                register_shallow(sha1);
  70        }
  71        fclose(fp);
  72        return is_shallow;
  73}
  74
  75struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
  76                int shallow_flag, int not_shallow_flag)
  77{
  78        int i = 0, cur_depth = 0;
  79        struct commit_list *result = NULL;
  80        struct object_array stack = OBJECT_ARRAY_INIT;
  81        struct commit *commit = NULL;
  82        struct commit_graft *graft;
  83
  84        while (commit || i < heads->nr || stack.nr) {
  85                struct commit_list *p;
  86                if (!commit) {
  87                        if (i < heads->nr) {
  88                                commit = (struct commit *)
  89                                        deref_tag(heads->objects[i++].item, NULL, 0);
  90                                if (!commit || commit->object.type != OBJ_COMMIT) {
  91                                        commit = NULL;
  92                                        continue;
  93                                }
  94                                if (!commit->util)
  95                                        commit->util = xmalloc(sizeof(int));
  96                                *(int *)commit->util = 0;
  97                                cur_depth = 0;
  98                        } else {
  99                                commit = (struct commit *)
 100                                        stack.objects[--stack.nr].item;
 101                                cur_depth = *(int *)commit->util;
 102                        }
 103                }
 104                parse_commit_or_die(commit);
 105                cur_depth++;
 106                if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
 107                    (is_repository_shallow() && !commit->parents &&
 108                     (graft = lookup_commit_graft(commit->object.sha1)) != NULL &&
 109                     graft->nr_parent < 0)) {
 110                        commit_list_insert(commit, &result);
 111                        commit->object.flags |= shallow_flag;
 112                        commit = NULL;
 113                        continue;
 114                }
 115                commit->object.flags |= not_shallow_flag;
 116                for (p = commit->parents, commit = NULL; p; p = p->next) {
 117                        if (!p->item->util) {
 118                                int *pointer = xmalloc(sizeof(int));
 119                                p->item->util = pointer;
 120                                *pointer =  cur_depth;
 121                        } else {
 122                                int *pointer = p->item->util;
 123                                if (cur_depth >= *pointer)
 124                                        continue;
 125                                *pointer = cur_depth;
 126                        }
 127                        if (p->next)
 128                                add_object_array(&p->item->object,
 129                                                NULL, &stack);
 130                        else {
 131                                commit = p->item;
 132                                cur_depth = *(int *)commit->util;
 133                        }
 134                }
 135        }
 136
 137        return result;
 138}
 139
 140static void check_shallow_file_for_update(void)
 141{
 142        if (is_shallow == -1)
 143                die("BUG: shallow must be initialized by now");
 144
 145        if (!stat_validity_check(&shallow_stat, git_path_shallow()))
 146                die("shallow file has changed since we read it");
 147}
 148
 149#define SEEN_ONLY 1
 150#define VERBOSE   2
 151
 152struct write_shallow_data {
 153        struct strbuf *out;
 154        int use_pack_protocol;
 155        int count;
 156        unsigned flags;
 157};
 158
 159static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
 160{
 161        struct write_shallow_data *data = cb_data;
 162        const char *hex = oid_to_hex(&graft->oid);
 163        if (graft->nr_parent != -1)
 164                return 0;
 165        if (data->flags & SEEN_ONLY) {
 166                struct commit *c = lookup_commit(graft->oid.hash);
 167                if (!c || !(c->object.flags & SEEN)) {
 168                        if (data->flags & VERBOSE)
 169                                printf("Removing %s from .git/shallow\n",
 170                                       sha1_to_hex(c->object.sha1));
 171                        return 0;
 172                }
 173        }
 174        data->count++;
 175        if (data->use_pack_protocol)
 176                packet_buf_write(data->out, "shallow %s", hex);
 177        else {
 178                strbuf_addstr(data->out, hex);
 179                strbuf_addch(data->out, '\n');
 180        }
 181        return 0;
 182}
 183
 184static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
 185                                   const struct sha1_array *extra,
 186                                   unsigned flags)
 187{
 188        struct write_shallow_data data;
 189        int i;
 190        data.out = out;
 191        data.use_pack_protocol = use_pack_protocol;
 192        data.count = 0;
 193        data.flags = flags;
 194        for_each_commit_graft(write_one_shallow, &data);
 195        if (!extra)
 196                return data.count;
 197        for (i = 0; i < extra->nr; i++) {
 198                strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
 199                strbuf_addch(out, '\n');
 200                data.count++;
 201        }
 202        return data.count;
 203}
 204
 205int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
 206                          const struct sha1_array *extra)
 207{
 208        return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
 209}
 210
 211static struct tempfile temporary_shallow;
 212
 213const char *setup_temporary_shallow(const struct sha1_array *extra)
 214{
 215        struct strbuf sb = STRBUF_INIT;
 216        int fd;
 217
 218        if (write_shallow_commits(&sb, 0, extra)) {
 219                fd = xmks_tempfile(&temporary_shallow, git_path("shallow_XXXXXX"));
 220
 221                if (write_in_full(fd, sb.buf, sb.len) != sb.len)
 222                        die_errno("failed to write to %s",
 223                                  get_tempfile_path(&temporary_shallow));
 224                close_tempfile(&temporary_shallow);
 225                strbuf_release(&sb);
 226                return get_tempfile_path(&temporary_shallow);
 227        }
 228        /*
 229         * is_repository_shallow() sees empty string as "no shallow
 230         * file".
 231         */
 232        return get_tempfile_path(&temporary_shallow);
 233}
 234
 235void setup_alternate_shallow(struct lock_file *shallow_lock,
 236                             const char **alternate_shallow_file,
 237                             const struct sha1_array *extra)
 238{
 239        struct strbuf sb = STRBUF_INIT;
 240        int fd;
 241
 242        fd = hold_lock_file_for_update(shallow_lock, git_path_shallow(),
 243                                       LOCK_DIE_ON_ERROR);
 244        check_shallow_file_for_update();
 245        if (write_shallow_commits(&sb, 0, extra)) {
 246                if (write_in_full(fd, sb.buf, sb.len) != sb.len)
 247                        die_errno("failed to write to %s",
 248                                  get_lock_file_path(shallow_lock));
 249                *alternate_shallow_file = get_lock_file_path(shallow_lock);
 250        } else
 251                /*
 252                 * is_repository_shallow() sees empty string as "no
 253                 * shallow file".
 254                 */
 255                *alternate_shallow_file = "";
 256        strbuf_release(&sb);
 257}
 258
 259static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
 260{
 261        int fd = *(int *)cb;
 262        if (graft->nr_parent == -1)
 263                packet_write(fd, "shallow %s\n", oid_to_hex(&graft->oid));
 264        return 0;
 265}
 266
 267void advertise_shallow_grafts(int fd)
 268{
 269        if (!is_repository_shallow())
 270                return;
 271        for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
 272}
 273
 274/*
 275 * mark_reachable_objects() should have been run prior to this and all
 276 * reachable commits marked as "SEEN".
 277 */
 278void prune_shallow(int show_only)
 279{
 280        static struct lock_file shallow_lock;
 281        struct strbuf sb = STRBUF_INIT;
 282        int fd;
 283
 284        if (show_only) {
 285                write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY | VERBOSE);
 286                strbuf_release(&sb);
 287                return;
 288        }
 289        fd = hold_lock_file_for_update(&shallow_lock, git_path_shallow(),
 290                                       LOCK_DIE_ON_ERROR);
 291        check_shallow_file_for_update();
 292        if (write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY)) {
 293                if (write_in_full(fd, sb.buf, sb.len) != sb.len)
 294                        die_errno("failed to write to %s",
 295                                  get_lock_file_path(&shallow_lock));
 296                commit_lock_file(&shallow_lock);
 297        } else {
 298                unlink(git_path_shallow());
 299                rollback_lock_file(&shallow_lock);
 300        }
 301        strbuf_release(&sb);
 302}
 303
 304struct trace_key trace_shallow = TRACE_KEY_INIT(SHALLOW);
 305
 306/*
 307 * Step 1, split sender shallow commits into "ours" and "theirs"
 308 * Step 2, clean "ours" based on .git/shallow
 309 */
 310void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
 311{
 312        int i;
 313        trace_printf_key(&trace_shallow, "shallow: prepare_shallow_info\n");
 314        memset(info, 0, sizeof(*info));
 315        info->shallow = sa;
 316        if (!sa)
 317                return;
 318        info->ours = xmalloc(sizeof(*info->ours) * sa->nr);
 319        info->theirs = xmalloc(sizeof(*info->theirs) * sa->nr);
 320        for (i = 0; i < sa->nr; i++) {
 321                if (has_sha1_file(sa->sha1[i])) {
 322                        struct commit_graft *graft;
 323                        graft = lookup_commit_graft(sa->sha1[i]);
 324                        if (graft && graft->nr_parent < 0)
 325                                continue;
 326                        info->ours[info->nr_ours++] = i;
 327                } else
 328                        info->theirs[info->nr_theirs++] = i;
 329        }
 330}
 331
 332void clear_shallow_info(struct shallow_info *info)
 333{
 334        free(info->ours);
 335        free(info->theirs);
 336}
 337
 338/* Step 4, remove non-existent ones in "theirs" after getting the pack */
 339
 340void remove_nonexistent_theirs_shallow(struct shallow_info *info)
 341{
 342        unsigned char (*sha1)[20] = info->shallow->sha1;
 343        int i, dst;
 344        trace_printf_key(&trace_shallow, "shallow: remove_nonexistent_theirs_shallow\n");
 345        for (i = dst = 0; i < info->nr_theirs; i++) {
 346                if (i != dst)
 347                        info->theirs[dst] = info->theirs[i];
 348                if (has_sha1_file(sha1[info->theirs[i]]))
 349                        dst++;
 350        }
 351        info->nr_theirs = dst;
 352}
 353
 354define_commit_slab(ref_bitmap, uint32_t *);
 355
 356struct paint_info {
 357        struct ref_bitmap ref_bitmap;
 358        unsigned nr_bits;
 359        char **slab;
 360        char *free, *end;
 361        unsigned slab_count;
 362};
 363
 364static uint32_t *paint_alloc(struct paint_info *info)
 365{
 366        unsigned nr = (info->nr_bits + 31) / 32;
 367        unsigned size = nr * sizeof(uint32_t);
 368        void *p;
 369        if (!info->slab_count || info->free + size > info->end) {
 370                info->slab_count++;
 371                REALLOC_ARRAY(info->slab, info->slab_count);
 372                info->free = xmalloc(COMMIT_SLAB_SIZE);
 373                info->slab[info->slab_count - 1] = info->free;
 374                info->end = info->free + COMMIT_SLAB_SIZE;
 375        }
 376        p = info->free;
 377        info->free += size;
 378        return p;
 379}
 380
 381/*
 382 * Given a commit SHA-1, walk down to parents until either SEEN,
 383 * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
 384 * all walked commits.
 385 */
 386static void paint_down(struct paint_info *info, const unsigned char *sha1,
 387                       int id)
 388{
 389        unsigned int i, nr;
 390        struct commit_list *head = NULL;
 391        int bitmap_nr = (info->nr_bits + 31) / 32;
 392        int bitmap_size = bitmap_nr * sizeof(uint32_t);
 393        uint32_t *tmp = xmalloc(bitmap_size); /* to be freed before return */
 394        uint32_t *bitmap = paint_alloc(info);
 395        struct commit *c = lookup_commit_reference_gently(sha1, 1);
 396        if (!c)
 397                return;
 398        memset(bitmap, 0, bitmap_size);
 399        bitmap[id / 32] |= (1 << (id % 32));
 400        commit_list_insert(c, &head);
 401        while (head) {
 402                struct commit_list *p;
 403                struct commit *c = head->item;
 404                uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);
 405
 406                p = head;
 407                head = head->next;
 408                free(p);
 409
 410                /* XXX check "UNINTERESTING" from pack bitmaps if available */
 411                if (c->object.flags & (SEEN | UNINTERESTING))
 412                        continue;
 413                else
 414                        c->object.flags |= SEEN;
 415
 416                if (*refs == NULL)
 417                        *refs = bitmap;
 418                else {
 419                        memcpy(tmp, *refs, bitmap_size);
 420                        for (i = 0; i < bitmap_nr; i++)
 421                                tmp[i] |= bitmap[i];
 422                        if (memcmp(tmp, *refs, bitmap_size)) {
 423                                *refs = paint_alloc(info);
 424                                memcpy(*refs, tmp, bitmap_size);
 425                        }
 426                }
 427
 428                if (c->object.flags & BOTTOM)
 429                        continue;
 430
 431                if (parse_commit(c))
 432                        die("unable to parse commit %s",
 433                            sha1_to_hex(c->object.sha1));
 434
 435                for (p = c->parents; p; p = p->next) {
 436                        uint32_t **p_refs = ref_bitmap_at(&info->ref_bitmap,
 437                                                          p->item);
 438                        if (p->item->object.flags & SEEN)
 439                                continue;
 440                        if (*p_refs == NULL || *p_refs == *refs)
 441                                *p_refs = *refs;
 442                        commit_list_insert(p->item, &head);
 443                }
 444        }
 445
 446        nr = get_max_object_index();
 447        for (i = 0; i < nr; i++) {
 448                struct object *o = get_indexed_object(i);
 449                if (o && o->type == OBJ_COMMIT)
 450                        o->flags &= ~SEEN;
 451        }
 452
 453        free(tmp);
 454}
 455
 456static int mark_uninteresting(const char *refname, const struct object_id *oid,
 457                              int flags, void *cb_data)
 458{
 459        struct commit *commit = lookup_commit_reference_gently(oid->hash, 1);
 460        if (!commit)
 461                return 0;
 462        commit->object.flags |= UNINTERESTING;
 463        mark_parents_uninteresting(commit);
 464        return 0;
 465}
 466
 467static void post_assign_shallow(struct shallow_info *info,
 468                                struct ref_bitmap *ref_bitmap,
 469                                int *ref_status);
 470/*
 471 * Step 6(+7), associate shallow commits with new refs
 472 *
 473 * info->ref must be initialized before calling this function.
 474 *
 475 * If used is not NULL, it's an array of info->shallow->nr
 476 * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
 477 * m-th shallow commit from info->shallow.
 478 *
 479 * If used is NULL, "ours" and "theirs" are updated. And if ref_status
 480 * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
 481 * the ref needs some shallow commits from either info->ours or
 482 * info->theirs.
 483 */
 484void assign_shallow_commits_to_refs(struct shallow_info *info,
 485                                    uint32_t **used, int *ref_status)
 486{
 487        unsigned char (*sha1)[20] = info->shallow->sha1;
 488        struct sha1_array *ref = info->ref;
 489        unsigned int i, nr;
 490        int *shallow, nr_shallow = 0;
 491        struct paint_info pi;
 492
 493        trace_printf_key(&trace_shallow, "shallow: assign_shallow_commits_to_refs\n");
 494        shallow = xmalloc(sizeof(*shallow) * (info->nr_ours + info->nr_theirs));
 495        for (i = 0; i < info->nr_ours; i++)
 496                shallow[nr_shallow++] = info->ours[i];
 497        for (i = 0; i < info->nr_theirs; i++)
 498                shallow[nr_shallow++] = info->theirs[i];
 499
 500        /*
 501         * Prepare the commit graph to track what refs can reach what
 502         * (new) shallow commits.
 503         */
 504        nr = get_max_object_index();
 505        for (i = 0; i < nr; i++) {
 506                struct object *o = get_indexed_object(i);
 507                if (!o || o->type != OBJ_COMMIT)
 508                        continue;
 509
 510                o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
 511        }
 512
 513        memset(&pi, 0, sizeof(pi));
 514        init_ref_bitmap(&pi.ref_bitmap);
 515        pi.nr_bits = ref->nr;
 516
 517        /*
 518         * "--not --all" to cut short the traversal if new refs
 519         * connect to old refs. If not (e.g. force ref updates) it'll
 520         * have to go down to the current shallow commits.
 521         */
 522        head_ref(mark_uninteresting, NULL);
 523        for_each_ref(mark_uninteresting, NULL);
 524
 525        /* Mark potential bottoms so we won't go out of bound */
 526        for (i = 0; i < nr_shallow; i++) {
 527                struct commit *c = lookup_commit(sha1[shallow[i]]);
 528                c->object.flags |= BOTTOM;
 529        }
 530
 531        for (i = 0; i < ref->nr; i++)
 532                paint_down(&pi, ref->sha1[i], i);
 533
 534        if (used) {
 535                int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
 536                memset(used, 0, sizeof(*used) * info->shallow->nr);
 537                for (i = 0; i < nr_shallow; i++) {
 538                        const struct commit *c = lookup_commit(sha1[shallow[i]]);
 539                        uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
 540                        if (*map)
 541                                used[shallow[i]] = xmemdupz(*map, bitmap_size);
 542                }
 543                /*
 544                 * unreachable shallow commits are not removed from
 545                 * "ours" and "theirs". The user is supposed to run
 546                 * step 7 on every ref separately and not trust "ours"
 547                 * and "theirs" any more.
 548                 */
 549        } else
 550                post_assign_shallow(info, &pi.ref_bitmap, ref_status);
 551
 552        clear_ref_bitmap(&pi.ref_bitmap);
 553        for (i = 0; i < pi.slab_count; i++)
 554                free(pi.slab[i]);
 555        free(pi.slab);
 556        free(shallow);
 557}
 558
 559struct commit_array {
 560        struct commit **commits;
 561        int nr, alloc;
 562};
 563
 564static int add_ref(const char *refname, const struct object_id *oid,
 565                   int flags, void *cb_data)
 566{
 567        struct commit_array *ca = cb_data;
 568        ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
 569        ca->commits[ca->nr] = lookup_commit_reference_gently(oid->hash, 1);
 570        if (ca->commits[ca->nr])
 571                ca->nr++;
 572        return 0;
 573}
 574
 575static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
 576{
 577        int i;
 578        if (!ref_status)
 579                return;
 580        for (i = 0; i < nr; i++)
 581                if (bitmap[i / 32] & (1 << (i % 32)))
 582                        ref_status[i]++;
 583}
 584
 585/*
 586 * Step 7, reachability test on "ours" at commit level
 587 */
 588static void post_assign_shallow(struct shallow_info *info,
 589                                struct ref_bitmap *ref_bitmap,
 590                                int *ref_status)
 591{
 592        unsigned char (*sha1)[20] = info->shallow->sha1;
 593        struct commit *c;
 594        uint32_t **bitmap;
 595        int dst, i, j;
 596        int bitmap_nr = (info->ref->nr + 31) / 32;
 597        struct commit_array ca;
 598
 599        trace_printf_key(&trace_shallow, "shallow: post_assign_shallow\n");
 600        if (ref_status)
 601                memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);
 602
 603        /* Remove unreachable shallow commits from "theirs" */
 604        for (i = dst = 0; i < info->nr_theirs; i++) {
 605                if (i != dst)
 606                        info->theirs[dst] = info->theirs[i];
 607                c = lookup_commit(sha1[info->theirs[i]]);
 608                bitmap = ref_bitmap_at(ref_bitmap, c);
 609                if (!*bitmap)
 610                        continue;
 611                for (j = 0; j < bitmap_nr; j++)
 612                        if (bitmap[0][j]) {
 613                                update_refstatus(ref_status, info->ref->nr, *bitmap);
 614                                dst++;
 615                                break;
 616                        }
 617        }
 618        info->nr_theirs = dst;
 619
 620        memset(&ca, 0, sizeof(ca));
 621        head_ref(add_ref, &ca);
 622        for_each_ref(add_ref, &ca);
 623
 624        /* Remove unreachable shallow commits from "ours" */
 625        for (i = dst = 0; i < info->nr_ours; i++) {
 626                if (i != dst)
 627                        info->ours[dst] = info->ours[i];
 628                c = lookup_commit(sha1[info->ours[i]]);
 629                bitmap = ref_bitmap_at(ref_bitmap, c);
 630                if (!*bitmap)
 631                        continue;
 632                for (j = 0; j < bitmap_nr; j++)
 633                        if (bitmap[0][j] &&
 634                            /* Step 7, reachability test at commit level */
 635                            !in_merge_bases_many(c, ca.nr, ca.commits)) {
 636                                update_refstatus(ref_status, info->ref->nr, *bitmap);
 637                                dst++;
 638                                break;
 639                        }
 640        }
 641        info->nr_ours = dst;
 642
 643        free(ca.commits);
 644}
 645
 646/* (Delayed) step 7, reachability test at commit level */
 647int delayed_reachability_test(struct shallow_info *si, int c)
 648{
 649        if (si->need_reachability_test[c]) {
 650                struct commit *commit = lookup_commit(si->shallow->sha1[c]);
 651
 652                if (!si->commits) {
 653                        struct commit_array ca;
 654
 655                        memset(&ca, 0, sizeof(ca));
 656                        head_ref(add_ref, &ca);
 657                        for_each_ref(add_ref, &ca);
 658                        si->commits = ca.commits;
 659                        si->nr_commits = ca.nr;
 660                }
 661
 662                si->reachable[c] = in_merge_bases_many(commit,
 663                                                       si->nr_commits,
 664                                                       si->commits);
 665                si->need_reachability_test[c] = 0;
 666        }
 667        return si->reachable[c];
 668}