be7a2008c52f582626dd18b47372a4765c8bd39c
   1#include "cache.h"
   2#include "object.h"
   3#include "delta.h"
   4#include "pack.h"
   5#include "csum-file.h"
   6#include "diff.h"
   7#include <sys/time.h>
   8#include <signal.h>
   9
  10static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
  11
  12struct object_entry {
  13        unsigned char sha1[20];
  14        unsigned long size;     /* uncompressed size */
  15        unsigned long offset;   /* offset into the final pack file;
  16                                 * nonzero if already written.
  17                                 */
  18        unsigned int depth;     /* delta depth */
  19        unsigned int delta_limit;       /* base adjustment for in-pack delta */
  20        unsigned int hash;      /* name hint hash */
  21        enum object_type type;
  22        enum object_type in_pack_type;  /* could be delta */
  23        unsigned long delta_size;       /* delta data size (uncompressed) */
  24        struct object_entry *delta;     /* delta base object */
  25        struct packed_git *in_pack;     /* already in pack */
  26        unsigned int in_pack_offset;
  27        struct object_entry *delta_child; /* delitified objects who bases me */
  28        struct object_entry *delta_sibling; /* other deltified objects who
  29                                             * uses the same base as me
  30                                             */
  31        int preferred_base;     /* we do not pack this, but is encouraged to
  32                                 * be used as the base objectto delta huge
  33                                 * objects against.
  34                                 */
  35        int based_on_preferred; /* current delta candidate is a preferred
  36                                 * one, or delta against a preferred one.
  37                                 */
  38};
  39
  40/*
  41 * Objects we are going to pack are colected in objects array (dynamically
  42 * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  43 * in the order we see -- typically rev-list --objects order that gives us
  44 * nice "minimum seek" order.
  45 *
  46 * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  47 * elements in the objects array.  The former is used to build the pack
  48 * index (lists object names in the ascending order to help offset lookup),
  49 * and the latter is used to group similar things together by try_delta()
  50 * heuristics.
  51 */
  52
  53static unsigned char object_list_sha1[20];
  54static int non_empty = 0;
  55static int no_reuse_delta = 0;
  56static int local = 0;
  57static int incremental = 0;
  58static struct object_entry **sorted_by_sha, **sorted_by_type;
  59static struct object_entry *objects = NULL;
  60static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
  61static const char *base_name;
  62static unsigned char pack_file_sha1[20];
  63static int progress = 1;
  64static volatile int progress_update = 0;
  65
  66/*
  67 * The object names in objects array are hashed with this hashtable,
  68 * to help looking up the entry by object name.  Binary search from
  69 * sorted_by_sha is also possible but this was easier to code and faster.
  70 * This hashtable is built after all the objects are seen.
  71 */
  72static int *object_ix = NULL;
  73static int object_ix_hashsz = 0;
  74
  75/*
  76 * Pack index for existing packs give us easy access to the offsets into
  77 * corresponding pack file where each object's data starts, but the entries
  78 * do not store the size of the compressed representation (uncompressed
  79 * size is easily available by examining the pack entry header).  We build
  80 * a hashtable of existing packs (pack_revindex), and keep reverse index
  81 * here -- pack index file is sorted by object name mapping to offset; this
  82 * pack_revindex[].revindex array is an ordered list of offsets, so if you
  83 * know the offset of an object, next offset is where its packed
  84 * representation ends.
  85 */
  86struct pack_revindex {
  87        struct packed_git *p;
  88        unsigned long *revindex;
  89} *pack_revindex = NULL;
  90static int pack_revindex_hashsz = 0;
  91
  92/*
  93 * stats
  94 */
  95static int written = 0;
  96static int written_delta = 0;
  97static int reused = 0;
  98static int reused_delta = 0;
  99
 100static int pack_revindex_ix(struct packed_git *p)
 101{
 102        unsigned int ui = (unsigned int) p;
 103        int i;
 104
 105        ui = ui ^ (ui >> 16); /* defeat structure alignment */
 106        i = (int)(ui % pack_revindex_hashsz);
 107        while (pack_revindex[i].p) {
 108                if (pack_revindex[i].p == p)
 109                        return i;
 110                if (++i == pack_revindex_hashsz)
 111                        i = 0;
 112        }
 113        return -1 - i;
 114}
 115
 116static void prepare_pack_ix(void)
 117{
 118        int num;
 119        struct packed_git *p;
 120        for (num = 0, p = packed_git; p; p = p->next)
 121                num++;
 122        if (!num)
 123                return;
 124        pack_revindex_hashsz = num * 11;
 125        pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 126        for (p = packed_git; p; p = p->next) {
 127                num = pack_revindex_ix(p);
 128                num = - 1 - num;
 129                pack_revindex[num].p = p;
 130        }
 131        /* revindex elements are lazily initialized */
 132}
 133
 134static int cmp_offset(const void *a_, const void *b_)
 135{
 136        unsigned long a = *(unsigned long *) a_;
 137        unsigned long b = *(unsigned long *) b_;
 138        if (a < b)
 139                return -1;
 140        else if (a == b)
 141                return 0;
 142        else
 143                return 1;
 144}
 145
 146/*
 147 * Ordered list of offsets of objects in the pack.
 148 */
 149static void prepare_pack_revindex(struct pack_revindex *rix)
 150{
 151        struct packed_git *p = rix->p;
 152        int num_ent = num_packed_objects(p);
 153        int i;
 154        void *index = p->index_base + 256;
 155
 156        rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 157        for (i = 0; i < num_ent; i++) {
 158                long hl = *((long *)(index + 24 * i));
 159                rix->revindex[i] = ntohl(hl);
 160        }
 161        /* This knows the pack format -- the 20-byte trailer
 162         * follows immediately after the last object data.
 163         */
 164        rix->revindex[num_ent] = p->pack_size - 20;
 165        qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 166}
 167
 168static unsigned long find_packed_object_size(struct packed_git *p,
 169                                             unsigned long ofs)
 170{
 171        int num;
 172        int lo, hi;
 173        struct pack_revindex *rix;
 174        unsigned long *revindex;
 175        num = pack_revindex_ix(p);
 176        if (num < 0)
 177                die("internal error: pack revindex uninitialized");
 178        rix = &pack_revindex[num];
 179        if (!rix->revindex)
 180                prepare_pack_revindex(rix);
 181        revindex = rix->revindex;
 182        lo = 0;
 183        hi = num_packed_objects(p) + 1;
 184        do {
 185                int mi = (lo + hi) / 2;
 186                if (revindex[mi] == ofs) {
 187                        return revindex[mi+1] - ofs;
 188                }
 189                else if (ofs < revindex[mi])
 190                        hi = mi;
 191                else
 192                        lo = mi + 1;
 193        } while (lo < hi);
 194        die("internal error: pack revindex corrupt");
 195}
 196
 197static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 198{
 199        unsigned long othersize, delta_size;
 200        char type[10];
 201        void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 202        void *delta_buf;
 203
 204        if (!otherbuf)
 205                die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 206        delta_buf = diff_delta(otherbuf, othersize,
 207                               buf, size, &delta_size, 0);
 208        if (!delta_buf || delta_size != entry->delta_size)
 209                die("delta size changed");
 210        free(buf);
 211        free(otherbuf);
 212        return delta_buf;
 213}
 214
 215/*
 216 * The per-object header is a pretty dense thing, which is
 217 *  - first byte: low four bits are "size", then three bits of "type",
 218 *    and the high bit is "size continues".
 219 *  - each byte afterwards: low seven bits are size continuation,
 220 *    with the high bit being "size continues"
 221 */
 222static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 223{
 224        int n = 1;
 225        unsigned char c;
 226
 227        if (type < OBJ_COMMIT || type > OBJ_DELTA)
 228                die("bad type %d", type);
 229
 230        c = (type << 4) | (size & 15);
 231        size >>= 4;
 232        while (size) {
 233                *hdr++ = c | 0x80;
 234                c = size & 0x7f;
 235                size >>= 7;
 236                n++;
 237        }
 238        *hdr = c;
 239        return n;
 240}
 241
 242static unsigned long write_object(struct sha1file *f,
 243                                  struct object_entry *entry)
 244{
 245        unsigned long size;
 246        char type[10];
 247        void *buf;
 248        unsigned char header[10];
 249        unsigned hdrlen, datalen;
 250        enum object_type obj_type;
 251        int to_reuse = 0;
 252
 253        if (entry->preferred_base)
 254                return 0;
 255
 256        obj_type = entry->type;
 257        if (! entry->in_pack)
 258                to_reuse = 0;   /* can't reuse what we don't have */
 259        else if (obj_type == OBJ_DELTA)
 260                to_reuse = 1;   /* check_object() decided it for us */
 261        else if (obj_type != entry->in_pack_type)
 262                to_reuse = 0;   /* pack has delta which is unusable */
 263        else if (entry->delta)
 264                to_reuse = 0;   /* we want to pack afresh */
 265        else
 266                to_reuse = 1;   /* we have it in-pack undeltified,
 267                                 * and we do not need to deltify it.
 268                                 */
 269
 270        if (! to_reuse) {
 271                buf = read_sha1_file(entry->sha1, type, &size);
 272                if (!buf)
 273                        die("unable to read %s", sha1_to_hex(entry->sha1));
 274                if (size != entry->size)
 275                        die("object %s size inconsistency (%lu vs %lu)",
 276                            sha1_to_hex(entry->sha1), size, entry->size);
 277                if (entry->delta) {
 278                        buf = delta_against(buf, size, entry);
 279                        size = entry->delta_size;
 280                        obj_type = OBJ_DELTA;
 281                }
 282                /*
 283                 * The object header is a byte of 'type' followed by zero or
 284                 * more bytes of length.  For deltas, the 20 bytes of delta
 285                 * sha1 follows that.
 286                 */
 287                hdrlen = encode_header(obj_type, size, header);
 288                sha1write(f, header, hdrlen);
 289
 290                if (entry->delta) {
 291                        sha1write(f, entry->delta, 20);
 292                        hdrlen += 20;
 293                }
 294                datalen = sha1write_compressed(f, buf, size);
 295                free(buf);
 296        }
 297        else {
 298                struct packed_git *p = entry->in_pack;
 299                use_packed_git(p);
 300
 301                datalen = find_packed_object_size(p, entry->in_pack_offset);
 302                buf = p->pack_base + entry->in_pack_offset;
 303                sha1write(f, buf, datalen);
 304                unuse_packed_git(p);
 305                hdrlen = 0; /* not really */
 306                if (obj_type == OBJ_DELTA)
 307                        reused_delta++;
 308                reused++;
 309        }
 310        if (obj_type == OBJ_DELTA)
 311                written_delta++;
 312        written++;
 313        return hdrlen + datalen;
 314}
 315
 316static unsigned long write_one(struct sha1file *f,
 317                               struct object_entry *e,
 318                               unsigned long offset)
 319{
 320        if (e->offset)
 321                /* offset starts from header size and cannot be zero
 322                 * if it is written already.
 323                 */
 324                return offset;
 325        e->offset = offset;
 326        offset += write_object(f, e);
 327        /* if we are deltified, write out its base object. */
 328        if (e->delta)
 329                offset = write_one(f, e->delta, offset);
 330        return offset;
 331}
 332
 333static void write_pack_file(void)
 334{
 335        int i;
 336        struct sha1file *f;
 337        unsigned long offset;
 338        struct pack_header hdr;
 339        unsigned last_percent = 999;
 340        int do_progress = 0;
 341
 342        if (!base_name)
 343                f = sha1fd(1, "<stdout>");
 344        else {
 345                f = sha1create("%s-%s.%s", base_name,
 346                               sha1_to_hex(object_list_sha1), "pack");
 347                do_progress = progress;
 348        }
 349        if (do_progress)
 350                fprintf(stderr, "Writing %d objects.\n", nr_result);
 351
 352        hdr.hdr_signature = htonl(PACK_SIGNATURE);
 353        hdr.hdr_version = htonl(PACK_VERSION);
 354        hdr.hdr_entries = htonl(nr_result);
 355        sha1write(f, &hdr, sizeof(hdr));
 356        offset = sizeof(hdr);
 357        if (!nr_result)
 358                goto done;
 359        for (i = 0; i < nr_objects; i++) {
 360                offset = write_one(f, objects + i, offset);
 361                if (do_progress) {
 362                        unsigned percent = written * 100 / nr_result;
 363                        if (progress_update || percent != last_percent) {
 364                                fprintf(stderr, "%4u%% (%u/%u) done\r",
 365                                        percent, written, nr_result);
 366                                progress_update = 0;
 367                                last_percent = percent;
 368                        }
 369                }
 370        }
 371        if (do_progress)
 372                fputc('\n', stderr);
 373 done:
 374        sha1close(f, pack_file_sha1, 1);
 375}
 376
 377static void write_index_file(void)
 378{
 379        int i;
 380        struct sha1file *f = sha1create("%s-%s.%s", base_name,
 381                                        sha1_to_hex(object_list_sha1), "idx");
 382        struct object_entry **list = sorted_by_sha;
 383        struct object_entry **last = list + nr_result;
 384        unsigned int array[256];
 385
 386        /*
 387         * Write the first-level table (the list is sorted,
 388         * but we use a 256-entry lookup to be able to avoid
 389         * having to do eight extra binary search iterations).
 390         */
 391        for (i = 0; i < 256; i++) {
 392                struct object_entry **next = list;
 393                while (next < last) {
 394                        struct object_entry *entry = *next;
 395                        if (entry->sha1[0] != i)
 396                                break;
 397                        next++;
 398                }
 399                array[i] = htonl(next - sorted_by_sha);
 400                list = next;
 401        }
 402        sha1write(f, array, 256 * sizeof(int));
 403
 404        /*
 405         * Write the actual SHA1 entries..
 406         */
 407        list = sorted_by_sha;
 408        for (i = 0; i < nr_result; i++) {
 409                struct object_entry *entry = *list++;
 410                unsigned int offset = htonl(entry->offset);
 411                sha1write(f, &offset, 4);
 412                sha1write(f, entry->sha1, 20);
 413        }
 414        sha1write(f, pack_file_sha1, 20);
 415        sha1close(f, NULL, 1);
 416}
 417
 418static int locate_object_entry_hash(const unsigned char *sha1)
 419{
 420        int i;
 421        unsigned int ui;
 422        memcpy(&ui, sha1, sizeof(unsigned int));
 423        i = ui % object_ix_hashsz;
 424        while (0 < object_ix[i]) {
 425                if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
 426                        return i;
 427                if (++i == object_ix_hashsz)
 428                        i = 0;
 429        }
 430        return -1 - i;
 431}
 432
 433static struct object_entry *locate_object_entry(const unsigned char *sha1)
 434{
 435        int i;
 436
 437        if (!object_ix_hashsz)
 438                return NULL;
 439
 440        i = locate_object_entry_hash(sha1);
 441        if (0 <= i)
 442                return &objects[object_ix[i]-1];
 443        return NULL;
 444}
 445
 446static void rehash_objects(void)
 447{
 448        int i;
 449        struct object_entry *oe;
 450
 451        object_ix_hashsz = nr_objects * 3;
 452        if (object_ix_hashsz < 1024)
 453                object_ix_hashsz = 1024;
 454        object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 455        object_ix = memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 456        for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 457                int ix = locate_object_entry_hash(oe->sha1);
 458                if (0 <= ix)
 459                        continue;
 460                ix = -1 - ix;
 461                object_ix[ix] = i + 1;
 462        }
 463}
 464
 465struct name_path {
 466        struct name_path *up;
 467        const char *elem;
 468        int len;
 469};
 470
 471#define DIRBITS 12
 472
 473static unsigned name_hash(struct name_path *path, const char *name)
 474{
 475        struct name_path *p = path;
 476        const char *n = name + strlen(name);
 477        unsigned hash = 0, name_hash = 0, name_done = 0;
 478
 479        if (n != name && n[-1] == '\n')
 480                n--;
 481        while (name <= --n) {
 482                unsigned char c = *n;
 483                if (c == '/' && !name_done) {
 484                        name_hash = hash;
 485                        name_done = 1;
 486                        hash = 0;
 487                }
 488                hash = hash * 11 + c;
 489        }
 490        if (!name_done) {
 491                name_hash = hash;
 492                hash = 0;
 493        }
 494        for (p = path; p; p = p->up) {
 495                hash = hash * 11 + '/';
 496                n = p->elem + p->len;
 497                while (p->elem <= --n) {
 498                        unsigned char c = *n;
 499                        hash = hash * 11 + c;
 500                }
 501        }
 502        /*
 503         * Make sure "Makefile" and "t/Makefile" are hashed separately
 504         * but close enough.
 505         */
 506        hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
 507
 508        if (0) { /* debug */
 509                n = name + strlen(name);
 510                if (n != name && n[-1] == '\n')
 511                        n--;
 512                while (name <= --n)
 513                        fputc(*n, stderr);
 514                for (p = path; p; p = p->up) {
 515                        fputc('/', stderr);
 516                        n = p->elem + p->len;
 517                        while (p->elem <= --n)
 518                                fputc(*n, stderr);
 519                }
 520                fprintf(stderr, "\t%08x\n", hash);
 521        }
 522        return hash;
 523}
 524
 525static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 526{
 527        unsigned int idx = nr_objects;
 528        struct object_entry *entry;
 529        struct packed_git *p;
 530        unsigned int found_offset = 0;
 531        struct packed_git *found_pack = NULL;
 532        int ix, status = 0;
 533
 534        if (!exclude) {
 535                for (p = packed_git; p; p = p->next) {
 536                        struct pack_entry e;
 537                        if (find_pack_entry_one(sha1, &e, p)) {
 538                                if (incremental)
 539                                        return 0;
 540                                if (local && !p->pack_local)
 541                                        return 0;
 542                                if (!found_pack) {
 543                                        found_offset = e.offset;
 544                                        found_pack = e.p;
 545                                }
 546                        }
 547                }
 548        }
 549        if ((entry = locate_object_entry(sha1)) != NULL)
 550                goto already_added;
 551
 552        if (idx >= nr_alloc) {
 553                unsigned int needed = (idx + 1024) * 3 / 2;
 554                objects = xrealloc(objects, needed * sizeof(*entry));
 555                nr_alloc = needed;
 556        }
 557        entry = objects + idx;
 558        nr_objects = idx + 1;
 559        memset(entry, 0, sizeof(*entry));
 560        memcpy(entry->sha1, sha1, 20);
 561        entry->hash = hash;
 562
 563        if (object_ix_hashsz * 3 <= nr_objects * 4)
 564                rehash_objects();
 565        else {
 566                ix = locate_object_entry_hash(entry->sha1);
 567                if (0 <= ix)
 568                        die("internal error in object hashing.");
 569                object_ix[-1 - ix] = idx + 1;
 570        }
 571        status = 1;
 572
 573 already_added:
 574        if (progress_update) {
 575                fprintf(stderr, "Counting objects...%d\r", nr_objects);
 576                progress_update = 0;
 577        }
 578        if (exclude)
 579                entry->preferred_base = 1;
 580        else {
 581                if (found_pack) {
 582                        entry->in_pack = found_pack;
 583                        entry->in_pack_offset = found_offset;
 584                }
 585        }
 586        return status;
 587}
 588
 589static void add_pbase_tree(struct tree_desc *tree, struct name_path *up)
 590{
 591        while (tree->size) {
 592                const unsigned char *sha1;
 593                const char *name;
 594                unsigned mode, hash;
 595                unsigned long size;
 596                char type[20];
 597
 598                sha1 = tree_entry_extract(tree, &name, &mode);
 599                update_tree_entry(tree);
 600                if (!has_sha1_file(sha1))
 601                        continue;
 602                if (sha1_object_info(sha1, type, &size))
 603                        continue;
 604
 605                hash = name_hash(up, name);
 606                if (!add_object_entry(sha1, hash, 1))
 607                        continue;
 608
 609                if (!strcmp(type, "tree")) {
 610                        struct tree_desc sub;
 611                        void *elem;
 612                        struct name_path me;
 613
 614                        elem = read_sha1_file(sha1, type, &sub.size);
 615                        sub.buf = elem;
 616                        if (sub.buf) {
 617                                me.up = up;
 618                                me.elem = name;
 619                                me.len = strlen(name);
 620                                add_pbase_tree(&sub, &me);
 621                                free(elem);
 622                        }
 623                }
 624        }
 625}
 626
 627static void add_preferred_base(unsigned char *sha1)
 628{
 629        struct tree_desc tree;
 630        void *elem;
 631
 632        elem = read_object_with_reference(sha1, "tree", &tree.size, NULL);
 633        tree.buf = elem;
 634        if (!tree.buf)
 635                return;
 636        if (add_object_entry(sha1, name_hash(NULL, ""), 1))
 637                add_pbase_tree(&tree, NULL);
 638        free(elem);
 639}
 640
 641static void check_object(struct object_entry *entry)
 642{
 643        char type[20];
 644
 645        if (entry->in_pack && !entry->preferred_base) {
 646                unsigned char base[20];
 647                unsigned long size;
 648                struct object_entry *base_entry;
 649
 650                /* We want in_pack_type even if we do not reuse delta.
 651                 * There is no point not reusing non-delta representations.
 652                 */
 653                check_reuse_pack_delta(entry->in_pack,
 654                                       entry->in_pack_offset,
 655                                       base, &size,
 656                                       &entry->in_pack_type);
 657
 658                /* Check if it is delta, and the base is also an object
 659                 * we are going to pack.  If so we will reuse the existing
 660                 * delta.
 661                 */
 662                if (!no_reuse_delta &&
 663                    entry->in_pack_type == OBJ_DELTA &&
 664                    (base_entry = locate_object_entry(base)) &&
 665                    (!base_entry->preferred_base)) {
 666
 667                        /* Depth value does not matter - find_deltas()
 668                         * will never consider reused delta as the
 669                         * base object to deltify other objects
 670                         * against, in order to avoid circular deltas.
 671                         */
 672
 673                        /* uncompressed size of the delta data */
 674                        entry->size = entry->delta_size = size;
 675                        entry->delta = base_entry;
 676                        entry->type = OBJ_DELTA;
 677
 678                        entry->delta_sibling = base_entry->delta_child;
 679                        base_entry->delta_child = entry;
 680
 681                        return;
 682                }
 683                /* Otherwise we would do the usual */
 684        }
 685
 686        if (sha1_object_info(entry->sha1, type, &entry->size))
 687                die("unable to get type of object %s",
 688                    sha1_to_hex(entry->sha1));
 689
 690        if (!strcmp(type, "commit")) {
 691                entry->type = OBJ_COMMIT;
 692        } else if (!strcmp(type, "tree")) {
 693                entry->type = OBJ_TREE;
 694        } else if (!strcmp(type, "blob")) {
 695                entry->type = OBJ_BLOB;
 696        } else if (!strcmp(type, "tag")) {
 697                entry->type = OBJ_TAG;
 698        } else
 699                die("unable to pack object %s of type %s",
 700                    sha1_to_hex(entry->sha1), type);
 701}
 702
 703static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 704{
 705        struct object_entry *child = me->delta_child;
 706        unsigned int m = n;
 707        while (child) {
 708                unsigned int c = check_delta_limit(child, n + 1);
 709                if (m < c)
 710                        m = c;
 711                child = child->delta_sibling;
 712        }
 713        return m;
 714}
 715
 716static void get_object_details(void)
 717{
 718        int i;
 719        struct object_entry *entry;
 720
 721        prepare_pack_ix();
 722        for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 723                check_object(entry);
 724
 725        if (nr_objects == nr_result) {
 726                /*
 727                 * Depth of objects that depend on the entry -- this
 728                 * is subtracted from depth-max to break too deep
 729                 * delta chain because of delta data reusing.
 730                 * However, we loosen this restriction when we know we
 731                 * are creating a thin pack -- it will have to be
 732                 * expanded on the other end anyway, so do not
 733                 * artificially cut the delta chain and let it go as
 734                 * deep as it wants.
 735                 */
 736                for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 737                        if (!entry->delta && entry->delta_child)
 738                                entry->delta_limit =
 739                                        check_delta_limit(entry, 1);
 740        }
 741}
 742
 743typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 744
 745static entry_sort_t current_sort;
 746
 747static int sort_comparator(const void *_a, const void *_b)
 748{
 749        struct object_entry *a = *(struct object_entry **)_a;
 750        struct object_entry *b = *(struct object_entry **)_b;
 751        return current_sort(a,b);
 752}
 753
 754static struct object_entry **create_sorted_list(entry_sort_t sort)
 755{
 756        struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 757        int i;
 758
 759        for (i = 0; i < nr_objects; i++)
 760                list[i] = objects + i;
 761        current_sort = sort;
 762        qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 763        return list;
 764}
 765
 766static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 767{
 768        return memcmp(a->sha1, b->sha1, 20);
 769}
 770
 771static struct object_entry **create_final_object_list()
 772{
 773        struct object_entry **list;
 774        int i, j;
 775
 776        for (i = nr_result = 0; i < nr_objects; i++)
 777                if (!objects[i].preferred_base)
 778                        nr_result++;
 779        list = xmalloc(nr_result * sizeof(struct object_entry *));
 780        for (i = j = 0; i < nr_objects; i++) {
 781                if (!objects[i].preferred_base)
 782                        list[j++] = objects + i;
 783        }
 784        current_sort = sha1_sort;
 785        qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
 786        return list;
 787}
 788
 789static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 790{
 791        if (a->type < b->type)
 792                return -1;
 793        if (a->type > b->type)
 794                return 1;
 795        if (a->hash < b->hash)
 796                return -1;
 797        if (a->hash > b->hash)
 798                return 1;
 799        if (a->preferred_base < b->preferred_base)
 800                return -1;
 801        if (a->preferred_base > b->preferred_base)
 802                return 1;
 803        if (a->size < b->size)
 804                return -1;
 805        if (a->size > b->size)
 806                return 1;
 807        return a < b ? -1 : (a > b);
 808}
 809
 810struct unpacked {
 811        struct object_entry *entry;
 812        void *data;
 813};
 814
 815/*
 816 * We search for deltas _backwards_ in a list sorted by type and
 817 * by size, so that we see progressively smaller and smaller files.
 818 * That's because we prefer deltas to be from the bigger file
 819 * to the smaller - deletes are potentially cheaper, but perhaps
 820 * more importantly, the bigger file is likely the more recent
 821 * one.
 822 */
 823static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
 824{
 825        struct object_entry *cur_entry = cur->entry;
 826        struct object_entry *old_entry = old->entry;
 827        int old_preferred = (old_entry->preferred_base ||
 828                             old_entry->based_on_preferred);
 829        unsigned long size, oldsize, delta_size, sizediff;
 830        long max_size;
 831        void *delta_buf;
 832
 833        /* Don't bother doing diffs between different types */
 834        if (cur_entry->type != old_entry->type)
 835                return -1;
 836
 837        /* We do not compute delta to *create* objects we are not
 838         * going to pack.
 839         */
 840        if (cur_entry->preferred_base)
 841                return -1;
 842
 843        /* If the current object is at pack edge, take the depth the
 844         * objects that depend on the current object into account --
 845         * otherwise they would become too deep.
 846         */
 847        if (cur_entry->delta_child) {
 848                if (max_depth <= cur_entry->delta_limit)
 849                        return 0;
 850                max_depth -= cur_entry->delta_limit;
 851        }
 852
 853        size = cur_entry->size;
 854        oldsize = old_entry->size;
 855        sizediff = oldsize > size ? oldsize - size : size - oldsize;
 856
 857        if (size < 50)
 858                return -1;
 859        if (old_entry->depth >= max_depth)
 860                return 0;
 861
 862        /*
 863         * NOTE!
 864         *
 865         * We always delta from the bigger to the smaller, since that's
 866         * more space-efficient (deletes don't have to say _what_ they
 867         * delete).
 868         */
 869        max_size = size / 2 - 20;
 870        if (cur_entry->delta) {
 871                if (cur_entry->based_on_preferred) {
 872                        if (old_preferred)
 873                                max_size = cur_entry->delta_size-1;
 874                        else
 875                                /* trying with non-preferred one when we
 876                                 * already have a delta based on preferred
 877                                 * one is pointless.
 878                                 */
 879                                return -1;
 880                }
 881                else if (!old_preferred)
 882                        max_size = cur_entry->delta_size-1;
 883                else
 884                        /* otherwise...  even if delta with a
 885                         * preferred one produces a bigger result than
 886                         * what we currently have, which is based on a
 887                         * non-preferred one, it is OK.
 888                         */
 889                        ;
 890        }
 891        if (sizediff >= max_size)
 892                return -1;
 893        delta_buf = diff_delta(old->data, oldsize,
 894                               cur->data, size, &delta_size, max_size);
 895        if (!delta_buf)
 896                return 0;
 897        cur_entry->delta = old_entry;
 898        cur_entry->delta_size = delta_size;
 899        cur_entry->depth = old_entry->depth + 1;
 900        cur_entry->based_on_preferred = old_preferred;
 901        free(delta_buf);
 902        return 0;
 903}
 904
 905static void progress_interval(int signum)
 906{
 907        signal(SIGALRM, progress_interval);
 908        progress_update = 1;
 909}
 910
 911static void find_deltas(struct object_entry **list, int window, int depth)
 912{
 913        int i, idx;
 914        unsigned int array_size = window * sizeof(struct unpacked);
 915        struct unpacked *array = xmalloc(array_size);
 916        unsigned processed = 0;
 917        unsigned last_percent = 999;
 918
 919        memset(array, 0, array_size);
 920        i = nr_objects;
 921        idx = 0;
 922        if (progress)
 923                fprintf(stderr, "Deltifying %d objects.\n", nr_result);
 924
 925        while (--i >= 0) {
 926                struct object_entry *entry = list[i];
 927                struct unpacked *n = array + idx;
 928                unsigned long size;
 929                char type[10];
 930                int j;
 931
 932                if (!entry->preferred_base)
 933                        processed++;
 934
 935                if (progress) {
 936                        unsigned percent = processed * 100 / nr_result;
 937                        if (percent != last_percent || progress_update) {
 938                                fprintf(stderr, "%4u%% (%u/%u) done\r",
 939                                        percent, processed, nr_result);
 940                                progress_update = 0;
 941                                last_percent = percent;
 942                        }
 943                }
 944
 945                if (entry->delta)
 946                        /* This happens if we decided to reuse existing
 947                         * delta from a pack.  "!no_reuse_delta &&" is implied.
 948                         */
 949                        continue;
 950
 951                free(n->data);
 952                n->entry = entry;
 953                n->data = read_sha1_file(entry->sha1, type, &size);
 954                if (size != entry->size)
 955                        die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
 956
 957                j = window;
 958                while (--j > 0) {
 959                        unsigned int other_idx = idx + j;
 960                        struct unpacked *m;
 961                        if (other_idx >= window)
 962                                other_idx -= window;
 963                        m = array + other_idx;
 964                        if (!m->entry)
 965                                break;
 966                        if (try_delta(n, m, depth) < 0)
 967                                break;
 968                }
 969                idx++;
 970                if (idx >= window)
 971                        idx = 0;
 972        }
 973
 974        if (progress)
 975                fputc('\n', stderr);
 976
 977        for (i = 0; i < window; ++i)
 978                free(array[i].data);
 979        free(array);
 980}
 981
 982static void prepare_pack(int window, int depth)
 983{
 984        get_object_details();
 985        sorted_by_type = create_sorted_list(type_size_sort);
 986        if (window && depth)
 987                find_deltas(sorted_by_type, window+1, depth);
 988}
 989
 990static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
 991{
 992        static const char cache[] = "pack-cache/pack-%s.%s";
 993        char *cached_pack, *cached_idx;
 994        int ifd, ofd, ifd_ix = -1;
 995
 996        cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
 997        ifd = open(cached_pack, O_RDONLY);
 998        if (ifd < 0)
 999                return 0;
1000
1001        if (!pack_to_stdout) {
1002                cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1003                ifd_ix = open(cached_idx, O_RDONLY);
1004                if (ifd_ix < 0) {
1005                        close(ifd);
1006                        return 0;
1007                }
1008        }
1009
1010        if (progress)
1011                fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1012                        sha1_to_hex(sha1));
1013
1014        if (pack_to_stdout) {
1015                if (copy_fd(ifd, 1))
1016                        exit(1);
1017                close(ifd);
1018        }
1019        else {
1020                char name[PATH_MAX];
1021                snprintf(name, sizeof(name),
1022                         "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1023                ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1024                if (ofd < 0)
1025                        die("unable to open %s (%s)", name, strerror(errno));
1026                if (copy_fd(ifd, ofd))
1027                        exit(1);
1028                close(ifd);
1029
1030                snprintf(name, sizeof(name),
1031                         "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1032                ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1033                if (ofd < 0)
1034                        die("unable to open %s (%s)", name, strerror(errno));
1035                if (copy_fd(ifd_ix, ofd))
1036                        exit(1);
1037                close(ifd_ix);
1038                puts(sha1_to_hex(sha1));
1039        }
1040
1041        return 1;
1042}
1043
1044int main(int argc, char **argv)
1045{
1046        SHA_CTX ctx;
1047        char line[PATH_MAX + 20];
1048        int window = 10, depth = 10, pack_to_stdout = 0;
1049        struct object_entry **list;
1050        int i;
1051
1052        setup_git_directory();
1053
1054        for (i = 1; i < argc; i++) {
1055                const char *arg = argv[i];
1056
1057                if (*arg == '-') {
1058                        if (!strcmp("--non-empty", arg)) {
1059                                non_empty = 1;
1060                                continue;
1061                        }
1062                        if (!strcmp("--local", arg)) {
1063                                local = 1;
1064                                continue;
1065                        }
1066                        if (!strcmp("--incremental", arg)) {
1067                                incremental = 1;
1068                                continue;
1069                        }
1070                        if (!strncmp("--window=", arg, 9)) {
1071                                char *end;
1072                                window = strtoul(arg+9, &end, 0);
1073                                if (!arg[9] || *end)
1074                                        usage(pack_usage);
1075                                continue;
1076                        }
1077                        if (!strncmp("--depth=", arg, 8)) {
1078                                char *end;
1079                                depth = strtoul(arg+8, &end, 0);
1080                                if (!arg[8] || *end)
1081                                        usage(pack_usage);
1082                                continue;
1083                        }
1084                        if (!strcmp("-q", arg)) {
1085                                progress = 0;
1086                                continue;
1087                        }
1088                        if (!strcmp("--no-reuse-delta", arg)) {
1089                                no_reuse_delta = 1;
1090                                continue;
1091                        }
1092                        if (!strcmp("--stdout", arg)) {
1093                                pack_to_stdout = 1;
1094                                continue;
1095                        }
1096                        usage(pack_usage);
1097                }
1098                if (base_name)
1099                        usage(pack_usage);
1100                base_name = arg;
1101        }
1102
1103        if (pack_to_stdout != !base_name)
1104                usage(pack_usage);
1105
1106        prepare_packed_git();
1107
1108        if (progress) {
1109                struct itimerval v;
1110                v.it_interval.tv_sec = 1;
1111                v.it_interval.tv_usec = 0;
1112                v.it_value = v.it_interval;
1113                signal(SIGALRM, progress_interval);
1114                setitimer(ITIMER_REAL, &v, NULL);
1115                fprintf(stderr, "Generating pack...\n");
1116        }
1117
1118        while (fgets(line, sizeof(line), stdin) != NULL) {
1119                unsigned char sha1[20];
1120
1121                if (line[0] == '-') {
1122                        if (get_sha1_hex(line+1, sha1))
1123                                die("expected edge sha1, got garbage:\n %s",
1124                                    line+1);
1125                        add_preferred_base(sha1);
1126                        continue;
1127                }
1128                if (get_sha1_hex(line, sha1))
1129                        die("expected sha1, got garbage:\n %s", line);
1130                add_object_entry(sha1, name_hash(NULL, line+41), 0);
1131        }
1132        if (progress)
1133                fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1134        sorted_by_sha = create_final_object_list();
1135        if (non_empty && !nr_result)
1136                return 0;
1137
1138        SHA1_Init(&ctx);
1139        list = sorted_by_sha;
1140        for (i = 0; i < nr_result; i++) {
1141                struct object_entry *entry = *list++;
1142                SHA1_Update(&ctx, entry->sha1, 20);
1143        }
1144        SHA1_Final(object_list_sha1, &ctx);
1145        if (progress && (nr_objects != nr_result))
1146                fprintf(stderr, "Result has %d objects.\n", nr_result);
1147
1148        if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1149                ;
1150        else {
1151                if (nr_result)
1152                        prepare_pack(window, depth);
1153                if (progress && pack_to_stdout) {
1154                        /* the other end usually displays progress itself */
1155                        struct itimerval v = {{0,},};
1156                        setitimer(ITIMER_REAL, &v, NULL);
1157                        signal(SIGALRM, SIG_IGN );
1158                        progress_update = 0;
1159                }
1160                write_pack_file();
1161                if (!pack_to_stdout) {
1162                        write_index_file();
1163                        puts(sha1_to_hex(object_list_sha1));
1164                }
1165        }
1166        if (progress)
1167                fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1168                        nr_result, written, written_delta, reused, reused_delta);
1169        return 0;
1170}