git.oblomov.eu Git - git/blob - pack-objects.c

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "blob.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "tree.h"
   7 #include "delta.h"
   8 #include "pack.h"
   9 #include "csum-file.h"
  10 #include "tree-walk.h"
  11 #include <sys/time.h>
  12 #include <signal.h>
  13
  14 static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
  15
  16 struct object_entry {
  17         unsigned char sha1[20];
  18         unsigned long size;     /* uncompressed size */
  19         unsigned long offset;   /* offset into the final pack file;
  20                                  * nonzero if already written.
  21                                  */
  22         unsigned int depth;     /* delta depth */
  23         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  24         unsigned int hash;      /* name hint hash */
  25         enum object_type type;
  26         enum object_type in_pack_type;  /* could be delta */
  27         unsigned long delta_size;       /* delta data size (uncompressed) */
  28         struct object_entry *delta;     /* delta base object */
  29         struct packed_git *in_pack;     /* already in pack */
  30         unsigned int in_pack_offset;
  31         struct object_entry *delta_child; /* deltified objects who bases me */
  32         struct object_entry *delta_sibling; /* other deltified objects who
  33                                              * uses the same base as me
  34                                              */
  35         int preferred_base;     /* we do not pack this, but is encouraged to
  36                                  * be used as the base objectto delta huge
  37                                  * objects against.
  38                                  */
  39 };
  40
  41 /*
  42  * Objects we are going to pack are collected in objects array (dynamically
  43  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  44  * in the order we see -- typically rev-list --objects order that gives us
  45  * nice "minimum seek" order.
  46  *
  47  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  48  * elements in the objects array.  The former is used to build the pack
  49  * index (lists object names in the ascending order to help offset lookup),
  50  * and the latter is used to group similar things together by try_delta()
  51  * heuristics.
  52  */
  53
  54 static unsigned char object_list_sha1[20];
  55 static int non_empty = 0;
  56 static int no_reuse_delta = 0;
  57 static int local = 0;
  58 static int incremental = 0;
  59 static struct object_entry **sorted_by_sha, **sorted_by_type;
  60 static struct object_entry *objects = NULL;
  61 static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
  62 static const char *base_name;
  63 static unsigned char pack_file_sha1[20];
  64 static int progress = 1;
  65 static volatile sig_atomic_t progress_update = 0;
  66 static int window = 10;
  67
  68 /*
  69  * The object names in objects array are hashed with this hashtable,
  70  * to help looking up the entry by object name.  Binary search from
  71  * sorted_by_sha is also possible but this was easier to code and faster.
  72  * This hashtable is built after all the objects are seen.
  73  */
  74 static int *object_ix = NULL;
  75 static int object_ix_hashsz = 0;
  76
  77 /*
  78  * Pack index for existing packs give us easy access to the offsets into
  79  * corresponding pack file where each object's data starts, but the entries
  80  * do not store the size of the compressed representation (uncompressed
  81  * size is easily available by examining the pack entry header).  We build
  82  * a hashtable of existing packs (pack_revindex), and keep reverse index
  83  * here -- pack index file is sorted by object name mapping to offset; this
  84  * pack_revindex[].revindex array is an ordered list of offsets, so if you
  85  * know the offset of an object, next offset is where its packed
  86  * representation ends.
  87  */
  88 struct pack_revindex {
  89         struct packed_git *p;
  90         unsigned long *revindex;
  91 } *pack_revindex = NULL;
  92 static int pack_revindex_hashsz = 0;
  93
  94 /*
  95  * stats
  96  */
  97 static int written = 0;
  98 static int written_delta = 0;
  99 static int reused = 0;
 100 static int reused_delta = 0;
 101
 102 static int pack_revindex_ix(struct packed_git *p)
 103 {
 104         unsigned long ui = (unsigned long)p;
 105         int i;
 106
 107         ui = ui ^ (ui >> 16); /* defeat structure alignment */
 108         i = (int)(ui % pack_revindex_hashsz);
 109         while (pack_revindex[i].p) {
 110                 if (pack_revindex[i].p == p)
 111                         return i;
 112                 if (++i == pack_revindex_hashsz)
 113                         i = 0;
 114         }
 115         return -1 - i;
 116 }
 117
 118 static void prepare_pack_ix(void)
 119 {
 120         int num;
 121         struct packed_git *p;
 122         for (num = 0, p = packed_git; p; p = p->next)
 123                 num++;
 124         if (!num)
 125                 return;
 126         pack_revindex_hashsz = num * 11;
 127         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 128         for (p = packed_git; p; p = p->next) {
 129                 num = pack_revindex_ix(p);
 130                 num = - 1 - num;
 131                 pack_revindex[num].p = p;
 132         }
 133         /* revindex elements are lazily initialized */
 134 }
 135
 136 static int cmp_offset(const void *a_, const void *b_)
 137 {
 138         unsigned long a = *(unsigned long *) a_;
 139         unsigned long b = *(unsigned long *) b_;
 140         if (a < b)
 141                 return -1;
 142         else if (a == b)
 143                 return 0;
 144         else
 145                 return 1;
 146 }
 147
 148 /*
 149  * Ordered list of offsets of objects in the pack.
 150  */
 151 static void prepare_pack_revindex(struct pack_revindex *rix)
 152 {
 153         struct packed_git *p = rix->p;
 154         int num_ent = num_packed_objects(p);
 155         int i;
 156         void *index = p->index_base + 256;
 157
 158         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 159         for (i = 0; i < num_ent; i++) {
 160                 unsigned int hl = *((unsigned int *)((char *) index + 24*i));
 161                 rix->revindex[i] = ntohl(hl);
 162         }
 163         /* This knows the pack format -- the 20-byte trailer
 164          * follows immediately after the last object data.
 165          */
 166         rix->revindex[num_ent] = p->pack_size - 20;
 167         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 168 }
 169
 170 static unsigned long find_packed_object_size(struct packed_git *p,
 171                                              unsigned long ofs)
 172 {
 173         int num;
 174         int lo, hi;
 175         struct pack_revindex *rix;
 176         unsigned long *revindex;
 177         num = pack_revindex_ix(p);
 178         if (num < 0)
 179                 die("internal error: pack revindex uninitialized");
 180         rix = &pack_revindex[num];
 181         if (!rix->revindex)
 182                 prepare_pack_revindex(rix);
 183         revindex = rix->revindex;
 184         lo = 0;
 185         hi = num_packed_objects(p) + 1;
 186         do {
 187                 int mi = (lo + hi) / 2;
 188                 if (revindex[mi] == ofs) {
 189                         return revindex[mi+1] - ofs;
 190                 }
 191                 else if (ofs < revindex[mi])
 192                         hi = mi;
 193                 else
 194                         lo = mi + 1;
 195         } while (lo < hi);
 196         die("internal error: pack revindex corrupt");
 197 }
 198
 199 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 200 {
 201         unsigned long othersize, delta_size;
 202         char type[10];
 203         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 204         void *delta_buf;
 205
 206         if (!otherbuf)
 207                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 208         delta_buf = diff_delta(otherbuf, othersize,
 209                                buf, size, &delta_size, 0);
 210         if (!delta_buf || delta_size != entry->delta_size)
 211                 die("delta size changed");
 212         free(buf);
 213         free(otherbuf);
 214         return delta_buf;
 215 }
 216
 217 /*
 218  * The per-object header is a pretty dense thing, which is
 219  *  - first byte: low four bits are "size", then three bits of "type",
 220  *    and the high bit is "size continues".
 221  *  - each byte afterwards: low seven bits are size continuation,
 222  *    with the high bit being "size continues"
 223  */
 224 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 225 {
 226         int n = 1;
 227         unsigned char c;
 228
 229         if (type < OBJ_COMMIT || type > OBJ_DELTA)
 230                 die("bad type %d", type);
 231
 232         c = (type << 4) | (size & 15);
 233         size >>= 4;
 234         while (size) {
 235                 *hdr++ = c | 0x80;
 236                 c = size & 0x7f;
 237                 size >>= 7;
 238                 n++;
 239         }
 240         *hdr = c;
 241         return n;
 242 }
 243
 244 static unsigned long write_object(struct sha1file *f,
 245                                   struct object_entry *entry)
 246 {
 247         unsigned long size;
 248         char type[10];
 249         void *buf;
 250         unsigned char header[10];
 251         unsigned hdrlen, datalen;
 252         enum object_type obj_type;
 253         int to_reuse = 0;
 254
 255         if (entry->preferred_base)
 256                 return 0;
 257
 258         obj_type = entry->type;
 259         if (! entry->in_pack)
 260                 to_reuse = 0;   /* can't reuse what we don't have */
 261         else if (obj_type == OBJ_DELTA)
 262                 to_reuse = 1;   /* check_object() decided it for us */
 263         else if (obj_type != entry->in_pack_type)
 264                 to_reuse = 0;   /* pack has delta which is unusable */
 265         else if (entry->delta)
 266                 to_reuse = 0;   /* we want to pack afresh */
 267         else
 268                 to_reuse = 1;   /* we have it in-pack undeltified,
 269                                  * and we do not need to deltify it.
 270                                  */
 271
 272         if (!entry->in_pack && !entry->delta) {
 273                 unsigned char *map;
 274                 unsigned long mapsize;
 275                 map = map_sha1_file(entry->sha1, &mapsize);
 276                 if (map && !legacy_loose_object(map)) {
 277                         /* We can copy straight into the pack file */
 278                         sha1write(f, map, mapsize);
 279                         munmap(map, mapsize);
 280                         written++;
 281                         reused++;
 282                         return mapsize;
 283                 }
 284                 if (map)
 285                         munmap(map, mapsize);
 286         }
 287
 288         if (! to_reuse) {
 289                 buf = read_sha1_file(entry->sha1, type, &size);
 290                 if (!buf)
 291                         die("unable to read %s", sha1_to_hex(entry->sha1));
 292                 if (size != entry->size)
 293                         die("object %s size inconsistency (%lu vs %lu)",
 294                             sha1_to_hex(entry->sha1), size, entry->size);
 295                 if (entry->delta) {
 296                         buf = delta_against(buf, size, entry);
 297                         size = entry->delta_size;
 298                         obj_type = OBJ_DELTA;
 299                 }
 300                 /*
 301                  * The object header is a byte of 'type' followed by zero or
 302                  * more bytes of length.  For deltas, the 20 bytes of delta
 303                  * sha1 follows that.
 304                  */
 305                 hdrlen = encode_header(obj_type, size, header);
 306                 sha1write(f, header, hdrlen);
 307
 308                 if (entry->delta) {
 309                         sha1write(f, entry->delta, 20);
 310                         hdrlen += 20;
 311                 }
 312                 datalen = sha1write_compressed(f, buf, size);
 313                 free(buf);
 314         }
 315         else {
 316                 struct packed_git *p = entry->in_pack;
 317                 use_packed_git(p);
 318
 319                 datalen = find_packed_object_size(p, entry->in_pack_offset);
 320                 buf = (char *) p->pack_base + entry->in_pack_offset;
 321                 sha1write(f, buf, datalen);
 322                 unuse_packed_git(p);
 323                 hdrlen = 0; /* not really */
 324                 if (obj_type == OBJ_DELTA)
 325                         reused_delta++;
 326                 reused++;
 327         }
 328         if (obj_type == OBJ_DELTA)
 329                 written_delta++;
 330         written++;
 331         return hdrlen + datalen;
 332 }
 333
 334 static unsigned long write_one(struct sha1file *f,
 335                                struct object_entry *e,
 336                                unsigned long offset)
 337 {
 338         if (e->offset)
 339                 /* offset starts from header size and cannot be zero
 340                  * if it is written already.
 341                  */
 342                 return offset;
 343         e->offset = offset;
 344         offset += write_object(f, e);
 345         /* if we are deltified, write out its base object. */
 346         if (e->delta)
 347                 offset = write_one(f, e->delta, offset);
 348         return offset;
 349 }
 350
 351 static void write_pack_file(void)
 352 {
 353         int i;
 354         struct sha1file *f;
 355         unsigned long offset;
 356         struct pack_header hdr;
 357         unsigned last_percent = 999;
 358         int do_progress = 0;
 359
 360         if (!base_name)
 361                 f = sha1fd(1, "<stdout>");
 362         else {
 363                 f = sha1create("%s-%s.%s", base_name,
 364                                sha1_to_hex(object_list_sha1), "pack");
 365                 do_progress = progress;
 366         }
 367         if (do_progress)
 368                 fprintf(stderr, "Writing %d objects.\n", nr_result);
 369
 370         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 371         hdr.hdr_version = htonl(PACK_VERSION);
 372         hdr.hdr_entries = htonl(nr_result);
 373         sha1write(f, &hdr, sizeof(hdr));
 374         offset = sizeof(hdr);
 375         if (!nr_result)
 376                 goto done;
 377         for (i = 0; i < nr_objects; i++) {
 378                 offset = write_one(f, objects + i, offset);
 379                 if (do_progress) {
 380                         unsigned percent = written * 100 / nr_result;
 381                         if (progress_update || percent != last_percent) {
 382                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 383                                         percent, written, nr_result);
 384                                 progress_update = 0;
 385                                 last_percent = percent;
 386                         }
 387                 }
 388         }
 389         if (do_progress)
 390                 fputc('\n', stderr);
 391  done:
 392         sha1close(f, pack_file_sha1, 1);
 393 }
 394
 395 static void write_index_file(void)
 396 {
 397         int i;
 398         struct sha1file *f = sha1create("%s-%s.%s", base_name,
 399                                         sha1_to_hex(object_list_sha1), "idx");
 400         struct object_entry **list = sorted_by_sha;
 401         struct object_entry **last = list + nr_result;
 402         unsigned int array[256];
 403
 404         /*
 405          * Write the first-level table (the list is sorted,
 406          * but we use a 256-entry lookup to be able to avoid
 407          * having to do eight extra binary search iterations).
 408          */
 409         for (i = 0; i < 256; i++) {
 410                 struct object_entry **next = list;
 411                 while (next < last) {
 412                         struct object_entry *entry = *next;
 413                         if (entry->sha1[0] != i)
 414                                 break;
 415                         next++;
 416                 }
 417                 array[i] = htonl(next - sorted_by_sha);
 418                 list = next;
 419         }
 420         sha1write(f, array, 256 * sizeof(int));
 421
 422         /*
 423          * Write the actual SHA1 entries..
 424          */
 425         list = sorted_by_sha;
 426         for (i = 0; i < nr_result; i++) {
 427                 struct object_entry *entry = *list++;
 428                 unsigned int offset = htonl(entry->offset);
 429                 sha1write(f, &offset, 4);
 430                 sha1write(f, entry->sha1, 20);
 431         }
 432         sha1write(f, pack_file_sha1, 20);
 433         sha1close(f, NULL, 1);
 434 }
 435
 436 static int locate_object_entry_hash(const unsigned char *sha1)
 437 {
 438         int i;
 439         unsigned int ui;
 440         memcpy(&ui, sha1, sizeof(unsigned int));
 441         i = ui % object_ix_hashsz;
 442         while (0 < object_ix[i]) {
 443                 if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
 444                         return i;
 445                 if (++i == object_ix_hashsz)
 446                         i = 0;
 447         }
 448         return -1 - i;
 449 }
 450
 451 static struct object_entry *locate_object_entry(const unsigned char *sha1)
 452 {
 453         int i;
 454
 455         if (!object_ix_hashsz)
 456                 return NULL;
 457
 458         i = locate_object_entry_hash(sha1);
 459         if (0 <= i)
 460                 return &objects[object_ix[i]-1];
 461         return NULL;
 462 }
 463
 464 static void rehash_objects(void)
 465 {
 466         int i;
 467         struct object_entry *oe;
 468
 469         object_ix_hashsz = nr_objects * 3;
 470         if (object_ix_hashsz < 1024)
 471                 object_ix_hashsz = 1024;
 472         object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 473         memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 474         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 475                 int ix = locate_object_entry_hash(oe->sha1);
 476                 if (0 <= ix)
 477                         continue;
 478                 ix = -1 - ix;
 479                 object_ix[ix] = i + 1;
 480         }
 481 }
 482
 483 static unsigned name_hash(const char *name)
 484 {
 485         unsigned char c;
 486         unsigned hash = 0;
 487
 488         /*
 489          * This effectively just creates a sortable number from the
 490          * last sixteen non-whitespace characters. Last characters
 491          * count "most", so things that end in ".c" sort together.
 492          */
 493         while ((c = *name++) != 0) {
 494                 if (isspace(c))
 495                         continue;
 496                 hash = (hash >> 2) + (c << 24);
 497         }
 498         return hash;
 499 }
 500
 501 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 502 {
 503         unsigned int idx = nr_objects;
 504         struct object_entry *entry;
 505         struct packed_git *p;
 506         unsigned int found_offset = 0;
 507         struct packed_git *found_pack = NULL;
 508         int ix, status = 0;
 509
 510         if (!exclude) {
 511                 for (p = packed_git; p; p = p->next) {
 512                         struct pack_entry e;
 513                         if (find_pack_entry_one(sha1, &e, p)) {
 514                                 if (incremental)
 515                                         return 0;
 516                                 if (local && !p->pack_local)
 517                                         return 0;
 518                                 if (!found_pack) {
 519                                         found_offset = e.offset;
 520                                         found_pack = e.p;
 521                                 }
 522                         }
 523                 }
 524         }
 525         if ((entry = locate_object_entry(sha1)) != NULL)
 526                 goto already_added;
 527
 528         if (idx >= nr_alloc) {
 529                 unsigned int needed = (idx + 1024) * 3 / 2;
 530                 objects = xrealloc(objects, needed * sizeof(*entry));
 531                 nr_alloc = needed;
 532         }
 533         entry = objects + idx;
 534         nr_objects = idx + 1;
 535         memset(entry, 0, sizeof(*entry));
 536         memcpy(entry->sha1, sha1, 20);
 537         entry->hash = hash;
 538
 539         if (object_ix_hashsz * 3 <= nr_objects * 4)
 540                 rehash_objects();
 541         else {
 542                 ix = locate_object_entry_hash(entry->sha1);
 543                 if (0 <= ix)
 544                         die("internal error in object hashing.");
 545                 object_ix[-1 - ix] = idx + 1;
 546         }
 547         status = 1;
 548
 549  already_added:
 550         if (progress_update) {
 551                 fprintf(stderr, "Counting objects...%d\r", nr_objects);
 552                 progress_update = 0;
 553         }
 554         if (exclude)
 555                 entry->preferred_base = 1;
 556         else {
 557                 if (found_pack) {
 558                         entry->in_pack = found_pack;
 559                         entry->in_pack_offset = found_offset;
 560                 }
 561         }
 562         return status;
 563 }
 564
 565 struct pbase_tree_cache {
 566         unsigned char sha1[20];
 567         int ref;
 568         int temporary;
 569         void *tree_data;
 570         unsigned long tree_size;
 571 };
 572
 573 static struct pbase_tree_cache *(pbase_tree_cache[256]);
 574 static int pbase_tree_cache_ix(const unsigned char *sha1)
 575 {
 576         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 577 }
 578 static int pbase_tree_cache_ix_incr(int ix)
 579 {
 580         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 581 }
 582
 583 static struct pbase_tree {
 584         struct pbase_tree *next;
 585         /* This is a phony "cache" entry; we are not
 586          * going to evict it nor find it through _get()
 587          * mechanism -- this is for the toplevel node that
 588          * would almost always change with any commit.
 589          */
 590         struct pbase_tree_cache pcache;
 591 } *pbase_tree;
 592
 593 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 594 {
 595         struct pbase_tree_cache *ent, *nent;
 596         void *data;
 597         unsigned long size;
 598         char type[20];
 599         int neigh;
 600         int my_ix = pbase_tree_cache_ix(sha1);
 601         int available_ix = -1;
 602
 603         /* pbase-tree-cache acts as a limited hashtable.
 604          * your object will be found at your index or within a few
 605          * slots after that slot if it is cached.
 606          */
 607         for (neigh = 0; neigh < 8; neigh++) {
 608                 ent = pbase_tree_cache[my_ix];
 609                 if (ent && !memcmp(ent->sha1, sha1, 20)) {
 610                         ent->ref++;
 611                         return ent;
 612                 }
 613                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 614                          ((0 <= available_ix) &&
 615                           (!ent && pbase_tree_cache[available_ix])))
 616                         available_ix = my_ix;
 617                 if (!ent)
 618                         break;
 619                 my_ix = pbase_tree_cache_ix_incr(my_ix);
 620         }
 621
 622         /* Did not find one.  Either we got a bogus request or
 623          * we need to read and perhaps cache.
 624          */
 625         data = read_sha1_file(sha1, type, &size);
 626         if (!data)
 627                 return NULL;
 628         if (strcmp(type, tree_type)) {
 629                 free(data);
 630                 return NULL;
 631         }
 632
 633         /* We need to either cache or return a throwaway copy */
 634
 635         if (available_ix < 0)
 636                 ent = NULL;
 637         else {
 638                 ent = pbase_tree_cache[available_ix];
 639                 my_ix = available_ix;
 640         }
 641
 642         if (!ent) {
 643                 nent = xmalloc(sizeof(*nent));
 644                 nent->temporary = (available_ix < 0);
 645         }
 646         else {
 647                 /* evict and reuse */
 648                 free(ent->tree_data);
 649                 nent = ent;
 650         }
 651         memcpy(nent->sha1, sha1, 20);
 652         nent->tree_data = data;
 653         nent->tree_size = size;
 654         nent->ref = 1;
 655         if (!nent->temporary)
 656                 pbase_tree_cache[my_ix] = nent;
 657         return nent;
 658 }
 659
 660 static void pbase_tree_put(struct pbase_tree_cache *cache)
 661 {
 662         if (!cache->temporary) {
 663                 cache->ref--;
 664                 return;
 665         }
 666         free(cache->tree_data);
 667         free(cache);
 668 }
 669
 670 static int name_cmp_len(const char *name)
 671 {
 672         int i;
 673         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 674                 ;
 675         return i;
 676 }
 677
 678 static void add_pbase_object(struct tree_desc *tree,
 679                              const char *name,
 680                              int cmplen,
 681                              const char *fullname)
 682 {
 683         struct name_entry entry;
 684
 685         while (tree_entry(tree,&entry)) {
 686                 unsigned long size;
 687                 char type[20];
 688
 689                 if (entry.pathlen != cmplen ||
 690                     memcmp(entry.path, name, cmplen) ||
 691                     !has_sha1_file(entry.sha1) ||
 692                     sha1_object_info(entry.sha1, type, &size))
 693                         continue;
 694                 if (name[cmplen] != '/') {
 695                         unsigned hash = name_hash(fullname);
 696                         add_object_entry(entry.sha1, hash, 1);
 697                         return;
 698                 }
 699                 if (!strcmp(type, tree_type)) {
 700                         struct tree_desc sub;
 701                         struct pbase_tree_cache *tree;
 702                         const char *down = name+cmplen+1;
 703                         int downlen = name_cmp_len(down);
 704
 705                         tree = pbase_tree_get(entry.sha1);
 706                         if (!tree)
 707                                 return;
 708                         sub.buf = tree->tree_data;
 709                         sub.size = tree->tree_size;
 710
 711                         add_pbase_object(&sub, down, downlen, fullname);
 712                         pbase_tree_put(tree);
 713                 }
 714         }
 715 }
 716
 717 static unsigned *done_pbase_paths;
 718 static int done_pbase_paths_num;
 719 static int done_pbase_paths_alloc;
 720 static int done_pbase_path_pos(unsigned hash)
 721 {
 722         int lo = 0;
 723         int hi = done_pbase_paths_num;
 724         while (lo < hi) {
 725                 int mi = (hi + lo) / 2;
 726                 if (done_pbase_paths[mi] == hash)
 727                         return mi;
 728                 if (done_pbase_paths[mi] < hash)
 729                         hi = mi;
 730                 else
 731                         lo = mi + 1;
 732         }
 733         return -lo-1;
 734 }
 735
 736 static int check_pbase_path(unsigned hash)
 737 {
 738         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
 739         if (0 <= pos)
 740                 return 1;
 741         pos = -pos - 1;
 742         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
 743                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
 744                 done_pbase_paths = xrealloc(done_pbase_paths,
 745                                             done_pbase_paths_alloc *
 746                                             sizeof(unsigned));
 747         }
 748         done_pbase_paths_num++;
 749         if (pos < done_pbase_paths_num)
 750                 memmove(done_pbase_paths + pos + 1,
 751                         done_pbase_paths + pos,
 752                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
 753         done_pbase_paths[pos] = hash;
 754         return 0;
 755 }
 756
 757 static void add_preferred_base_object(char *name, unsigned hash)
 758 {
 759         struct pbase_tree *it;
 760         int cmplen = name_cmp_len(name);
 761
 762         if (check_pbase_path(hash))
 763                 return;
 764
 765         for (it = pbase_tree; it; it = it->next) {
 766                 if (cmplen == 0) {
 767                         hash = name_hash("");
 768                         add_object_entry(it->pcache.sha1, hash, 1);
 769                 }
 770                 else {
 771                         struct tree_desc tree;
 772                         tree.buf = it->pcache.tree_data;
 773                         tree.size = it->pcache.tree_size;
 774                         add_pbase_object(&tree, name, cmplen, name);
 775                 }
 776         }
 777 }
 778
 779 static void add_preferred_base(unsigned char *sha1)
 780 {
 781         struct pbase_tree *it;
 782         void *data;
 783         unsigned long size;
 784         unsigned char tree_sha1[20];
 785
 786         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
 787         if (!data)
 788                 return;
 789
 790         for (it = pbase_tree; it; it = it->next) {
 791                 if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
 792                         free(data);
 793                         return;
 794                 }
 795         }
 796
 797         it = xcalloc(1, sizeof(*it));
 798         it->next = pbase_tree;
 799         pbase_tree = it;
 800
 801         memcpy(it->pcache.sha1, tree_sha1, 20);
 802         it->pcache.tree_data = data;
 803         it->pcache.tree_size = size;
 804 }
 805
 806 static void check_object(struct object_entry *entry)
 807 {
 808         char type[20];
 809
 810         if (entry->in_pack && !entry->preferred_base) {
 811                 unsigned char base[20];
 812                 unsigned long size;
 813                 struct object_entry *base_entry;
 814
 815                 /* We want in_pack_type even if we do not reuse delta.
 816                  * There is no point not reusing non-delta representations.
 817                  */
 818                 check_reuse_pack_delta(entry->in_pack,
 819                                        entry->in_pack_offset,
 820                                        base, &size,
 821                                        &entry->in_pack_type);
 822
 823                 /* Check if it is delta, and the base is also an object
 824                  * we are going to pack.  If so we will reuse the existing
 825                  * delta.
 826                  */
 827                 if (!no_reuse_delta &&
 828                     entry->in_pack_type == OBJ_DELTA &&
 829                     (base_entry = locate_object_entry(base)) &&
 830                     (!base_entry->preferred_base)) {
 831
 832                         /* Depth value does not matter - find_deltas()
 833                          * will never consider reused delta as the
 834                          * base object to deltify other objects
 835                          * against, in order to avoid circular deltas.
 836                          */
 837
 838                         /* uncompressed size of the delta data */
 839                         entry->size = entry->delta_size = size;
 840                         entry->delta = base_entry;
 841                         entry->type = OBJ_DELTA;
 842
 843                         entry->delta_sibling = base_entry->delta_child;
 844                         base_entry->delta_child = entry;
 845
 846                         return;
 847                 }
 848                 /* Otherwise we would do the usual */
 849         }
 850
 851         if (sha1_object_info(entry->sha1, type, &entry->size))
 852                 die("unable to get type of object %s",
 853                     sha1_to_hex(entry->sha1));
 854
 855         if (!strcmp(type, commit_type)) {
 856                 entry->type = OBJ_COMMIT;
 857         } else if (!strcmp(type, tree_type)) {
 858                 entry->type = OBJ_TREE;
 859         } else if (!strcmp(type, blob_type)) {
 860                 entry->type = OBJ_BLOB;
 861         } else if (!strcmp(type, tag_type)) {
 862                 entry->type = OBJ_TAG;
 863         } else
 864                 die("unable to pack object %s of type %s",
 865                     sha1_to_hex(entry->sha1), type);
 866 }
 867
 868 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 869 {
 870         struct object_entry *child = me->delta_child;
 871         unsigned int m = n;
 872         while (child) {
 873                 unsigned int c = check_delta_limit(child, n + 1);
 874                 if (m < c)
 875                         m = c;
 876                 child = child->delta_sibling;
 877         }
 878         return m;
 879 }
 880
 881 static void get_object_details(void)
 882 {
 883         int i;
 884         struct object_entry *entry;
 885
 886         prepare_pack_ix();
 887         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 888                 check_object(entry);
 889
 890         if (nr_objects == nr_result) {
 891                 /*
 892                  * Depth of objects that depend on the entry -- this
 893                  * is subtracted from depth-max to break too deep
 894                  * delta chain because of delta data reusing.
 895                  * However, we loosen this restriction when we know we
 896                  * are creating a thin pack -- it will have to be
 897                  * expanded on the other end anyway, so do not
 898                  * artificially cut the delta chain and let it go as
 899                  * deep as it wants.
 900                  */
 901                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 902                         if (!entry->delta && entry->delta_child)
 903                                 entry->delta_limit =
 904                                         check_delta_limit(entry, 1);
 905         }
 906 }
 907
 908 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 909
 910 static entry_sort_t current_sort;
 911
 912 static int sort_comparator(const void *_a, const void *_b)
 913 {
 914         struct object_entry *a = *(struct object_entry **)_a;
 915         struct object_entry *b = *(struct object_entry **)_b;
 916         return current_sort(a,b);
 917 }
 918
 919 static struct object_entry **create_sorted_list(entry_sort_t sort)
 920 {
 921         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 922         int i;
 923
 924         for (i = 0; i < nr_objects; i++)
 925                 list[i] = objects + i;
 926         current_sort = sort;
 927         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 928         return list;
 929 }
 930
 931 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 932 {
 933         return memcmp(a->sha1, b->sha1, 20);
 934 }
 935
 936 static struct object_entry **create_final_object_list(void)
 937 {
 938         struct object_entry **list;
 939         int i, j;
 940
 941         for (i = nr_result = 0; i < nr_objects; i++)
 942                 if (!objects[i].preferred_base)
 943                         nr_result++;
 944         list = xmalloc(nr_result * sizeof(struct object_entry *));
 945         for (i = j = 0; i < nr_objects; i++) {
 946                 if (!objects[i].preferred_base)
 947                         list[j++] = objects + i;
 948         }
 949         current_sort = sha1_sort;
 950         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
 951         return list;
 952 }
 953
 954 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 955 {
 956         if (a->type < b->type)
 957                 return -1;
 958         if (a->type > b->type)
 959                 return 1;
 960         if (a->hash < b->hash)
 961                 return -1;
 962         if (a->hash > b->hash)
 963                 return 1;
 964         if (a->preferred_base < b->preferred_base)
 965                 return -1;
 966         if (a->preferred_base > b->preferred_base)
 967                 return 1;
 968         if (a->size < b->size)
 969                 return -1;
 970         if (a->size > b->size)
 971                 return 1;
 972         return a < b ? -1 : (a > b);
 973 }
 974
 975 struct unpacked {
 976         struct object_entry *entry;
 977         void *data;
 978         struct delta_index *index;
 979 };
 980
 981 /*
 982  * We search for deltas _backwards_ in a list sorted by type and
 983  * by size, so that we see progressively smaller and smaller files.
 984  * That's because we prefer deltas to be from the bigger file
 985  * to the smaller - deletes are potentially cheaper, but perhaps
 986  * more importantly, the bigger file is likely the more recent
 987  * one.
 988  */
 989 static int try_delta(struct unpacked *trg, struct unpacked *src,
 990                      unsigned max_depth)
 991 {
 992         struct object_entry *trg_entry = trg->entry;
 993         struct object_entry *src_entry = src->entry;
 994         unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
 995         char type[10];
 996         void *delta_buf;
 997
 998         /* Don't bother doing diffs between different types */
 999         if (trg_entry->type != src_entry->type)
1000                 return -1;
1001
1002         /* We do not compute delta to *create* objects we are not
1003          * going to pack.
1004          */
1005         if (trg_entry->preferred_base)
1006                 return -1;
1007
1008         /*
1009          * We do not bother to try a delta that we discarded
1010          * on an earlier try, but only when reusing delta data.
1011          */
1012         if (!no_reuse_delta && trg_entry->in_pack &&
1013             trg_entry->in_pack == src_entry->in_pack)
1014                 return 0;
1015
1016         /*
1017          * If the current object is at pack edge, take the depth the
1018          * objects that depend on the current object into account --
1019          * otherwise they would become too deep.
1020          */
1021         if (trg_entry->delta_child) {
1022                 if (max_depth <= trg_entry->delta_limit)
1023                         return 0;
1024                 max_depth -= trg_entry->delta_limit;
1025         }
1026         if (src_entry->depth >= max_depth)
1027                 return 0;
1028
1029         /* Now some size filtering heuristics. */
1030         trg_size = trg_entry->size;
1031         max_size = trg_size/2 - 20;
1032         max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1033         if (max_size == 0)
1034                 return 0;
1035         if (trg_entry->delta && trg_entry->delta_size <= max_size)
1036                 max_size = trg_entry->delta_size-1;
1037         src_size = src_entry->size;
1038         sizediff = src_size < trg_size ? trg_size - src_size : 0;
1039         if (sizediff >= max_size)
1040                 return 0;
1041
1042         /* Load data if not already done */
1043         if (!trg->data) {
1044                 trg->data = read_sha1_file(trg_entry->sha1, type, &sz);
1045                 if (sz != trg_size)
1046                         die("object %s inconsistent object length (%lu vs %lu)",
1047                             sha1_to_hex(trg_entry->sha1), sz, trg_size);
1048         }
1049         if (!src->data) {
1050                 src->data = read_sha1_file(src_entry->sha1, type, &sz);
1051                 if (sz != src_size)
1052                         die("object %s inconsistent object length (%lu vs %lu)",
1053                             sha1_to_hex(src_entry->sha1), sz, src_size);
1054         }
1055         if (!src->index) {
1056                 src->index = create_delta_index(src->data, src_size);
1057                 if (!src->index)
1058                         die("out of memory");
1059         }
1060
1061         delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1062         if (!delta_buf)
1063                 return 0;
1064
1065         trg_entry->delta = src_entry;
1066         trg_entry->delta_size = delta_size;
1067         trg_entry->depth = src_entry->depth + 1;
1068         free(delta_buf);
1069         return 1;
1070 }
1071
1072 static void progress_interval(int signum)
1073 {
1074         progress_update = 1;
1075 }
1076
1077 static void find_deltas(struct object_entry **list, int window, int depth)
1078 {
1079         int i, idx;
1080         unsigned int array_size = window * sizeof(struct unpacked);
1081         struct unpacked *array = xmalloc(array_size);
1082         unsigned processed = 0;
1083         unsigned last_percent = 999;
1084
1085         memset(array, 0, array_size);
1086         i = nr_objects;
1087         idx = 0;
1088         if (progress)
1089                 fprintf(stderr, "Deltifying %d objects.\n", nr_result);
1090
1091         while (--i >= 0) {
1092                 struct object_entry *entry = list[i];
1093                 struct unpacked *n = array + idx;
1094                 int j;
1095
1096                 if (!entry->preferred_base)
1097                         processed++;
1098
1099                 if (progress) {
1100                         unsigned percent = processed * 100 / nr_result;
1101                         if (percent != last_percent || progress_update) {
1102                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1103                                         percent, processed, nr_result);
1104                                 progress_update = 0;
1105                                 last_percent = percent;
1106                         }
1107                 }
1108
1109                 if (entry->delta)
1110                         /* This happens if we decided to reuse existing
1111                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1112                          */
1113                         continue;
1114
1115                 if (entry->size < 50)
1116                         continue;
1117                 free_delta_index(n->index);
1118                 n->index = NULL;
1119                 free(n->data);
1120                 n->data = NULL;
1121                 n->entry = entry;
1122
1123                 j = window;
1124                 while (--j > 0) {
1125                         unsigned int other_idx = idx + j;
1126                         struct unpacked *m;
1127                         if (other_idx >= window)
1128                                 other_idx -= window;
1129                         m = array + other_idx;
1130                         if (!m->entry)
1131                                 break;
1132                         if (try_delta(n, m, depth) < 0)
1133                                 break;
1134                 }
1135                 /* if we made n a delta, and if n is already at max
1136                  * depth, leaving it in the window is pointless.  we
1137                  * should evict it first.
1138                  */
1139                 if (entry->delta && depth <= entry->depth)
1140                         continue;
1141
1142                 idx++;
1143                 if (idx >= window)
1144                         idx = 0;
1145         }
1146
1147         if (progress)
1148                 fputc('\n', stderr);
1149
1150         for (i = 0; i < window; ++i) {
1151                 free_delta_index(array[i].index);
1152                 free(array[i].data);
1153         }
1154         free(array);
1155 }
1156
1157 static void prepare_pack(int window, int depth)
1158 {
1159         get_object_details();
1160         sorted_by_type = create_sorted_list(type_size_sort);
1161         if (window && depth)
1162                 find_deltas(sorted_by_type, window+1, depth);
1163 }
1164
1165 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
1166 {
1167         static const char cache[] = "pack-cache/pack-%s.%s";
1168         char *cached_pack, *cached_idx;
1169         int ifd, ofd, ifd_ix = -1;
1170
1171         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1172         ifd = open(cached_pack, O_RDONLY);
1173         if (ifd < 0)
1174                 return 0;
1175
1176         if (!pack_to_stdout) {
1177                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1178                 ifd_ix = open(cached_idx, O_RDONLY);
1179                 if (ifd_ix < 0) {
1180                         close(ifd);
1181                         return 0;
1182                 }
1183         }
1184
1185         if (progress)
1186                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1187                         sha1_to_hex(sha1));
1188
1189         if (pack_to_stdout) {
1190                 if (copy_fd(ifd, 1))
1191                         exit(1);
1192                 close(ifd);
1193         }
1194         else {
1195                 char name[PATH_MAX];
1196                 snprintf(name, sizeof(name),
1197                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1198                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1199                 if (ofd < 0)
1200                         die("unable to open %s (%s)", name, strerror(errno));
1201                 if (copy_fd(ifd, ofd))
1202                         exit(1);
1203                 close(ifd);
1204
1205                 snprintf(name, sizeof(name),
1206                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1207                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1208                 if (ofd < 0)
1209                         die("unable to open %s (%s)", name, strerror(errno));
1210                 if (copy_fd(ifd_ix, ofd))
1211                         exit(1);
1212                 close(ifd_ix);
1213                 puts(sha1_to_hex(sha1));
1214         }
1215
1216         return 1;
1217 }
1218
1219 static void setup_progress_signal(void)
1220 {
1221         struct sigaction sa;
1222         struct itimerval v;
1223
1224         memset(&sa, 0, sizeof(sa));
1225         sa.sa_handler = progress_interval;
1226         sigemptyset(&sa.sa_mask);
1227         sa.sa_flags = SA_RESTART;
1228         sigaction(SIGALRM, &sa, NULL);
1229
1230         v.it_interval.tv_sec = 1;
1231         v.it_interval.tv_usec = 0;
1232         v.it_value = v.it_interval;
1233         setitimer(ITIMER_REAL, &v, NULL);
1234 }
1235
1236 static int git_pack_config(const char *k, const char *v)
1237 {
1238         if(!strcmp(k, "pack.window")) {
1239                 window = git_config_int(k, v);
1240                 return 0;
1241         }
1242         return git_default_config(k, v);
1243 }
1244
1245 int main(int argc, char **argv)
1246 {
1247         SHA_CTX ctx;
1248         char line[40 + 1 + PATH_MAX + 2];
1249         int depth = 10, pack_to_stdout = 0;
1250         struct object_entry **list;
1251         int num_preferred_base = 0;
1252         int i;
1253
1254         setup_git_directory();
1255         git_config(git_pack_config);
1256
1257         progress = isatty(2);
1258         for (i = 1; i < argc; i++) {
1259                 const char *arg = argv[i];
1260
1261                 if (*arg == '-') {
1262                         if (!strcmp("--non-empty", arg)) {
1263                                 non_empty = 1;
1264                                 continue;
1265                         }
1266                         if (!strcmp("--local", arg)) {
1267                                 local = 1;
1268                                 continue;
1269                         }
1270                         if (!strcmp("--progress", arg)) {
1271                                 progress = 1;
1272                                 continue;
1273                         }
1274                         if (!strcmp("--incremental", arg)) {
1275                                 incremental = 1;
1276                                 continue;
1277                         }
1278                         if (!strncmp("--window=", arg, 9)) {
1279                                 char *end;
1280                                 window = strtoul(arg+9, &end, 0);
1281                                 if (!arg[9] || *end)
1282                                         usage(pack_usage);
1283                                 continue;
1284                         }
1285                         if (!strncmp("--depth=", arg, 8)) {
1286                                 char *end;
1287                                 depth = strtoul(arg+8, &end, 0);
1288                                 if (!arg[8] || *end)
1289                                         usage(pack_usage);
1290                                 continue;
1291                         }
1292                         if (!strcmp("--progress", arg)) {
1293                                 progress = 1;
1294                                 continue;
1295                         }
1296                         if (!strcmp("-q", arg)) {
1297                                 progress = 0;
1298                                 continue;
1299                         }
1300                         if (!strcmp("--no-reuse-delta", arg)) {
1301                                 no_reuse_delta = 1;
1302                                 continue;
1303                         }
1304                         if (!strcmp("--stdout", arg)) {
1305                                 pack_to_stdout = 1;
1306                                 continue;
1307                         }
1308                         usage(pack_usage);
1309                 }
1310                 if (base_name)
1311                         usage(pack_usage);
1312                 base_name = arg;
1313         }
1314
1315         if (pack_to_stdout != !base_name)
1316                 usage(pack_usage);
1317
1318         prepare_packed_git();
1319
1320         if (progress) {
1321                 fprintf(stderr, "Generating pack...\n");
1322                 setup_progress_signal();
1323         }
1324
1325         for (;;) {
1326                 unsigned char sha1[20];
1327                 unsigned hash;
1328
1329                 if (!fgets(line, sizeof(line), stdin)) {
1330                         if (feof(stdin))
1331                                 break;
1332                         if (!ferror(stdin))
1333                                 die("fgets returned NULL, not EOF, not error!");
1334                         if (errno != EINTR)
1335                                 die("fgets: %s", strerror(errno));
1336                         clearerr(stdin);
1337                         continue;
1338                 }
1339
1340                 if (line[0] == '-') {
1341                         if (get_sha1_hex(line+1, sha1))
1342                                 die("expected edge sha1, got garbage:\n %s",
1343                                     line+1);
1344                         if (num_preferred_base++ < window)
1345                                 add_preferred_base(sha1);
1346                         continue;
1347                 }
1348                 if (get_sha1_hex(line, sha1))
1349                         die("expected sha1, got garbage:\n %s", line);
1350                 hash = name_hash(line+41);
1351                 add_preferred_base_object(line+41, hash);
1352                 add_object_entry(sha1, hash, 0);
1353         }
1354         if (progress)
1355                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1356         sorted_by_sha = create_final_object_list();
1357         if (non_empty && !nr_result)
1358                 return 0;
1359
1360         SHA1_Init(&ctx);
1361         list = sorted_by_sha;
1362         for (i = 0; i < nr_result; i++) {
1363                 struct object_entry *entry = *list++;
1364                 SHA1_Update(&ctx, entry->sha1, 20);
1365         }
1366         SHA1_Final(object_list_sha1, &ctx);
1367         if (progress && (nr_objects != nr_result))
1368                 fprintf(stderr, "Result has %d objects.\n", nr_result);
1369
1370         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1371                 ;
1372         else {
1373                 if (nr_result)
1374                         prepare_pack(window, depth);
1375                 if (progress && pack_to_stdout) {
1376                         /* the other end usually displays progress itself */
1377                         struct itimerval v = {{0,},};
1378                         setitimer(ITIMER_REAL, &v, NULL);
1379                         signal(SIGALRM, SIG_IGN );
1380                         progress_update = 0;
1381                 }
1382                 write_pack_file();
1383                 if (!pack_to_stdout) {
1384                         write_index_file();
1385                         puts(sha1_to_hex(object_list_sha1));
1386                 }
1387         }
1388         if (progress)
1389                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1390                         nr_result, written, written_delta, reused, reused_delta);
1391         return 0;
1392 }