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