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 struct name_path {
 467         struct name_path *up;
 468         const char *elem;
 469         int len;
 470 };
 471
 472 #define DIRBITS 12
 473
 474 static unsigned name_hash(struct name_path *path, const char *name)
 475 {
 476         struct name_path *p = path;
 477         const char *n = name + strlen(name);
 478         unsigned hash = 0, name_hash = 0, name_done = 0;
 479
 480         if (n != name && n[-1] == '\n')
 481                 n--;
 482         while (name <= --n) {
 483                 unsigned char c = *n;
 484                 if (c == '/' && !name_done) {
 485                         name_hash = hash;
 486                         name_done = 1;
 487                         hash = 0;
 488                 }
 489                 hash = hash * 11 + c;
 490         }
 491         if (!name_done) {
 492                 name_hash = hash;
 493                 hash = 0;
 494         }
 495         for (p = path; p; p = p->up) {
 496                 hash = hash * 11 + '/';
 497                 n = p->elem + p->len;
 498                 while (p->elem <= --n) {
 499                         unsigned char c = *n;
 500                         hash = hash * 11 + c;
 501                 }
 502         }
 503         /*
 504          * Make sure "Makefile" and "t/Makefile" are hashed separately
 505          * but close enough.
 506          */
 507         hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
 508         return hash;
 509 }
 510
 511 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 512 {
 513         unsigned int idx = nr_objects;
 514         struct object_entry *entry;
 515         struct packed_git *p;
 516         unsigned int found_offset = 0;
 517         struct packed_git *found_pack = NULL;
 518         int ix, status = 0;
 519
 520         if (!exclude) {
 521                 for (p = packed_git; p; p = p->next) {
 522                         struct pack_entry e;
 523                         if (find_pack_entry_one(sha1, &e, p)) {
 524                                 if (incremental)
 525                                         return 0;
 526                                 if (local && !p->pack_local)
 527                                         return 0;
 528                                 if (!found_pack) {
 529                                         found_offset = e.offset;
 530                                         found_pack = e.p;
 531                                 }
 532                         }
 533                 }
 534         }
 535         if ((entry = locate_object_entry(sha1)) != NULL)
 536                 goto already_added;
 537
 538         if (idx >= nr_alloc) {
 539                 unsigned int needed = (idx + 1024) * 3 / 2;
 540                 objects = xrealloc(objects, needed * sizeof(*entry));
 541                 nr_alloc = needed;
 542         }
 543         entry = objects + idx;
 544         nr_objects = idx + 1;
 545         memset(entry, 0, sizeof(*entry));
 546         memcpy(entry->sha1, sha1, 20);
 547         entry->hash = hash;
 548
 549         if (object_ix_hashsz * 3 <= nr_objects * 4)
 550                 rehash_objects();
 551         else {
 552                 ix = locate_object_entry_hash(entry->sha1);
 553                 if (0 <= ix)
 554                         die("internal error in object hashing.");
 555                 object_ix[-1 - ix] = idx + 1;
 556         }
 557         status = 1;
 558
 559  already_added:
 560         if (progress_update) {
 561                 fprintf(stderr, "Counting objects...%d\r", nr_objects);
 562                 progress_update = 0;
 563         }
 564         if (exclude)
 565                 entry->preferred_base = 1;
 566         else {
 567                 if (found_pack) {
 568                         entry->in_pack = found_pack;
 569                         entry->in_pack_offset = found_offset;
 570                 }
 571         }
 572         return status;
 573 }
 574
 575 struct pbase_tree_cache {
 576         unsigned char sha1[20];
 577         int ref;
 578         int temporary;
 579         void *tree_data;
 580         unsigned long tree_size;
 581 };
 582
 583 static struct pbase_tree_cache *(pbase_tree_cache[256]);
 584 static int pbase_tree_cache_ix(const unsigned char *sha1)
 585 {
 586         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 587 }
 588 static int pbase_tree_cache_ix_incr(int ix)
 589 {
 590         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 591 }
 592
 593 static struct pbase_tree {
 594         struct pbase_tree *next;
 595         /* This is a phony "cache" entry; we are not
 596          * going to evict it nor find it through _get()
 597          * mechanism -- this is for the toplevel node that
 598          * would almost always change with any commit.
 599          */
 600         struct pbase_tree_cache pcache;
 601 } *pbase_tree;
 602
 603 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 604 {
 605         struct pbase_tree_cache *ent, *nent;
 606         void *data;
 607         unsigned long size;
 608         char type[20];
 609         int neigh;
 610         int my_ix = pbase_tree_cache_ix(sha1);
 611         int available_ix = -1;
 612
 613         /* pbase-tree-cache acts as a limited hashtable.
 614          * your object will be found at your index or within a few
 615          * slots after that slot if it is cached.
 616          */
 617         for (neigh = 0; neigh < 8; neigh++) {
 618                 ent = pbase_tree_cache[my_ix];
 619                 if (ent && !memcmp(ent->sha1, sha1, 20)) {
 620                         ent->ref++;
 621                         return ent;
 622                 }
 623                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 624                          ((0 <= available_ix) &&
 625                           (!ent && pbase_tree_cache[available_ix])))
 626                         available_ix = my_ix;
 627                 if (!ent)
 628                         break;
 629                 my_ix = pbase_tree_cache_ix_incr(my_ix);
 630         }
 631
 632         /* Did not find one.  Either we got a bogus request or
 633          * we need to read and perhaps cache.
 634          */
 635         data = read_sha1_file(sha1, type, &size);
 636         if (!data)
 637                 return NULL;
 638         if (strcmp(type, tree_type)) {
 639                 free(data);
 640                 return NULL;
 641         }
 642
 643         /* We need to either cache or return a throwaway copy */
 644
 645         if (available_ix < 0)
 646                 ent = NULL;
 647         else {
 648                 ent = pbase_tree_cache[available_ix];
 649                 my_ix = available_ix;
 650         }
 651
 652         if (!ent) {
 653                 nent = xmalloc(sizeof(*nent));
 654                 nent->temporary = (available_ix < 0);
 655         }
 656         else {
 657                 /* evict and reuse */
 658                 free(ent->tree_data);
 659                 nent = ent;
 660         }
 661         memcpy(nent->sha1, sha1, 20);
 662         nent->tree_data = data;
 663         nent->tree_size = size;
 664         nent->ref = 1;
 665         if (!nent->temporary)
 666                 pbase_tree_cache[my_ix] = nent;
 667         return nent;
 668 }
 669
 670 static void pbase_tree_put(struct pbase_tree_cache *cache)
 671 {
 672         if (!cache->temporary) {
 673                 cache->ref--;
 674                 return;
 675         }
 676         free(cache->tree_data);
 677         free(cache);
 678 }
 679
 680 static int name_cmp_len(const char *name)
 681 {
 682         int i;
 683         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 684                 ;
 685         return i;
 686 }
 687
 688 static void add_pbase_object(struct tree_desc *tree,
 689                              struct name_path *up,
 690                              const char *name,
 691                              int cmplen)
 692 {
 693         struct name_entry entry;
 694
 695         while (tree_entry(tree,&entry)) {
 696                 unsigned long size;
 697                 char type[20];
 698
 699                 if (entry.pathlen != cmplen ||
 700                     memcmp(entry.path, name, cmplen) ||
 701                     !has_sha1_file(entry.sha1) ||
 702                     sha1_object_info(entry.sha1, type, &size))
 703                         continue;
 704                 if (name[cmplen] != '/') {
 705                         unsigned hash = name_hash(up, name);
 706                         add_object_entry(entry.sha1, hash, 1);
 707                         return;
 708                 }
 709                 if (!strcmp(type, tree_type)) {
 710                         struct tree_desc sub;
 711                         struct name_path me;
 712                         struct pbase_tree_cache *tree;
 713                         const char *down = name+cmplen+1;
 714                         int downlen = name_cmp_len(down);
 715
 716                         tree = pbase_tree_get(entry.sha1);
 717                         if (!tree)
 718                                 return;
 719                         sub.buf = tree->tree_data;
 720                         sub.size = tree->tree_size;
 721
 722                         me.up = up;
 723                         me.elem = entry.path;
 724                         me.len = entry.pathlen;
 725                         add_pbase_object(&sub, &me, down, downlen);
 726                         pbase_tree_put(tree);
 727                 }
 728         }
 729 }
 730
 731 static unsigned *done_pbase_paths;
 732 static int done_pbase_paths_num;
 733 static int done_pbase_paths_alloc;
 734 static int done_pbase_path_pos(unsigned hash)
 735 {
 736         int lo = 0;
 737         int hi = done_pbase_paths_num;
 738         while (lo < hi) {
 739                 int mi = (hi + lo) / 2;
 740                 if (done_pbase_paths[mi] == hash)
 741                         return mi;
 742                 if (done_pbase_paths[mi] < hash)
 743                         hi = mi;
 744                 else
 745                         lo = mi + 1;
 746         }
 747         return -lo-1;
 748 }
 749
 750 static int check_pbase_path(unsigned hash)
 751 {
 752         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
 753         if (0 <= pos)
 754                 return 1;
 755         pos = -pos - 1;
 756         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
 757                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
 758                 done_pbase_paths = xrealloc(done_pbase_paths,
 759                                             done_pbase_paths_alloc *
 760                                             sizeof(unsigned));
 761         }
 762         done_pbase_paths_num++;
 763         if (pos < done_pbase_paths_num)
 764                 memmove(done_pbase_paths + pos + 1,
 765                         done_pbase_paths + pos,
 766                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
 767         done_pbase_paths[pos] = hash;
 768         return 0;
 769 }
 770
 771 static void add_preferred_base_object(char *name, unsigned hash)
 772 {
 773         struct pbase_tree *it;
 774         int cmplen = name_cmp_len(name);
 775
 776         if (check_pbase_path(hash))
 777                 return;
 778
 779         for (it = pbase_tree; it; it = it->next) {
 780                 if (cmplen == 0) {
 781                         hash = name_hash(NULL, "");
 782                         add_object_entry(it->pcache.sha1, hash, 1);
 783                 }
 784                 else {
 785                         struct tree_desc tree;
 786                         tree.buf = it->pcache.tree_data;
 787                         tree.size = it->pcache.tree_size;
 788                         add_pbase_object(&tree, NULL, name, cmplen);
 789                 }
 790         }
 791 }
 792
 793 static void add_preferred_base(unsigned char *sha1)
 794 {
 795         struct pbase_tree *it;
 796         void *data;
 797         unsigned long size;
 798         unsigned char tree_sha1[20];
 799
 800         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
 801         if (!data)
 802                 return;
 803
 804         for (it = pbase_tree; it; it = it->next) {
 805                 if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
 806                         free(data);
 807                         return;
 808                 }
 809         }
 810
 811         it = xcalloc(1, sizeof(*it));
 812         it->next = pbase_tree;
 813         pbase_tree = it;
 814
 815         memcpy(it->pcache.sha1, tree_sha1, 20);
 816         it->pcache.tree_data = data;
 817         it->pcache.tree_size = size;
 818 }
 819
 820 static void check_object(struct object_entry *entry)
 821 {
 822         char type[20];
 823
 824         if (entry->in_pack && !entry->preferred_base) {
 825                 unsigned char base[20];
 826                 unsigned long size;
 827                 struct object_entry *base_entry;
 828
 829                 /* We want in_pack_type even if we do not reuse delta.
 830                  * There is no point not reusing non-delta representations.
 831                  */
 832                 check_reuse_pack_delta(entry->in_pack,
 833                                        entry->in_pack_offset,
 834                                        base, &size,
 835                                        &entry->in_pack_type);
 836
 837                 /* Check if it is delta, and the base is also an object
 838                  * we are going to pack.  If so we will reuse the existing
 839                  * delta.
 840                  */
 841                 if (!no_reuse_delta &&
 842                     entry->in_pack_type == OBJ_DELTA &&
 843                     (base_entry = locate_object_entry(base)) &&
 844                     (!base_entry->preferred_base)) {
 845
 846                         /* Depth value does not matter - find_deltas()
 847                          * will never consider reused delta as the
 848                          * base object to deltify other objects
 849                          * against, in order to avoid circular deltas.
 850                          */
 851
 852                         /* uncompressed size of the delta data */
 853                         entry->size = entry->delta_size = size;
 854                         entry->delta = base_entry;
 855                         entry->type = OBJ_DELTA;
 856
 857                         entry->delta_sibling = base_entry->delta_child;
 858                         base_entry->delta_child = entry;
 859
 860                         return;
 861                 }
 862                 /* Otherwise we would do the usual */
 863         }
 864
 865         if (sha1_object_info(entry->sha1, type, &entry->size))
 866                 die("unable to get type of object %s",
 867                     sha1_to_hex(entry->sha1));
 868
 869         if (!strcmp(type, commit_type)) {
 870                 entry->type = OBJ_COMMIT;
 871         } else if (!strcmp(type, tree_type)) {
 872                 entry->type = OBJ_TREE;
 873         } else if (!strcmp(type, blob_type)) {
 874                 entry->type = OBJ_BLOB;
 875         } else if (!strcmp(type, tag_type)) {
 876                 entry->type = OBJ_TAG;
 877         } else
 878                 die("unable to pack object %s of type %s",
 879                     sha1_to_hex(entry->sha1), type);
 880 }
 881
 882 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 883 {
 884         struct object_entry *child = me->delta_child;
 885         unsigned int m = n;
 886         while (child) {
 887                 unsigned int c = check_delta_limit(child, n + 1);
 888                 if (m < c)
 889                         m = c;
 890                 child = child->delta_sibling;
 891         }
 892         return m;
 893 }
 894
 895 static void get_object_details(void)
 896 {
 897         int i;
 898         struct object_entry *entry;
 899
 900         prepare_pack_ix();
 901         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 902                 check_object(entry);
 903
 904         if (nr_objects == nr_result) {
 905                 /*
 906                  * Depth of objects that depend on the entry -- this
 907                  * is subtracted from depth-max to break too deep
 908                  * delta chain because of delta data reusing.
 909                  * However, we loosen this restriction when we know we
 910                  * are creating a thin pack -- it will have to be
 911                  * expanded on the other end anyway, so do not
 912                  * artificially cut the delta chain and let it go as
 913                  * deep as it wants.
 914                  */
 915                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 916                         if (!entry->delta && entry->delta_child)
 917                                 entry->delta_limit =
 918                                         check_delta_limit(entry, 1);
 919         }
 920 }
 921
 922 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 923
 924 static entry_sort_t current_sort;
 925
 926 static int sort_comparator(const void *_a, const void *_b)
 927 {
 928         struct object_entry *a = *(struct object_entry **)_a;
 929         struct object_entry *b = *(struct object_entry **)_b;
 930         return current_sort(a,b);
 931 }
 932
 933 static struct object_entry **create_sorted_list(entry_sort_t sort)
 934 {
 935         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 936         int i;
 937
 938         for (i = 0; i < nr_objects; i++)
 939                 list[i] = objects + i;
 940         current_sort = sort;
 941         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 942         return list;
 943 }
 944
 945 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 946 {
 947         return memcmp(a->sha1, b->sha1, 20);
 948 }
 949
 950 static struct object_entry **create_final_object_list(void)
 951 {
 952         struct object_entry **list;
 953         int i, j;
 954
 955         for (i = nr_result = 0; i < nr_objects; i++)
 956                 if (!objects[i].preferred_base)
 957                         nr_result++;
 958         list = xmalloc(nr_result * sizeof(struct object_entry *));
 959         for (i = j = 0; i < nr_objects; i++) {
 960                 if (!objects[i].preferred_base)
 961                         list[j++] = objects + i;
 962         }
 963         current_sort = sha1_sort;
 964         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
 965         return list;
 966 }
 967
 968 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 969 {
 970         if (a->type < b->type)
 971                 return -1;
 972         if (a->type > b->type)
 973                 return 1;
 974         if (a->hash < b->hash)
 975                 return -1;
 976         if (a->hash > b->hash)
 977                 return 1;
 978         if (a->preferred_base < b->preferred_base)
 979                 return -1;
 980         if (a->preferred_base > b->preferred_base)
 981                 return 1;
 982         if (a->size < b->size)
 983                 return -1;
 984         if (a->size > b->size)
 985                 return 1;
 986         return a < b ? -1 : (a > b);
 987 }
 988
 989 struct unpacked {
 990         struct object_entry *entry;
 991         void *data;
 992         struct delta_index *index;
 993 };
 994
 995 /*
 996  * We search for deltas _backwards_ in a list sorted by type and
 997  * by size, so that we see progressively smaller and smaller files.
 998  * That's because we prefer deltas to be from the bigger file
 999  * to the smaller - deletes are potentially cheaper, but perhaps
1000  * more importantly, the bigger file is likely the more recent
1001  * one.
1002  */
1003 static int try_delta(struct unpacked *trg, struct unpacked *src,
1004                      struct delta_index *src_index, unsigned max_depth)
1005 {
1006         struct object_entry *trg_entry = trg->entry;
1007         struct object_entry *src_entry = src->entry;
1008         unsigned long size, src_size, delta_size, sizediff, max_size;
1009         void *delta_buf;
1010
1011         /* Don't bother doing diffs between different types */
1012         if (trg_entry->type != src_entry->type)
1013                 return -1;
1014
1015         /* We do not compute delta to *create* objects we are not
1016          * going to pack.
1017          */
1018         if (trg_entry->preferred_base)
1019                 return -1;
1020
1021         /*
1022          * If the current object is at pack edge, take the depth the
1023          * objects that depend on the current object into account --
1024          * otherwise they would become too deep.
1025          */
1026         if (trg_entry->delta_child) {
1027                 if (max_depth <= trg_entry->delta_limit)
1028                         return 0;
1029                 max_depth -= trg_entry->delta_limit;
1030         }
1031         if (src_entry->depth >= max_depth)
1032                 return 0;
1033
1034         /* Now some size filtering heuristics. */
1035         size = trg_entry->size;
1036         max_size = size/2 - 20;
1037         max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1038         if (max_size == 0)
1039                 return 0;
1040         if (trg_entry->delta && trg_entry->delta_size <= max_size)
1041                 max_size = trg_entry->delta_size-1;
1042         src_size = src_entry->size;
1043         sizediff = src_size < size ? size - src_size : 0;
1044         if (sizediff >= max_size)
1045                 return 0;
1046
1047         delta_buf = create_delta(src_index, trg->data, size, &delta_size, max_size);
1048         if (!delta_buf)
1049                 return 0;
1050
1051         trg_entry->delta = src_entry;
1052         trg_entry->delta_size = delta_size;
1053         trg_entry->depth = src_entry->depth + 1;
1054         free(delta_buf);
1055         return 1;
1056 }
1057
1058 static void progress_interval(int signum)
1059 {
1060         progress_update = 1;
1061 }
1062
1063 static void find_deltas(struct object_entry **list, int window, int depth)
1064 {
1065         int i, idx;
1066         unsigned int array_size = window * sizeof(struct unpacked);
1067         struct unpacked *array = xmalloc(array_size);
1068         unsigned processed = 0;
1069         unsigned last_percent = 999;
1070
1071         memset(array, 0, array_size);
1072         i = nr_objects;
1073         idx = 0;
1074         if (progress)
1075                 fprintf(stderr, "Deltifying %d objects.\n", nr_result);
1076
1077         while (--i >= 0) {
1078                 struct object_entry *entry = list[i];
1079                 struct unpacked *n = array + idx;
1080                 unsigned long size;
1081                 char type[10];
1082                 int j;
1083
1084                 if (!entry->preferred_base)
1085                         processed++;
1086
1087                 if (progress) {
1088                         unsigned percent = processed * 100 / nr_result;
1089                         if (percent != last_percent || progress_update) {
1090                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1091                                         percent, processed, nr_result);
1092                                 progress_update = 0;
1093                                 last_percent = percent;
1094                         }
1095                 }
1096
1097                 if (entry->delta)
1098                         /* This happens if we decided to reuse existing
1099                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1100                          */
1101                         continue;
1102
1103                 if (entry->size < 50)
1104                         continue;
1105                 free_delta_index(n->index);
1106                 n->index = NULL;
1107                 free(n->data);
1108                 n->entry = entry;
1109                 n->data = read_sha1_file(entry->sha1, type, &size);
1110                 if (size != entry->size)
1111                         die("object %s inconsistent object length (%lu vs %lu)",
1112                             sha1_to_hex(entry->sha1), size, entry->size);
1113
1114                 j = window;
1115                 while (--j > 0) {
1116                         unsigned int other_idx = idx + j;
1117                         struct unpacked *m;
1118                         if (other_idx >= window)
1119                                 other_idx -= window;
1120                         m = array + other_idx;
1121                         if (!m->entry)
1122                                 break;
1123                         if (try_delta(n, m, m->index, depth) < 0)
1124                                 break;
1125                 }
1126                 /* if we made n a delta, and if n is already at max
1127                  * depth, leaving it in the window is pointless.  we
1128                  * should evict it first.
1129                  */
1130                 if (entry->delta && depth <= entry->depth)
1131                         continue;
1132
1133                 n->index = create_delta_index(n->data, size);
1134                 if (!n->index)
1135                         die("out of memory");
1136
1137                 idx++;
1138                 if (idx >= window)
1139                         idx = 0;
1140         }
1141
1142         if (progress)
1143                 fputc('\n', stderr);
1144
1145         for (i = 0; i < window; ++i) {
1146                 free_delta_index(array[i].index);
1147                 free(array[i].data);
1148         }
1149         free(array);
1150 }
1151
1152 static void prepare_pack(int window, int depth)
1153 {
1154         get_object_details();
1155         sorted_by_type = create_sorted_list(type_size_sort);
1156         if (window && depth)
1157                 find_deltas(sorted_by_type, window+1, depth);
1158 }
1159
1160 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
1161 {
1162         static const char cache[] = "pack-cache/pack-%s.%s";
1163         char *cached_pack, *cached_idx;
1164         int ifd, ofd, ifd_ix = -1;
1165
1166         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1167         ifd = open(cached_pack, O_RDONLY);
1168         if (ifd < 0)
1169                 return 0;
1170
1171         if (!pack_to_stdout) {
1172                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1173                 ifd_ix = open(cached_idx, O_RDONLY);
1174                 if (ifd_ix < 0) {
1175                         close(ifd);
1176                         return 0;
1177                 }
1178         }
1179
1180         if (progress)
1181                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1182                         sha1_to_hex(sha1));
1183
1184         if (pack_to_stdout) {
1185                 if (copy_fd(ifd, 1))
1186                         exit(1);
1187                 close(ifd);
1188         }
1189         else {
1190                 char name[PATH_MAX];
1191                 snprintf(name, sizeof(name),
1192                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1193                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1194                 if (ofd < 0)
1195                         die("unable to open %s (%s)", name, strerror(errno));
1196                 if (copy_fd(ifd, ofd))
1197                         exit(1);
1198                 close(ifd);
1199
1200                 snprintf(name, sizeof(name),
1201                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1202                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1203                 if (ofd < 0)
1204                         die("unable to open %s (%s)", name, strerror(errno));
1205                 if (copy_fd(ifd_ix, ofd))
1206                         exit(1);
1207                 close(ifd_ix);
1208                 puts(sha1_to_hex(sha1));
1209         }
1210
1211         return 1;
1212 }
1213
1214 static void setup_progress_signal(void)
1215 {
1216         struct sigaction sa;
1217         struct itimerval v;
1218
1219         memset(&sa, 0, sizeof(sa));
1220         sa.sa_handler = progress_interval;
1221         sigemptyset(&sa.sa_mask);
1222         sa.sa_flags = SA_RESTART;
1223         sigaction(SIGALRM, &sa, NULL);
1224
1225         v.it_interval.tv_sec = 1;
1226         v.it_interval.tv_usec = 0;
1227         v.it_value = v.it_interval;
1228         setitimer(ITIMER_REAL, &v, NULL);
1229 }
1230
1231 int main(int argc, char **argv)
1232 {
1233         SHA_CTX ctx;
1234         char line[40 + 1 + PATH_MAX + 2];
1235         int window = 10, depth = 10, pack_to_stdout = 0;
1236         struct object_entry **list;
1237         int num_preferred_base = 0;
1238         int i;
1239
1240         setup_git_directory();
1241
1242         progress = isatty(2);
1243         for (i = 1; i < argc; i++) {
1244                 const char *arg = argv[i];
1245
1246                 if (*arg == '-') {
1247                         if (!strcmp("--non-empty", arg)) {
1248                                 non_empty = 1;
1249                                 continue;
1250                         }
1251                         if (!strcmp("--local", arg)) {
1252                                 local = 1;
1253                                 continue;
1254                         }
1255                         if (!strcmp("--incremental", arg)) {
1256                                 incremental = 1;
1257                                 continue;
1258                         }
1259                         if (!strncmp("--window=", arg, 9)) {
1260                                 char *end;
1261                                 window = strtoul(arg+9, &end, 0);
1262                                 if (!arg[9] || *end)
1263                                         usage(pack_usage);
1264                                 continue;
1265                         }
1266                         if (!strncmp("--depth=", arg, 8)) {
1267                                 char *end;
1268                                 depth = strtoul(arg+8, &end, 0);
1269                                 if (!arg[8] || *end)
1270                                         usage(pack_usage);
1271                                 continue;
1272                         }
1273                         if (!strcmp("--progress", arg)) {
1274                                 progress = 1;
1275                                 continue;
1276                         }
1277                         if (!strcmp("-q", arg)) {
1278                                 progress = 0;
1279                                 continue;
1280                         }
1281                         if (!strcmp("--no-reuse-delta", arg)) {
1282                                 no_reuse_delta = 1;
1283                                 continue;
1284                         }
1285                         if (!strcmp("--stdout", arg)) {
1286                                 pack_to_stdout = 1;
1287                                 continue;
1288                         }
1289                         usage(pack_usage);
1290                 }
1291                 if (base_name)
1292                         usage(pack_usage);
1293                 base_name = arg;
1294         }
1295
1296         if (pack_to_stdout != !base_name)
1297                 usage(pack_usage);
1298
1299         prepare_packed_git();
1300
1301         if (progress) {
1302                 fprintf(stderr, "Generating pack...\n");
1303                 setup_progress_signal();
1304         }
1305
1306         for (;;) {
1307                 unsigned char sha1[20];
1308                 unsigned hash;
1309
1310                 if (!fgets(line, sizeof(line), stdin)) {
1311                         if (feof(stdin))
1312                                 break;
1313                         if (!ferror(stdin))
1314                                 die("fgets returned NULL, not EOF, not error!");
1315                         if (errno != EINTR)
1316                                 die("fgets: %s", strerror(errno));
1317                         clearerr(stdin);
1318                         continue;
1319                 }
1320
1321                 if (line[0] == '-') {
1322                         if (get_sha1_hex(line+1, sha1))
1323                                 die("expected edge sha1, got garbage:\n %s",
1324                                     line+1);
1325                         if (num_preferred_base++ < window)
1326                                 add_preferred_base(sha1);
1327                         continue;
1328                 }
1329                 if (get_sha1_hex(line, sha1))
1330                         die("expected sha1, got garbage:\n %s", line);
1331                 hash = name_hash(NULL, line+41);
1332                 add_preferred_base_object(line+41, hash);
1333                 add_object_entry(sha1, hash, 0);
1334         }
1335         if (progress)
1336                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1337         sorted_by_sha = create_final_object_list();
1338         if (non_empty && !nr_result)
1339                 return 0;
1340
1341         SHA1_Init(&ctx);
1342         list = sorted_by_sha;
1343         for (i = 0; i < nr_result; i++) {
1344                 struct object_entry *entry = *list++;
1345                 SHA1_Update(&ctx, entry->sha1, 20);
1346         }
1347         SHA1_Final(object_list_sha1, &ctx);
1348         if (progress && (nr_objects != nr_result))
1349                 fprintf(stderr, "Result has %d objects.\n", nr_result);
1350
1351         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1352                 ;
1353         else {
1354                 if (nr_result)
1355                         prepare_pack(window, depth);
1356                 if (progress && pack_to_stdout) {
1357                         /* the other end usually displays progress itself */
1358                         struct itimerval v = {{0,},};
1359                         setitimer(ITIMER_REAL, &v, NULL);
1360                         signal(SIGALRM, SIG_IGN );
1361                         progress_update = 0;
1362                 }
1363                 write_pack_file();
1364                 if (!pack_to_stdout) {
1365                         write_index_file();
1366                         puts(sha1_to_hex(object_list_sha1));
1367                 }
1368         }
1369         if (progress)
1370                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1371                         nr_result, written, written_delta, reused, reused_delta);
1372         return 0;
1373 }