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

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "blob.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "tree.h"
   7 #include "delta.h"
   8 #include "pack.h"
   9 #include "csum-file.h"
  10 #include "tree-walk.h"
  11 #include "rabinpoly.h"
  12 #include "gsimm.h"
  13 #include <sys/time.h>
  14 #include <signal.h>
  15
  16 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";
  17
  18 struct object_entry {
  19         unsigned char sha1[20];
  20         unsigned long size;     /* uncompressed size */
  21         unsigned long offset;   /* offset into the final pack file;
  22                                  * nonzero if already written.
  23                                  */
  24         unsigned int depth;     /* delta depth */
  25         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  26         unsigned int hash;      /* name hint hash */
  27         enum object_type type;
  28         enum object_type in_pack_type;  /* could be delta */
  29         unsigned long delta_size;       /* delta data size (uncompressed) */
  30         struct object_entry *delta;     /* delta base object */
  31         struct packed_git *in_pack;     /* already in pack */
  32         unsigned int in_pack_offset;
  33         struct object_entry *delta_child; /* delitified objects who bases me */
  34         struct object_entry *delta_sibling; /* other deltified objects who
  35                                              * uses the same base as me
  36                                              */
  37         int preferred_base;     /* we do not pack this, but is encouraged to
  38                                  * be used as the base objectto delta huge
  39                                  * objects against.
  40                                  */
  41 };
  42
  43 /*
  44  * Objects we are going to pack are colected in objects array (dynamically
  45  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  46  * in the order we see -- typically rev-list --objects order that gives us
  47  * nice "minimum seek" order.
  48  *
  49  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  50  * elements in the objects array.  The former is used to build the pack
  51  * index (lists object names in the ascending order to help offset lookup),
  52  * and the latter is used to group similar things together by try_delta()
  53  * heuristics.
  54  */
  55
  56 static unsigned char object_list_sha1[20];
  57 static int non_empty = 0;
  58 static int no_reuse_delta = 0;
  59 static int local = 0;
  60 static int incremental = 0;
  61 static struct object_entry **sorted_by_sha, **sorted_by_type;
  62 static struct object_entry *objects = NULL;
  63 static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
  64 static const char *base_name;
  65 static unsigned char pack_file_sha1[20];
  66 static int progress = 1;
  67 static volatile sig_atomic_t progress_update = 0;
  68
  69 /*
  70  * The object names in objects array are hashed with this hashtable,
  71  * to help looking up the entry by object name.  Binary search from
  72  * sorted_by_sha is also possible but this was easier to code and faster.
  73  * This hashtable is built after all the objects are seen.
  74  */
  75 static int *object_ix = NULL;
  76 static int object_ix_hashsz = 0;
  77
  78 /*
  79  * Pack index for existing packs give us easy access to the offsets into
  80  * corresponding pack file where each object's data starts, but the entries
  81  * do not store the size of the compressed representation (uncompressed
  82  * size is easily available by examining the pack entry header).  We build
  83  * a hashtable of existing packs (pack_revindex), and keep reverse index
  84  * here -- pack index file is sorted by object name mapping to offset; this
  85  * pack_revindex[].revindex array is an ordered list of offsets, so if you
  86  * know the offset of an object, next offset is where its packed
  87  * representation ends.
  88  */
  89 struct pack_revindex {
  90         struct packed_git *p;
  91         unsigned long *revindex;
  92 } *pack_revindex = NULL;
  93 static int pack_revindex_hashsz = 0;
  94
  95 /*
  96  * stats
  97  */
  98 static int written = 0;
  99 static int written_delta = 0;
 100 static int reused = 0;
 101 static int reused_delta = 0;
 102
 103 static int pack_revindex_ix(struct packed_git *p)
 104 {
 105         unsigned long ui = (unsigned long)p;
 106         int i;
 107
 108         ui = ui ^ (ui >> 16); /* defeat structure alignment */
 109         i = (int)(ui % pack_revindex_hashsz);
 110         while (pack_revindex[i].p) {
 111                 if (pack_revindex[i].p == p)
 112                         return i;
 113                 if (++i == pack_revindex_hashsz)
 114                         i = 0;
 115         }
 116         return -1 - i;
 117 }
 118
 119 static void prepare_pack_ix(void)
 120 {
 121         int num;
 122         struct packed_git *p;
 123         for (num = 0, p = packed_git; p; p = p->next)
 124                 num++;
 125         if (!num)
 126                 return;
 127         pack_revindex_hashsz = num * 11;
 128         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 129         for (p = packed_git; p; p = p->next) {
 130                 num = pack_revindex_ix(p);
 131                 num = - 1 - num;
 132                 pack_revindex[num].p = p;
 133         }
 134         /* revindex elements are lazily initialized */
 135 }
 136
 137 static int cmp_offset(const void *a_, const void *b_)
 138 {
 139         unsigned long a = *(unsigned long *) a_;
 140         unsigned long b = *(unsigned long *) b_;
 141         if (a < b)
 142                 return -1;
 143         else if (a == b)
 144                 return 0;
 145         else
 146                 return 1;
 147 }
 148
 149 /*
 150  * Ordered list of offsets of objects in the pack.
 151  */
 152 static void prepare_pack_revindex(struct pack_revindex *rix)
 153 {
 154         struct packed_git *p = rix->p;
 155         int num_ent = num_packed_objects(p);
 156         int i;
 157         void *index = p->index_base + 256;
 158
 159         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 160         for (i = 0; i < num_ent; i++) {
 161                 long hl = *((long *)(index + 24 * i));
 162                 rix->revindex[i] = ntohl(hl);
 163         }
 164         /* This knows the pack format -- the 20-byte trailer
 165          * follows immediately after the last object data.
 166          */
 167         rix->revindex[num_ent] = p->pack_size - 20;
 168         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 169 }
 170
 171 static unsigned long find_packed_object_size(struct packed_git *p,
 172                                              unsigned long ofs)
 173 {
 174         int num;
 175         int lo, hi;
 176         struct pack_revindex *rix;
 177         unsigned long *revindex;
 178         num = pack_revindex_ix(p);
 179         if (num < 0)
 180                 die("internal error: pack revindex uninitialized");
 181         rix = &pack_revindex[num];
 182         if (!rix->revindex)
 183                 prepare_pack_revindex(rix);
 184         revindex = rix->revindex;
 185         lo = 0;
 186         hi = num_packed_objects(p) + 1;
 187         do {
 188                 int mi = (lo + hi) / 2;
 189                 if (revindex[mi] == ofs) {
 190                         return revindex[mi+1] - ofs;
 191                 }
 192                 else if (ofs < revindex[mi])
 193                         hi = mi;
 194                 else
 195                         lo = mi + 1;
 196         } while (lo < hi);
 197         die("internal error: pack revindex corrupt");
 198 }
 199
 200 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 201 {
 202         unsigned long othersize, delta_size;
 203         char type[10];
 204         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 205         void *delta_buf;
 206
 207         if (!otherbuf)
 208                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 209         delta_buf = diff_delta(otherbuf, othersize,
 210                                buf, size, &delta_size, 0);
 211         if (!delta_buf || delta_size != entry->delta_size)
 212                 die("delta size changed");
 213         free(buf);
 214         free(otherbuf);
 215         return delta_buf;
 216 }
 217
 218 /*
 219  * The per-object header is a pretty dense thing, which is
 220  *  - first byte: low four bits are "size", then three bits of "type",
 221  *    and the high bit is "size continues".
 222  *  - each byte afterwards: low seven bits are size continuation,
 223  *    with the high bit being "size continues"
 224  */
 225 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 226 {
 227         int n = 1;
 228         unsigned char c;
 229
 230         if (type < OBJ_COMMIT || type > OBJ_DELTA)
 231                 die("bad type %d", type);
 232
 233         c = (type << 4) | (size & 15);
 234         size >>= 4;
 235         while (size) {
 236                 *hdr++ = c | 0x80;
 237                 c = size & 0x7f;
 238                 size >>= 7;
 239                 n++;
 240         }
 241         *hdr = c;
 242         return n;
 243 }
 244
 245 static unsigned long write_object(struct sha1file *f,
 246                                   struct object_entry *entry)
 247 {
 248         unsigned long size;
 249         char type[10];
 250         void *buf;
 251         unsigned char header[10];
 252         unsigned hdrlen, datalen;
 253         enum object_type obj_type;
 254         int to_reuse = 0;
 255
 256         if (entry->preferred_base)
 257                 return 0;
 258
 259         obj_type = entry->type;
 260         if (! entry->in_pack)
 261                 to_reuse = 0;   /* can't reuse what we don't have */
 262         else if (obj_type == OBJ_DELTA)
 263                 to_reuse = 1;   /* check_object() decided it for us */
 264         else if (obj_type != entry->in_pack_type)
 265                 to_reuse = 0;   /* pack has delta which is unusable */
 266         else if (entry->delta)
 267                 to_reuse = 0;   /* we want to pack afresh */
 268         else
 269                 to_reuse = 1;   /* we have it in-pack undeltified,
 270                                  * and we do not need to deltify it.
 271                                  */
 272
 273         if (! to_reuse) {
 274                 buf = read_sha1_file(entry->sha1, type, &size);
 275                 if (!buf)
 276                         die("unable to read %s", sha1_to_hex(entry->sha1));
 277                 if (size != entry->size)
 278                         die("object %s size inconsistency (%lu vs %lu)",
 279                             sha1_to_hex(entry->sha1), size, entry->size);
 280                 if (entry->delta) {
 281                         buf = delta_against(buf, size, entry);
 282                         size = entry->delta_size;
 283                         obj_type = OBJ_DELTA;
 284                 }
 285                 /*
 286                  * The object header is a byte of 'type' followed by zero or
 287                  * more bytes of length.  For deltas, the 20 bytes of delta
 288                  * sha1 follows that.
 289                  */
 290                 hdrlen = encode_header(obj_type, size, header);
 291                 sha1write(f, header, hdrlen);
 292
 293                 if (entry->delta) {
 294                         sha1write(f, entry->delta, 20);
 295                         hdrlen += 20;
 296                 }
 297                 datalen = sha1write_compressed(f, buf, size);
 298                 free(buf);
 299         }
 300         else {
 301                 struct packed_git *p = entry->in_pack;
 302                 use_packed_git(p);
 303
 304                 datalen = find_packed_object_size(p, entry->in_pack_offset);
 305                 buf = p->pack_base + entry->in_pack_offset;
 306                 sha1write(f, buf, datalen);
 307                 unuse_packed_git(p);
 308                 hdrlen = 0; /* not really */
 309                 if (obj_type == OBJ_DELTA)
 310                         reused_delta++;
 311                 reused++;
 312         }
 313         if (obj_type == OBJ_DELTA)
 314                 written_delta++;
 315         written++;
 316         return hdrlen + datalen;
 317 }
 318
 319 static unsigned long write_one(struct sha1file *f,
 320                                struct object_entry *e,
 321                                unsigned long offset)
 322 {
 323         if (e->offset)
 324                 /* offset starts from header size and cannot be zero
 325                  * if it is written already.
 326                  */
 327                 return offset;
 328         e->offset = offset;
 329         offset += write_object(f, e);
 330         /* if we are deltified, write out its base object. */
 331         if (e->delta)
 332                 offset = write_one(f, e->delta, offset);
 333         return offset;
 334 }
 335
 336 static void write_pack_file(void)
 337 {
 338         int i;
 339         struct sha1file *f;
 340         unsigned long offset;
 341         struct pack_header hdr;
 342         unsigned last_percent = 999;
 343         int do_progress = 0;
 344
 345         if (!base_name)
 346                 f = sha1fd(1, "<stdout>");
 347         else {
 348                 f = sha1create("%s-%s.%s", base_name,
 349                                sha1_to_hex(object_list_sha1), "pack");
 350                 do_progress = progress;
 351         }
 352         if (do_progress)
 353                 fprintf(stderr, "Writing %d objects.\n", nr_result);
 354
 355         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 356         hdr.hdr_version = htonl(PACK_VERSION);
 357         hdr.hdr_entries = htonl(nr_result);
 358         sha1write(f, &hdr, sizeof(hdr));
 359         offset = sizeof(hdr);
 360         if (!nr_result)
 361                 goto done;
 362         for (i = 0; i < nr_objects; i++) {
 363                 offset = write_one(f, objects + i, offset);
 364                 if (do_progress) {
 365                         unsigned percent = written * 100 / nr_result;
 366                         if (progress_update || percent != last_percent) {
 367                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 368                                         percent, written, nr_result);
 369                                 progress_update = 0;
 370                                 last_percent = percent;
 371                         }
 372                 }
 373         }
 374         if (do_progress)
 375                 fputc('\n', stderr);
 376  done:
 377         sha1close(f, pack_file_sha1, 1);
 378 }
 379
 380 static void write_index_file(void)
 381 {
 382         int i;
 383         struct sha1file *f = sha1create("%s-%s.%s", base_name,
 384                                         sha1_to_hex(object_list_sha1), "idx");
 385         struct object_entry **list = sorted_by_sha;
 386         struct object_entry **last = list + nr_result;
 387         unsigned int array[256];
 388
 389         /*
 390          * Write the first-level table (the list is sorted,
 391          * but we use a 256-entry lookup to be able to avoid
 392          * having to do eight extra binary search iterations).
 393          */
 394         for (i = 0; i < 256; i++) {
 395                 struct object_entry **next = list;
 396                 while (next < last) {
 397                         struct object_entry *entry = *next;
 398                         if (entry->sha1[0] != i)
 399                                 break;
 400                         next++;
 401                 }
 402                 array[i] = htonl(next - sorted_by_sha);
 403                 list = next;
 404         }
 405         sha1write(f, array, 256 * sizeof(int));
 406
 407         /*
 408          * Write the actual SHA1 entries..
 409          */
 410         list = sorted_by_sha;
 411         for (i = 0; i < nr_result; i++) {
 412                 struct object_entry *entry = *list++;
 413                 unsigned int offset = htonl(entry->offset);
 414                 sha1write(f, &offset, 4);
 415                 sha1write(f, entry->sha1, 20);
 416         }
 417         sha1write(f, pack_file_sha1, 20);
 418         sha1close(f, NULL, 1);
 419 }
 420
 421 static int locate_object_entry_hash(const unsigned char *sha1)
 422 {
 423         int i;
 424         unsigned int ui;
 425         memcpy(&ui, sha1, sizeof(unsigned int));
 426         i = ui % object_ix_hashsz;
 427         while (0 < object_ix[i]) {
 428                 if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
 429                         return i;
 430                 if (++i == object_ix_hashsz)
 431                         i = 0;
 432         }
 433         return -1 - i;
 434 }
 435
 436 static struct object_entry *locate_object_entry(const unsigned char *sha1)
 437 {
 438         int i;
 439
 440         if (!object_ix_hashsz)
 441                 return NULL;
 442
 443         i = locate_object_entry_hash(sha1);
 444         if (0 <= i)
 445                 return &objects[object_ix[i]-1];
 446         return NULL;
 447 }
 448
 449 static void rehash_objects(void)
 450 {
 451         int i;
 452         struct object_entry *oe;
 453
 454         object_ix_hashsz = nr_objects * 3;
 455         if (object_ix_hashsz < 1024)
 456                 object_ix_hashsz = 1024;
 457         object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 458         memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 459         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 460                 int ix = locate_object_entry_hash(oe->sha1);
 461                 if (0 <= ix)
 462                         continue;
 463                 ix = -1 - ix;
 464                 object_ix[ix] = i + 1;
 465         }
 466 }
 467
 468 struct name_path {
 469         struct name_path *up;
 470         const char *elem;
 471         int len;
 472 };
 473
 474 #define DIRBITS 12
 475
 476 static unsigned name_hash(struct name_path *path, const char *name)
 477 {
 478         struct name_path *p = path;
 479         const char *n = name + strlen(name);
 480         unsigned hash = 0, name_hash = 0, name_done = 0;
 481
 482         if (n != name && n[-1] == '\n')
 483                 n--;
 484         while (name <= --n) {
 485                 unsigned char c = *n;
 486                 if (c == '/' && !name_done) {
 487                         name_hash = hash;
 488                         name_done = 1;
 489                         hash = 0;
 490                 }
 491                 hash = hash * 11 + c;
 492         }
 493         if (!name_done) {
 494                 name_hash = hash;
 495                 hash = 0;
 496         }
 497         for (p = path; p; p = p->up) {
 498                 hash = hash * 11 + '/';
 499                 n = p->elem + p->len;
 500                 while (p->elem <= --n) {
 501                         unsigned char c = *n;
 502                         hash = hash * 11 + c;
 503                 }
 504         }
 505         /*
 506          * Make sure "Makefile" and "t/Makefile" are hashed separately
 507          * but close enough.
 508          */
 509         hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
 510         return hash;
 511 }
 512
 513 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 514 {
 515         unsigned int idx = nr_objects;
 516         struct object_entry *entry;
 517         struct packed_git *p;
 518         unsigned int found_offset = 0;
 519         struct packed_git *found_pack = NULL;
 520         int ix, status = 0;
 521
 522         if (!exclude) {
 523                 for (p = packed_git; p; p = p->next) {
 524                         struct pack_entry e;
 525                         if (find_pack_entry_one(sha1, &e, p)) {
 526                                 if (incremental)
 527                                         return 0;
 528                                 if (local && !p->pack_local)
 529                                         return 0;
 530                                 if (!found_pack) {
 531                                         found_offset = e.offset;
 532                                         found_pack = e.p;
 533                                 }
 534                         }
 535                 }
 536         }
 537         if ((entry = locate_object_entry(sha1)) != NULL)
 538                 goto already_added;
 539
 540         if (idx >= nr_alloc) {
 541                 unsigned int needed = (idx + 1024) * 3 / 2;
 542                 objects = xrealloc(objects, needed * sizeof(*entry));
 543                 nr_alloc = needed;
 544         }
 545         entry = objects + idx;
 546         nr_objects = idx + 1;
 547         memset(entry, 0, sizeof(*entry));
 548         memcpy(entry->sha1, sha1, 20);
 549         entry->hash = hash;
 550
 551         if (object_ix_hashsz * 3 <= nr_objects * 4)
 552                 rehash_objects();
 553         else {
 554                 ix = locate_object_entry_hash(entry->sha1);
 555                 if (0 <= ix)
 556                         die("internal error in object hashing.");
 557                 object_ix[-1 - ix] = idx + 1;
 558         }
 559         status = 1;
 560
 561  already_added:
 562         if (progress_update) {
 563                 fprintf(stderr, "Counting objects...%d\r", nr_objects);
 564                 progress_update = 0;
 565         }
 566         if (exclude)
 567                 entry->preferred_base = 1;
 568         else {
 569                 if (found_pack) {
 570                         entry->in_pack = found_pack;
 571                         entry->in_pack_offset = found_offset;
 572                 }
 573         }
 574         return status;
 575 }
 576
 577 struct pbase_tree_cache {
 578         unsigned char sha1[20];
 579         int ref;
 580         int temporary;
 581         void *tree_data;
 582         unsigned long tree_size;
 583 };
 584
 585 static struct pbase_tree_cache *(pbase_tree_cache[256]);
 586 static int pbase_tree_cache_ix(const unsigned char *sha1)
 587 {
 588         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 589 }
 590 static int pbase_tree_cache_ix_incr(int ix)
 591 {
 592         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 593 }
 594
 595 static struct pbase_tree {
 596         struct pbase_tree *next;
 597         /* This is a phony "cache" entry; we are not
 598          * going to evict it nor find it through _get()
 599          * mechanism -- this is for the toplevel node that
 600          * would almost always change with any commit.
 601          */
 602         struct pbase_tree_cache pcache;
 603 } *pbase_tree;
 604
 605 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 606 {
 607         struct pbase_tree_cache *ent, *nent;
 608         void *data;
 609         unsigned long size;
 610         char type[20];
 611         int neigh;
 612         int my_ix = pbase_tree_cache_ix(sha1);
 613         int available_ix = -1;
 614
 615         /* pbase-tree-cache acts as a limited hashtable.
 616          * your object will be found at your index or within a few
 617          * slots after that slot if it is cached.
 618          */
 619         for (neigh = 0; neigh < 8; neigh++) {
 620                 ent = pbase_tree_cache[my_ix];
 621                 if (ent && !memcmp(ent->sha1, sha1, 20)) {
 622                         ent->ref++;
 623                         return ent;
 624                 }
 625                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 626                          ((0 <= available_ix) &&
 627                           (!ent && pbase_tree_cache[available_ix])))
 628                         available_ix = my_ix;
 629                 if (!ent)
 630                         break;
 631                 my_ix = pbase_tree_cache_ix_incr(my_ix);
 632         }
 633
 634         /* Did not find one.  Either we got a bogus request or
 635          * we need to read and perhaps cache.
 636          */
 637         data = read_sha1_file(sha1, type, &size);
 638         if (!data)
 639                 return NULL;
 640         if (strcmp(type, tree_type)) {
 641                 free(data);
 642                 return NULL;
 643         }
 644
 645         /* We need to either cache or return a throwaway copy */
 646
 647         if (available_ix < 0)
 648                 ent = NULL;
 649         else {
 650                 ent = pbase_tree_cache[available_ix];
 651                 my_ix = available_ix;
 652         }
 653
 654         if (!ent) {
 655                 nent = xmalloc(sizeof(*nent));
 656                 nent->temporary = (available_ix < 0);
 657         }
 658         else {
 659                 /* evict and reuse */
 660                 free(ent->tree_data);
 661                 nent = ent;
 662         }
 663         memcpy(nent->sha1, sha1, 20);
 664         nent->tree_data = data;
 665         nent->tree_size = size;
 666         nent->ref = 1;
 667         if (!nent->temporary)
 668                 pbase_tree_cache[my_ix] = nent;
 669         return nent;
 670 }
 671
 672 static void pbase_tree_put(struct pbase_tree_cache *cache)
 673 {
 674         if (!cache->temporary) {
 675                 cache->ref--;
 676                 return;
 677         }
 678         free(cache->tree_data);
 679         free(cache);
 680 }
 681
 682 static int name_cmp_len(const char *name)
 683 {
 684         int i;
 685         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 686                 ;
 687         return i;
 688 }
 689
 690 static void add_pbase_object(struct tree_desc *tree,
 691                              struct name_path *up,
 692                              const char *name,
 693                              int cmplen)
 694 {
 695         while (tree->size) {
 696                 const unsigned char *sha1;
 697                 const char *entry_name;
 698                 int entry_len;
 699                 unsigned mode;
 700                 unsigned long size;
 701                 char type[20];
 702
 703                 sha1 = tree_entry_extract(tree, &entry_name, &mode);
 704                 update_tree_entry(tree);
 705                 entry_len = strlen(entry_name);
 706                 if (entry_len != cmplen ||
 707                     memcmp(entry_name, name, cmplen) ||
 708                     !has_sha1_file(sha1) ||
 709                     sha1_object_info(sha1, type, &size))
 710                         continue;
 711                 if (name[cmplen] != '/') {
 712                         unsigned hash = name_hash(up, name);
 713                         add_object_entry(sha1, hash, 1);
 714                         return;
 715                 }
 716                 if (!strcmp(type, tree_type)) {
 717                         struct tree_desc sub;
 718                         struct name_path me;
 719                         struct pbase_tree_cache *tree;
 720                         const char *down = name+cmplen+1;
 721                         int downlen = name_cmp_len(down);
 722
 723                         tree = pbase_tree_get(sha1);
 724                         if (!tree)
 725                                 return;
 726                         sub.buf = tree->tree_data;
 727                         sub.size = tree->tree_size;
 728
 729                         me.up = up;
 730                         me.elem = entry_name;
 731                         me.len = entry_len;
 732                         add_pbase_object(&sub, &me, down, downlen);
 733                         pbase_tree_put(tree);
 734                 }
 735         }
 736 }
 737
 738 static unsigned *done_pbase_paths;
 739 static int done_pbase_paths_num;
 740 static int done_pbase_paths_alloc;
 741 static int done_pbase_path_pos(unsigned hash)
 742 {
 743         int lo = 0;
 744         int hi = done_pbase_paths_num;
 745         while (lo < hi) {
 746                 int mi = (hi + lo) / 2;
 747                 if (done_pbase_paths[mi] == hash)
 748                         return mi;
 749                 if (done_pbase_paths[mi] < hash)
 750                         hi = mi;
 751                 else
 752                         lo = mi + 1;
 753         }
 754         return -lo-1;
 755 }
 756
 757 static int check_pbase_path(unsigned hash)
 758 {
 759         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
 760         if (0 <= pos)
 761                 return 1;
 762         pos = -pos - 1;
 763         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
 764                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
 765                 done_pbase_paths = xrealloc(done_pbase_paths,
 766                                             done_pbase_paths_alloc *
 767                                             sizeof(unsigned));
 768         }
 769         done_pbase_paths_num++;
 770         if (pos < done_pbase_paths_num)
 771                 memmove(done_pbase_paths + pos + 1,
 772                         done_pbase_paths + pos,
 773                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
 774         done_pbase_paths[pos] = hash;
 775         return 0;
 776 }
 777
 778 static void add_preferred_base_object(char *name, unsigned hash)
 779 {
 780         struct pbase_tree *it;
 781         int cmplen = name_cmp_len(name);
 782
 783         if (check_pbase_path(hash))
 784                 return;
 785
 786         for (it = pbase_tree; it; it = it->next) {
 787                 if (cmplen == 0) {
 788                         hash = name_hash(NULL, "");
 789                         add_object_entry(it->pcache.sha1, hash, 1);
 790                 }
 791                 else {
 792                         struct tree_desc tree;
 793                         tree.buf = it->pcache.tree_data;
 794                         tree.size = it->pcache.tree_size;
 795                         add_pbase_object(&tree, NULL, name, cmplen);
 796                 }
 797         }
 798 }
 799
 800 static void add_preferred_base(unsigned char *sha1)
 801 {
 802         struct pbase_tree *it;
 803         void *data;
 804         unsigned long size;
 805         unsigned char tree_sha1[20];
 806
 807         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
 808         if (!data)
 809                 return;
 810
 811         for (it = pbase_tree; it; it = it->next) {
 812                 if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
 813                         free(data);
 814                         return;
 815                 }
 816         }
 817
 818         it = xcalloc(1, sizeof(*it));
 819         it->next = pbase_tree;
 820         pbase_tree = it;
 821
 822         memcpy(it->pcache.sha1, tree_sha1, 20);
 823         it->pcache.tree_data = data;
 824         it->pcache.tree_size = size;
 825 }
 826
 827 static void check_object(struct object_entry *entry)
 828 {
 829         char type[20];
 830
 831         if (entry->in_pack && !entry->preferred_base) {
 832                 unsigned char base[20];
 833                 unsigned long size;
 834                 struct object_entry *base_entry;
 835
 836                 /* We want in_pack_type even if we do not reuse delta.
 837                  * There is no point not reusing non-delta representations.
 838                  */
 839                 check_reuse_pack_delta(entry->in_pack,
 840                                        entry->in_pack_offset,
 841                                        base, &size,
 842                                        &entry->in_pack_type);
 843
 844                 /* Check if it is delta, and the base is also an object
 845                  * we are going to pack.  If so we will reuse the existing
 846                  * delta.
 847                  */
 848                 if (!no_reuse_delta &&
 849                     entry->in_pack_type == OBJ_DELTA &&
 850                     (base_entry = locate_object_entry(base)) &&
 851                     (!base_entry->preferred_base)) {
 852
 853                         /* Depth value does not matter - find_deltas()
 854                          * will never consider reused delta as the
 855                          * base object to deltify other objects
 856                          * against, in order to avoid circular deltas.
 857                          */
 858
 859                         /* uncompressed size of the delta data */
 860                         entry->size = entry->delta_size = size;
 861                         entry->delta = base_entry;
 862                         entry->type = OBJ_DELTA;
 863
 864                         entry->delta_sibling = base_entry->delta_child;
 865                         base_entry->delta_child = entry;
 866
 867                         return;
 868                 }
 869                 /* Otherwise we would do the usual */
 870         }
 871
 872         if (sha1_object_info(entry->sha1, type, &entry->size))
 873                 die("unable to get type of object %s",
 874                     sha1_to_hex(entry->sha1));
 875
 876         if (!strcmp(type, commit_type)) {
 877                 entry->type = OBJ_COMMIT;
 878         } else if (!strcmp(type, tree_type)) {
 879                 entry->type = OBJ_TREE;
 880         } else if (!strcmp(type, blob_type)) {
 881                 entry->type = OBJ_BLOB;
 882         } else if (!strcmp(type, tag_type)) {
 883                 entry->type = OBJ_TAG;
 884         } else
 885                 die("unable to pack object %s of type %s",
 886                     sha1_to_hex(entry->sha1), type);
 887 }
 888
 889 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 890 {
 891         struct object_entry *child = me->delta_child;
 892         unsigned int m = n;
 893         while (child) {
 894                 unsigned int c = check_delta_limit(child, n + 1);
 895                 if (m < c)
 896                         m = c;
 897                 child = child->delta_sibling;
 898         }
 899         return m;
 900 }
 901
 902 static void get_object_details(void)
 903 {
 904         int i;
 905         struct object_entry *entry;
 906
 907         prepare_pack_ix();
 908         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 909                 check_object(entry);
 910
 911         if (nr_objects == nr_result) {
 912                 /*
 913                  * Depth of objects that depend on the entry -- this
 914                  * is subtracted from depth-max to break too deep
 915                  * delta chain because of delta data reusing.
 916                  * However, we loosen this restriction when we know we
 917                  * are creating a thin pack -- it will have to be
 918                  * expanded on the other end anyway, so do not
 919                  * artificially cut the delta chain and let it go as
 920                  * deep as it wants.
 921                  */
 922                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 923                         if (!entry->delta && entry->delta_child)
 924                                 entry->delta_limit =
 925                                         check_delta_limit(entry, 1);
 926         }
 927 }
 928
 929 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 930
 931 static entry_sort_t current_sort;
 932
 933 static int sort_comparator(const void *_a, const void *_b)
 934 {
 935         struct object_entry *a = *(struct object_entry **)_a;
 936         struct object_entry *b = *(struct object_entry **)_b;
 937         return current_sort(a,b);
 938 }
 939
 940 static struct object_entry **create_sorted_list(entry_sort_t sort)
 941 {
 942         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 943         int i;
 944
 945         for (i = 0; i < nr_objects; i++)
 946                 list[i] = objects + i;
 947         current_sort = sort;
 948         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 949         return list;
 950 }
 951
 952 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 953 {
 954         return memcmp(a->sha1, b->sha1, 20);
 955 }
 956
 957 static struct object_entry **create_final_object_list(void)
 958 {
 959         struct object_entry **list;
 960         int i, j;
 961
 962         for (i = nr_result = 0; i < nr_objects; i++)
 963                 if (!objects[i].preferred_base)
 964                         nr_result++;
 965         list = xmalloc(nr_result * sizeof(struct object_entry *));
 966         for (i = j = 0; i < nr_objects; i++) {
 967                 if (!objects[i].preferred_base)
 968                         list[j++] = objects + i;
 969         }
 970         current_sort = sha1_sort;
 971         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
 972         return list;
 973 }
 974
 975 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 976 {
 977         if (a->type < b->type)
 978                 return -1;
 979         if (a->type > b->type)
 980                 return 1;
 981         if (a->hash < b->hash)
 982                 return -1;
 983         if (a->hash > b->hash)
 984                 return 1;
 985         if (a->preferred_base < b->preferred_base)
 986                 return -1;
 987         if (a->preferred_base > b->preferred_base)
 988                 return 1;
 989         if (a->size < b->size)
 990                 return -1;
 991         if (a->size > b->size)
 992                 return 1;
 993         return a < b ? -1 : (a > b);
 994 }
 995
 996 struct unpacked {
 997         struct object_entry *entry;
 998         unsigned char fingerprint[MD_LENGTH];
 999         void *data;
1000 };
1001
1002 /*
1003  * We search for deltas _backwards_ in a list sorted by type and
1004  * by size, so that we see progressively smaller and smaller files.
1005  * That's because we prefer deltas to be from the bigger file
1006  * to the smaller - deletes are potentially cheaper, but perhaps
1007  * more importantly, the bigger file is likely the more recent
1008  * one.
1009  */
1010 static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
1011 {
1012         struct object_entry *cur_entry = cur->entry;
1013         struct object_entry *old_entry = old->entry;
1014         unsigned long size, oldsize, delta_size, sizediff;
1015         long max_size;
1016         void *delta_buf;
1017
1018         /* Don't bother doing diffs between different types */
1019         if (cur_entry->type != old_entry->type)
1020                 return -1;
1021
1022         /* We do not compute delta to *create* objects we are not
1023          * going to pack.
1024          */
1025         if (cur_entry->preferred_base)
1026                 return -1;
1027
1028         /* If the current object is at pack edge, take the depth the
1029          * objects that depend on the current object into account --
1030          * otherwise they would become too deep.
1031          */
1032         if (cur_entry->delta_child) {
1033                 if (max_depth <= cur_entry->delta_limit)
1034                         return 0;
1035                 max_depth -= cur_entry->delta_limit;
1036         }
1037
1038         size = cur_entry->size;
1039         oldsize = old_entry->size;
1040         sizediff = oldsize > size ? oldsize - size : size - oldsize;
1041
1042         if (size < 50)
1043                 return -1;
1044         if (old_entry->depth >= max_depth)
1045                 return 0;
1046
1047         if (gb_simm_score(cur->fingerprint, old->fingerprint) < 0.4)
1048                 return 0;
1049
1050         /*
1051          * NOTE!
1052          *
1053          * We always delta from the bigger to the smaller, since that's
1054          * more space-efficient (deletes don't have to say _what_ they
1055          * delete).
1056          */
1057         max_size = size / 2 - 20;
1058         if (cur_entry->delta)
1059                 max_size = cur_entry->delta_size-1;
1060         if (sizediff >= max_size)
1061                 return -1;
1062         delta_buf = diff_delta(old->data, oldsize,
1063                                cur->data, size, &delta_size, max_size);
1064         if (!delta_buf)
1065                 return 0;
1066         cur_entry->delta = old_entry;
1067         cur_entry->delta_size = delta_size;
1068         cur_entry->depth = old_entry->depth + 1;
1069         free(delta_buf);
1070         return 0;
1071 }
1072
1073 static void progress_interval(int signum)
1074 {
1075         progress_update = 1;
1076 }
1077
1078 static void find_deltas(struct object_entry **list, int window, int depth)
1079 {
1080         int i, idx;
1081         unsigned int array_size = window * sizeof(struct unpacked);
1082         struct unpacked *array = xmalloc(array_size);
1083         unsigned processed = 0;
1084         unsigned last_percent = 999;
1085
1086         rabin_reset ();
1087         memset(array, 0, array_size);
1088         i = nr_objects;
1089         idx = 0;
1090         if (progress)
1091                 fprintf(stderr, "Deltifying %d objects.\n", nr_result);
1092
1093         while (--i >= 0) {
1094                 struct object_entry *entry = list[i];
1095                 struct unpacked *n = array + idx;
1096                 unsigned long size;
1097                 char type[10];
1098                 int j;
1099
1100                 if (!entry->preferred_base)
1101                         processed++;
1102
1103                 if (progress) {
1104                         unsigned percent = processed * 100 / nr_result;
1105                         if (percent != last_percent || progress_update) {
1106                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1107                                         percent, processed, nr_result);
1108                                 progress_update = 0;
1109                                 last_percent = percent;
1110                         }
1111                 }
1112
1113                 if (entry->delta)
1114                         /* This happens if we decided to reuse existing
1115                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1116                          */
1117                         continue;
1118
1119                 free(n->data);
1120                 n->entry = entry;
1121                 n->data = read_sha1_file(entry->sha1, type, &size);
1122                 if (size != entry->size)
1123                         die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
1124
1125                 gb_simm_process(n->data, size, n->fingerprint);
1126
1127                 j = window;
1128                 while (--j > 0) {
1129                         unsigned int other_idx = idx + j;
1130                         struct unpacked *m;
1131                         if (other_idx >= window)
1132                                 other_idx -= window;
1133                         m = array + other_idx;
1134                         if (!m->entry)
1135                                 break;
1136
1137                         if (try_delta(n, m, depth) < 0)
1138                                 break;
1139                 }
1140 #if 0
1141                 /* if we made n a delta, and if n is already at max
1142                  * depth, leaving it in the window is pointless.  we
1143                  * should evict it first.
1144                  * ... in theory only; somehow this makes things worse.
1145                  */
1146                 if (entry->delta && depth <= entry->depth)
1147                         continue;
1148 #endif
1149                 idx++;
1150                 if (idx >= window)
1151                         idx = 0;
1152         }
1153
1154         if (progress)
1155                 fputc('\n', stderr);
1156
1157         for (i = 0; i < window; ++i)
1158                 free(array[i].data);
1159         free(array);
1160 }
1161
1162 static void prepare_pack(int window, int depth)
1163 {
1164         get_object_details();
1165         sorted_by_type = create_sorted_list(type_size_sort);
1166         if (window && depth)
1167                 find_deltas(sorted_by_type, window+1, depth);
1168 }
1169
1170 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
1171 {
1172         static const char cache[] = "pack-cache/pack-%s.%s";
1173         char *cached_pack, *cached_idx;
1174         int ifd, ofd, ifd_ix = -1;
1175
1176         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1177         ifd = open(cached_pack, O_RDONLY);
1178         if (ifd < 0)
1179                 return 0;
1180
1181         if (!pack_to_stdout) {
1182                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1183                 ifd_ix = open(cached_idx, O_RDONLY);
1184                 if (ifd_ix < 0) {
1185                         close(ifd);
1186                         return 0;
1187                 }
1188         }
1189
1190         if (progress)
1191                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1192                         sha1_to_hex(sha1));
1193
1194         if (pack_to_stdout) {
1195                 if (copy_fd(ifd, 1))
1196                         exit(1);
1197                 close(ifd);
1198         }
1199         else {
1200                 char name[PATH_MAX];
1201                 snprintf(name, sizeof(name),
1202                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1203                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1204                 if (ofd < 0)
1205                         die("unable to open %s (%s)", name, strerror(errno));
1206                 if (copy_fd(ifd, ofd))
1207                         exit(1);
1208                 close(ifd);
1209
1210                 snprintf(name, sizeof(name),
1211                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1212                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1213                 if (ofd < 0)
1214                         die("unable to open %s (%s)", name, strerror(errno));
1215                 if (copy_fd(ifd_ix, ofd))
1216                         exit(1);
1217                 close(ifd_ix);
1218                 puts(sha1_to_hex(sha1));
1219         }
1220
1221         return 1;
1222 }
1223
1224 static void setup_progress_signal(void)
1225 {
1226         struct sigaction sa;
1227         struct itimerval v;
1228
1229         memset(&sa, 0, sizeof(sa));
1230         sa.sa_handler = progress_interval;
1231         sigemptyset(&sa.sa_mask);
1232         sa.sa_flags = SA_RESTART;
1233         sigaction(SIGALRM, &sa, NULL);
1234
1235         v.it_interval.tv_sec = 1;
1236         v.it_interval.tv_usec = 0;
1237         v.it_value = v.it_interval;
1238         setitimer(ITIMER_REAL, &v, NULL);
1239 }
1240
1241 int main(int argc, char **argv)
1242 {
1243         SHA_CTX ctx;
1244         char line[PATH_MAX + 20];
1245         int window = 10, depth = 10, pack_to_stdout = 0;
1246         struct object_entry **list;
1247         int num_preferred_base = 0;
1248         int i;
1249
1250         setup_git_directory();
1251
1252         for (i = 1; i < argc; i++) {
1253                 const char *arg = argv[i];
1254
1255                 if (*arg == '-') {
1256                         if (!strcmp("--non-empty", arg)) {
1257                                 non_empty = 1;
1258                                 continue;
1259                         }
1260                         if (!strcmp("--local", arg)) {
1261                                 local = 1;
1262                                 continue;
1263                         }
1264                         if (!strcmp("--incremental", arg)) {
1265                                 incremental = 1;
1266                                 continue;
1267                         }
1268                         if (!strncmp("--window=", arg, 9)) {
1269                                 char *end;
1270                                 window = strtoul(arg+9, &end, 0);
1271                                 if (!arg[9] || *end)
1272                                         usage(pack_usage);
1273                                 continue;
1274                         }
1275                         if (!strncmp("--depth=", arg, 8)) {
1276                                 char *end;
1277                                 depth = strtoul(arg+8, &end, 0);
1278                                 if (!arg[8] || *end)
1279                                         usage(pack_usage);
1280                                 continue;
1281                         }
1282                         if (!strcmp("-q", arg)) {
1283                                 progress = 0;
1284                                 continue;
1285                         }
1286                         if (!strcmp("--no-reuse-delta", arg)) {
1287                                 no_reuse_delta = 1;
1288                                 continue;
1289                         }
1290                         if (!strcmp("--stdout", arg)) {
1291                                 pack_to_stdout = 1;
1292                                 continue;
1293                         }
1294                         usage(pack_usage);
1295                 }
1296                 if (base_name)
1297                         usage(pack_usage);
1298                 base_name = arg;
1299         }
1300
1301         if (pack_to_stdout != !base_name)
1302                 usage(pack_usage);
1303
1304         prepare_packed_git();
1305
1306         if (progress) {
1307                 fprintf(stderr, "Generating pack...\n");
1308                 setup_progress_signal();
1309         }
1310
1311         for (;;) {
1312                 unsigned char sha1[20];
1313                 unsigned hash;
1314
1315                 if (!fgets(line, sizeof(line), stdin)) {
1316                         if (feof(stdin))
1317                                 break;
1318                         if (!ferror(stdin))
1319                                 die("fgets returned NULL, not EOF, not error!");
1320                         if (errno != EINTR)
1321                                 die("fgets: %s", strerror(errno));
1322                         clearerr(stdin);
1323                         continue;
1324                 }
1325
1326                 if (line[0] == '-') {
1327                         if (get_sha1_hex(line+1, sha1))
1328                                 die("expected edge sha1, got garbage:\n %s",
1329                                     line+1);
1330                         if (num_preferred_base++ < window)
1331                                 add_preferred_base(sha1);
1332                         continue;
1333                 }
1334                 if (get_sha1_hex(line, sha1))
1335                         die("expected sha1, got garbage:\n %s", line);
1336                 hash = name_hash(NULL, line+41);
1337                 add_preferred_base_object(line+41, hash);
1338                 add_object_entry(sha1, hash, 0);
1339         }
1340         if (progress)
1341                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1342         sorted_by_sha = create_final_object_list();
1343         if (non_empty && !nr_result)
1344                 return 0;
1345
1346         SHA1_Init(&ctx);
1347         list = sorted_by_sha;
1348         for (i = 0; i < nr_result; i++) {
1349                 struct object_entry *entry = *list++;
1350                 SHA1_Update(&ctx, entry->sha1, 20);
1351         }
1352         SHA1_Final(object_list_sha1, &ctx);
1353         if (progress && (nr_objects != nr_result))
1354                 fprintf(stderr, "Result has %d objects.\n", nr_result);
1355
1356         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1357                 ;
1358         else {
1359                 if (nr_result)
1360                         prepare_pack(window, depth);
1361                 if (progress && pack_to_stdout) {
1362                         /* the other end usually displays progress itself */
1363                         struct itimerval v = {{0,},};
1364                         setitimer(ITIMER_REAL, &v, NULL);
1365                         signal(SIGALRM, SIG_IGN );
1366                         progress_update = 0;
1367                 }
1368                 write_pack_file();
1369                 if (!pack_to_stdout) {
1370                         write_index_file();
1371                         puts(sha1_to_hex(object_list_sha1));
1372                 }
1373         }
1374         if (progress)
1375                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1376                         nr_result, written, written_delta, reused, reused_delta);
1377         return 0;
1378 }