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