diff options
| -rw-r--r-- | pack-objects.c | 367 | ||||
| -rw-r--r-- | pack.h | 4 | ||||
| -rw-r--r-- | sha1_file.c | 19 |
3 files changed, 332 insertions, 58 deletions
diff --git a/pack-objects.c b/pack-objects.c index c5a5e6160..70fb2afeb 100644 --- a/pack-objects.c +++ b/pack-objects.c @@ -9,15 +9,31 @@ static const char pack_usage[] = "git-pack-objects [-q] [--non-empty] [--local] struct object_entry { unsigned char sha1[20]; - unsigned long size; - unsigned long offset; - unsigned int depth; - unsigned int hash; + unsigned long size; /* uncompressed size */ + unsigned long offset; /* offset into the final pack file (nonzero if already written) */ + unsigned int depth; /* delta depth */ + unsigned int hash; /* name hint hash */ enum object_type type; - unsigned long delta_size; - struct object_entry *delta; + unsigned long delta_size; /* delta data size (uncompressed) */ + struct object_entry *delta; /* delta base object */ + struct packed_git *in_pack; /* already in pack */ + enum object_type in_pack_type; /* could be delta */ + unsigned int in_pack_offset; }; +/* + * Objects we are going to pack are colected in objects array (dynamically + * expanded). nr_objects & nr_alloc controls this array. They are stored + * in the order we see -- typically rev-list --objects order that gives us + * nice "minimum seek" order. + * + * sorted-by-sha ans sorted-by-type are arrays of pointers that point at + * elements in the objects array. The former is used to build the pack + * index (lists object names in the ascending order to help offset lookup), + * and the latter is used to group similar things together by try_delta() + * heuristics. + */ + static unsigned char object_list_sha1[20]; static int non_empty = 0; static int local = 0; @@ -29,6 +45,135 @@ static const char *base_name; static unsigned char pack_file_sha1[20]; static int progress = 1; +/* + * The object names in objects array are hashed with this hashtable, + * to help looking up the entry by object name. Binary search from + * sorted_by_sha is also possible but this was easier to code and faster. + * This hashtable is built after all the objects are seen. + */ +static int *object_ix = NULL; +static int object_ix_hashsz = 0; + +/* + * Pack index for existing packs give us easy access to the offsets into + * corresponding pack file where each object's data starts, but the entries + * do not store the size of the compressed representation (uncompressed + * size is easily available by examining the pack entry header). We build + * a hashtable of existing packs (pack_revindex), and keep reverse index + * here -- pack index file is sorted by object name mapping to offset; this + * pack_revindex[].revindex array is an ordered list of offsets, so if you + * know the offset of an object, next offset is where its packed + * representation ends. + */ +struct pack_revindex { + struct packed_git *p; + unsigned long *revindex; +} *pack_revindex = NULL; +static int pack_revindex_hashsz = 0; + +/* + * stats + */ +static int written = 0; +static int reused = 0; + +static int pack_revindex_ix(struct packed_git *p) +{ + unsigned int ui = (unsigned int) p; + int i; + + ui = ui ^ (ui >> 16); /* defeat structure alignment */ + i = (int)(ui % pack_revindex_hashsz); + while (pack_revindex[i].p) { + if (pack_revindex[i].p == p) + return i; + if (++i == pack_revindex_hashsz) + i = 0; + } + return -1 - i; +} + +static void prepare_pack_ix(void) +{ + int num; + struct packed_git *p; + for (num = 0, p = packed_git; p; p = p->next) + num++; + if (!num) + return; + pack_revindex_hashsz = num * 11; + pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz); + for (p = packed_git; p; p = p->next) { + num = pack_revindex_ix(p); + num = - 1 - num; + pack_revindex[num].p = p; + } + /* revindex elements are lazily initialized */ +} + +static int cmp_offset(const void *a_, const void *b_) +{ + unsigned long a = *(unsigned long *) a_; + unsigned long b = *(unsigned long *) b_; + if (a < b) + return -1; + else if (a == b) + return 0; + else + return 1; +} + +/* + * Ordered list of offsets of objects in the pack. + */ +static void prepare_pack_revindex(struct pack_revindex *rix) +{ + struct packed_git *p = rix->p; + int num_ent = num_packed_objects(p); + int i; + void *index = p->index_base + 256; + + rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1)); + for (i = 0; i < num_ent; i++) { + long hl = *((long *)(index + 24 * i)); + rix->revindex[i] = ntohl(hl); + } + /* This knows the pack format -- the 20-byte trailer + * follows immediately after the last object data. + */ + rix->revindex[num_ent] = p->pack_size - 20; + qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset); +} + +static unsigned long find_packed_object_size(struct packed_git *p, + unsigned long ofs) +{ + int num; + int lo, hi; + struct pack_revindex *rix; + unsigned long *revindex; + num = pack_revindex_ix(p); + if (num < 0) + die("internal error: pack revindex uninitialized"); + rix = &pack_revindex[num]; + if (!rix->revindex) + prepare_pack_revindex(rix); + revindex = rix->revindex; + lo = 0; + hi = num_packed_objects(p) + 1; + do { + int mi = (lo + hi) / 2; + if (revindex[mi] == ofs) { + return revindex[mi+1] - ofs; + } + else if (ofs < revindex[mi]) + hi = mi; + else + lo = mi + 1; + } while (lo < hi); + die("internal error: pack revindex corrupt"); +} + static void *delta_against(void *buf, unsigned long size, struct object_entry *entry) { unsigned long othersize, delta_size; @@ -78,35 +223,52 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry { unsigned long size; char type[10]; - void *buf = read_sha1_file(entry->sha1, type, &size); + void *buf; unsigned char header[10]; unsigned hdrlen, datalen; enum object_type obj_type; - if (!buf) - die("unable to read %s", sha1_to_hex(entry->sha1)); - if (size != entry->size) - die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size); - - /* - * The object header is a byte of 'type' followed by zero or - * more bytes of length. For deltas, the 20 bytes of delta sha1 - * follows that. - */ obj_type = entry->type; - if (entry->delta) { - buf = delta_against(buf, size, entry); - size = entry->delta_size; - obj_type = OBJ_DELTA; + if (!entry->in_pack || + (obj_type != entry->in_pack_type)) { + buf = read_sha1_file(entry->sha1, type, &size); + if (!buf) + die("unable to read %s", sha1_to_hex(entry->sha1)); + if (size != entry->size) + die("object %s size inconsistency (%lu vs %lu)", + sha1_to_hex(entry->sha1), size, entry->size); + if (entry->delta) { + buf = delta_against(buf, size, entry); + size = entry->delta_size; + obj_type = OBJ_DELTA; + } + /* + * The object header is a byte of 'type' followed by zero or + * more bytes of length. For deltas, the 20 bytes of delta + * sha1 follows that. + */ + hdrlen = encode_header(obj_type, size, header); + sha1write(f, header, hdrlen); + + if (entry->delta) { + sha1write(f, entry->delta, 20); + hdrlen += 20; + } + datalen = sha1write_compressed(f, buf, size); + free(buf); } - hdrlen = encode_header(obj_type, size, header); - sha1write(f, header, hdrlen); - if (entry->delta) { - sha1write(f, entry->delta, 20); - hdrlen += 20; + else { + struct packed_git *p = entry->in_pack; + use_packed_git(p); + + datalen = find_packed_object_size(p, entry->in_pack_offset); + buf = p->pack_base + entry->in_pack_offset; + sha1write(f, buf, datalen); + unuse_packed_git(p); + hdrlen = 0; /* not really */ + reused++; } - datalen = sha1write_compressed(f, buf, size); - free(buf); + written++; return hdrlen + datalen; } @@ -148,8 +310,6 @@ static void write_pack_file(void) offset = write_one(f, objects + i, offset); sha1close(f, pack_file_sha1, 1); - mb = offset >> 20; - offset &= 0xfffff; } static void write_index_file(void) @@ -196,18 +356,21 @@ static int add_object_entry(unsigned char *sha1, unsigned int hash) { unsigned int idx = nr_objects; struct object_entry *entry; - - if (incremental || local) { - struct packed_git *p; - - for (p = packed_git; p; p = p->next) { - struct pack_entry e; - - if (find_pack_entry_one(sha1, &e, p)) { - if (incremental) - return 0; - if (local && !p->pack_local) - return 0; + struct packed_git *p; + unsigned int found_offset; + struct packed_git *found_pack; + + found_pack = NULL; + for (p = packed_git; p; p = p->next) { + struct pack_entry e; + if (find_pack_entry_one(sha1, &e, p)) { + if (incremental) + return 0; + if (local && !p->pack_local) + return 0; + if (!found_pack) { + found_offset = e.offset; + found_pack = e.p; } } } @@ -221,30 +384,107 @@ static int add_object_entry(unsigned char *sha1, unsigned int hash) memset(entry, 0, sizeof(*entry)); memcpy(entry->sha1, sha1, 20); entry->hash = hash; + if (found_pack) { + entry->in_pack = found_pack; + entry->in_pack_offset = found_offset; + } nr_objects = idx+1; return 1; } +static int locate_object_entry_hash(unsigned char *sha1) +{ + int i; + unsigned int ui; + memcpy(&ui, sha1, sizeof(unsigned int)); + i = ui % object_ix_hashsz; + while (0 < object_ix[i]) { + if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20)) + return i; + if (++i == object_ix_hashsz) + i = 0; + } + return -1 - i; +} + +static struct object_entry *locate_object_entry(unsigned char *sha1) +{ + int i = locate_object_entry_hash(sha1); + if (0 <= i) + return &objects[object_ix[i]-1]; + return NULL; +} + static void check_object(struct object_entry *entry) { char type[20]; - if (!sha1_object_info(entry->sha1, type, &entry->size)) { - if (!strcmp(type, "commit")) { - entry->type = OBJ_COMMIT; - } else if (!strcmp(type, "tree")) { - entry->type = OBJ_TREE; - } else if (!strcmp(type, "blob")) { - entry->type = OBJ_BLOB; - } else if (!strcmp(type, "tag")) { - entry->type = OBJ_TAG; - } else - die("unable to pack object %s of type %s", - sha1_to_hex(entry->sha1), type); + if (entry->in_pack) { + /* Check if it is delta, and the base is also an object + * we are going to pack. If so we will reuse the existing + * delta. + */ + unsigned char base[20]; + unsigned long size; + struct object_entry *base_entry; + if (!check_reuse_pack_delta(entry->in_pack, + entry->in_pack_offset, + base, &size, + &entry->in_pack_type) && + (base_entry = locate_object_entry(base))) { + /* We do not know depth at this point, but it + * does not matter. Getting delta_chain_length + * with packed_object_info_detail() is not so + * expensive, so we could do that later if we + * wanted to. Calling sha1_object_info to get + * the true size (and later an uncompressed + * representation) of deeply deltified object + * is quite expensive. + */ + entry->depth = 1; + /* uncompressed size */ + entry->size = entry->delta_size = size; + entry->delta = base_entry; + entry->type = OBJ_DELTA; + return; + } + /* Otherwise we would do the usual */ } - else + + if (sha1_object_info(entry->sha1, type, &entry->size)) die("unable to get type of object %s", sha1_to_hex(entry->sha1)); + + if (!strcmp(type, "commit")) { + entry->type = OBJ_COMMIT; + } else if (!strcmp(type, "tree")) { + entry->type = OBJ_TREE; + } else if (!strcmp(type, "blob")) { + entry->type = OBJ_BLOB; + } else if (!strcmp(type, "tag")) { + entry->type = OBJ_TAG; + } else + die("unable to pack object %s of type %s", + sha1_to_hex(entry->sha1), type); +} + +static void hash_objects(void) +{ + int i; + struct object_entry *oe; + + object_ix_hashsz = nr_objects * 2; + object_ix = xcalloc(sizeof(int), object_ix_hashsz); + for (i = 0, oe = objects; i < nr_objects; i++, oe++) { + int ix = locate_object_entry_hash(oe->sha1); + if (0 <= ix) { + error("the same object '%s' added twice", + sha1_to_hex(oe->sha1)); + continue; + } + ix = -1 - ix; + object_ix[ix] = i + 1; + } } static void get_object_details(void) @@ -252,6 +492,8 @@ static void get_object_details(void) int i; struct object_entry *entry = objects; + hash_objects(); + prepare_pack_ix(); for (i = 0; i < nr_objects; i++) check_object(entry++); } @@ -382,6 +624,13 @@ static void find_deltas(struct object_entry **list, int window, int depth) eye_candy -= nr_objects / 20; fputc('.', stderr); } + + if (entry->delta) + /* This happens if we decided to reuse existing + * delta from a pack. + */ + continue; + free(n->data); n->entry = entry; n->data = read_sha1_file(entry->sha1, type, &size); @@ -411,10 +660,12 @@ static void find_deltas(struct object_entry **list, int window, int depth) static void prepare_pack(int window, int depth) { - get_object_details(); - if (progress) fprintf(stderr, "Packing %d objects", nr_objects); + get_object_details(); + if (progress) + fprintf(stderr, "."); + sorted_by_type = create_sorted_list(type_size_sort); if (window && depth) find_deltas(sorted_by_type, window+1, depth); @@ -599,5 +850,7 @@ int main(int argc, char **argv) puts(sha1_to_hex(object_list_sha1)); } } + fprintf(stderr, "Total %d, written %d, reused %d\n", + nr_objects, written, reused); return 0; } @@ -29,5 +29,7 @@ struct pack_header { }; extern int verify_pack(struct packed_git *, int); - +extern int check_reuse_pack_delta(struct packed_git *, unsigned long, + unsigned char *, unsigned long *, + enum object_type *); #endif diff --git a/sha1_file.c b/sha1_file.c index 64cf24541..0a3a721e9 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -826,6 +826,25 @@ static unsigned long unpack_object_header(struct packed_git *p, unsigned long of return offset; } +int check_reuse_pack_delta(struct packed_git *p, unsigned long offset, + unsigned char *base, unsigned long *sizep, + enum object_type *kindp) +{ + unsigned long ptr; + int status = -1; + + use_packed_git(p); + ptr = offset; + ptr = unpack_object_header(p, ptr, kindp, sizep); + if (*kindp != OBJ_DELTA) + goto done; + memcpy(base, p->pack_base + ptr, 20); + status = 0; + done: + unuse_packed_git(p); + return status; +} + void packed_object_info_detail(struct pack_entry *e, char *type, unsigned long *size, |