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index-pack: restructure pack processing into three main functions
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The second pass in parse_pack_objects() are split into
resolve_deltas(). The final phase, fixing thin pack or just seal the
pack, is now in conclude_pack() function. Main pack processing is now
a sequence of these functions:

 - parse_pack_objects() reads through the input pack
 - resolve_deltas()     makes sure all deltas can be resolved
 - conclude_pack()      seals the output pack
 - write_idx_file()     writes companion index file
 - final()              moves the pack/index to proper place

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Nguyễn Thái Ngọc Duy authored and Junio C Hamano committed May 7, 2012
1 parent 9ba604a commit 5272f75
Showing 1 changed file with 75 additions and 53 deletions.
128 changes: 75 additions & 53 deletions builtin/index-pack.c
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Original file line number Diff line number Diff line change
Expand Up @@ -682,19 +682,26 @@ static int compare_delta_entry(const void *a, const void *b)
objects[delta_b->obj_no].type);
}

/* Parse all objects and return the pack content SHA1 hash */
static void resolve_base(struct object_entry *obj)
{
struct base_data *base_obj = alloc_base_data();
base_obj->obj = obj;
base_obj->data = NULL;
find_unresolved_deltas(base_obj);
}

/*
* First pass:
* - find locations of all objects;
* - calculate SHA1 of all non-delta objects;
* - remember base (SHA1 or offset) for all deltas.
*/
static void parse_pack_objects(unsigned char *sha1)
{
int i;
struct delta_entry *delta = deltas;
struct stat st;

/*
* First pass:
* - find locations of all objects;
* - calculate SHA1 of all non-delta objects;
* - remember base (SHA1 or offset) for all deltas.
*/
if (verbose)
progress = start_progress(
from_stdin ? "Receiving objects" : "Indexing objects",
Expand Down Expand Up @@ -728,6 +735,19 @@ static void parse_pack_objects(unsigned char *sha1)
if (S_ISREG(st.st_mode) &&
lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
die("pack has junk at the end");
}

/*
* Second pass:
* - for all non-delta objects, look if it is used as a base for
* deltas;
* - if used as a base, uncompress the object and apply all deltas,
* recursively checking if the resulting object is used as a base
* for some more deltas.
*/
static void resolve_deltas(void)
{
int i;

if (!nr_deltas)
return;
Expand All @@ -736,29 +756,63 @@ static void parse_pack_objects(unsigned char *sha1)
qsort(deltas, nr_deltas, sizeof(struct delta_entry),
compare_delta_entry);

/*
* Second pass:
* - for all non-delta objects, look if it is used as a base for
* deltas;
* - if used as a base, uncompress the object and apply all deltas,
* recursively checking if the resulting object is used as a base
* for some more deltas.
*/
if (verbose)
progress = start_progress("Resolving deltas", nr_deltas);
for (i = 0; i < nr_objects; i++) {
struct object_entry *obj = &objects[i];
struct base_data *base_obj = alloc_base_data();

if (is_delta_type(obj->type))
continue;
base_obj->obj = obj;
base_obj->data = NULL;
find_unresolved_deltas(base_obj);
resolve_base(obj);
display_progress(progress, nr_resolved_deltas);
}
}

/*
* Third pass:
* - append objects to convert thin pack to full pack if required
* - write the final 20-byte SHA-1
*/
static void fix_unresolved_deltas(struct sha1file *f, int nr_unresolved);
static void conclude_pack(int fix_thin_pack, const char *curr_pack, unsigned char *pack_sha1)
{
if (nr_deltas == nr_resolved_deltas) {
stop_progress(&progress);
/* Flush remaining pack final 20-byte SHA1. */
flush();
return;
}

if (fix_thin_pack) {
struct sha1file *f;
unsigned char read_sha1[20], tail_sha1[20];
char msg[48];
int nr_unresolved = nr_deltas - nr_resolved_deltas;
int nr_objects_initial = nr_objects;
if (nr_unresolved <= 0)
die("confusion beyond insanity");
objects = xrealloc(objects,
(nr_objects + nr_unresolved + 1)
* sizeof(*objects));
f = sha1fd(output_fd, curr_pack);
fix_unresolved_deltas(f, nr_unresolved);
sprintf(msg, "completed with %d local objects",
nr_objects - nr_objects_initial);
stop_progress_msg(&progress, msg);
sha1close(f, tail_sha1, 0);
hashcpy(read_sha1, pack_sha1);
fixup_pack_header_footer(output_fd, pack_sha1,
curr_pack, nr_objects,
read_sha1, consumed_bytes-20);
if (hashcmp(read_sha1, tail_sha1) != 0)
die("Unexpected tail checksum for %s "
"(disk corruption?)", curr_pack);
}
if (nr_deltas != nr_resolved_deltas)
die("pack has %d unresolved deltas",
nr_deltas - nr_resolved_deltas);
}

static int write_compressed(struct sha1file *f, void *in, unsigned int size)
{
git_zstream stream;
Expand Down Expand Up @@ -1196,40 +1250,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
parse_pack_objects(pack_sha1);
if (nr_deltas == nr_resolved_deltas) {
stop_progress(&progress);
/* Flush remaining pack final 20-byte SHA1. */
flush();
} else {
if (fix_thin_pack) {
struct sha1file *f;
unsigned char read_sha1[20], tail_sha1[20];
char msg[48];
int nr_unresolved = nr_deltas - nr_resolved_deltas;
int nr_objects_initial = nr_objects;
if (nr_unresolved <= 0)
die("confusion beyond insanity");
objects = xrealloc(objects,
(nr_objects + nr_unresolved + 1)
* sizeof(*objects));
f = sha1fd(output_fd, curr_pack);
fix_unresolved_deltas(f, nr_unresolved);
sprintf(msg, "completed with %d local objects",
nr_objects - nr_objects_initial);
stop_progress_msg(&progress, msg);
sha1close(f, tail_sha1, 0);
hashcpy(read_sha1, pack_sha1);
fixup_pack_header_footer(output_fd, pack_sha1,
curr_pack, nr_objects,
read_sha1, consumed_bytes-20);
if (hashcmp(read_sha1, tail_sha1) != 0)
die("Unexpected tail checksum for %s "
"(disk corruption?)", curr_pack);
}
if (nr_deltas != nr_resolved_deltas)
die("pack has %d unresolved deltas",
nr_deltas - nr_resolved_deltas);
}
resolve_deltas();
conclude_pack(fix_thin_pack, curr_pack, pack_sha1);
free(deltas);
if (strict)
check_objects();
Expand Down

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