git/pack-objects.c
Nicolas Pitre 0dec30b978 fix pack-object buffer size
The input line has 40 _chars_ of sha1 and no 20 _bytes_. It should also
account for the space before the pathname, and the terminating \n and \0.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-04-21 00:45:10 -07:00

1369 lines
33 KiB
C

#include "cache.h"
#include "object.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "delta.h"
#include "pack.h"
#include "csum-file.h"
#include "tree-walk.h"
#include <sys/time.h>
#include <signal.h>
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";
struct object_entry {
unsigned char sha1[20];
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 delta_limit; /* base adjustment for in-pack delta */
unsigned int hash; /* name hint hash */
enum object_type type;
enum object_type in_pack_type; /* could be delta */
unsigned long delta_size; /* delta data size (uncompressed) */
struct object_entry *delta; /* delta base object */
struct packed_git *in_pack; /* already in pack */
unsigned int in_pack_offset;
struct object_entry *delta_child; /* delitified objects who bases me */
struct object_entry *delta_sibling; /* other deltified objects who
* uses the same base as me
*/
int preferred_base; /* we do not pack this, but is encouraged to
* be used as the base objectto delta huge
* objects against.
*/
};
/*
* 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 no_reuse_delta = 0;
static int local = 0;
static int incremental = 0;
static struct object_entry **sorted_by_sha, **sorted_by_type;
static struct object_entry *objects = NULL;
static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
static const char *base_name;
static unsigned char pack_file_sha1[20];
static int progress = 1;
static volatile sig_atomic_t progress_update = 0;
/*
* 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 written_delta = 0;
static int reused = 0;
static int reused_delta = 0;
static int pack_revindex_ix(struct packed_git *p)
{
unsigned long ui = (unsigned long)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;
char type[10];
void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
void *delta_buf;
if (!otherbuf)
die("unable to read %s", sha1_to_hex(entry->delta->sha1));
delta_buf = diff_delta(otherbuf, othersize,
buf, size, &delta_size, 0);
if (!delta_buf || delta_size != entry->delta_size)
die("delta size changed");
free(buf);
free(otherbuf);
return delta_buf;
}
/*
* The per-object header is a pretty dense thing, which is
* - first byte: low four bits are "size", then three bits of "type",
* and the high bit is "size continues".
* - each byte afterwards: low seven bits are size continuation,
* with the high bit being "size continues"
*/
static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
{
int n = 1;
unsigned char c;
if (type < OBJ_COMMIT || type > OBJ_DELTA)
die("bad type %d", type);
c = (type << 4) | (size & 15);
size >>= 4;
while (size) {
*hdr++ = c | 0x80;
c = size & 0x7f;
size >>= 7;
n++;
}
*hdr = c;
return n;
}
static unsigned long write_object(struct sha1file *f,
struct object_entry *entry)
{
unsigned long size;
char type[10];
void *buf;
unsigned char header[10];
unsigned hdrlen, datalen;
enum object_type obj_type;
int to_reuse = 0;
if (entry->preferred_base)
return 0;
obj_type = entry->type;
if (! entry->in_pack)
to_reuse = 0; /* can't reuse what we don't have */
else if (obj_type == OBJ_DELTA)
to_reuse = 1; /* check_object() decided it for us */
else if (obj_type != entry->in_pack_type)
to_reuse = 0; /* pack has delta which is unusable */
else if (entry->delta)
to_reuse = 0; /* we want to pack afresh */
else
to_reuse = 1; /* we have it in-pack undeltified,
* and we do not need to deltify it.
*/
if (! to_reuse) {
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);
}
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 */
if (obj_type == OBJ_DELTA)
reused_delta++;
reused++;
}
if (obj_type == OBJ_DELTA)
written_delta++;
written++;
return hdrlen + datalen;
}
static unsigned long write_one(struct sha1file *f,
struct object_entry *e,
unsigned long offset)
{
if (e->offset)
/* offset starts from header size and cannot be zero
* if it is written already.
*/
return offset;
e->offset = offset;
offset += write_object(f, e);
/* if we are deltified, write out its base object. */
if (e->delta)
offset = write_one(f, e->delta, offset);
return offset;
}
static void write_pack_file(void)
{
int i;
struct sha1file *f;
unsigned long offset;
struct pack_header hdr;
unsigned last_percent = 999;
int do_progress = 0;
if (!base_name)
f = sha1fd(1, "<stdout>");
else {
f = sha1create("%s-%s.%s", base_name,
sha1_to_hex(object_list_sha1), "pack");
do_progress = progress;
}
if (do_progress)
fprintf(stderr, "Writing %d objects.\n", nr_result);
hdr.hdr_signature = htonl(PACK_SIGNATURE);
hdr.hdr_version = htonl(PACK_VERSION);
hdr.hdr_entries = htonl(nr_result);
sha1write(f, &hdr, sizeof(hdr));
offset = sizeof(hdr);
if (!nr_result)
goto done;
for (i = 0; i < nr_objects; i++) {
offset = write_one(f, objects + i, offset);
if (do_progress) {
unsigned percent = written * 100 / nr_result;
if (progress_update || percent != last_percent) {
fprintf(stderr, "%4u%% (%u/%u) done\r",
percent, written, nr_result);
progress_update = 0;
last_percent = percent;
}
}
}
if (do_progress)
fputc('\n', stderr);
done:
sha1close(f, pack_file_sha1, 1);
}
static void write_index_file(void)
{
int i;
struct sha1file *f = sha1create("%s-%s.%s", base_name,
sha1_to_hex(object_list_sha1), "idx");
struct object_entry **list = sorted_by_sha;
struct object_entry **last = list + nr_result;
unsigned int array[256];
/*
* Write the first-level table (the list is sorted,
* but we use a 256-entry lookup to be able to avoid
* having to do eight extra binary search iterations).
*/
for (i = 0; i < 256; i++) {
struct object_entry **next = list;
while (next < last) {
struct object_entry *entry = *next;
if (entry->sha1[0] != i)
break;
next++;
}
array[i] = htonl(next - sorted_by_sha);
list = next;
}
sha1write(f, array, 256 * sizeof(int));
/*
* Write the actual SHA1 entries..
*/
list = sorted_by_sha;
for (i = 0; i < nr_result; i++) {
struct object_entry *entry = *list++;
unsigned int offset = htonl(entry->offset);
sha1write(f, &offset, 4);
sha1write(f, entry->sha1, 20);
}
sha1write(f, pack_file_sha1, 20);
sha1close(f, NULL, 1);
}
static int locate_object_entry_hash(const 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(const unsigned char *sha1)
{
int i;
if (!object_ix_hashsz)
return NULL;
i = locate_object_entry_hash(sha1);
if (0 <= i)
return &objects[object_ix[i]-1];
return NULL;
}
static void rehash_objects(void)
{
int i;
struct object_entry *oe;
object_ix_hashsz = nr_objects * 3;
if (object_ix_hashsz < 1024)
object_ix_hashsz = 1024;
object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
memset(object_ix, 0, 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)
continue;
ix = -1 - ix;
object_ix[ix] = i + 1;
}
}
struct name_path {
struct name_path *up;
const char *elem;
int len;
};
#define DIRBITS 12
static unsigned name_hash(struct name_path *path, const char *name)
{
struct name_path *p = path;
const char *n = name + strlen(name);
unsigned hash = 0, name_hash = 0, name_done = 0;
if (n != name && n[-1] == '\n')
n--;
while (name <= --n) {
unsigned char c = *n;
if (c == '/' && !name_done) {
name_hash = hash;
name_done = 1;
hash = 0;
}
hash = hash * 11 + c;
}
if (!name_done) {
name_hash = hash;
hash = 0;
}
for (p = path; p; p = p->up) {
hash = hash * 11 + '/';
n = p->elem + p->len;
while (p->elem <= --n) {
unsigned char c = *n;
hash = hash * 11 + c;
}
}
/*
* Make sure "Makefile" and "t/Makefile" are hashed separately
* but close enough.
*/
hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
return hash;
}
static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
{
unsigned int idx = nr_objects;
struct object_entry *entry;
struct packed_git *p;
unsigned int found_offset = 0;
struct packed_git *found_pack = NULL;
int ix, status = 0;
if (!exclude) {
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;
}
}
}
}
if ((entry = locate_object_entry(sha1)) != NULL)
goto already_added;
if (idx >= nr_alloc) {
unsigned int needed = (idx + 1024) * 3 / 2;
objects = xrealloc(objects, needed * sizeof(*entry));
nr_alloc = needed;
}
entry = objects + idx;
nr_objects = idx + 1;
memset(entry, 0, sizeof(*entry));
memcpy(entry->sha1, sha1, 20);
entry->hash = hash;
if (object_ix_hashsz * 3 <= nr_objects * 4)
rehash_objects();
else {
ix = locate_object_entry_hash(entry->sha1);
if (0 <= ix)
die("internal error in object hashing.");
object_ix[-1 - ix] = idx + 1;
}
status = 1;
already_added:
if (progress_update) {
fprintf(stderr, "Counting objects...%d\r", nr_objects);
progress_update = 0;
}
if (exclude)
entry->preferred_base = 1;
else {
if (found_pack) {
entry->in_pack = found_pack;
entry->in_pack_offset = found_offset;
}
}
return status;
}
struct pbase_tree_cache {
unsigned char sha1[20];
int ref;
int temporary;
void *tree_data;
unsigned long tree_size;
};
static struct pbase_tree_cache *(pbase_tree_cache[256]);
static int pbase_tree_cache_ix(const unsigned char *sha1)
{
return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
}
static int pbase_tree_cache_ix_incr(int ix)
{
return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
}
static struct pbase_tree {
struct pbase_tree *next;
/* This is a phony "cache" entry; we are not
* going to evict it nor find it through _get()
* mechanism -- this is for the toplevel node that
* would almost always change with any commit.
*/
struct pbase_tree_cache pcache;
} *pbase_tree;
static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
{
struct pbase_tree_cache *ent, *nent;
void *data;
unsigned long size;
char type[20];
int neigh;
int my_ix = pbase_tree_cache_ix(sha1);
int available_ix = -1;
/* pbase-tree-cache acts as a limited hashtable.
* your object will be found at your index or within a few
* slots after that slot if it is cached.
*/
for (neigh = 0; neigh < 8; neigh++) {
ent = pbase_tree_cache[my_ix];
if (ent && !memcmp(ent->sha1, sha1, 20)) {
ent->ref++;
return ent;
}
else if (((available_ix < 0) && (!ent || !ent->ref)) ||
((0 <= available_ix) &&
(!ent && pbase_tree_cache[available_ix])))
available_ix = my_ix;
if (!ent)
break;
my_ix = pbase_tree_cache_ix_incr(my_ix);
}
/* Did not find one. Either we got a bogus request or
* we need to read and perhaps cache.
*/
data = read_sha1_file(sha1, type, &size);
if (!data)
return NULL;
if (strcmp(type, tree_type)) {
free(data);
return NULL;
}
/* We need to either cache or return a throwaway copy */
if (available_ix < 0)
ent = NULL;
else {
ent = pbase_tree_cache[available_ix];
my_ix = available_ix;
}
if (!ent) {
nent = xmalloc(sizeof(*nent));
nent->temporary = (available_ix < 0);
}
else {
/* evict and reuse */
free(ent->tree_data);
nent = ent;
}
memcpy(nent->sha1, sha1, 20);
nent->tree_data = data;
nent->tree_size = size;
nent->ref = 1;
if (!nent->temporary)
pbase_tree_cache[my_ix] = nent;
return nent;
}
static void pbase_tree_put(struct pbase_tree_cache *cache)
{
if (!cache->temporary) {
cache->ref--;
return;
}
free(cache->tree_data);
free(cache);
}
static int name_cmp_len(const char *name)
{
int i;
for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
;
return i;
}
static void add_pbase_object(struct tree_desc *tree,
struct name_path *up,
const char *name,
int cmplen)
{
while (tree->size) {
const unsigned char *sha1;
const char *entry_name;
int entry_len;
unsigned mode;
unsigned long size;
char type[20];
sha1 = tree_entry_extract(tree, &entry_name, &mode);
update_tree_entry(tree);
entry_len = strlen(entry_name);
if (entry_len != cmplen ||
memcmp(entry_name, name, cmplen) ||
!has_sha1_file(sha1) ||
sha1_object_info(sha1, type, &size))
continue;
if (name[cmplen] != '/') {
unsigned hash = name_hash(up, name);
add_object_entry(sha1, hash, 1);
return;
}
if (!strcmp(type, tree_type)) {
struct tree_desc sub;
struct name_path me;
struct pbase_tree_cache *tree;
const char *down = name+cmplen+1;
int downlen = name_cmp_len(down);
tree = pbase_tree_get(sha1);
if (!tree)
return;
sub.buf = tree->tree_data;
sub.size = tree->tree_size;
me.up = up;
me.elem = entry_name;
me.len = entry_len;
add_pbase_object(&sub, &me, down, downlen);
pbase_tree_put(tree);
}
}
}
static unsigned *done_pbase_paths;
static int done_pbase_paths_num;
static int done_pbase_paths_alloc;
static int done_pbase_path_pos(unsigned hash)
{
int lo = 0;
int hi = done_pbase_paths_num;
while (lo < hi) {
int mi = (hi + lo) / 2;
if (done_pbase_paths[mi] == hash)
return mi;
if (done_pbase_paths[mi] < hash)
hi = mi;
else
lo = mi + 1;
}
return -lo-1;
}
static int check_pbase_path(unsigned hash)
{
int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
if (0 <= pos)
return 1;
pos = -pos - 1;
if (done_pbase_paths_alloc <= done_pbase_paths_num) {
done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
done_pbase_paths = xrealloc(done_pbase_paths,
done_pbase_paths_alloc *
sizeof(unsigned));
}
done_pbase_paths_num++;
if (pos < done_pbase_paths_num)
memmove(done_pbase_paths + pos + 1,
done_pbase_paths + pos,
(done_pbase_paths_num - pos - 1) * sizeof(unsigned));
done_pbase_paths[pos] = hash;
return 0;
}
static void add_preferred_base_object(char *name, unsigned hash)
{
struct pbase_tree *it;
int cmplen = name_cmp_len(name);
if (check_pbase_path(hash))
return;
for (it = pbase_tree; it; it = it->next) {
if (cmplen == 0) {
hash = name_hash(NULL, "");
add_object_entry(it->pcache.sha1, hash, 1);
}
else {
struct tree_desc tree;
tree.buf = it->pcache.tree_data;
tree.size = it->pcache.tree_size;
add_pbase_object(&tree, NULL, name, cmplen);
}
}
}
static void add_preferred_base(unsigned char *sha1)
{
struct pbase_tree *it;
void *data;
unsigned long size;
unsigned char tree_sha1[20];
data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
if (!data)
return;
for (it = pbase_tree; it; it = it->next) {
if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
free(data);
return;
}
}
it = xcalloc(1, sizeof(*it));
it->next = pbase_tree;
pbase_tree = it;
memcpy(it->pcache.sha1, tree_sha1, 20);
it->pcache.tree_data = data;
it->pcache.tree_size = size;
}
static void check_object(struct object_entry *entry)
{
char type[20];
if (entry->in_pack && !entry->preferred_base) {
unsigned char base[20];
unsigned long size;
struct object_entry *base_entry;
/* We want in_pack_type even if we do not reuse delta.
* There is no point not reusing non-delta representations.
*/
check_reuse_pack_delta(entry->in_pack,
entry->in_pack_offset,
base, &size,
&entry->in_pack_type);
/* 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.
*/
if (!no_reuse_delta &&
entry->in_pack_type == OBJ_DELTA &&
(base_entry = locate_object_entry(base)) &&
(!base_entry->preferred_base)) {
/* Depth value does not matter - find_deltas()
* will never consider reused delta as the
* base object to deltify other objects
* against, in order to avoid circular deltas.
*/
/* uncompressed size of the delta data */
entry->size = entry->delta_size = size;
entry->delta = base_entry;
entry->type = OBJ_DELTA;
entry->delta_sibling = base_entry->delta_child;
base_entry->delta_child = entry;
return;
}
/* Otherwise we would do the usual */
}
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_type)) {
entry->type = OBJ_COMMIT;
} else if (!strcmp(type, tree_type)) {
entry->type = OBJ_TREE;
} else if (!strcmp(type, blob_type)) {
entry->type = OBJ_BLOB;
} else if (!strcmp(type, tag_type)) {
entry->type = OBJ_TAG;
} else
die("unable to pack object %s of type %s",
sha1_to_hex(entry->sha1), type);
}
static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
{
struct object_entry *child = me->delta_child;
unsigned int m = n;
while (child) {
unsigned int c = check_delta_limit(child, n + 1);
if (m < c)
m = c;
child = child->delta_sibling;
}
return m;
}
static void get_object_details(void)
{
int i;
struct object_entry *entry;
prepare_pack_ix();
for (i = 0, entry = objects; i < nr_objects; i++, entry++)
check_object(entry);
if (nr_objects == nr_result) {
/*
* Depth of objects that depend on the entry -- this
* is subtracted from depth-max to break too deep
* delta chain because of delta data reusing.
* However, we loosen this restriction when we know we
* are creating a thin pack -- it will have to be
* expanded on the other end anyway, so do not
* artificially cut the delta chain and let it go as
* deep as it wants.
*/
for (i = 0, entry = objects; i < nr_objects; i++, entry++)
if (!entry->delta && entry->delta_child)
entry->delta_limit =
check_delta_limit(entry, 1);
}
}
typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
static entry_sort_t current_sort;
static int sort_comparator(const void *_a, const void *_b)
{
struct object_entry *a = *(struct object_entry **)_a;
struct object_entry *b = *(struct object_entry **)_b;
return current_sort(a,b);
}
static struct object_entry **create_sorted_list(entry_sort_t sort)
{
struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
int i;
for (i = 0; i < nr_objects; i++)
list[i] = objects + i;
current_sort = sort;
qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
return list;
}
static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
{
return memcmp(a->sha1, b->sha1, 20);
}
static struct object_entry **create_final_object_list(void)
{
struct object_entry **list;
int i, j;
for (i = nr_result = 0; i < nr_objects; i++)
if (!objects[i].preferred_base)
nr_result++;
list = xmalloc(nr_result * sizeof(struct object_entry *));
for (i = j = 0; i < nr_objects; i++) {
if (!objects[i].preferred_base)
list[j++] = objects + i;
}
current_sort = sha1_sort;
qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
return list;
}
static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
{
if (a->type < b->type)
return -1;
if (a->type > b->type)
return 1;
if (a->hash < b->hash)
return -1;
if (a->hash > b->hash)
return 1;
if (a->preferred_base < b->preferred_base)
return -1;
if (a->preferred_base > b->preferred_base)
return 1;
if (a->size < b->size)
return -1;
if (a->size > b->size)
return 1;
return a < b ? -1 : (a > b);
}
struct unpacked {
struct object_entry *entry;
void *data;
};
/*
* We search for deltas _backwards_ in a list sorted by type and
* by size, so that we see progressively smaller and smaller files.
* That's because we prefer deltas to be from the bigger file
* to the smaller - deletes are potentially cheaper, but perhaps
* more importantly, the bigger file is likely the more recent
* one.
*/
static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
{
struct object_entry *cur_entry = cur->entry;
struct object_entry *old_entry = old->entry;
unsigned long size, oldsize, delta_size, sizediff;
long max_size;
void *delta_buf;
/* Don't bother doing diffs between different types */
if (cur_entry->type != old_entry->type)
return -1;
/* We do not compute delta to *create* objects we are not
* going to pack.
*/
if (cur_entry->preferred_base)
return -1;
/* If the current object is at pack edge, take the depth the
* objects that depend on the current object into account --
* otherwise they would become too deep.
*/
if (cur_entry->delta_child) {
if (max_depth <= cur_entry->delta_limit)
return 0;
max_depth -= cur_entry->delta_limit;
}
size = cur_entry->size;
oldsize = old_entry->size;
sizediff = oldsize > size ? oldsize - size : size - oldsize;
if (size < 50)
return -1;
if (old_entry->depth >= max_depth)
return 0;
/*
* NOTE!
*
* We always delta from the bigger to the smaller, since that's
* more space-efficient (deletes don't have to say _what_ they
* delete).
*/
max_size = size / 2 - 20;
if (cur_entry->delta)
max_size = cur_entry->delta_size-1;
if (sizediff >= max_size)
return 0;
delta_buf = diff_delta(old->data, oldsize,
cur->data, size, &delta_size, max_size);
if (!delta_buf)
return 0;
cur_entry->delta = old_entry;
cur_entry->delta_size = delta_size;
cur_entry->depth = old_entry->depth + 1;
free(delta_buf);
return 0;
}
static void progress_interval(int signum)
{
progress_update = 1;
}
static void find_deltas(struct object_entry **list, int window, int depth)
{
int i, idx;
unsigned int array_size = window * sizeof(struct unpacked);
struct unpacked *array = xmalloc(array_size);
unsigned processed = 0;
unsigned last_percent = 999;
memset(array, 0, array_size);
i = nr_objects;
idx = 0;
if (progress)
fprintf(stderr, "Deltifying %d objects.\n", nr_result);
while (--i >= 0) {
struct object_entry *entry = list[i];
struct unpacked *n = array + idx;
unsigned long size;
char type[10];
int j;
if (!entry->preferred_base)
processed++;
if (progress) {
unsigned percent = processed * 100 / nr_result;
if (percent != last_percent || progress_update) {
fprintf(stderr, "%4u%% (%u/%u) done\r",
percent, processed, nr_result);
progress_update = 0;
last_percent = percent;
}
}
if (entry->delta)
/* This happens if we decided to reuse existing
* delta from a pack. "!no_reuse_delta &&" is implied.
*/
continue;
free(n->data);
n->entry = entry;
n->data = read_sha1_file(entry->sha1, type, &size);
if (size != entry->size)
die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
j = window;
while (--j > 0) {
unsigned int other_idx = idx + j;
struct unpacked *m;
if (other_idx >= window)
other_idx -= window;
m = array + other_idx;
if (!m->entry)
break;
if (try_delta(n, m, depth) < 0)
break;
}
#if 0
/* if we made n a delta, and if n is already at max
* depth, leaving it in the window is pointless. we
* should evict it first.
* ... in theory only; somehow this makes things worse.
*/
if (entry->delta && depth <= entry->depth)
continue;
#endif
idx++;
if (idx >= window)
idx = 0;
}
if (progress)
fputc('\n', stderr);
for (i = 0; i < window; ++i)
free(array[i].data);
free(array);
}
static void prepare_pack(int window, int depth)
{
get_object_details();
sorted_by_type = create_sorted_list(type_size_sort);
if (window && depth)
find_deltas(sorted_by_type, window+1, depth);
}
static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
{
static const char cache[] = "pack-cache/pack-%s.%s";
char *cached_pack, *cached_idx;
int ifd, ofd, ifd_ix = -1;
cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
ifd = open(cached_pack, O_RDONLY);
if (ifd < 0)
return 0;
if (!pack_to_stdout) {
cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
ifd_ix = open(cached_idx, O_RDONLY);
if (ifd_ix < 0) {
close(ifd);
return 0;
}
}
if (progress)
fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
sha1_to_hex(sha1));
if (pack_to_stdout) {
if (copy_fd(ifd, 1))
exit(1);
close(ifd);
}
else {
char name[PATH_MAX];
snprintf(name, sizeof(name),
"%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
if (ofd < 0)
die("unable to open %s (%s)", name, strerror(errno));
if (copy_fd(ifd, ofd))
exit(1);
close(ifd);
snprintf(name, sizeof(name),
"%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
if (ofd < 0)
die("unable to open %s (%s)", name, strerror(errno));
if (copy_fd(ifd_ix, ofd))
exit(1);
close(ifd_ix);
puts(sha1_to_hex(sha1));
}
return 1;
}
static void setup_progress_signal(void)
{
struct sigaction sa;
struct itimerval v;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = progress_interval;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sigaction(SIGALRM, &sa, NULL);
v.it_interval.tv_sec = 1;
v.it_interval.tv_usec = 0;
v.it_value = v.it_interval;
setitimer(ITIMER_REAL, &v, NULL);
}
int main(int argc, char **argv)
{
SHA_CTX ctx;
char line[40 + 1 + PATH_MAX + 2];
int window = 10, depth = 10, pack_to_stdout = 0;
struct object_entry **list;
int num_preferred_base = 0;
int i;
setup_git_directory();
for (i = 1; i < argc; i++) {
const char *arg = argv[i];
if (*arg == '-') {
if (!strcmp("--non-empty", arg)) {
non_empty = 1;
continue;
}
if (!strcmp("--local", arg)) {
local = 1;
continue;
}
if (!strcmp("--incremental", arg)) {
incremental = 1;
continue;
}
if (!strncmp("--window=", arg, 9)) {
char *end;
window = strtoul(arg+9, &end, 0);
if (!arg[9] || *end)
usage(pack_usage);
continue;
}
if (!strncmp("--depth=", arg, 8)) {
char *end;
depth = strtoul(arg+8, &end, 0);
if (!arg[8] || *end)
usage(pack_usage);
continue;
}
if (!strcmp("-q", arg)) {
progress = 0;
continue;
}
if (!strcmp("--no-reuse-delta", arg)) {
no_reuse_delta = 1;
continue;
}
if (!strcmp("--stdout", arg)) {
pack_to_stdout = 1;
continue;
}
usage(pack_usage);
}
if (base_name)
usage(pack_usage);
base_name = arg;
}
if (pack_to_stdout != !base_name)
usage(pack_usage);
prepare_packed_git();
if (progress) {
fprintf(stderr, "Generating pack...\n");
setup_progress_signal();
}
for (;;) {
unsigned char sha1[20];
unsigned hash;
if (!fgets(line, sizeof(line), stdin)) {
if (feof(stdin))
break;
if (!ferror(stdin))
die("fgets returned NULL, not EOF, not error!");
if (errno != EINTR)
die("fgets: %s", strerror(errno));
clearerr(stdin);
continue;
}
if (line[0] == '-') {
if (get_sha1_hex(line+1, sha1))
die("expected edge sha1, got garbage:\n %s",
line+1);
if (num_preferred_base++ < window)
add_preferred_base(sha1);
continue;
}
if (get_sha1_hex(line, sha1))
die("expected sha1, got garbage:\n %s", line);
hash = name_hash(NULL, line+41);
add_preferred_base_object(line+41, hash);
add_object_entry(sha1, hash, 0);
}
if (progress)
fprintf(stderr, "Done counting %d objects.\n", nr_objects);
sorted_by_sha = create_final_object_list();
if (non_empty && !nr_result)
return 0;
SHA1_Init(&ctx);
list = sorted_by_sha;
for (i = 0; i < nr_result; i++) {
struct object_entry *entry = *list++;
SHA1_Update(&ctx, entry->sha1, 20);
}
SHA1_Final(object_list_sha1, &ctx);
if (progress && (nr_objects != nr_result))
fprintf(stderr, "Result has %d objects.\n", nr_result);
if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
;
else {
if (nr_result)
prepare_pack(window, depth);
if (progress && pack_to_stdout) {
/* the other end usually displays progress itself */
struct itimerval v = {{0,},};
setitimer(ITIMER_REAL, &v, NULL);
signal(SIGALRM, SIG_IGN );
progress_update = 0;
}
write_pack_file();
if (!pack_to_stdout) {
write_index_file();
puts(sha1_to_hex(object_list_sha1));
}
}
if (progress)
fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
nr_result, written, written_delta, reused, reused_delta);
return 0;
}