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factorize revindex code out of builtin-pack-objects.c

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No functional change. This is needed to fix verify-pack in a later patch.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nicolas Pitre 2008-02-28 00:25:17 -05:00 committed by Junio C Hamano
parent 6d21667206
commit 3449f8c4cb
4 changed files with 167 additions and 152 deletions
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5
Makefile
View File

@ -304,7 +304,8 @@ LIB_H = \
run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h \
tree-walk.h log-tree.h dir.h path-list.h unpack-trees.h builtin.h \
utf8.h reflog-walk.h patch-ids.h attr.h decorate.h progress.h \
mailmap.h remote.h parse-options.h transport.h diffcore.h hash.h
mailmap.h remote.h parse-options.h transport.h diffcore.h hash.h \
pack-revindex.h
DIFF_OBJS = \
diff.o diff-lib.o diffcore-break.o diffcore-order.o \
@ -328,7 +329,7 @@ LIB_OBJS = \
color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
convert.o attr.o decorate.o progress.o mailmap.o symlinks.o remote.o \
transport.o bundle.o walker.o parse-options.o ws.o archive.o branch.o \
alias.o
alias.o pack-revindex.o
BUILTIN_OBJS = \
builtin-add.o \

160
builtin-pack-objects.c
View File

@ -8,6 +8,7 @@
#include "tree.h"
#include "delta.h"
#include "pack.h"
#include "pack-revindex.h"
#include "csum-file.h"
#include "tree-walk.h"
#include "diff.h"
@ -92,158 +93,12 @@ static unsigned long window_memory_limit = 0;
static int *object_ix;
static int object_ix_hashsz;
/*
* 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). It is
* also rather expensive to find the sha1 for an object given its offset.
*
* 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 a list of offset/index_nr pairs
* ordered by offset, so if you know the offset of an object, next offset
* is where its packed representation ends and the index_nr can be used to
* get the object sha1 from the main index.
*/
struct revindex_entry {
off_t offset;
unsigned int nr;
};
struct pack_revindex {
struct packed_git *p;
struct revindex_entry *revindex;
};
static struct pack_revindex *pack_revindex;
static int pack_revindex_hashsz;
/*
* stats
*/
static uint32_t written, written_delta;
static uint32_t reused, reused_delta;
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_)
{
const struct revindex_entry *a = a_;
const struct revindex_entry *b = b_;
return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
}
/*
* 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 = p->num_objects;
int i;
const char *index = p->index_data;
rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
index += 4 * 256;
if (p->index_version > 1) {
const uint32_t *off_32 =
(uint32_t *)(index + 8 + p->num_objects * (20 + 4));
const uint32_t *off_64 = off_32 + p->num_objects;
for (i = 0; i < num_ent; i++) {
uint32_t off = ntohl(*off_32++);
if (!(off & 0x80000000)) {
rix->revindex[i].offset = off;
} else {
rix->revindex[i].offset =
((uint64_t)ntohl(*off_64++)) << 32;
rix->revindex[i].offset |=
ntohl(*off_64++);
}
rix->revindex[i].nr = i;
}
} else {
for (i = 0; i < num_ent; i++) {
uint32_t hl = *((uint32_t *)(index + 24 * i));
rix->revindex[i].offset = ntohl(hl);
rix->revindex[i].nr = i;
}
}
/* This knows the pack format -- the 20-byte trailer
* follows immediately after the last object data.
*/
rix->revindex[num_ent].offset = p->pack_size - 20;
rix->revindex[num_ent].nr = -1;
qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
}
static struct revindex_entry * find_packed_object(struct packed_git *p,
off_t ofs)
{
int num;
int lo, hi;
struct pack_revindex *rix;
struct revindex_entry *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 = p->num_objects + 1;
do {
int mi = (lo + hi) / 2;
if (revindex[mi].offset == ofs) {
return revindex + mi;
}
else if (ofs < revindex[mi].offset)
hi = mi;
else
lo = mi + 1;
} while (lo < hi);
die("internal error: pack revindex corrupt");
}
static const unsigned char *find_packed_object_name(struct packed_git *p,
off_t ofs)
{
struct revindex_entry *entry = find_packed_object(p, ofs);
return nth_packed_object_sha1(p, entry->nr);
}
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
{
@ -510,7 +365,7 @@ static unsigned long write_object(struct sha1file *f,
}
hdrlen = encode_header(obj_type, entry->size, header);
offset = entry->in_pack_offset;
revidx = find_packed_object(p, offset);
revidx = find_pack_revindex(p, offset);
datalen = revidx[1].offset - offset;
if (!pack_to_stdout && p->index_version > 1 &&
check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
@ -1162,8 +1017,11 @@ static void check_object(struct object_entry *entry)
die("delta base offset out of bound for %s",
sha1_to_hex(entry->idx.sha1));
ofs = entry->in_pack_offset - ofs;
if (!no_reuse_delta && !entry->preferred_base)
base_ref = find_packed_object_name(p, ofs);
if (!no_reuse_delta && !entry->preferred_base) {
struct revindex_entry *revidx;
revidx = find_pack_revindex(p, ofs);
base_ref = nth_packed_object_sha1(p, revidx->nr);
}
entry->in_pack_header_size = used + used_0;
break;
}
@ -1240,9 +1098,11 @@ static void get_object_details(void)
sorted_by_offset[i] = objects + i;
qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
prepare_pack_ix();
init_pack_revindex();
for (i = 0; i < nr_objects; i++)
check_object(sorted_by_offset[i]);
free(sorted_by_offset);
}

142
pack-revindex.c Normal file
View File

@ -0,0 +1,142 @@
#include "cache.h"
#include "pack-revindex.h"
/*
* 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). It is
* also rather expensive to find the sha1 for an object given its offset.
*
* 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 a list of offset/index_nr pairs
* ordered by offset, so if you know the offset of an object, next offset
* is where its packed representation ends and the index_nr can be used to
* get the object sha1 from the main index.
*/
struct pack_revindex {
struct packed_git *p;
struct revindex_entry *revindex;
};
static struct pack_revindex *pack_revindex;
static int pack_revindex_hashsz;
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;
}
void init_pack_revindex(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_)
{
const struct revindex_entry *a = a_;
const struct revindex_entry *b = b_;
return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
}
/*
* Ordered list of offsets of objects in the pack.
*/
static void create_pack_revindex(struct pack_revindex *rix)
{
struct packed_git *p = rix->p;
int num_ent = p->num_objects;
int i;
const char *index = p->index_data;
rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
index += 4 * 256;
if (p->index_version > 1) {
const uint32_t *off_32 =
(uint32_t *)(index + 8 + p->num_objects * (20 + 4));
const uint32_t *off_64 = off_32 + p->num_objects;
for (i = 0; i < num_ent; i++) {
uint32_t off = ntohl(*off_32++);
if (!(off & 0x80000000)) {
rix->revindex[i].offset = off;
} else {
rix->revindex[i].offset =
((uint64_t)ntohl(*off_64++)) << 32;
rix->revindex[i].offset |=
ntohl(*off_64++);
}
rix->revindex[i].nr = i;
}
} else {
for (i = 0; i < num_ent; i++) {
uint32_t hl = *((uint32_t *)(index + 24 * i));
rix->revindex[i].offset = ntohl(hl);
rix->revindex[i].nr = i;
}
}
/* This knows the pack format -- the 20-byte trailer
* follows immediately after the last object data.
*/
rix->revindex[num_ent].offset = p->pack_size - 20;
rix->revindex[num_ent].nr = -1;
qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
}
struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs)
{
int num;
int lo, hi;
struct pack_revindex *rix;
struct revindex_entry *revindex;
num = pack_revindex_ix(p);
if (num < 0)
die("internal error: pack revindex uninitialized");
rix = &pack_revindex[num];
if (!rix->revindex)
create_pack_revindex(rix);
revindex = rix->revindex;
lo = 0;
hi = p->num_objects + 1;
do {
int mi = (lo + hi) / 2;
if (revindex[mi].offset == ofs) {
return revindex + mi;
} else if (ofs < revindex[mi].offset)
hi = mi;
else
lo = mi + 1;
} while (lo < hi);
die("internal error: pack revindex corrupt");
}

12
pack-revindex.h Normal file
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@ -0,0 +1,12 @@
#ifndef PACK_REVINDEX_H
#define PACK_REVINDEX_H
struct revindex_entry {
off_t offset;
unsigned int nr;
};
void init_pack_revindex(void);
struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs);
#endif