pack-mtimes: support writing pack .mtimes files

Now that the `.mtimes` format is defined, supplement the pack-write API
to be able to conditionally write an `.mtimes` file along with a pack by
setting an additional flag and passing an oidmap that contains the
timestamps corresponding to each object in the pack.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau 2022-05-20 19:17:43 -04:00 committed by Junio C Hamano
parent d9fef9d90d
commit 5dfaf49a5a
4 changed files with 109 additions and 0 deletions

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@ -170,6 +170,9 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
if (pdata->layer)
REALLOC_ARRAY(pdata->layer, pdata->nr_alloc);
if (pdata->cruft_mtime)
REALLOC_ARRAY(pdata->cruft_mtime, pdata->nr_alloc);
}
new_entry = pdata->objects + pdata->nr_objects++;
@ -198,6 +201,9 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
if (pdata->layer)
pdata->layer[pdata->nr_objects - 1] = 0;
if (pdata->cruft_mtime)
pdata->cruft_mtime[pdata->nr_objects - 1] = 0;
return new_entry;
}

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@ -168,6 +168,14 @@ struct packing_data {
/* delta islands */
unsigned int *tree_depth;
unsigned char *layer;
/*
* Used when writing cruft packs.
*
* Object mtimes are stored in pack order when writing, but
* written out in lexicographic (index) order.
*/
uint32_t *cruft_mtime;
};
void prepare_packing_data(struct repository *r, struct packing_data *pdata);
@ -289,4 +297,21 @@ static inline void oe_set_layer(struct packing_data *pack,
pack->layer[e - pack->objects] = layer;
}
static inline uint32_t oe_cruft_mtime(struct packing_data *pack,
struct object_entry *e)
{
if (!pack->cruft_mtime)
return 0;
return pack->cruft_mtime[e - pack->objects];
}
static inline void oe_set_cruft_mtime(struct packing_data *pack,
struct object_entry *e,
uint32_t mtime)
{
if (!pack->cruft_mtime)
CALLOC_ARRAY(pack->cruft_mtime, pack->nr_alloc);
pack->cruft_mtime[e - pack->objects] = mtime;
}
#endif

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@ -3,6 +3,10 @@
#include "csum-file.h"
#include "remote.h"
#include "chunk-format.h"
#include "pack-mtimes.h"
#include "oidmap.h"
#include "chunk-format.h"
#include "pack-objects.h"
void reset_pack_idx_option(struct pack_idx_option *opts)
{
@ -277,6 +281,70 @@ const char *write_rev_file_order(const char *rev_name,
return rev_name;
}
static void write_mtimes_header(struct hashfile *f)
{
hashwrite_be32(f, MTIMES_SIGNATURE);
hashwrite_be32(f, MTIMES_VERSION);
hashwrite_be32(f, oid_version(the_hash_algo));
}
/*
* Writes the object mtimes of "objects" for use in a .mtimes file.
* Note that objects must be in lexicographic (index) order, which is
* the expected ordering of these values in the .mtimes file.
*/
static void write_mtimes_objects(struct hashfile *f,
struct packing_data *to_pack,
struct pack_idx_entry **objects,
uint32_t nr_objects)
{
uint32_t i;
for (i = 0; i < nr_objects; i++) {
struct object_entry *e = (struct object_entry*)objects[i];
hashwrite_be32(f, oe_cruft_mtime(to_pack, e));
}
}
static void write_mtimes_trailer(struct hashfile *f, const unsigned char *hash)
{
hashwrite(f, hash, the_hash_algo->rawsz);
}
static const char *write_mtimes_file(const char *mtimes_name,
struct packing_data *to_pack,
struct pack_idx_entry **objects,
uint32_t nr_objects,
const unsigned char *hash)
{
struct hashfile *f;
int fd;
if (!to_pack)
BUG("cannot call write_mtimes_file with NULL packing_data");
if (!mtimes_name) {
struct strbuf tmp_file = STRBUF_INIT;
fd = odb_mkstemp(&tmp_file, "pack/tmp_mtimes_XXXXXX");
mtimes_name = strbuf_detach(&tmp_file, NULL);
} else {
unlink(mtimes_name);
fd = xopen(mtimes_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
}
f = hashfd(fd, mtimes_name);
write_mtimes_header(f);
write_mtimes_objects(f, to_pack, objects, nr_objects);
write_mtimes_trailer(f, hash);
if (adjust_shared_perm(mtimes_name) < 0)
die(_("failed to make %s readable"), mtimes_name);
finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
CSUM_HASH_IN_STREAM | CSUM_CLOSE | CSUM_FSYNC);
return mtimes_name;
}
off_t write_pack_header(struct hashfile *f, uint32_t nr_entries)
{
struct pack_header hdr;
@ -479,6 +547,7 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
char **idx_tmp_name)
{
const char *rev_tmp_name = NULL;
const char *mtimes_tmp_name = NULL;
if (adjust_shared_perm(pack_tmp_name))
die_errno("unable to make temporary pack file readable");
@ -491,9 +560,17 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
rev_tmp_name = write_rev_file(NULL, written_list, nr_written, hash,
pack_idx_opts->flags);
if (pack_idx_opts->flags & WRITE_MTIMES) {
mtimes_tmp_name = write_mtimes_file(NULL, to_pack, written_list,
nr_written,
hash);
}
rename_tmp_packfile(name_buffer, pack_tmp_name, "pack");
if (rev_tmp_name)
rename_tmp_packfile(name_buffer, rev_tmp_name, "rev");
if (mtimes_tmp_name)
rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
}
void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)

1
pack.h
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@ -44,6 +44,7 @@ struct pack_idx_option {
#define WRITE_IDX_STRICT 02
#define WRITE_REV 04
#define WRITE_REV_VERIFY 010
#define WRITE_MTIMES 020
uint32_t version;
uint32_t off32_limit;