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sha1-file: remove OBJECT_INFO_SKIP_CACHED 

In a partial clone, if a user provides the hash of the empty tree ("git
mktree </dev/null" - for SHA-1, this is 4b825d...) to a command which
requires that that object be parsed, for example:

  git diff-tree 4b825d <a non-empty tree>

then Git will lazily fetch the empty tree, unnecessarily, because
parsing of that object invokes repo_has_object_file(), which does not
special-case the empty tree.

Instead, teach repo_has_object_file() to consult find_cached_object()
(which handles the empty tree), thus bringing it in line with the rest
of the object-store-accessing functions. A cost is that
repo_has_object_file() will now need to oideq upon each invocation, but
that is trivial compared to the filesystem lookup or the pack index
search required anyway. (And if find_cached_object() needs to do more
because of previous invocations to pretend_object_file(), all the more
reason to be consistent in whether we present cached objects.)

As a historical note, the function now known as repo_read_object_file()
was taught the empty tree in 346245a1bb ("hard-code the empty tree
object", 2008-02-13), and the function now known as oid_object_info()
was taught the empty tree in c4d9986f5f ("sha1_object_info: examine
cached_object store too", 2011-02-07). repo_has_object_file() was never
updated, perhaps due to oversight. The flag OBJECT_INFO_SKIP_CACHED,
introduced later in dfdd4afcf9 ("sha1_file: teach
sha1_object_info_extended more flags", 2017-06-26) and used in
e83e71c5e1 ("sha1_file: refactor has_sha1_file_with_flags", 2017-06-26),
was introduced to preserve this difference in empty-tree handling, but
now it can be removed.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jonathan Tan 2020-01-02 12:16:30 -08:00 committed by Junio C Hamano
parent 53a06cf39b
commit 9c8a294a1a
2 changed files with 18 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
object-store.h
View File

@ -271,8 +271,6 @@ struct object_info {
#define OBJECT_INFO_LOOKUP_REPLACE 1
/* Allow reading from a loose object file of unknown/bogus type */
#define OBJECT_INFO_ALLOW_UNKNOWN_TYPE 2
/* Do not check cached storage */
#define OBJECT_INFO_SKIP_CACHED 4
/* Do not retry packed storage after checking packed and loose storage */
#define OBJECT_INFO_QUICK 8
/* Do not check loose object */

38
sha1-file.c
View File

@ -1417,6 +1417,7 @@ int oid_object_info_extended(struct repository *r, const struct object_id *oid,
struct object_info *oi, unsigned flags)
{
static struct object_info blank_oi = OBJECT_INFO_INIT;
struct cached_object *co;
struct pack_entry e;
int rtype;
const struct object_id *real = oid;
@ -1431,24 +1432,22 @@ int oid_object_info_extended(struct repository *r, const struct object_id *oid,
if (!oi)
oi = &blank_oi;
if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
struct cached_object *co = find_cached_object(real);
if (co) {
if (oi->typep)
*(oi->typep) = co->type;
if (oi->sizep)
*(oi->sizep) = co->size;
if (oi->disk_sizep)
*(oi->disk_sizep) = 0;
if (oi->delta_base_sha1)
hashclr(oi->delta_base_sha1);
if (oi->type_name)
strbuf_addstr(oi->type_name, type_name(co->type));
if (oi->contentp)
*oi->contentp = xmemdupz(co->buf, co->size);
oi->whence = OI_CACHED;
return 0;
}
co = find_cached_object(real);
if (co) {
if (oi->typep)
*(oi->typep) = co->type;
if (oi->sizep)
*(oi->sizep) = co->size;
if (oi->disk_sizep)
*(oi->disk_sizep) = 0;
if (oi->delta_base_sha1)
hashclr(oi->delta_base_sha1);
if (oi->type_name)
strbuf_addstr(oi->type_name, type_name(co->type));
if (oi->contentp)
*oi->contentp = xmemdupz(co->buf, co->size);
oi->whence = OI_CACHED;
return 0;
}
while (1) {
@ -1932,8 +1931,7 @@ int repo_has_object_file_with_flags(struct repository *r,
{
if (!startup_info->have_repository)
return 0;
return oid_object_info_extended(r, oid, NULL,
flags | OBJECT_INFO_SKIP_CACHED) >= 0;
return oid_object_info_extended(r, oid, NULL, flags) >= 0;
}
int repo_has_object_file(struct repository *r,