undef/git-commit-vandalism
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make the sender advertise shallow commits to the receiver

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If either receive-pack or upload-pack is called on a shallow
repository, shallow commits (*) will be sent after the ref
advertisement (but before the packet flush), so that the receiver has
the full "shape" of the sender's commit graph. This will be needed for
the receiver to update its .git/shallow if necessary.

This breaks the protocol for all clients trying to push to a shallow
repo, or fetch from one. Which is basically the same end result as
today's "is_repository_shallow() && die()" in receive-pack and
upload-pack. New clients will be made aware of shallow upstream and
can make use of this information.

The sender must send all shallow commits that are sent in the
following pack. It may send more shallow commits than necessary.

upload-pack for example may choose to advertise no shallow commits if
it knows in advance that the pack it's going to send contains no
shallow commits. But upload-pack is the server, so we choose the
cheaper way, send full .git/shallow and let the client deal with it.

Smart HTTP is not affected by this patch. Shallow support on
smart-http comes later separately.

(*) A shallow commit is a commit that terminates the revision
    walker. It is usually put in .git/shallow in order to keep the
    revision walker from going out of bound because there is no
    guarantee that objects behind this commit is available.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nguyễn Thái Ngọc Duy 2013-12-05 20:02:32 +07:00 committed by Junio C Hamano
parent 606e435a0a
commit ad491366de
5 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/technical/pack-protocol.txt
View File

@ -161,6 +161,7 @@ MUST peel the ref if it's an annotated tag.
----
advertised-refs = (no-refs / list-of-refs)
*shallow
flush-pkt
no-refs = PKT-LINE(zero-id SP "capabilities^{}"
@ -174,6 +175,8 @@ MUST peel the ref if it's an annotated tag.
other-tip = obj-id SP refname LF
other-peeled = obj-id SP refname "^{}" LF
shallow = PKT-LINE("shallow" SP obj-id)
capability-list = capability *(SP capability)
capability = 1*(LC_ALPHA / DIGIT / "-" / "_")
LC_ALPHA = %x61-7A

4
builtin/receive-pack.c
View File

@ -178,6 +178,8 @@ static void write_head_info(void)
if (!sent_capabilities)
show_ref("capabilities^{}", null_sha1);
advertise_shallow_grafts(1);
/* EOF */
packet_flush(1);
}
@ -998,7 +1000,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
if (!enter_repo(dir, 0))
die("'%s' does not appear to be a git repository", dir);
if (is_repository_shallow())
if (is_repository_shallow() && stateless_rpc)
die("attempt to push into a shallow repository");
git_config(receive_pack_config, NULL);

1
commit.h
View File

@ -205,6 +205,7 @@ extern int write_shallow_commits(struct strbuf *out, int use_pack_protocol);
extern void setup_alternate_shallow(struct lock_file *shallow_lock,
const char **alternate_shallow_file);
extern char *setup_temporary_shallow(void);
extern void advertise_shallow_grafts(int);
int is_descendant_of(struct commit *, struct commit_list *);
int in_merge_bases(struct commit *, struct commit *);

15
shallow.c
View File

@ -220,3 +220,18 @@ void setup_alternate_shallow(struct lock_file *shallow_lock,
*alternate_shallow_file = "";
strbuf_release(&sb);
}
static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
{
int fd = *(int *)cb;
if (graft->nr_parent == -1)
packet_write(fd, "shallow %s\n", sha1_to_hex(graft->sha1));
return 0;
}
void advertise_shallow_grafts(int fd)
{
if (!is_repository_shallow())
return;
for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
}

6
upload-pack.c
View File

@ -758,6 +758,7 @@ static void upload_pack(void)
reset_timeout();
head_ref_namespaced(send_ref, &symref);
for_each_namespaced_ref(send_ref, &symref);
advertise_shallow_grafts(1);
packet_flush(1);
} else {
head_ref_namespaced(mark_our_ref, NULL);
@ -835,8 +836,9 @@ int main(int argc, char **argv)
if (!enter_repo(dir, strict))
die("'%s' does not appear to be a git repository", dir);
if (is_repository_shallow())
die("attempt to fetch/clone from a shallow repository");
if (is_repository_shallow() && stateless_rpc)
die("attempt to push into a shallow repository");
git_config(upload_pack_config, NULL);
upload_pack();
return 0;