@matheusbsbs / matheus-bagliano / commits / ad491366de

make the sender advertise shallow commits to the receiver

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>

Nguyễn Thái Ngọc Duy committed Dec 5, 2013 at 20:02 UTC ad491366de6c883cd04539cb86db31049201dfbd
5 files changed +26 -3
Documentation/technical/pack-protocol.txt
+3
@@ -161,6 +161,7 @@ MUST peel the ref if it's an annotated tag.
161
162 ----
163 advertised-refs = (no-refs / list-of-refs)
164 + *shallow
165 flush-pkt
166
167 no-refs = PKT-LINE(zero-id SP "capabilities^{}"
@@ -174,6 +175,8 @@ MUST peel the ref if it's an annotated tag.
175 other-tip = obj-id SP refname LF
176 other-peeled = obj-id SP refname "^{}" LF
177
178 + shallow = PKT-LINE("shallow" SP obj-id)
179 +
180 capability-list = capability *(SP capability)
181 capability = 1*(LC_ALPHA / DIGIT / "-" / "_")
182 LC_ALPHA = %x61-7A
builtin/receive-pack.c
+3 -1
@@ -178,6 +178,8 @@ static void write_head_info(void)
178 if (!sent_capabilities)
179 show_ref("capabilities^{}", null_sha1);
180
181 + advertise_shallow_grafts(1);
182 +
183 /* EOF */
184 packet_flush(1);
185 }
@@ -998,7 +1000,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
1000 if (!enter_repo(dir, 0))
1001 die("'%s' does not appear to be a git repository", dir);
1002
1001 - if (is_repository_shallow())
1003 + if (is_repository_shallow() && stateless_rpc)
1004 die("attempt to push into a shallow repository");
1005
1006 git_config(receive_pack_config, NULL);
commit.h
+1
@@ -205,6 +205,7 @@ extern int write_shallow_commits(struct strbuf *out, int use_pack_protocol);
205 extern void setup_alternate_shallow(struct lock_file *shallow_lock,
206 const char **alternate_shallow_file);
207 extern char *setup_temporary_shallow(void);
208 +extern void advertise_shallow_grafts(int);
209
210 int is_descendant_of(struct commit *, struct commit_list *);
211 int in_merge_bases(struct commit *, struct commit *);
shallow.c
+15
@@ -220,3 +220,18 @@ void setup_alternate_shallow(struct lock_file *shallow_lock,
220 *alternate_shallow_file = "";
221 strbuf_release(&sb);
222 }
223 +
224 +static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
225 +{
226 + int fd = *(int *)cb;
227 + if (graft->nr_parent == -1)
228 + packet_write(fd, "shallow %s\n", sha1_to_hex(graft->sha1));
229 + return 0;
230 +}
231 +
232 +void advertise_shallow_grafts(int fd)
233 +{
234 + if (!is_repository_shallow())
235 + return;
236 + for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
237 +}
upload-pack.c
+4 -2
@@ -758,6 +758,7 @@ static void upload_pack(void)
758 reset_timeout();
759 head_ref_namespaced(send_ref, &symref);
760 for_each_namespaced_ref(send_ref, &symref);
761 + advertise_shallow_grafts(1);
762 packet_flush(1);
763 } else {
764 head_ref_namespaced(mark_our_ref, NULL);
@@ -835,8 +836,9 @@ int main(int argc, char **argv)
836
837 if (!enter_repo(dir, strict))
838 die("'%s' does not appear to be a git repository", dir);
838 - if (is_repository_shallow())
839 - die("attempt to fetch/clone from a shallow repository");
839 + if (is_repository_shallow() && stateless_rpc)
840 + die("attempt to push into a shallow repository");
841 +
842 git_config(upload_pack_config, NULL);
843 upload_pack();
844 return 0;