Re: [PATCH/RFC] upload-pack: ignore 'shallow' lines with unknown obj-ids
From: Duy Nguyen <hidden>
Date: 2016-06-15 22:56:55
On Sun, Apr 21, 2013 at 6:51 AM, Junio C Hamano [off-list ref] wrote:
Duy Nguyen [off-list ref] writes: But the shallow list is also used to compute the updated boundary (i.e. "this client does not have a valid history behind these commits")? When we know their current shallow boundary, after sending history that crosses that boundary, we can tell them "before this fetch, you did not have any history behind this commit, but we know that you now have a bit more. Update your record with these new boundaries. You still do not have any history behind these commits." That is how deepening works. When you receive a shallow boundary unknown to you, it might not hurt if you keep it and parrot it at the end, so that the fetcher will still remember that it does not have any history behind the commit. There may be reasons why doing so is not sufficient and we have to reject clients whose history is truncated at a place unknown to us. You would declare "now you have everything behind that unknown shallow boundary", if you ignore an unknown shallow boundary and do not send it back. That sounds ourright wrong to me. You simply do not know enough to make such a declaration.
It's a good point. But I think the receiver does not rely solely on "shallow " lines from the sender to create new shallow file. If it receives "shallow " line, it registers the received sha-1 as a cut point. If it receives "unshallow " line, it unregisters. If it receives neither, the current registered cutpoints in memory are simply written back to disk. So not sending it back should not be a big problem (at least for C Git).
I do not seem to find the patch you are responding to, so I do not know how the patch handled the unshallowing part, but the impression I got from reading the log message quoted is that the patch was not even aware of the issue.
I can't find it on gmane.org either. Patch quoted below. On Sat, Apr 20, 2013 at 8:05 PM, Michael Heemskerk [off-list ref] wrote:
quoted hunk ↗ jump to hunk
diff --git a/Documentation/technical/pack-protocol.txtb/Documentation/technical/pack-protocol.txt index f1a51ed..b898e97 100644--- a/Documentation/technical/pack-protocol.txt +++ b/Documentation/technical/pack-protocol.txt@@ -228,8 +228,7 @@ obtained through ref discovery. The client MUST write all obj-ids which it only has shallow copies of (meaning that it does not have the parents of a commit) as 'shallow' lines so that the server is aware of the limitations of -the client's history. Clients MUST NOT mention an obj-id which -it does not know exists on the server. +the client's history. The client now sends the maximum commit history depth it wants for this transaction, which is the number of commits it wants from thediff --git a/upload-pack.c b/upload-pack.c index bfa6279..127e59a 100644 --- a/upload-pack.c +++ b/upload-pack.c@@ -592,7 +592,7 @@ static void receive_needs(void) die("invalid shallow line: %s", line); object = parse_object(sha1); if (!object) - die("did not find object for %s", line); + continue; if (object->type != OBJ_COMMIT) die("invalid shallow object %s",sha1_to_hex(sha1)); if (!(object->flags & CLIENT_SHALLOW)) { -- 1.8.0.2
-- Duy