> On 14 May 2016, at 20:15, Junio C Hamano <[email protected]> wrote:
>
> Lars Schneider <[email protected]> writes:
>
>>> On 13 May 2016, at 18:37, Junio C Hamano <[email protected]> wrote:
>>>
>>> Are you saying that "git p4" itself breaks unless fast-import always
>>> writes a new (tiny) packfile? That sounds quite broken, and setting
>>> unpacklimit to 0 does not sound like a sensible "fix". Of course,
>>> if the test script is somehow looking at the number of packs or
>>> loose objects and declaring a failure, even when the resulting
>>> history in p4 and git are correct, then that is a different issue,
>>> and forcing to explode a tiny pack is a reasonable workaround. I
>>> couldn't quite tell which the case is.
>>>
>>> Puzzled. Please help.
>>
>> t9801 "import depot, branch detection" is the first test that fails
>> with a fast import error:
>> https://github.com/git/git/blob/78b384c29366e199741393e56030a8384110760d/t/t9801-git-p4-branch.sh#L110
>>
>> fast-import crash report:
>> fast-import process: 77079
>> parent process : 77077
>> at 2016-05-14 07:48:40 +0000
>>
>> fatal: offset beyond end of packfile (truncated pack?)
>
> Hmm, does that suggest Eric's "explode them into loose instead of
> keeping a small pack" insufficient? It sounds like that somebody
> wanted to read some data back from its packfile without knowing that
> the updated code may make it available in a loose object form, which
> would mean that somebody needs to be told about what is going on,
> namely, these objects are not in a half-written pack but are found
> as loose objects.
I think that is pretty much the problem. Here is what is happening:
1. git-p4 imports all changelists for the "main" branch
2. git-p4 starts to import a second branch and creates a fast-import
"progress checkpoint". This triggers:
--> fast-import.c: cycle_packfile
--> fast-import.c: end_packfile
--> fast-import.c: loosen_small_pack
At this point we have no packfile anymore.
3. git-p4 sends the command "commit refs/remotes/p4/depot/branch2"
to fast-import in order to create a new branch. This triggers:
--> fast-import.c: parse_new_commit
--> fast-import.c: load_branch
--> fast-import.c: load_tree
"load_tree" calls "find_object" and the result has a "pack_id" of 0.
I think this indicates that the object is in the packfile. Shouldn't
the "pack_id" be "MAX_PACK_ID" instead?
myoe = find_object(sha1);
if (myoe && myoe->pack_id != MAX_PACK_ID) {
--> fast-import.c: gfi_unpack_entry
In "gfi_unpack_entry" this condition evaluates to "true":
struct packed_git *p = all_packs[oe->pack_id];
if (p == pack_data && p->pack_size < (pack_size + 20))
In the comment below Git thinks that the object is stored in the
packfile. This seems wrong but the flow continues:
--> sha1_filec: unpack_entry
--> sha1_filec: unpack_object_header
--> sha1_filec: use_pack
At this point fast-import dies with "offset beyond end of packfile
(truncated pack?)".
I am no expert in "fast-import". Does anyone have a few hints how to
proceed?
Thanks,
Lars--
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