@matheusbsbs / matheus-bagliano / commits / f7f91086a3

pack-objects: turn off bitmaps when we see --shallow lines

Reachability bitmaps do not work with shallow operations, because they cache a view of the object reachability that represents the true objects. Whereas a shallow repository (or a shallow operation in a repository) is inherently cutting off the object graph with a graft. We explicitly disallow the use of bitmaps in shallow repositories by checking is_repository_shallow(), and we should continue to do that. However, we also want to disallow bitmaps when we are serving a fetch to a shallow client, since we momentarily take on their grafted view of the world. It used to be enough to call is_repository_shallow at the start of pack-objects. Upload-pack wrote the other side's shallow state to a temporary file and pointed the whole pack-objects process at this state with "git --shallow-file", and from the perspective of pack-objects, we really were in a shallow repo. But since b790e0f (upload-pack: send shallow info over stdin to pack-objects, 2014-03-11), we do it differently: we send --shallow lines to pack-objects over stdin, and it registers them itself. This means that our is_repository_shallow check is way too early (we have not been told about the shallowness yet), and that it is insufficient (calling is_repository_shallow is not enough, as the shallow grafts we register do not change its return value). Instead, we can just turn off bitmaps explicitly when we see these lines. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Aug 12, 2014 at 00:34 UTC f7f91086a376ba53f8270ea80b7bbbd8274c3c2d

2 files changed +40

builtin/pack-objects.c

@@ -2498,6 +2498,7 @@ static void get_object_list(int ac, const char **av)

2498 if (get_sha1_hex(line + 10, sha1))

2499 die("not an SHA-1 '%s'", line + 10);

2500 register_shallow(sha1);

2501 + use_bitmap_index = 0;

2502 continue;

2503 }

2504 die("not a rev '%s'", line);

t/t5311-pack-bitmaps-shallow.sh new

+39

@@ -0,0 +1,39 @@

1 +#!/bin/sh

2 +

3 +test_description='check bitmap operation with shallow repositories'

4 +. ./test-lib.sh

5 +

6 +# We want to create a situation where the shallow, grafted

7 +# view of reachability does not match reality in a way that

8 +# might cause us to send insufficient objects.

9 +#

10 +# We do this with a history that repeats a state, like:

11 +#

12 +# A -- B -- C

13 +# file=1 file=2 file=1

14 +#

15 +# and then create a shallow clone to the second commit, B.

16 +# In a non-shallow clone, that would mean we already have

17 +# the tree for A. But in a shallow one, we've grafted away

18 +# A, and fetching A to B requires that the other side send

19 +# us the tree for file=1.

20 +test_expect_success 'setup shallow repo' '

21 + echo 1 >file &&

22 + git add file &&

23 + git commit -m orig &&

24 + echo 2 >file &&

25 + git commit -a -m update &&

26 + git clone --no-local --bare --depth=1 . shallow.git &&

27 + echo 1 >file &&

28 + git commit -a -m repeat

29 +'

30 +

31 +test_expect_success 'turn on bitmaps in the parent' '

32 + git repack -adb

33 +'

34 +

35 +test_expect_success 'shallow fetch from bitmapped repo' '

36 + (cd shallow.git && git fetch)

37 +'

38 +

39 +test_done