git/t/t5304-prune.sh
Jeff King 2ba582ba4c prune: save reachable-from-recent objects with bitmaps
We pass our prune expiration to mark_reachable_objects(), which will
traverse not only the reachable objects, but consider any recent ones as
tips for reachability; see d3038d22f9 (prune: keep objects reachable
from recent objects, 2014-10-15) for details.

However, this interacts badly with the bitmap code path added in
fde67d6896 (prune: use bitmaps for reachability traversal, 2019-02-13).
If we hit the bitmap-optimized path, we return immediately to avoid the
regular traversal, accidentally skipping the "also traverse recent"
code.

Instead, we should do an if-else for the bitmap versus regular
traversal, and then follow up with the "recent" traversal in either
case. This reuses the "rev_info" for a bitmap and then a regular
traversal, but that should work OK (the bitmap code clears the pending
array in the usual way, just like a regular traversal would).

Note that I dropped the comment above the regular traversal here.  It
has little explanatory value, and makes the if-else logic much harder to
read.

Here are a few variants that I rejected:

  - it seems like both the reachability and recent traversals could be
    done in a single traversal. This was rejected by d3038d22f9 (prune:
    keep objects reachable from recent objects, 2014-10-15), though the
    balance may be different when using bitmaps. However, there's a
    subtle correctness issue, too: we use revs->ignore_missing_links for
    the recent traversal, but not the reachability one.

  - we could try using bitmaps for the recent traversal, too, which
    could possibly improve performance. But it would require some fixes
    in the bitmap code, which uses ignore_missing_links for its own
    purposes. Plus it would probably not help all that much in practice.
    We use the reachable tips to generate bitmaps, so those objects are
    likely not covered by bitmaps (unless they just became unreachable).
    And in general, we expect the set of unreachable objects to be much
    smaller anyway, so there's less to gain.

The test in t5304 detects the bug and confirms the fix.

I also beefed up the tests in t6501, which covers the mtime-checking
code more thoroughly, to handle the bitmap case (in addition to just
"loose" and "packed" cases). Interestingly, this test doesn't actually
detect the bug, because it is running "git gc", and not "prune"
directly. And "gc" will call "repack" first, which does not suffer the
same bug. So the old-but-reachable-from-recent objects get scooped up
into the new pack along with the actually-recent objects, which gives
both a recent mtime. But it seemed prudent to get more coverage of the
bitmap case for related code.

Reported-by: David Emett <dave@sp4m.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-29 10:38:25 +09:00

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#!/bin/sh
#
# Copyright (c) 2008 Johannes E. Schindelin
#
test_description='prune'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
. ./test-lib.sh
day=$((60*60*24))
week=$(($day*7))
add_blob() {
before=$(git count-objects | sed "s/ .*//") &&
BLOB=$(echo aleph_0 | git hash-object -w --stdin) &&
BLOB_FILE=.git/objects/$(echo $BLOB | sed "s/^../&\//") &&
verbose test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
test_path_is_file $BLOB_FILE &&
test-tool chmtime =+0 $BLOB_FILE
}
test_expect_success setup '
: > file &&
git add file &&
test_tick &&
git commit -m initial &&
git gc
'
test_expect_success 'prune stale packs' '
orig_pack=$(echo .git/objects/pack/*.pack) &&
: > .git/objects/tmp_1.pack &&
: > .git/objects/tmp_2.pack &&
test-tool chmtime =-86501 .git/objects/tmp_1.pack &&
git prune --expire 1.day &&
test_path_is_file $orig_pack &&
test_path_is_file .git/objects/tmp_2.pack &&
test_path_is_missing .git/objects/tmp_1.pack
'
test_expect_success 'prune --expire' '
add_blob &&
git prune --expire=1.hour.ago &&
verbose test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
test_path_is_file $BLOB_FILE &&
test-tool chmtime =-86500 $BLOB_FILE &&
git prune --expire 1.day &&
verbose test $before = $(git count-objects | sed "s/ .*//") &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc: implicit prune --expire' '
add_blob &&
test-tool chmtime =-$((2*$week-30)) $BLOB_FILE &&
git gc &&
verbose test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
test_path_is_file $BLOB_FILE &&
test-tool chmtime =-$((2*$week+1)) $BLOB_FILE &&
git gc &&
verbose test $before = $(git count-objects | sed "s/ .*//") &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc: refuse to start with invalid gc.pruneExpire' '
git config gc.pruneExpire invalid &&
test_must_fail git gc
'
test_expect_success 'gc: start with ok gc.pruneExpire' '
git config gc.pruneExpire 2.days.ago &&
git gc
'
test_expect_success 'prune: prune nonsense parameters' '
test_must_fail git prune garbage &&
test_must_fail git prune --- &&
test_must_fail git prune --no-such-option
'
test_expect_success 'prune: prune unreachable heads' '
git config core.logAllRefUpdates false &&
mv .git/logs .git/logs.old &&
: > file2 &&
git add file2 &&
git commit -m temporary &&
tmp_head=$(git rev-list -1 HEAD) &&
git reset HEAD^ &&
git prune &&
test_must_fail git reset $tmp_head --
'
test_expect_success 'prune: do not prune detached HEAD with no reflog' '
git checkout --detach --quiet &&
git commit --allow-empty -m "detached commit" &&
# verify that there is no reflogs
# (should be removed and disabled by previous test)
test_path_is_missing .git/logs &&
git prune -n >prune_actual &&
test_must_be_empty prune_actual
'
test_expect_success 'prune: prune former HEAD after checking out branch' '
head_oid=$(git rev-parse HEAD) &&
git checkout --quiet main &&
git prune -v >prune_actual &&
grep "$head_oid" prune_actual
'
test_expect_success 'prune: do not prune heads listed as an argument' '
: > file2 &&
git add file2 &&
git commit -m temporary &&
tmp_head=$(git rev-list -1 HEAD) &&
git reset HEAD^ &&
git prune -- $tmp_head &&
git reset $tmp_head --
'
test_expect_success 'gc --no-prune' '
add_blob &&
test-tool chmtime =-$((5001*$day)) $BLOB_FILE &&
git config gc.pruneExpire 2.days.ago &&
git gc --no-prune &&
verbose test 1 = $(git count-objects | sed "s/ .*//") &&
test_path_is_file $BLOB_FILE
'
test_expect_success 'gc respects gc.pruneExpire' '
git config gc.pruneExpire 5002.days.ago &&
git gc &&
test_path_is_file $BLOB_FILE &&
git config gc.pruneExpire 5000.days.ago &&
git gc &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc --prune=<date>' '
add_blob &&
test-tool chmtime =-$((5001*$day)) $BLOB_FILE &&
git gc --prune=5002.days.ago &&
test_path_is_file $BLOB_FILE &&
git gc --prune=5000.days.ago &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc --prune=never' '
add_blob &&
git gc --prune=never &&
test_path_is_file $BLOB_FILE &&
git gc --prune=now &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc respects gc.pruneExpire=never' '
git config gc.pruneExpire never &&
add_blob &&
git gc &&
test_path_is_file $BLOB_FILE &&
git config gc.pruneExpire now &&
git gc &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'prune --expire=never' '
add_blob &&
git prune --expire=never &&
test_path_is_file $BLOB_FILE &&
git prune &&
test_path_is_missing $BLOB_FILE
'
test_expect_success 'gc: prune old objects after local clone' '
add_blob &&
test-tool chmtime =-$((2*$week+1)) $BLOB_FILE &&
git clone --no-hardlinks . aclone &&
(
cd aclone &&
verbose test 1 = $(git count-objects | sed "s/ .*//") &&
test_path_is_file $BLOB_FILE &&
git gc --prune &&
verbose test 0 = $(git count-objects | sed "s/ .*//") &&
test_path_is_missing $BLOB_FILE
)
'
test_expect_success 'garbage report in count-objects -v' '
test_when_finished "rm -f .git/objects/pack/fake*" &&
test_when_finished "rm -f .git/objects/pack/foo*" &&
: >.git/objects/pack/foo &&
: >.git/objects/pack/foo.bar &&
: >.git/objects/pack/foo.keep &&
: >.git/objects/pack/foo.pack &&
: >.git/objects/pack/fake.bar &&
: >.git/objects/pack/fake.keep &&
: >.git/objects/pack/fake.pack &&
: >.git/objects/pack/fake.idx &&
: >.git/objects/pack/fake2.keep &&
: >.git/objects/pack/fake3.idx &&
git count-objects -v 2>stderr &&
grep "index file .git/objects/pack/fake.idx is too small" stderr &&
grep "^warning:" stderr | sort >actual &&
cat >expected <<\EOF &&
warning: garbage found: .git/objects/pack/fake.bar
warning: garbage found: .git/objects/pack/foo
warning: garbage found: .git/objects/pack/foo.bar
warning: no corresponding .idx or .pack: .git/objects/pack/fake2.keep
warning: no corresponding .idx: .git/objects/pack/foo.keep
warning: no corresponding .idx: .git/objects/pack/foo.pack
warning: no corresponding .pack: .git/objects/pack/fake3.idx
EOF
test_cmp expected actual
'
test_expect_success 'clean pack garbage with gc' '
test_when_finished "rm -f .git/objects/pack/fake*" &&
test_when_finished "rm -f .git/objects/pack/foo*" &&
: >.git/objects/pack/foo.keep &&
: >.git/objects/pack/foo.pack &&
: >.git/objects/pack/fake.idx &&
: >.git/objects/pack/fake2.keep &&
: >.git/objects/pack/fake2.idx &&
: >.git/objects/pack/fake3.keep &&
git gc &&
git count-objects -v 2>stderr &&
grep "^warning:" stderr | sort >actual &&
cat >expected <<\EOF &&
warning: no corresponding .idx or .pack: .git/objects/pack/fake3.keep
warning: no corresponding .idx: .git/objects/pack/foo.keep
warning: no corresponding .idx: .git/objects/pack/foo.pack
EOF
test_cmp expected actual
'
test_expect_success 'prune .git/shallow' '
oid=$(echo hi|git commit-tree HEAD^{tree}) &&
echo $oid >.git/shallow &&
git prune --dry-run >out &&
grep $oid .git/shallow &&
grep $oid out &&
git prune &&
test_path_is_missing .git/shallow
'
test_expect_success 'prune .git/shallow when there are no loose objects' '
oid=$(echo hi|git commit-tree HEAD^{tree}) &&
echo $oid >.git/shallow &&
git update-ref refs/heads/shallow-tip $oid &&
git repack -ad &&
# verify assumption that all loose objects are gone
git count-objects | grep ^0 &&
git prune &&
echo $oid >expect &&
test_cmp expect .git/shallow
'
test_expect_success 'prune: handle alternate object database' '
test_create_repo A &&
git -C A commit --allow-empty -m "initial commit" &&
git clone --shared A B &&
git -C B commit --allow-empty -m "next commit" &&
git -C B prune
'
test_expect_success 'prune: handle index in multiple worktrees' '
git worktree add second-worktree &&
echo "new blob for second-worktree" >second-worktree/blob &&
git -C second-worktree add blob &&
git prune --expire=now &&
git -C second-worktree show :blob >actual &&
test_cmp second-worktree/blob actual
'
test_expect_success 'prune: handle HEAD in multiple worktrees' '
git worktree add --detach third-worktree &&
echo "new blob for third-worktree" >third-worktree/blob &&
git -C third-worktree add blob &&
git -C third-worktree commit -m "third" &&
rm .git/worktrees/third-worktree/index &&
test_must_fail git -C third-worktree show :blob &&
git prune --expire=now &&
git -C third-worktree show HEAD:blob >actual &&
test_cmp third-worktree/blob actual
'
test_expect_success 'prune: handle HEAD reflog in multiple worktrees' '
git config core.logAllRefUpdates true &&
echo "lost blob for third-worktree" >expected &&
(
cd third-worktree &&
cat ../expected >blob &&
git add blob &&
git commit -m "second commit in third" &&
git reset --hard HEAD^
) &&
git prune --expire=now &&
oid=`git hash-object expected` &&
git -C third-worktree show "$oid" >actual &&
test_cmp expected actual
'
test_expect_success 'prune: handle expire option correctly' '
test_must_fail git prune --expire 2>error &&
test_i18ngrep "requires a value" error &&
test_must_fail git prune --expire=nyah 2>error &&
test_i18ngrep "malformed expiration" error &&
git prune --no-expire
'
test_expect_success 'trivial prune with bitmaps enabled' '
git repack -adb &&
blob=$(echo bitmap-unreachable-blob | git hash-object -w --stdin) &&
git prune --expire=now &&
git cat-file -e HEAD &&
test_must_fail git cat-file -e $blob
'
test_expect_success 'old reachable-from-recent retained with bitmaps' '
git repack -adb &&
to_drop=$(echo bitmap-from-recent-1 | git hash-object -w --stdin) &&
test-tool chmtime -86400 .git/objects/$(test_oid_to_path $to_drop) &&
to_save=$(echo bitmap-from-recent-2 | git hash-object -w --stdin) &&
test-tool chmtime -86400 .git/objects/$(test_oid_to_path $to_save) &&
tree=$(printf "100644 blob $to_save\tfile\n" | git mktree) &&
test-tool chmtime -86400 .git/objects/$(test_oid_to_path $tree) &&
commit=$(echo foo | git commit-tree $tree) &&
git prune --expire=12.hours.ago &&
git cat-file -e $commit &&
git cat-file -e $tree &&
git cat-file -e $to_save &&
test_must_fail git cat-file -e $to_drop
'
test_done