git-commit-vandalism/t/t6120-describe.sh
SZEDER Gábor 49f7a2fde9 name-rev: eliminate recursion in name_rev()
The name_rev() function calls itself recursively for each interesting
parent of the commit it got as parameter, and, consequently, it can
segfault when processing a deep history if it exhausts the available
stack space.  E.g. running 'git name-rev --all' and 'git name-rev
HEAD~100000' in the gcc, gecko-dev, llvm, and WebKit repositories
results in segfaults on my machine ('ulimit -s' reports 8192kB of
stack size limit), and nowadays the former segfaults in the Linux repo
as well (it reached the necessasry depth sometime between v5.3-rc4 and
-rc5).

Eliminate the recursion by inserting the interesting parents into a
LIFO 'prio_queue' [1] and iterating until the queue becomes empty.

Note that the parent commits must be added in reverse order to the
LIFO 'prio_queue', so their relative order is preserved during
processing, i.e. the first parent should come out first from the
queue, because otherwise performance greatly suffers on mergy
histories [2].

The stacksize-limited test 'name-rev works in a deep repo' in
't6120-describe.sh' demonstrated this issue and expected failure.  Now
the recursion is gone, so flip it to expect success.  Also gone are
the dmesg entries logging the segfault of that segfaulting 'git
name-rev' process on every execution of the test suite.

Note that this slightly changes the order of lines in the output of
'git name-rev --all', usually swapping two lines every 35 lines in
git.git or every 150 lines in linux.git.  This shouldn't matter in
practice, because the output has always been unordered anyway.

This patch is best viewed with '--ignore-all-space'.

[1] Early versions of this patch used a 'commit_list', resulting in
    ~15% performance penalty for 'git name-rev --all' in 'linux.git',
    presumably because of the memory allocation and release for each
    insertion and removal. Using a LIFO 'prio_queue' has basically no
    effect on performance.

[2] We prefer shorter names, i.e. 'v0.1~234' is preferred over
    'v0.1^2~5', meaning that usually following the first parent of a
    merge results in the best name for its ancestors.  So when later
    we follow the remaining parent(s) of a merge, and reach an already
    named commit, then we usually find that we can't give that commit
    a better name, and thus we don't have to visit any of its
    ancestors again.

    OTOH, if we were to follow the Nth parent of the merge first, then
    the name of all its ancestors would include a corresponding '^N'.
    Those are not the best names for those commits, so when later we
    reach an already named commit following the first parent of that
    merge, then we would have to update the name of that commit and
    the names of all of its ancestors as well.  Consequently, we would
    have to visit many commits several times, resulting in a
    significant slowdown.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-09 13:33:01 -08:00

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#!/bin/sh
test_description='test describe'
# o---o-----o----o----o-------o----x
# \ D,R e /
# \---o-------------o-'
# \ B /
# `-o----o----o-'
# A c
#
# First parent of a merge commit is on the same line, second parent below.
. ./test-lib.sh
check_describe () {
expect="$1"
shift
describe_opts="$@"
test_expect_success "describe $describe_opts" '
R=$(git describe $describe_opts 2>err.actual) &&
case "$R" in
$expect) echo happy ;;
*) echo "Oops - $R is not $expect" &&
false ;;
esac
'
}
test_expect_success setup '
test_tick &&
echo one >file && git add file && git commit -m initial &&
one=$(git rev-parse HEAD) &&
git describe --always HEAD &&
test_tick &&
echo two >file && git add file && git commit -m second &&
two=$(git rev-parse HEAD) &&
test_tick &&
echo three >file && git add file && git commit -m third &&
test_tick &&
echo A >file && git add file && git commit -m A &&
test_tick &&
git tag -a -m A A &&
test_tick &&
echo c >file && git add file && git commit -m c &&
test_tick &&
git tag c &&
git reset --hard $two &&
test_tick &&
echo B >side && git add side && git commit -m B &&
test_tick &&
git tag -a -m B B &&
test_tick &&
git merge -m Merged c &&
merged=$(git rev-parse HEAD) &&
git reset --hard $two &&
test_tick &&
echo D >another && git add another && git commit -m D &&
test_tick &&
git tag -a -m D D &&
test_tick &&
git tag -a -m R R &&
test_tick &&
echo DD >another && git commit -a -m another &&
test_tick &&
git tag e &&
test_tick &&
echo DDD >another && git commit -a -m "yet another" &&
test_tick &&
git merge -m Merged $merged &&
test_tick &&
echo X >file && echo X >side && git add file side &&
git commit -m x
'
check_describe A-* HEAD
check_describe A-* HEAD^
check_describe R-* HEAD^^
check_describe A-* HEAD^^2
check_describe B HEAD^^2^
check_describe R-* HEAD^^^
check_describe c-* --tags HEAD
check_describe c-* --tags HEAD^
check_describe e-* --tags HEAD^^
check_describe c-* --tags HEAD^^2
check_describe B --tags HEAD^^2^
check_describe e --tags HEAD^^^
check_describe heads/master --all HEAD
check_describe tags/c-* --all HEAD^
check_describe tags/e --all HEAD^^^
check_describe B-0-* --long HEAD^^2^
check_describe A-3-* --long HEAD^^2
check_describe c-7-* --tags
check_describe e-3-* --first-parent --tags
test_expect_success 'describe --contains defaults to HEAD without commit-ish' '
echo "A^0" >expect &&
git checkout A &&
test_when_finished "git checkout -" &&
git describe --contains >actual &&
test_cmp expect actual
'
check_describe tags/A --all A^0
test_expect_success 'no warning was displayed for A' '
test_must_be_empty err.actual
'
test_expect_success 'rename tag A to Q locally' '
mv .git/refs/tags/A .git/refs/tags/Q
'
cat - >err.expect <<EOF
warning: tag 'A' is really 'Q' here
EOF
check_describe A-* HEAD
test_expect_success 'warning was displayed for Q' '
test_i18ncmp err.expect err.actual
'
test_expect_success 'rename tag Q back to A' '
mv .git/refs/tags/Q .git/refs/tags/A
'
test_expect_success 'pack tag refs' 'git pack-refs'
check_describe A-* HEAD
test_expect_success 'describe works from outside repo using --git-dir' '
git clone --bare "$TRASH_DIRECTORY" "$TRASH_DIRECTORY/bare" &&
git --git-dir "$TRASH_DIRECTORY/bare" describe >out &&
grep -E "^A-[1-9][0-9]?-g[0-9a-f]+$" out
'
check_describe "A-*[0-9a-f]" --dirty
test_expect_success 'describe --dirty with --work-tree' '
(
cd "$TEST_DIRECTORY" &&
git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty >"$TRASH_DIRECTORY/out"
) &&
grep -E "^A-[1-9][0-9]?-g[0-9a-f]+$" out
'
test_expect_success 'set-up dirty work tree' '
echo >>file
'
check_describe "A-*[0-9a-f]-dirty" --dirty
test_expect_success 'describe --dirty with --work-tree (dirty)' '
(
cd "$TEST_DIRECTORY" &&
git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty >"$TRASH_DIRECTORY/out"
) &&
grep -E "^A-[1-9][0-9]?-g[0-9a-f]+-dirty$" out
'
check_describe "A-*[0-9a-f].mod" --dirty=.mod
test_expect_success 'describe --dirty=.mod with --work-tree (dirty)' '
(
cd "$TEST_DIRECTORY" &&
git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty=.mod >"$TRASH_DIRECTORY/out"
) &&
grep -E "^A-[1-9][0-9]?-g[0-9a-f]+.mod$" out
'
test_expect_success 'describe --dirty HEAD' '
test_must_fail git describe --dirty HEAD
'
test_expect_success 'set-up matching pattern tests' '
git tag -a -m test-annotated test-annotated &&
echo >>file &&
test_tick &&
git commit -a -m "one more" &&
git tag test1-lightweight &&
echo >>file &&
test_tick &&
git commit -a -m "yet another" &&
git tag test2-lightweight &&
echo >>file &&
test_tick &&
git commit -a -m "even more"
'
check_describe "test-annotated-*" --match="test-*"
check_describe "test1-lightweight-*" --tags --match="test1-*"
check_describe "test2-lightweight-*" --tags --match="test2-*"
check_describe "test2-lightweight-*" --long --tags --match="test2-*" HEAD^
check_describe "test2-lightweight-*" --long --tags --match="test1-*" --match="test2-*" HEAD^
check_describe "test2-lightweight-*" --long --tags --match="test1-*" --no-match --match="test2-*" HEAD^
check_describe "test1-lightweight-*" --long --tags --match="test1-*" --match="test3-*" HEAD
check_describe "test1-lightweight-*" --long --tags --match="test3-*" --match="test1-*" HEAD
test_expect_success 'set-up branches' '
git branch branch_A A &&
git branch branch_C c &&
git update-ref refs/remotes/origin/remote_branch_A "A^{commit}" &&
git update-ref refs/remotes/origin/remote_branch_C "c^{commit}" &&
git update-ref refs/original/original_branch_A test-annotated~2
'
check_describe "heads/branch_A*" --all --match="branch_*" --exclude="branch_C" HEAD
check_describe "remotes/origin/remote_branch_A*" --all --match="origin/remote_branch_*" --exclude="origin/remote_branch_C" HEAD
check_describe "original/original_branch_A*" --all test-annotated~1
test_expect_success '--match does not work for other types' '
test_must_fail git describe --all --match="*original_branch_*" test-annotated~1
'
test_expect_success '--exclude does not work for other types' '
R=$(git describe --all --exclude="any_pattern_even_not_matching" test-annotated~1) &&
case "$R" in
*original_branch_A*) echo "fail: Found unknown reference $R with --exclude"
false;;
*) echo ok: Found some known type;;
esac
'
test_expect_success 'name-rev with exact tags' '
echo A >expect &&
tag_object=$(git rev-parse refs/tags/A) &&
git name-rev --tags --name-only $tag_object >actual &&
test_cmp expect actual &&
echo "A^0" >expect &&
tagged_commit=$(git rev-parse "refs/tags/A^0") &&
git name-rev --tags --name-only $tagged_commit >actual &&
test_cmp expect actual
'
test_expect_success 'name-rev --all' '
>expect.unsorted &&
for rev in $(git rev-list --all)
do
git name-rev $rev >>expect.unsorted
done &&
sort <expect.unsorted >expect &&
git name-rev --all >actual.unsorted &&
sort <actual.unsorted >actual &&
test_cmp expect actual
'
test_expect_success 'name-rev --stdin' '
>expect.unsorted &&
for rev in $(git rev-list --all)
do
name=$(git name-rev --name-only $rev) &&
echo "$rev ($name)" >>expect.unsorted
done &&
sort <expect.unsorted >expect &&
git rev-list --all | git name-rev --stdin >actual.unsorted &&
sort <actual.unsorted >actual &&
test_cmp expect actual
'
test_expect_success 'describe --contains with the exact tags' '
echo "A^0" >expect &&
tag_object=$(git rev-parse refs/tags/A) &&
git describe --contains $tag_object >actual &&
test_cmp expect actual &&
echo "A^0" >expect &&
tagged_commit=$(git rev-parse "refs/tags/A^0") &&
git describe --contains $tagged_commit >actual &&
test_cmp expect actual
'
test_expect_success 'describe --contains and --match' '
echo "A^0" >expect &&
tagged_commit=$(git rev-parse "refs/tags/A^0") &&
test_must_fail git describe --contains --match="B" $tagged_commit &&
git describe --contains --match="B" --match="A" $tagged_commit >actual &&
test_cmp expect actual
'
test_expect_success 'describe --exclude' '
echo "c~1" >expect &&
tagged_commit=$(git rev-parse "refs/tags/A^0") &&
test_must_fail git describe --contains --match="B" $tagged_commit &&
git describe --contains --match="?" --exclude="A" $tagged_commit >actual &&
test_cmp expect actual
'
test_expect_success 'describe --contains and --no-match' '
echo "A^0" >expect &&
tagged_commit=$(git rev-parse "refs/tags/A^0") &&
git describe --contains --match="B" --no-match $tagged_commit >actual &&
test_cmp expect actual
'
test_expect_success 'setup and absorb a submodule' '
test_create_repo sub1 &&
test_commit -C sub1 initial &&
git submodule add ./sub1 &&
git submodule absorbgitdirs &&
git commit -a -m "add submodule" &&
git describe --dirty >expect &&
git describe --broken >out &&
test_cmp expect out
'
test_expect_success 'describe chokes on severely broken submodules' '
mv .git/modules/sub1/ .git/modules/sub_moved &&
test_must_fail git describe --dirty
'
test_expect_success 'describe ignoring a broken submodule' '
git describe --broken >out &&
grep broken out
'
test_expect_success 'describe with --work-tree ignoring a broken submodule' '
(
cd "$TEST_DIRECTORY" &&
git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --broken >"$TRASH_DIRECTORY/out"
) &&
test_when_finished "mv .git/modules/sub_moved .git/modules/sub1" &&
grep broken out
'
test_expect_success 'describe a blob at a directly tagged commit' '
echo "make it a unique blob" >file &&
git add file && git commit -m "content in file" &&
git tag -a -m "latest annotated tag" unique-file &&
git describe HEAD:file >actual &&
echo "unique-file:file" >expect &&
test_cmp expect actual
'
test_expect_success 'describe a blob with its first introduction' '
git commit --allow-empty -m "empty commit" &&
git rm file &&
git commit -m "delete blob" &&
git revert HEAD &&
git commit --allow-empty -m "empty commit" &&
git describe HEAD:file >actual &&
echo "unique-file:file" >expect &&
test_cmp expect actual
'
test_expect_success 'describe directly tagged blob' '
git tag test-blob unique-file:file &&
git describe test-blob >actual &&
echo "unique-file:file" >expect &&
# suboptimal: we rather want to see "test-blob"
test_cmp expect actual
'
test_expect_success 'describe tag object' '
git tag test-blob-1 -a -m msg unique-file:file &&
test_must_fail git describe test-blob-1 2>actual &&
test_i18ngrep "fatal: test-blob-1 is neither a commit nor blob" actual
'
test_expect_success ULIMIT_STACK_SIZE 'name-rev works in a deep repo' '
i=1 &&
while test $i -lt 8000
do
echo "commit refs/heads/master
committer A U Thor <author@example.com> $((1000000000 + $i * 100)) +0200
data <<EOF
commit #$i
EOF"
test $i = 1 && echo "from refs/heads/master^0"
i=$(($i + 1))
done | git fast-import &&
git checkout master &&
git tag far-far-away HEAD^ &&
echo "HEAD~4000 tags/far-far-away~3999" >expect &&
git name-rev HEAD~4000 >actual &&
test_cmp expect actual &&
run_with_limited_stack git name-rev HEAD~4000 >actual &&
test_cmp expect actual
'
test_expect_success ULIMIT_STACK_SIZE 'describe works in a deep repo' '
git tag -f far-far-away HEAD~7999 &&
echo "far-far-away" >expect &&
git describe --tags --abbrev=0 HEAD~4000 >actual &&
test_cmp expect actual &&
run_with_limited_stack git describe --tags --abbrev=0 HEAD~4000 >actual &&
test_cmp expect actual
'
check_describe tags/A --all A
check_describe tags/c --all c
check_describe heads/branch_A --all --match='branch_*' branch_A
test_expect_success 'describe complains about tree object' '
test_must_fail git describe HEAD^{tree}
'
test_expect_success 'describe complains about missing object' '
test_must_fail git describe $ZERO_OID
'
test_expect_success 'name-rev a rev shortly after epoch' '
test_when_finished "git checkout master" &&
git checkout --orphan no-timestamp-underflow &&
# Any date closer to epoch than the CUTOFF_DATE_SLOP constant
# in builtin/name-rev.c.
GIT_COMMITTER_DATE="@1234 +0000" \
git commit -m "committer date shortly after epoch" &&
old_commit_oid=$(git rev-parse HEAD) &&
echo "$old_commit_oid no-timestamp-underflow" >expect &&
git name-rev $old_commit_oid >actual &&
test_cmp expect actual
'
# A--------------master
# \ /
# \----------M2
# \ /
# \---M1-C
# \ /
# B
test_expect_success 'name-rev covers all conditions while looking at parents' '
git init repo &&
(
cd repo &&
echo A >file &&
git add file &&
git commit -m A &&
A=$(git rev-parse HEAD) &&
git checkout --detach &&
echo B >file &&
git commit -m B file &&
B=$(git rev-parse HEAD) &&
git checkout $A &&
git merge --no-ff $B && # M1
echo C >file &&
git commit -m C file &&
git checkout $A &&
git merge --no-ff HEAD@{1} && # M2
git checkout master &&
git merge --no-ff HEAD@{1} &&
echo "$B master^2^2~1^2" >expect &&
git name-rev $B >actual &&
test_cmp expect actual
)
'
test_done