git-commit-vandalism/t/t1416-ref-transaction-hooks.sh
Patrick Steinhardt 2ed1b64ebd refs: skip hooks when deleting uncovered packed refs
When deleting refs from the loose-files refs backend, then we need to be
careful to also delete the same ref from the packed refs backend, if it
exists. If we don't, then deleting the loose ref would "uncover" the
packed ref. We thus always have to queue up deletions of refs for both
the loose and the packed refs backend. This is done in two separate
transactions, where the end result is that the reference-transaction
hook is executed twice for the deleted refs.

This behaviour is quite misleading: it's exposing implementation details
of how the files backend works to the user, in contrast to the logical
updates that we'd really want to expose via the hook. Worse yet, whether
the hook gets executed once or twice depends on how well-packed the
repository is: if the ref only exists as a loose ref, then we execute it
once, otherwise if it is also packed then we execute it twice.

Fix this behaviour and don't execute the reference-transaction hook at
all when refs in the packed-refs backend if it's driven by the files
backend. This works as expected even in case the refs to be deleted only
exist in the packed-refs backend because the loose-backend always queues
refs in its own transaction even if they don't exist such that they can
be locked for concurrent creation. And it also does the right thing in
case neither of the backends has the ref because that would cause the
transaction to fail completely.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-17 11:01:45 -08:00

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#!/bin/sh
test_description='reference transaction hooks'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
. ./test-lib.sh
test_expect_success setup '
mkdir -p .git/hooks &&
test_commit PRE &&
PRE_OID=$(git rev-parse PRE) &&
test_commit POST &&
POST_OID=$(git rev-parse POST)
'
test_expect_success 'hook allows updating ref if successful' '
test_when_finished "rm .git/hooks/reference-transaction" &&
git reset --hard PRE &&
write_script .git/hooks/reference-transaction <<-\EOF &&
echo "$*" >>actual
EOF
cat >expect <<-EOF &&
prepared
committed
EOF
git update-ref HEAD POST &&
test_cmp expect actual
'
test_expect_success 'hook aborts updating ref in prepared state' '
test_when_finished "rm .git/hooks/reference-transaction" &&
git reset --hard PRE &&
write_script .git/hooks/reference-transaction <<-\EOF &&
if test "$1" = prepared
then
exit 1
fi
EOF
test_must_fail git update-ref HEAD POST 2>err &&
test_i18ngrep "ref updates aborted by hook" err
'
test_expect_success 'hook gets all queued updates in prepared state' '
test_when_finished "rm .git/hooks/reference-transaction actual" &&
git reset --hard PRE &&
write_script .git/hooks/reference-transaction <<-\EOF &&
if test "$1" = prepared
then
while read -r line
do
printf "%s\n" "$line"
done >actual
fi
EOF
cat >expect <<-EOF &&
$ZERO_OID $POST_OID HEAD
$ZERO_OID $POST_OID refs/heads/main
EOF
git update-ref HEAD POST <<-EOF &&
update HEAD $ZERO_OID $POST_OID
update refs/heads/main $ZERO_OID $POST_OID
EOF
test_cmp expect actual
'
test_expect_success 'hook gets all queued updates in committed state' '
test_when_finished "rm .git/hooks/reference-transaction actual" &&
git reset --hard PRE &&
write_script .git/hooks/reference-transaction <<-\EOF &&
if test "$1" = committed
then
while read -r line
do
printf "%s\n" "$line"
done >actual
fi
EOF
cat >expect <<-EOF &&
$ZERO_OID $POST_OID HEAD
$ZERO_OID $POST_OID refs/heads/main
EOF
git update-ref HEAD POST &&
test_cmp expect actual
'
test_expect_success 'hook gets all queued updates in aborted state' '
test_when_finished "rm .git/hooks/reference-transaction actual" &&
git reset --hard PRE &&
write_script .git/hooks/reference-transaction <<-\EOF &&
if test "$1" = aborted
then
while read -r line
do
printf "%s\n" "$line"
done >actual
fi
EOF
cat >expect <<-EOF &&
$ZERO_OID $POST_OID HEAD
$ZERO_OID $POST_OID refs/heads/main
EOF
git update-ref --stdin <<-EOF &&
start
update HEAD POST $ZERO_OID
update refs/heads/main POST $ZERO_OID
abort
EOF
test_cmp expect actual
'
test_expect_success 'interleaving hook calls succeed' '
test_when_finished "rm -r target-repo.git" &&
git init --bare target-repo.git &&
write_script target-repo.git/hooks/reference-transaction <<-\EOF &&
echo $0 "$@" >>actual
EOF
write_script target-repo.git/hooks/update <<-\EOF &&
echo $0 "$@" >>actual
EOF
cat >expect <<-EOF &&
hooks/update refs/tags/PRE $ZERO_OID $PRE_OID
hooks/reference-transaction prepared
hooks/reference-transaction committed
hooks/update refs/tags/POST $ZERO_OID $POST_OID
hooks/reference-transaction prepared
hooks/reference-transaction committed
EOF
git push ./target-repo.git PRE POST &&
test_cmp expect target-repo.git/actual
'
test_expect_success 'hook does not get called on packing refs' '
# Pack references first such that we are in a known state.
git pack-refs --all &&
write_script .git/hooks/reference-transaction <<-\EOF &&
echo "$@" >>actual
cat >>actual
EOF
rm -f actual &&
git update-ref refs/heads/unpacked-ref $POST_OID &&
git pack-refs --all &&
# We only expect a single hook invocation, which is the call to
# git-update-ref(1).
cat >expect <<-EOF &&
prepared
$ZERO_OID $POST_OID refs/heads/unpacked-ref
committed
$ZERO_OID $POST_OID refs/heads/unpacked-ref
EOF
test_cmp expect actual
'
test_expect_success 'deleting packed ref calls hook once' '
# Create a reference and pack it.
git update-ref refs/heads/to-be-deleted $POST_OID &&
git pack-refs --all &&
write_script .git/hooks/reference-transaction <<-\EOF &&
echo "$@" >>actual
cat >>actual
EOF
rm -f actual &&
git update-ref -d refs/heads/to-be-deleted $POST_OID &&
# We only expect a single hook invocation, which is the logical
# deletion.
cat >expect <<-EOF &&
prepared
$POST_OID $ZERO_OID refs/heads/to-be-deleted
committed
$POST_OID $ZERO_OID refs/heads/to-be-deleted
EOF
test_cmp expect actual
'
test_done