From 69840cc0f7b4f3352903bd2b8f3de7077916c26b Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:31 +0100 Subject: refs: extract packed_refs_delete_refs() to allow control of transaction When deleting loose refs, then we also have to delete the refs in the packed backend. This is done by calling `refs_delete_refs()`, which then uses the packed-backend's logic to delete refs. This doesn't allow us to exercise any control over the reference transaction which is being created in the packed backend, which is required in a subsequent commit. Extract a new function `packed_refs_delete_refs()`, which hosts most of the logic to delete refs except for creating the transaction itself. Like this, we can easily create the transaction in the files backend and thus exert more control over it. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs/files-backend.c | 13 ++++++++++--- refs/packed-backend.c | 26 ++++++++++++++++++++------ refs/packed-backend.h | 7 +++++++ 3 files changed, 37 insertions(+), 9 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 90b671025a..459f18dbc1 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1249,6 +1249,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, { struct files_ref_store *refs = files_downcast(ref_store, REF_STORE_WRITE, "delete_refs"); + struct ref_transaction *transaction = NULL; struct strbuf err = STRBUF_INIT; int i, result = 0; @@ -1258,10 +1259,14 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, if (packed_refs_lock(refs->packed_ref_store, 0, &err)) goto error; - if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) { - packed_refs_unlock(refs->packed_ref_store); + transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); + if (!transaction) + goto error; + + result = packed_refs_delete_refs(refs->packed_ref_store, + transaction, msg, refnames, flags); + if (result) goto error; - } packed_refs_unlock(refs->packed_ref_store); @@ -1272,6 +1277,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, result |= error(_("could not remove reference %s"), refname); } + ref_transaction_free(transaction); strbuf_release(&err); return result; @@ -1288,6 +1294,7 @@ error: else error(_("could not delete references: %s"), err.buf); + ref_transaction_free(transaction); strbuf_release(&err); return -1; } diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 67152c664e..c964dd1617 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -1522,15 +1522,10 @@ static int packed_initial_transaction_commit(struct ref_store *ref_store, static int packed_delete_refs(struct ref_store *ref_store, const char *msg, struct string_list *refnames, unsigned int flags) { - struct packed_ref_store *refs = - packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs"); struct strbuf err = STRBUF_INIT; struct ref_transaction *transaction; - struct string_list_item *item; int ret; - (void)refs; /* We need the check above, but don't use the variable */ - if (!refnames->nr) return 0; @@ -1544,6 +1539,26 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg, if (!transaction) return -1; + ret = packed_refs_delete_refs(ref_store, transaction, + msg, refnames, flags); + + ref_transaction_free(transaction); + return ret; +} + +int packed_refs_delete_refs(struct ref_store *ref_store, + struct ref_transaction *transaction, + const char *msg, + struct string_list *refnames, + unsigned int flags) +{ + struct strbuf err = STRBUF_INIT; + struct string_list_item *item; + int ret; + + /* Assert that the ref store refers to a packed backend. */ + packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs"); + for_each_string_list_item(item, refnames) { if (ref_transaction_delete(transaction, item->string, NULL, flags, msg, &err)) { @@ -1563,7 +1578,6 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg, error(_("could not delete references: %s"), err.buf); } - ref_transaction_free(transaction); strbuf_release(&err); return ret; } diff --git a/refs/packed-backend.h b/refs/packed-backend.h index f61a73ec25..a2cca5d9a3 100644 --- a/refs/packed-backend.h +++ b/refs/packed-backend.h @@ -3,6 +3,7 @@ struct repository; struct ref_transaction; +struct string_list; /* * Support for storing references in a `packed-refs` file. @@ -27,6 +28,12 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err) void packed_refs_unlock(struct ref_store *ref_store); int packed_refs_is_locked(struct ref_store *ref_store); +int packed_refs_delete_refs(struct ref_store *ref_store, + struct ref_transaction *transaction, + const char *msg, + struct string_list *refnames, + unsigned int flags); + /* * Return true if `transaction` really needs to be carried out against * the specified packed_ref_store, or false if it can be skipped -- cgit v1.2.3 From fbe73f61cbc29f6c4a85478cf792c37dbe5aa26c Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:35 +0100 Subject: refs: allow passing flags when beginning transactions We do not currently have any flags when creating reference transactions, but we'll add one to disable execution of the reference transaction hook in some cases. Allow passing flags to `ref_store_transaction_begin()` to prepare for this change. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs.c | 8 +++++--- refs.h | 3 ++- refs/files-backend.c | 10 +++++----- refs/packed-backend.c | 2 +- refs/refs-internal.h | 1 + sequencer.c | 2 +- 6 files changed, 15 insertions(+), 11 deletions(-) diff --git a/refs.c b/refs.c index 4da4996c4d..7415864b62 100644 --- a/refs.c +++ b/refs.c @@ -800,7 +800,7 @@ int refs_delete_ref(struct ref_store *refs, const char *msg, struct ref_transaction *transaction; struct strbuf err = STRBUF_INIT; - transaction = ref_store_transaction_begin(refs, &err); + transaction = ref_store_transaction_begin(refs, 0, &err); if (!transaction || ref_transaction_delete(transaction, refname, old_oid, flags, msg, &err) || @@ -1005,6 +1005,7 @@ int read_ref_at(struct ref_store *refs, const char *refname, } struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs, + unsigned int flags, struct strbuf *err) { struct ref_transaction *tr; @@ -1012,12 +1013,13 @@ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs, CALLOC_ARRAY(tr, 1); tr->ref_store = refs; + tr->flags = flags; return tr; } struct ref_transaction *ref_transaction_begin(struct strbuf *err) { - return ref_store_transaction_begin(get_main_ref_store(the_repository), err); + return ref_store_transaction_begin(get_main_ref_store(the_repository), 0, err); } void ref_transaction_free(struct ref_transaction *transaction) @@ -1156,7 +1158,7 @@ int refs_update_ref(struct ref_store *refs, const char *msg, struct strbuf err = STRBUF_INIT; int ret = 0; - t = ref_store_transaction_begin(refs, &err); + t = ref_store_transaction_begin(refs, 0, &err); if (!t || ref_transaction_update(t, refname, new_oid, old_oid, flags, msg, &err) || diff --git a/refs.h b/refs.h index 92360e55a2..31f7bf9642 100644 --- a/refs.h +++ b/refs.h @@ -231,7 +231,7 @@ char *repo_default_branch_name(struct repository *r, int quiet); * struct strbuf err = STRBUF_INIT; * int ret = 0; * - * transaction = ref_store_transaction_begin(refs, &err); + * transaction = ref_store_transaction_begin(refs, 0, &err); * if (!transaction || * ref_transaction_update(...) || * ref_transaction_create(...) || @@ -573,6 +573,7 @@ enum action_on_err { * be freed by calling ref_transaction_free(). */ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs, + unsigned int flags, struct strbuf *err); struct ref_transaction *ref_transaction_begin(struct strbuf *err); diff --git a/refs/files-backend.c b/refs/files-backend.c index 459f18dbc1..4d4f0c2099 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1121,7 +1121,7 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r) if (check_refname_format(r->name, 0)) return; - transaction = ref_store_transaction_begin(&refs->base, &err); + transaction = ref_store_transaction_begin(&refs->base, 0, &err); if (!transaction) goto cleanup; ref_transaction_add_update( @@ -1192,7 +1192,7 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) struct strbuf err = STRBUF_INIT; struct ref_transaction *transaction; - transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); + transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, &err); if (!transaction) return -1; @@ -1259,7 +1259,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, if (packed_refs_lock(refs->packed_ref_store, 0, &err)) goto error; - transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); + transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, &err); if (!transaction) goto error; @@ -2774,7 +2774,7 @@ static int files_transaction_prepare(struct ref_store *ref_store, */ if (!packed_transaction) { packed_transaction = ref_store_transaction_begin( - refs->packed_ref_store, err); + refs->packed_ref_store, 0, err); if (!packed_transaction) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; @@ -3045,7 +3045,7 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, &affected_refnames)) BUG("initial ref transaction called with existing refs"); - packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err); + packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, err); if (!packed_transaction) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; diff --git a/refs/packed-backend.c b/refs/packed-backend.c index c964dd1617..0b45598e18 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -1535,7 +1535,7 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg, * updates into a single transaction. */ - transaction = ref_store_transaction_begin(ref_store, &err); + transaction = ref_store_transaction_begin(ref_store, 0, &err); if (!transaction) return -1; diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 46a839539e..a0af63f162 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -213,6 +213,7 @@ struct ref_transaction { size_t nr; enum ref_transaction_state state; void *backend_data; + unsigned int flags; }; /* diff --git a/sequencer.c b/sequencer.c index 6abd72160c..61edd39d7a 100644 --- a/sequencer.c +++ b/sequencer.c @@ -3588,7 +3588,7 @@ static int do_label(struct repository *r, const char *name, int len) strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name); strbuf_addf(&msg, "rebase (label) '%.*s'", len, name); - transaction = ref_store_transaction_begin(refs, &err); + transaction = ref_store_transaction_begin(refs, 0, &err); if (!transaction) { error("%s", err.buf); ret = -1; -- cgit v1.2.3 From 958fbc74e3d0fcc88b2065190e23db556a963644 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:39 +0100 Subject: refs: allow skipping the reference-transaction hook The reference-transaction hook is executing whenever we prepare, commit or abort a reference transaction. While this is mostly intentional, in case of the files backend we're leaking the implementation detail that the store is in fact a composite store with one loose and one packed backend to the caller. So while we want to execute the hook for all logical updates, executing it for such implementation details is unexpected. Prepare for a fix by adding a new flag which allows to skip execution of the hook. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs.c | 3 +++ refs.h | 5 +++++ 2 files changed, 8 insertions(+) diff --git a/refs.c b/refs.c index 7415864b62..526bf5ed97 100644 --- a/refs.c +++ b/refs.c @@ -2084,6 +2084,9 @@ static int run_transaction_hook(struct ref_transaction *transaction, const char *hook; int ret = 0, i; + if (transaction->flags & REF_TRANSACTION_SKIP_HOOK) + return 0; + hook = find_hook("reference-transaction"); if (!hook) return ret; diff --git a/refs.h b/refs.h index 31f7bf9642..d4056f9fe2 100644 --- a/refs.h +++ b/refs.h @@ -568,6 +568,11 @@ enum action_on_err { UPDATE_REFS_QUIET_ON_ERR }; +/* + * Skip executing the reference-transaction hook. + */ +#define REF_TRANSACTION_SKIP_HOOK (1 << 0) + /* * Begin a reference transaction. The reference transaction must * be freed by calling ref_transaction_free(). -- cgit v1.2.3 From 2ce825436268d6409bee8ebb5f5500b7ff172b1e Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:44 +0100 Subject: refs: demonstrate excessive execution of the reference-transaction hook Add tests which demonstate that we're executing the reference-transaction hook too often in some cases, which thus leaks implementation details about the reference store's implementation itself. Behaviour will be fixed in follow-up commits. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- t/t1416-ref-transaction-hooks.sh | 64 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/t/t1416-ref-transaction-hooks.sh b/t/t1416-ref-transaction-hooks.sh index 6c941027a8..0567fbdf0b 100755 --- a/t/t1416-ref-transaction-hooks.sh +++ b/t/t1416-ref-transaction-hooks.sh @@ -136,4 +136,68 @@ test_expect_success 'interleaving hook calls succeed' ' 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). But currently, packing refs will also trigger the + # hook. + cat >expect <<-EOF && + prepared + $ZERO_OID $POST_OID refs/heads/unpacked-ref + committed + $ZERO_OID $POST_OID refs/heads/unpacked-ref + prepared + $ZERO_OID $POST_OID refs/heads/unpacked-ref + committed + $ZERO_OID $POST_OID refs/heads/unpacked-ref + prepared + $POST_OID $ZERO_OID refs/heads/unpacked-ref + committed + $POST_OID $ZERO_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. But currently, we see two interleaving transactions, once + # for deleting the loose refs and once for deleting the packed ref. + cat >expect <<-EOF && + prepared + $ZERO_OID $ZERO_OID refs/heads/to-be-deleted + prepared + $POST_OID $ZERO_OID refs/heads/to-be-deleted + committed + $ZERO_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 -- cgit v1.2.3 From ffad9941383465553bf26d88050f3243726f30df Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:48 +0100 Subject: refs: do not execute reference-transaction hook on packing refs The reference-transaction hook is supposed to track logical changes to references, but it currently also gets executed when packing refs in a repository. This is unexpected and ultimately not all that useful: packing refs is not supposed to result in any user-visible change to the refs' state, and it ultimately is an implementation detail of how refs stores work. Fix this excessive execution of the hook when packing refs. Reported-by: Waleed Khan Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs/files-backend.c | 6 ++++-- t/t1416-ref-transaction-hooks.sh | 11 +---------- 2 files changed, 5 insertions(+), 12 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 4d4f0c2099..565929210a 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1121,7 +1121,8 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r) if (check_refname_format(r->name, 0)) return; - transaction = ref_store_transaction_begin(&refs->base, 0, &err); + transaction = ref_store_transaction_begin(&refs->base, + REF_TRANSACTION_SKIP_HOOK, &err); if (!transaction) goto cleanup; ref_transaction_add_update( @@ -1192,7 +1193,8 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) struct strbuf err = STRBUF_INIT; struct ref_transaction *transaction; - transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, &err); + transaction = ref_store_transaction_begin(refs->packed_ref_store, + REF_TRANSACTION_SKIP_HOOK, &err); if (!transaction) return -1; diff --git a/t/t1416-ref-transaction-hooks.sh b/t/t1416-ref-transaction-hooks.sh index 0567fbdf0b..f9d3d5213f 100755 --- a/t/t1416-ref-transaction-hooks.sh +++ b/t/t1416-ref-transaction-hooks.sh @@ -150,21 +150,12 @@ test_expect_success 'hook does not get called on packing refs' ' git pack-refs --all && # We only expect a single hook invocation, which is the call to - # git-update-ref(1). But currently, packing refs will also trigger the - # hook. + # 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 - prepared - $ZERO_OID $POST_OID refs/heads/unpacked-ref - committed - $ZERO_OID $POST_OID refs/heads/unpacked-ref - prepared - $POST_OID $ZERO_OID refs/heads/unpacked-ref - committed - $POST_OID $ZERO_OID refs/heads/unpacked-ref EOF test_cmp expect actual -- cgit v1.2.3 From 2ed1b64ebdeefc7f9473ae159fb45ff0c6cf121a Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 17 Jan 2022 09:12:53 +0100 Subject: 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 Signed-off-by: Junio C Hamano --- refs/files-backend.c | 9 ++++++--- t/t1416-ref-transaction-hooks.sh | 7 +------ 2 files changed, 7 insertions(+), 9 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 565929210a..844918cbd8 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1261,7 +1261,8 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, if (packed_refs_lock(refs->packed_ref_store, 0, &err)) goto error; - transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, &err); + transaction = ref_store_transaction_begin(refs->packed_ref_store, + REF_TRANSACTION_SKIP_HOOK, &err); if (!transaction) goto error; @@ -2776,7 +2777,8 @@ static int files_transaction_prepare(struct ref_store *ref_store, */ if (!packed_transaction) { packed_transaction = ref_store_transaction_begin( - refs->packed_ref_store, 0, err); + refs->packed_ref_store, + REF_TRANSACTION_SKIP_HOOK, err); if (!packed_transaction) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; @@ -3047,7 +3049,8 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, &affected_refnames)) BUG("initial ref transaction called with existing refs"); - packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, 0, err); + packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, + REF_TRANSACTION_SKIP_HOOK, err); if (!packed_transaction) { ret = TRANSACTION_GENERIC_ERROR; goto cleanup; diff --git a/t/t1416-ref-transaction-hooks.sh b/t/t1416-ref-transaction-hooks.sh index f9d3d5213f..4e1e84a91f 100755 --- a/t/t1416-ref-transaction-hooks.sh +++ b/t/t1416-ref-transaction-hooks.sh @@ -175,16 +175,11 @@ test_expect_success 'deleting packed ref calls hook once' ' git update-ref -d refs/heads/to-be-deleted $POST_OID && # We only expect a single hook invocation, which is the logical - # deletion. But currently, we see two interleaving transactions, once - # for deleting the loose refs and once for deleting the packed ref. + # deletion. cat >expect <<-EOF && - prepared - $ZERO_OID $ZERO_OID refs/heads/to-be-deleted prepared $POST_OID $ZERO_OID refs/heads/to-be-deleted committed - $ZERO_OID $ZERO_OID refs/heads/to-be-deleted - committed $POST_OID $ZERO_OID refs/heads/to-be-deleted EOF -- cgit v1.2.3