From 2a0cafd464709cfa22fe7249290c644a2a26c520 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:16 +0100 Subject: [PATCH 1/7] fetch: increase test coverage of fetches When using git-fetch(1) with the `--atomic` flag the expectation is that either all of the references are updated, or alternatively none are in case the fetch fails. While we already have tests for this, we do not have any tests which exercise atomicity either when pruning deleted refs or when backfilling tags. This gap in test coverage hides that we indeed don't handle atomicity correctly for both of these cases. Add test cases which cover these testing gaps to demonstrate the broken behaviour. Note that tests are not marked as `test_expect_failure`: this is done to explicitly demonstrate the current known-wrong behaviour, and they will be fixed up as soon as we fix the underlying bugs. While at it this commit also adds another test case which demonstrates that backfilling of tags does not return an error code in case the backfill fails. This bug will also be fixed by a subsequent commit. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- t/t5503-tagfollow.sh | 81 ++++++++++++++++++++++++++++++++++++++++++++ t/t5510-fetch.sh | 33 ++++++++++++++++++ 2 files changed, 114 insertions(+) diff --git a/t/t5503-tagfollow.sh b/t/t5503-tagfollow.sh index 195fc64dd4..6ffe2a5719 100755 --- a/t/t5503-tagfollow.sh +++ b/t/t5503-tagfollow.sh @@ -160,4 +160,85 @@ test_expect_success 'new clone fetch main and tags' ' test_cmp expect actual ' +test_expect_success 'atomic fetch with failing backfill' ' + git init clone3 && + + # We want to test whether a failure when backfilling tags correctly + # aborts the complete transaction when `--atomic` is passed: we should + # neither create the branch nor should we create the tag when either + # one of both fails to update correctly. + # + # To trigger failure we simply abort when backfilling a tag. + write_script clone3/.git/hooks/reference-transaction <<-\EOF && + while read oldrev newrev reference + do + if test "$reference" = refs/tags/tag1 + then + exit 1 + fi + done + EOF + + test_must_fail git -C clone3 fetch --atomic .. $B:refs/heads/something && + + # Creation of the tag has failed, so ideally refs/heads/something + # should not exist. The fact that it does demonstrates that there is + # a bug in the `--atomic` flag. + test $B = "$(git -C clone3 rev-parse --verify refs/heads/something)" +' + +test_expect_success 'atomic fetch with backfill should use single transaction' ' + git init clone4 && + + # Fetching with the `--atomic` flag should update all references in a + # single transaction, including backfilled tags. We thus expect to see + # a single reference transaction for the created branch and tags. + cat >expected <<-EOF && + prepared + $ZERO_OID $B refs/heads/something + $ZERO_OID $S refs/tags/tag2 + committed + $ZERO_OID $B refs/heads/something + $ZERO_OID $S refs/tags/tag2 + prepared + $ZERO_OID $T refs/tags/tag1 + committed + $ZERO_OID $T refs/tags/tag1 + EOF + + write_script clone4/.git/hooks/reference-transaction <<-\EOF && + ( echo "$*" && cat ) >>actual + EOF + + git -C clone4 fetch --atomic .. $B:refs/heads/something && + test_cmp expected clone4/actual +' + +test_expect_success 'backfill failure causes command to fail' ' + git init clone5 && + + write_script clone5/.git/hooks/reference-transaction <<-EOF && + while read oldrev newrev reference + do + if test "\$reference" = refs/tags/tag1 + then + # Create a nested tag below the actual tag we + # wanted to write, which causes a D/F conflict + # later when we want to commit refs/tags/tag1. + # We cannot just `exit 1` here given that this + # would cause us to die immediately. + git update-ref refs/tags/tag1/nested $B + exit \$! + fi + done + EOF + + # Even though we fail to create refs/tags/tag1 the below command + # unexpectedly succeeds. + git -C clone5 fetch .. $B:refs/heads/something && + test $B = $(git -C clone5 rev-parse --verify refs/heads/something) && + test $S = $(git -C clone5 rev-parse --verify tag2) && + test_must_fail git -C clone5 rev-parse --verify tag1 +' + test_done diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh index ef0da0a63b..70d51f343b 100755 --- a/t/t5510-fetch.sh +++ b/t/t5510-fetch.sh @@ -343,6 +343,39 @@ test_expect_success 'fetch --atomic --append appends to FETCH_HEAD' ' test_cmp expected atomic/.git/FETCH_HEAD ' +test_expect_success 'fetch --atomic --prune executes a single reference transaction only' ' + test_when_finished "rm -rf \"$D\"/atomic" && + + cd "$D" && + git branch scheduled-for-deletion && + git clone . atomic && + git branch -D scheduled-for-deletion && + git branch new-branch && + head_oid=$(git rev-parse HEAD) && + + # Fetching with the `--atomic` flag should update all references in a + # single transaction. It is currently missing coverage of pruned + # references though, and as a result those may be committed to disk + # even if updating references fails later. + cat >expected <<-EOF && + prepared + $ZERO_OID $ZERO_OID refs/remotes/origin/scheduled-for-deletion + committed + $ZERO_OID $ZERO_OID refs/remotes/origin/scheduled-for-deletion + prepared + $ZERO_OID $head_oid refs/remotes/origin/new-branch + committed + $ZERO_OID $head_oid refs/remotes/origin/new-branch + EOF + + write_script atomic/.git/hooks/reference-transaction <<-\EOF && + ( echo "$*" && cat ) >>actual + EOF + + git -C atomic fetch --atomic --prune origin && + test_cmp expected atomic/actual +' + test_expect_success '--refmap="" ignores configured refspec' ' cd "$TRASH_DIRECTORY" && git clone "$D" remote-refs && From efbade066083eb0a8ccee5a8290cd3fc834705f3 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:20 +0100 Subject: [PATCH 2/7] fetch: backfill tags before setting upstream The fetch code flow is a bit hard to understand right now: 1. We optionally prune all references which have vanished on the remote side. 2. We fetch and update all other references locally. 3. We update the upstream branch in the gitconfig. 4. We backfill tags pointing into the history we have just fetched. It is quite confusing that we fetch objects and update references in both (2) and (4), which is further stressed by the point that we use a `skip` goto label to jump from (3) to (4) in case we fail to update the gitconfig as expected. Reorder the code to first update all local references, and only after we have done so update the upstream branch information. This improves the code flow and furthermore makes it easier to refactor the way we update references together. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- builtin/fetch.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index 6f5e157863..904ca9f1ca 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -1536,7 +1536,7 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map, static int do_fetch(struct transport *transport, struct refspec *rs) { - struct ref *ref_map; + struct ref *ref_map = NULL; int autotags = (transport->remote->fetch_tags == 1); int retcode = 0; const struct ref *remote_refs; @@ -1620,11 +1620,24 @@ static int do_fetch(struct transport *transport, retcode = 1; } if (fetch_and_consume_refs(transport, ref_map, worktrees)) { - free_refs(ref_map); retcode = 1; goto cleanup; } + /* + * If neither --no-tags nor --tags was specified, do automated tag + * following. + */ + if (tags == TAGS_DEFAULT && autotags) { + struct ref *tags_ref_map = NULL, **tail = &tags_ref_map; + + find_non_local_tags(remote_refs, &tags_ref_map, &tail); + if (tags_ref_map) + backfill_tags(transport, tags_ref_map, worktrees); + + free_refs(tags_ref_map); + } + if (set_upstream) { struct branch *branch = branch_get("HEAD"); struct ref *rm; @@ -1644,7 +1657,7 @@ static int do_fetch(struct transport *transport, if (!rm->peer_ref) { if (source_ref) { warning(_("multiple branches detected, incompatible with --set-upstream")); - goto skip; + goto cleanup; } else { source_ref = rm; } @@ -1658,7 +1671,7 @@ static int do_fetch(struct transport *transport, warning(_("could not set upstream of HEAD to '%s' from '%s' when " "it does not point to any branch."), shortname, transport->remote->name); - goto skip; + goto cleanup; } if (!strcmp(source_ref->name, "HEAD") || @@ -1678,21 +1691,9 @@ static int do_fetch(struct transport *transport, "you need to specify exactly one branch with the --set-upstream option")); } } -skip: - free_refs(ref_map); - - /* if neither --no-tags nor --tags was specified, do automated tag - * following ... */ - if (tags == TAGS_DEFAULT && autotags) { - struct ref **tail = &ref_map; - ref_map = NULL; - find_non_local_tags(remote_refs, &ref_map, &tail); - if (ref_map) - backfill_tags(transport, ref_map, worktrees); - free_refs(ref_map); - } cleanup: + free_refs(ref_map); free_worktrees(worktrees); return retcode; } From 2983cec0f26b7409ccc2dd5710b40ff4809cd4b1 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:24 +0100 Subject: [PATCH 3/7] fetch: control lifecycle of FETCH_HEAD in a single place There are two different locations where we're appending to FETCH_HEAD: first when storing updated references, and second when backfilling tags. Both times we open the file, append to it and then commit it into place, which is essentially duplicate work. Improve the lifecycle of updating FETCH_HEAD by opening and committing it once in `do_fetch()`, where we pass the structure down to the code which wants to append to it. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- builtin/fetch.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index 904ca9f1ca..f8adb40b45 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -1084,9 +1084,8 @@ N_("it took %.2f seconds to check forced updates; you can use\n" static int store_updated_refs(const char *raw_url, const char *remote_name, int connectivity_checked, struct ref *ref_map, - struct worktree **worktrees) + struct fetch_head *fetch_head, struct worktree **worktrees) { - struct fetch_head fetch_head; int url_len, i, rc = 0; struct strbuf note = STRBUF_INIT, err = STRBUF_INIT; struct ref_transaction *transaction = NULL; @@ -1096,10 +1095,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, int want_status; int summary_width = transport_summary_width(ref_map); - rc = open_fetch_head(&fetch_head); - if (rc) - return -1; - if (raw_url) url = transport_anonymize_url(raw_url); else @@ -1206,7 +1201,7 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, strbuf_addf(¬e, "'%s' of ", what); } - append_fetch_head(&fetch_head, &rm->old_oid, + append_fetch_head(fetch_head, &rm->old_oid, rm->fetch_head_status, note.buf, url, url_len); @@ -1246,9 +1241,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, } } - if (!rc) - commit_fetch_head(&fetch_head); - if (rc & STORE_REF_ERROR_DF_CONFLICT) error(_("some local refs could not be updated; try running\n" " 'git remote prune %s' to remove any old, conflicting " @@ -1268,7 +1260,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, strbuf_release(&err); ref_transaction_free(transaction); free(url); - close_fetch_head(&fetch_head); return rc; } @@ -1309,6 +1300,7 @@ static int check_exist_and_connected(struct ref *ref_map) static int fetch_and_consume_refs(struct transport *transport, struct ref *ref_map, + struct fetch_head *fetch_head, struct worktree **worktrees) { int connectivity_checked = 1; @@ -1331,7 +1323,7 @@ static int fetch_and_consume_refs(struct transport *transport, trace2_region_enter("fetch", "consume_refs", the_repository); ret = store_updated_refs(transport->url, transport->remote->name, - connectivity_checked, ref_map, worktrees); + connectivity_checked, ref_map, fetch_head, worktrees); trace2_region_leave("fetch", "consume_refs", the_repository); out: @@ -1503,7 +1495,9 @@ static struct transport *prepare_transport(struct remote *remote, int deepen) return transport; } -static void backfill_tags(struct transport *transport, struct ref *ref_map, +static void backfill_tags(struct transport *transport, + struct ref *ref_map, + struct fetch_head *fetch_head, struct worktree **worktrees) { int cannot_reuse; @@ -1525,7 +1519,7 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map, transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL); transport_set_option(transport, TRANS_OPT_DEPTH, "0"); transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL); - fetch_and_consume_refs(transport, ref_map, worktrees); + fetch_and_consume_refs(transport, ref_map, fetch_head, worktrees); if (gsecondary) { transport_disconnect(gsecondary); @@ -1544,6 +1538,7 @@ static int do_fetch(struct transport *transport, TRANSPORT_LS_REFS_OPTIONS_INIT; int must_list_refs = 1; struct worktree **worktrees = get_worktrees(); + struct fetch_head fetch_head = { 0 }; if (tags == TAGS_DEFAULT) { if (transport->remote->fetch_tags == 2) @@ -1601,6 +1596,10 @@ static int do_fetch(struct transport *transport, if (!update_head_ok) check_not_current_branch(ref_map, worktrees); + retcode = open_fetch_head(&fetch_head); + if (retcode) + goto cleanup; + if (tags == TAGS_DEFAULT && autotags) transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1"); if (prune) { @@ -1619,7 +1618,8 @@ static int do_fetch(struct transport *transport, if (retcode != 0) retcode = 1; } - if (fetch_and_consume_refs(transport, ref_map, worktrees)) { + + if (fetch_and_consume_refs(transport, ref_map, &fetch_head, worktrees)) { retcode = 1; goto cleanup; } @@ -1633,11 +1633,13 @@ static int do_fetch(struct transport *transport, find_non_local_tags(remote_refs, &tags_ref_map, &tail); if (tags_ref_map) - backfill_tags(transport, tags_ref_map, worktrees); + backfill_tags(transport, tags_ref_map, &fetch_head, worktrees); free_refs(tags_ref_map); } + commit_fetch_head(&fetch_head); + if (set_upstream) { struct branch *branch = branch_get("HEAD"); struct ref *rm; @@ -1693,6 +1695,7 @@ static int do_fetch(struct transport *transport, } cleanup: + close_fetch_head(&fetch_head); free_refs(ref_map); free_worktrees(worktrees); return retcode; From 62091b4c87a199c172556f15c5662c6c3679e9cd Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:28 +0100 Subject: [PATCH 4/7] fetch: report errors when backfilling tags fails When the backfilling of tags fails we do not report this error to the caller, but only report it implicitly at a later point when reporting updated references. This leaves callers unable to act upon the information of whether the backfilling succeeded or not. Refactor the function to return an error code and pass it up the callstack. This causes us to correctly propagate the error back to the user of git-fetch(1). Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- builtin/fetch.c | 26 ++++++++++++++++++-------- t/t5503-tagfollow.sh | 4 +--- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index f8adb40b45..d304314f16 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -1495,12 +1495,12 @@ static struct transport *prepare_transport(struct remote *remote, int deepen) return transport; } -static void backfill_tags(struct transport *transport, - struct ref *ref_map, - struct fetch_head *fetch_head, - struct worktree **worktrees) +static int backfill_tags(struct transport *transport, + struct ref *ref_map, + struct fetch_head *fetch_head, + struct worktree **worktrees) { - int cannot_reuse; + int retcode, cannot_reuse; /* * Once we have set TRANS_OPT_DEEPEN_SINCE, we can't unset it @@ -1519,12 +1519,14 @@ static void backfill_tags(struct transport *transport, transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL); transport_set_option(transport, TRANS_OPT_DEPTH, "0"); transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL); - fetch_and_consume_refs(transport, ref_map, fetch_head, worktrees); + retcode = fetch_and_consume_refs(transport, ref_map, fetch_head, worktrees); if (gsecondary) { transport_disconnect(gsecondary); gsecondary = NULL; } + + return retcode; } static int do_fetch(struct transport *transport, @@ -1632,8 +1634,16 @@ static int do_fetch(struct transport *transport, struct ref *tags_ref_map = NULL, **tail = &tags_ref_map; find_non_local_tags(remote_refs, &tags_ref_map, &tail); - if (tags_ref_map) - backfill_tags(transport, tags_ref_map, &fetch_head, worktrees); + if (tags_ref_map) { + /* + * If backfilling of tags fails then we want to tell + * the user so, but we have to continue regardless to + * populate upstream information of the references we + * have already fetched above. + */ + if (backfill_tags(transport, tags_ref_map, &fetch_head, worktrees)) + retcode = 1; + } free_refs(tags_ref_map); } diff --git a/t/t5503-tagfollow.sh b/t/t5503-tagfollow.sh index 6ffe2a5719..c057c49e80 100755 --- a/t/t5503-tagfollow.sh +++ b/t/t5503-tagfollow.sh @@ -233,9 +233,7 @@ test_expect_success 'backfill failure causes command to fail' ' done EOF - # Even though we fail to create refs/tags/tag1 the below command - # unexpectedly succeeds. - git -C clone5 fetch .. $B:refs/heads/something && + test_must_fail git -C clone5 fetch .. $B:refs/heads/something && test $B = $(git -C clone5 rev-parse --verify refs/heads/something) && test $S = $(git -C clone5 rev-parse --verify tag2) && test_must_fail git -C clone5 rev-parse --verify tag1 From 4f2ba2d06a7dd7e84e105a2779a7f07549d04231 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:32 +0100 Subject: [PATCH 5/7] refs: add interface to iterate over queued transactional updates There is no way for a caller to see whether a reference update has already been queued up for a given reference transaction. There are multiple alternatives to provide this functionality: - We may add a function that simply tells us whether a specific reference has already been queued. If implemented naively then this would potentially be quadratic in runtime behaviour if this question is asked repeatedly because we have to iterate over all references every time. The alternative would be to add a hashmap of all queued reference updates to speed up the lookup, but this adds overhead to all callers. - We may add a flag to `ref_transaction_add_update()` that causes it to skip duplicates, but this has the same runtime concerns as the first alternative. - We may add an interface which lets callers collect all updates which have already been queued such that he can avoid re-adding them. This is the most flexible approach and puts the burden on the caller, but also allows us to not impact any of the existing callsites which don't need this information. This commit implements the last approach: it allows us to compute the map of already-queued updates once up front such that we can then skip all subsequent references which are already part of this map. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs.c | 16 ++++++++++++++++ refs.h | 14 ++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/refs.c b/refs.c index 7017ae5980..7dc6c35ebc 100644 --- a/refs.c +++ b/refs.c @@ -2412,6 +2412,22 @@ int initial_ref_transaction_commit(struct ref_transaction *transaction, return refs->be->initial_transaction_commit(refs, transaction, err); } +void ref_transaction_for_each_queued_update(struct ref_transaction *transaction, + ref_transaction_for_each_queued_update_fn cb, + void *cb_data) +{ + int i; + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + cb(update->refname, + (update->flags & REF_HAVE_OLD) ? &update->old_oid : NULL, + (update->flags & REF_HAVE_NEW) ? &update->new_oid : NULL, + cb_data); + } +} + int refs_delete_refs(struct ref_store *refs, const char *logmsg, struct string_list *refnames, unsigned int flags) { diff --git a/refs.h b/refs.h index cd2d0c1ac0..991ed6268d 100644 --- a/refs.h +++ b/refs.h @@ -770,6 +770,20 @@ int ref_transaction_abort(struct ref_transaction *transaction, int initial_ref_transaction_commit(struct ref_transaction *transaction, struct strbuf *err); +/* + * Execute the given callback function for each of the reference updates which + * have been queued in the given transaction. `old_oid` and `new_oid` may be + * `NULL` pointers depending on whether the update has these object IDs set or + * not. + */ +typedef void ref_transaction_for_each_queued_update_fn(const char *refname, + const struct object_id *old_oid, + const struct object_id *new_oid, + void *cb_data); +void ref_transaction_for_each_queued_update(struct ref_transaction *transaction, + ref_transaction_for_each_queued_update_fn cb, + void *cb_data); + /* * Free `*transaction` and all associated data. */ From b3a804663c4682f6df55dd6703f8f8af9a7c6ab5 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:36 +0100 Subject: [PATCH 6/7] fetch: make `--atomic` flag cover backfilling of tags When fetching references from a remote we by default also fetch all tags which point into the history we have fetched. This is a separate step performed after updating local references because it requires us to walk over the history on the client-side to determine whether the remote has announced any tags which point to one of the fetched commits. This backfilling of tags isn't covered by the `--atomic` flag: right now, it only applies to the step where we update our local references. This is an oversight at the time the flag was introduced: its purpose is to either update all references or none, but right now we happily update local references even in the case where backfilling failed. Fix this by pulling up creation of the reference transaction such that we can pass the same transaction to both the code which updates local references and to the code which backfills tags. This allows us to only commit the transaction in case both actions succeed. Note that we also have to start passing the transaction into `find_non_local_tags()`: this function is responsible for finding all tags which we need to backfill. Right now, it will happily return tags which have already been updated with our local references. But when we use a single transaction for both local references and backfilling then it may happen that we try to queue the same reference update twice to the transaction, which consequently triggers a bug. We thus have to skip over any tags which have already been queued. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- builtin/fetch.c | 92 +++++++++++++++++++++++++++++++------------- t/t5503-tagfollow.sh | 11 ++---- 2 files changed, 69 insertions(+), 34 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index d304314f16..67af842091 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -349,7 +349,19 @@ static void clear_item(struct refname_hash_entry *item) item->ignore = 1; } + +static void add_already_queued_tags(const char *refname, + const struct object_id *old_oid, + const struct object_id *new_oid, + void *cb_data) +{ + struct hashmap *queued_tags = cb_data; + if (starts_with(refname, "refs/tags/") && new_oid) + (void) refname_hash_add(queued_tags, refname, new_oid); +} + static void find_non_local_tags(const struct ref *refs, + struct ref_transaction *transaction, struct ref **head, struct ref ***tail) { @@ -367,6 +379,16 @@ static void find_non_local_tags(const struct ref *refs, create_fetch_oidset(head, &fetch_oids); for_each_ref(add_one_refname, &existing_refs); + + /* + * If we already have a transaction, then we need to filter out all + * tags which have already been queued up. + */ + if (transaction) + ref_transaction_for_each_queued_update(transaction, + add_already_queued_tags, + &existing_refs); + for (ref = refs; ref; ref = ref->next) { if (!starts_with(ref->name, "refs/tags/")) continue; @@ -600,7 +622,7 @@ static struct ref *get_ref_map(struct remote *remote, /* also fetch all tags */ get_fetch_map(remote_refs, tag_refspec, &tail, 0); else if (tags == TAGS_DEFAULT && *autotags) - find_non_local_tags(remote_refs, &ref_map, &tail); + find_non_local_tags(remote_refs, NULL, &ref_map, &tail); /* Now append any refs to be updated opportunistically: */ *tail = orefs; @@ -1083,12 +1105,12 @@ N_("it took %.2f seconds to check forced updates; you can use\n" "to avoid this check\n"); static int store_updated_refs(const char *raw_url, const char *remote_name, - int connectivity_checked, struct ref *ref_map, + int connectivity_checked, + struct ref_transaction *transaction, struct ref *ref_map, struct fetch_head *fetch_head, struct worktree **worktrees) { int url_len, i, rc = 0; struct strbuf note = STRBUF_INIT, err = STRBUF_INIT; - struct ref_transaction *transaction = NULL; const char *what, *kind; struct ref *rm; char *url; @@ -1110,14 +1132,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, } } - if (atomic_fetch) { - transaction = ref_transaction_begin(&err); - if (!transaction) { - error("%s", err.buf); - goto abort; - } - } - prepare_format_display(ref_map); /* @@ -1233,14 +1247,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, } } - if (!rc && transaction) { - rc = ref_transaction_commit(transaction, &err); - if (rc) { - error("%s", err.buf); - goto abort; - } - } - if (rc & STORE_REF_ERROR_DF_CONFLICT) error(_("some local refs could not be updated; try running\n" " 'git remote prune %s' to remove any old, conflicting " @@ -1258,7 +1264,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, abort: strbuf_release(¬e); strbuf_release(&err); - ref_transaction_free(transaction); free(url); return rc; } @@ -1299,6 +1304,7 @@ static int check_exist_and_connected(struct ref *ref_map) } static int fetch_and_consume_refs(struct transport *transport, + struct ref_transaction *transaction, struct ref *ref_map, struct fetch_head *fetch_head, struct worktree **worktrees) @@ -1323,7 +1329,8 @@ static int fetch_and_consume_refs(struct transport *transport, trace2_region_enter("fetch", "consume_refs", the_repository); ret = store_updated_refs(transport->url, transport->remote->name, - connectivity_checked, ref_map, fetch_head, worktrees); + connectivity_checked, transaction, ref_map, + fetch_head, worktrees); trace2_region_leave("fetch", "consume_refs", the_repository); out: @@ -1496,6 +1503,7 @@ static struct transport *prepare_transport(struct remote *remote, int deepen) } static int backfill_tags(struct transport *transport, + struct ref_transaction *transaction, struct ref *ref_map, struct fetch_head *fetch_head, struct worktree **worktrees) @@ -1519,7 +1527,7 @@ static int backfill_tags(struct transport *transport, transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL); transport_set_option(transport, TRANS_OPT_DEPTH, "0"); transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL); - retcode = fetch_and_consume_refs(transport, ref_map, fetch_head, worktrees); + retcode = fetch_and_consume_refs(transport, transaction, ref_map, fetch_head, worktrees); if (gsecondary) { transport_disconnect(gsecondary); @@ -1532,6 +1540,7 @@ static int backfill_tags(struct transport *transport, static int do_fetch(struct transport *transport, struct refspec *rs) { + struct ref_transaction *transaction = NULL; struct ref *ref_map = NULL; int autotags = (transport->remote->fetch_tags == 1); int retcode = 0; @@ -1541,6 +1550,7 @@ static int do_fetch(struct transport *transport, int must_list_refs = 1; struct worktree **worktrees = get_worktrees(); struct fetch_head fetch_head = { 0 }; + struct strbuf err = STRBUF_INIT; if (tags == TAGS_DEFAULT) { if (transport->remote->fetch_tags == 2) @@ -1602,6 +1612,14 @@ static int do_fetch(struct transport *transport, if (retcode) goto cleanup; + if (atomic_fetch) { + transaction = ref_transaction_begin(&err); + if (!transaction) { + retcode = error("%s", err.buf); + goto cleanup; + } + } + if (tags == TAGS_DEFAULT && autotags) transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1"); if (prune) { @@ -1621,7 +1639,7 @@ static int do_fetch(struct transport *transport, retcode = 1; } - if (fetch_and_consume_refs(transport, ref_map, &fetch_head, worktrees)) { + if (fetch_and_consume_refs(transport, transaction, ref_map, &fetch_head, worktrees)) { retcode = 1; goto cleanup; } @@ -1633,21 +1651,37 @@ static int do_fetch(struct transport *transport, if (tags == TAGS_DEFAULT && autotags) { struct ref *tags_ref_map = NULL, **tail = &tags_ref_map; - find_non_local_tags(remote_refs, &tags_ref_map, &tail); + find_non_local_tags(remote_refs, transaction, &tags_ref_map, &tail); if (tags_ref_map) { /* * If backfilling of tags fails then we want to tell * the user so, but we have to continue regardless to * populate upstream information of the references we - * have already fetched above. + * have already fetched above. The exception though is + * when `--atomic` is passed: in that case we'll abort + * the transaction and don't commit anything. */ - if (backfill_tags(transport, tags_ref_map, &fetch_head, worktrees)) + if (backfill_tags(transport, transaction, tags_ref_map, + &fetch_head, worktrees)) retcode = 1; } free_refs(tags_ref_map); } + if (transaction) { + if (retcode) + goto cleanup; + + retcode = ref_transaction_commit(transaction, &err); + if (retcode) { + error("%s", err.buf); + ref_transaction_free(transaction); + transaction = NULL; + goto cleanup; + } + } + commit_fetch_head(&fetch_head); if (set_upstream) { @@ -1705,7 +1739,13 @@ static int do_fetch(struct transport *transport, } cleanup: + if (retcode && transaction) { + ref_transaction_abort(transaction, &err); + error("%s", err.buf); + } + close_fetch_head(&fetch_head); + strbuf_release(&err); free_refs(ref_map); free_worktrees(worktrees); return retcode; diff --git a/t/t5503-tagfollow.sh b/t/t5503-tagfollow.sh index c057c49e80..e72fdc2534 100755 --- a/t/t5503-tagfollow.sh +++ b/t/t5503-tagfollow.sh @@ -180,11 +180,8 @@ test_expect_success 'atomic fetch with failing backfill' ' EOF test_must_fail git -C clone3 fetch --atomic .. $B:refs/heads/something && - - # Creation of the tag has failed, so ideally refs/heads/something - # should not exist. The fact that it does demonstrates that there is - # a bug in the `--atomic` flag. - test $B = "$(git -C clone3 rev-parse --verify refs/heads/something)" + test_must_fail git -C clone3 rev-parse --verify refs/heads/something && + test_must_fail git -C clone3 rev-parse --verify refs/tags/tag2 ' test_expect_success 'atomic fetch with backfill should use single transaction' ' @@ -197,12 +194,10 @@ test_expect_success 'atomic fetch with backfill should use single transaction' ' prepared $ZERO_OID $B refs/heads/something $ZERO_OID $S refs/tags/tag2 + $ZERO_OID $T refs/tags/tag1 committed $ZERO_OID $B refs/heads/something $ZERO_OID $S refs/tags/tag2 - prepared - $ZERO_OID $T refs/tags/tag1 - committed $ZERO_OID $T refs/tags/tag1 EOF From 583bc419235cedc6a2ba12593f058a9f812b9594 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 17 Feb 2022 14:04:41 +0100 Subject: [PATCH 7/7] fetch: make `--atomic` flag cover pruning of refs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When fetching with the `--prune` flag we will delete any local references matching the fetch refspec which have disappeared on the remote. This step is not currently covered by the `--atomic` flag: we delete branches even though updating of local references has failed, which means that the fetch is not an all-or-nothing operation. Fix this bug by passing in the global transaction into `prune_refs()`: if one is given, then we'll only queue up deletions and not commit them right away. This change also improves performance when pruning many branches in a repository with a big packed-refs file: every references is pruned in its own transaction, which means that we potentially have to rewrite the packed-refs files for every single reference we're about to prune. The following benchmark demonstrates this: it performs a pruning fetch from a repository with a single reference into a repository with 100k references, which causes us to prune all but one reference. This is of course a very artificial setup, but serves to demonstrate the impact of only having to write the packed-refs file once: Benchmark 1: git fetch --prune --atomic +refs/*:refs/* (HEAD~) Time (mean ± σ): 2.366 s ± 0.021 s [User: 0.858 s, System: 1.508 s] Range (min … max): 2.328 s … 2.407 s 10 runs Benchmark 2: git fetch --prune --atomic +refs/*:refs/* (HEAD) Time (mean ± σ): 1.369 s ± 0.017 s [User: 0.715 s, System: 0.641 s] Range (min … max): 1.346 s … 1.400 s 10 runs Summary 'git fetch --prune --atomic +refs/*:refs/* (HEAD)' ran 1.73 ± 0.03 times faster than 'git fetch --prune --atomic +refs/*:refs/* (HEAD~)' Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- builtin/fetch.c | 30 ++++++++++++++++++++++-------- t/t5510-fetch.sh | 8 ++------ 2 files changed, 24 insertions(+), 14 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index 67af842091..9a2b5c03a4 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -1338,11 +1338,14 @@ out: return ret; } -static int prune_refs(struct refspec *rs, struct ref *ref_map, +static int prune_refs(struct refspec *rs, + struct ref_transaction *transaction, + struct ref *ref_map, const char *raw_url) { int url_len, i, result = 0; struct ref *ref, *stale_refs = get_stale_heads(rs, ref_map); + struct strbuf err = STRBUF_INIT; char *url; int summary_width = transport_summary_width(stale_refs); const char *dangling_msg = dry_run @@ -1363,13 +1366,22 @@ static int prune_refs(struct refspec *rs, struct ref *ref_map, url_len = i - 3; if (!dry_run) { - struct string_list refnames = STRING_LIST_INIT_NODUP; + if (transaction) { + for (ref = stale_refs; ref; ref = ref->next) { + result = ref_transaction_delete(transaction, ref->name, NULL, 0, + "fetch: prune", &err); + if (result) + goto cleanup; + } + } else { + struct string_list refnames = STRING_LIST_INIT_NODUP; - for (ref = stale_refs; ref; ref = ref->next) - string_list_append(&refnames, ref->name); + for (ref = stale_refs; ref; ref = ref->next) + string_list_append(&refnames, ref->name); - result = delete_refs("fetch: prune", &refnames, 0); - string_list_clear(&refnames, 0); + result = delete_refs("fetch: prune", &refnames, 0); + string_list_clear(&refnames, 0); + } } if (verbosity >= 0) { @@ -1388,6 +1400,8 @@ static int prune_refs(struct refspec *rs, struct ref *ref_map, } } +cleanup: + strbuf_release(&err); free(url); free_refs(stale_refs); return result; @@ -1629,10 +1643,10 @@ static int do_fetch(struct transport *transport, * don't care whether --tags was specified. */ if (rs->nr) { - retcode = prune_refs(rs, ref_map, transport->url); + retcode = prune_refs(rs, transaction, ref_map, transport->url); } else { retcode = prune_refs(&transport->remote->fetch, - ref_map, + transaction, ref_map, transport->url); } if (retcode != 0) diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh index 70d51f343b..48e14e2dab 100755 --- a/t/t5510-fetch.sh +++ b/t/t5510-fetch.sh @@ -354,17 +354,13 @@ test_expect_success 'fetch --atomic --prune executes a single reference transact head_oid=$(git rev-parse HEAD) && # Fetching with the `--atomic` flag should update all references in a - # single transaction. It is currently missing coverage of pruned - # references though, and as a result those may be committed to disk - # even if updating references fails later. + # single transaction. cat >expected <<-EOF && prepared $ZERO_OID $ZERO_OID refs/remotes/origin/scheduled-for-deletion - committed - $ZERO_OID $ZERO_OID refs/remotes/origin/scheduled-for-deletion - prepared $ZERO_OID $head_oid refs/remotes/origin/new-branch committed + $ZERO_OID $ZERO_OID refs/remotes/origin/scheduled-for-deletion $ZERO_OID $head_oid refs/remotes/origin/new-branch EOF