diff options
Diffstat (limited to 'refs')
| -rw-r--r-- | refs/files-backend.c | 150 | ||||
| -rw-r--r-- | refs/packed-backend.c | 112 | ||||
| -rw-r--r-- | refs/packed-backend.h | 9 | ||||
| -rw-r--r-- | refs/ref-cache.c | 4 | ||||
| -rw-r--r-- | refs/refs-internal.h | 81 |
5 files changed, 247 insertions, 109 deletions
diff --git a/refs/files-backend.c b/refs/files-backend.c index 2bd54e11a..f75d960e1 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -10,6 +10,51 @@ #include "../object.h" #include "../dir.h" +/* + * This backend uses the following flags in `ref_update::flags` for + * internal bookkeeping purposes. Their numerical values must not + * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW, + * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in + * `ref_update::flags`. + */ + +/* + * Used as a flag in ref_update::flags when a loose ref is being + * pruned. This flag must only be used when REF_NO_DEREF is set. + */ +#define REF_IS_PRUNING (1 << 4) + +/* + * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken + * refs (i.e., because the reference is about to be deleted anyway). + */ +#define REF_DELETING (1 << 5) + +/* + * Used as a flag in ref_update::flags when the lockfile needs to be + * committed. + */ +#define REF_NEEDS_COMMIT (1 << 6) + +/* + * Used as a flag in ref_update::flags when we want to log a ref + * update but not actually perform it. This is used when a symbolic + * ref update is split up. + */ +#define REF_LOG_ONLY (1 << 7) + +/* + * Used as a flag in ref_update::flags when the ref_update was via an + * update to HEAD. + */ +#define REF_UPDATE_VIA_HEAD (1 << 8) + +/* + * Used as a flag in ref_update::flags when the loose reference has + * been deleted. + */ +#define REF_DELETED_LOOSE (1 << 9) + struct ref_lock { char *ref_name; struct lock_file lk; @@ -195,7 +240,7 @@ static void loose_fill_ref_dir(struct ref_store *ref_store, } else if (is_null_oid(&oid)) { /* * It is so astronomically unlikely - * that NULL_SHA1 is the SHA-1 of an + * that null_oid is the OID of an * actual object that we consider its * appearance in a loose reference * file to be repo corruption @@ -428,7 +473,7 @@ static void unlock_ref(struct ref_lock *lock) * are passed to refs_verify_refname_available() for this check. * * If mustexist is not set and the reference is not found or is - * broken, lock the reference anyway but clear sha1. + * broken, lock the reference anyway but clear old_oid. * * Return 0 on success. On failure, write an error message to err and * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR. @@ -989,22 +1034,29 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r) { struct ref_transaction *transaction; struct strbuf err = STRBUF_INIT; + int ret = -1; if (check_refname_format(r->name, 0)) return; transaction = ref_store_transaction_begin(&refs->base, &err); - if (!transaction || - ref_transaction_delete(transaction, r->name, &r->oid, - REF_ISPRUNING | REF_NODEREF, NULL, &err) || - ref_transaction_commit(transaction, &err)) { - ref_transaction_free(transaction); + if (!transaction) + goto cleanup; + ref_transaction_add_update( + transaction, r->name, + REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING, + &null_oid, &r->oid, NULL); + if (ref_transaction_commit(transaction, &err)) + goto cleanup; + + ret = 0; + +cleanup: + if (ret) error("%s", err.buf); - strbuf_release(&err); - return; - } - ref_transaction_free(transaction); strbuf_release(&err); + ref_transaction_free(transaction); + return; } /* @@ -1081,7 +1133,7 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) */ if (ref_transaction_update(transaction, iter->refname, iter->oid, NULL, - REF_NODEREF, NULL, &err)) + REF_NO_DEREF, NULL, &err)) die("failure preparing to create packed reference %s: %s", iter->refname, err.buf); @@ -1284,7 +1336,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, } if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname, - &orig_oid, REF_NODEREF)) { + &orig_oid, REF_NO_DEREF)) { error("unable to delete old %s", oldrefname); goto rollback; } @@ -1300,7 +1352,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE, &oid, NULL) && refs_delete_ref(&refs->base, NULL, newrefname, - NULL, REF_NODEREF)) { + NULL, REF_NO_DEREF)) { if (errno == EISDIR) { struct strbuf path = STRBUF_INIT; int result; @@ -1325,7 +1377,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, logmoved = log; lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL, - REF_NODEREF, NULL, &err); + REF_NO_DEREF, NULL, &err); if (!lock) { if (copy) error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf); @@ -1348,7 +1400,7 @@ static int files_copy_or_rename_ref(struct ref_store *ref_store, rollback: lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL, - REF_NODEREF, NULL, &err); + REF_NO_DEREF, NULL, &err); if (!lock) { error("unable to lock %s for rollback: %s", oldrefname, err.buf); strbuf_release(&err); @@ -1596,9 +1648,8 @@ static int files_log_ref_write(struct files_ref_store *refs, } /* - * Write sha1 into the open lockfile, then close the lockfile. On - * errors, rollback the lockfile, fill in *err and - * return -1. + * Write oid into the open lockfile, then close the lockfile. On + * errors, rollback the lockfile, fill in *err and return -1. */ static int write_ref_to_lockfile(struct ref_lock *lock, const struct object_id *oid, struct strbuf *err) @@ -1764,7 +1815,7 @@ static int files_create_symref(struct ref_store *ref_store, int ret; lock = lock_ref_oid_basic(refs, refname, NULL, - NULL, NULL, REF_NODEREF, NULL, + NULL, NULL, REF_NO_DEREF, NULL, &err); if (!lock) { error("%s", err.buf); @@ -2125,7 +2176,7 @@ static int split_head_update(struct ref_update *update, struct ref_update *new_update; if ((update->flags & REF_LOG_ONLY) || - (update->flags & REF_ISPRUNING) || + (update->flags & REF_IS_PRUNING) || (update->flags & REF_UPDATE_VIA_HEAD)) return 0; @@ -2148,7 +2199,7 @@ static int split_head_update(struct ref_update *update, new_update = ref_transaction_add_update( transaction, "HEAD", - update->flags | REF_LOG_ONLY | REF_NODEREF, + update->flags | REF_LOG_ONLY | REF_NO_DEREF, &update->new_oid, &update->old_oid, update->msg); @@ -2167,8 +2218,8 @@ static int split_head_update(struct ref_update *update, /* * update is for a symref that points at referent and doesn't have - * REF_NODEREF set. Split it into two updates: - * - The original update, but with REF_LOG_ONLY and REF_NODEREF set + * REF_NO_DEREF set. Split it into two updates: + * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set * - A new, separate update for the referent reference * Note that the new update will itself be subject to splitting when * the iteration gets to it. @@ -2220,10 +2271,10 @@ static int split_symref_update(struct files_ref_store *refs, /* * Change the symbolic ref update to log only. Also, it - * doesn't need to check its old SHA-1 value, as that will be + * doesn't need to check its old OID value, as that will be * done when new_update is processed. */ - update->flags |= REF_LOG_ONLY | REF_NODEREF; + update->flags |= REF_LOG_ONLY | REF_NO_DEREF; update->flags &= ~REF_HAVE_OLD; /* @@ -2289,10 +2340,10 @@ static int check_old_oid(struct ref_update *update, struct object_id *oid, * Prepare for carrying out update: * - Lock the reference referred to by update. * - Read the reference under lock. - * - Check that its old SHA-1 value (if specified) is correct, and in + * - Check that its old OID value (if specified) is correct, and in * any case record it in update->lock->old_oid for later use when * writing the reflog. - * - If it is a symref update without REF_NODEREF, split it up into a + * - If it is a symref update without REF_NO_DEREF, split it up into a * REF_LOG_ONLY update of the symref and add a separate update for * the referent to transaction. * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY @@ -2340,11 +2391,11 @@ static int lock_ref_for_update(struct files_ref_store *refs, update->backend_data = lock; if (update->type & REF_ISSYMREF) { - if (update->flags & REF_NODEREF) { + if (update->flags & REF_NO_DEREF) { /* * We won't be reading the referent as part of * the transaction, so we have to read it here - * to record and possibly check old_sha1: + * to record and possibly check old_oid: */ if (refs_read_ref_full(&refs->base, referent.buf, 0, @@ -2364,7 +2415,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, /* * Create a new update for the reference this * symref is pointing at. Also, we will record - * and verify old_sha1 for this update as part + * and verify old_oid for this update as part * of processing the split-off update, so we * don't have to do it here. */ @@ -2384,7 +2435,7 @@ static int lock_ref_for_update(struct files_ref_store *refs, /* * If this update is happening indirectly because of a - * symref update, record the old SHA-1 in the parent + * symref update, record the old OID in the parent * update: */ for (parent_update = update->parent_update; @@ -2511,13 +2562,18 @@ static int files_transaction_prepare(struct ref_store *ref_store, * transaction. (If we end up splitting up any updates using * split_symref_update() or split_head_update(), those * functions will check that the new updates don't have the - * same refname as any existing ones.) + * same refname as any existing ones.) Also fail if any of the + * updates use REF_IS_PRUNING without REF_NO_DEREF. */ for (i = 0; i < transaction->nr; i++) { struct ref_update *update = transaction->updates[i]; struct string_list_item *item = string_list_append(&affected_refnames, update->refname); + if ((update->flags & REF_IS_PRUNING) && + !(update->flags & REF_NO_DEREF)) + BUG("REF_IS_PRUNING set without REF_NO_DEREF"); + /* * We store a pointer to update in item->util, but at * the moment we never use the value of this field @@ -2575,7 +2631,7 @@ static int files_transaction_prepare(struct ref_store *ref_store, if (update->flags & REF_DELETING && !(update->flags & REF_LOG_ONLY) && - !(update->flags & REF_ISPRUNING)) { + !(update->flags & REF_IS_PRUNING)) { /* * This reference has to be deleted from * packed-refs if it exists there. @@ -2594,8 +2650,8 @@ static int files_transaction_prepare(struct ref_store *ref_store, ref_transaction_add_update( packed_transaction, update->refname, - update->flags & ~REF_HAVE_OLD, - &update->new_oid, &update->old_oid, + REF_HAVE_NEW | REF_NO_DEREF, + &update->new_oid, NULL, NULL); } } @@ -2606,7 +2662,23 @@ static int files_transaction_prepare(struct ref_store *ref_store, goto cleanup; } backend_data->packed_refs_locked = 1; - ret = ref_transaction_prepare(packed_transaction, err); + + if (is_packed_transaction_needed(refs->packed_ref_store, + packed_transaction)) { + ret = ref_transaction_prepare(packed_transaction, err); + } else { + /* + * We can skip rewriting the `packed-refs` + * file. But we do need to leave it locked, so + * that somebody else doesn't pack a reference + * that we are trying to delete. + */ + if (ref_transaction_abort(packed_transaction, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + backend_data->packed_transaction = NULL; + } } cleanup: @@ -2692,7 +2764,7 @@ static int files_transaction_finish(struct ref_store *ref_store, struct ref_update *update = transaction->updates[i]; if (update->flags & REF_DELETING && !(update->flags & REF_LOG_ONLY) && - !(update->flags & REF_ISPRUNING)) { + !(update->flags & REF_IS_PRUNING)) { strbuf_reset(&sb); files_reflog_path(refs, &sb, update->refname); if (!unlink_or_warn(sb.buf)) @@ -2938,7 +3010,7 @@ static int files_reflog_expire(struct ref_store *ref_store, * reference if --updateref was specified: */ lock = lock_ref_oid_basic(refs, refname, oid, - NULL, NULL, REF_NODEREF, + NULL, NULL, REF_NO_DEREF, &type, &err); if (!lock) { error("cannot lock ref '%s': %s", refname, err.buf); diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 74f1dea0f..023243fd5 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -744,7 +744,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store, /* * This value is set in `base.flags` if the peeled value of the * current reference is known. In that case, `peeled` contains the - * correct peeled value for the reference, which might be `null_sha1` + * correct peeled value for the reference, which might be `null_oid` * if the reference is not a tag or if it is broken. */ #define REF_KNOWS_PEELED 0x40 @@ -961,11 +961,11 @@ static struct ref_iterator *packed_ref_iterator_begin( * by the failing call to `fprintf()`. */ static int write_packed_entry(FILE *fh, const char *refname, - const unsigned char *sha1, - const unsigned char *peeled) + const struct object_id *oid, + const struct object_id *peeled) { - if (fprintf(fh, "%s %s\n", sha1_to_hex(sha1), refname) < 0 || - (peeled && fprintf(fh, "^%s\n", sha1_to_hex(peeled)) < 0)) + if (fprintf(fh, "%s %s\n", oid_to_hex(oid), refname) < 0 || + (peeled && fprintf(fh, "^%s\n", oid_to_hex(peeled)) < 0)) return -1; return 0; @@ -1203,8 +1203,8 @@ static int write_with_updates(struct packed_ref_store *refs, int peel_error = ref_iterator_peel(iter, &peeled); if (write_packed_entry(out, iter->refname, - iter->oid->hash, - peel_error ? NULL : peeled.hash)) + iter->oid, + peel_error ? NULL : &peeled)) goto write_error; if ((ok = ref_iterator_advance(iter)) != ITER_OK) @@ -1224,8 +1224,8 @@ static int write_with_updates(struct packed_ref_store *refs, &peeled); if (write_packed_entry(out, update->refname, - update->new_oid.hash, - peel_error ? NULL : peeled.hash)) + &update->new_oid, + peel_error ? NULL : &peeled)) goto write_error; i++; @@ -1261,6 +1261,100 @@ error: return -1; } +int is_packed_transaction_needed(struct ref_store *ref_store, + struct ref_transaction *transaction) +{ + struct packed_ref_store *refs = packed_downcast( + ref_store, + REF_STORE_READ, + "is_packed_transaction_needed"); + struct strbuf referent = STRBUF_INIT; + size_t i; + int ret; + + if (!is_lock_file_locked(&refs->lock)) + BUG("is_packed_transaction_needed() called while unlocked"); + + /* + * We're only going to bother returning false for the common, + * trivial case that references are only being deleted, their + * old values are not being checked, and the old `packed-refs` + * file doesn't contain any of those reference(s). This gives + * false positives for some other cases that could + * theoretically be optimized away: + * + * 1. It could be that the old value is being verified without + * setting a new value. In this case, we could verify the + * old value here and skip the update if it agrees. If it + * disagrees, we could either let the update go through + * (the actual commit would re-detect and report the + * problem), or come up with a way of reporting such an + * error to *our* caller. + * + * 2. It could be that a new value is being set, but that it + * is identical to the current packed value of the + * reference. + * + * Neither of these cases will come up in the current code, + * because the only caller of this function passes to it a + * transaction that only includes `delete` updates with no + * `old_id`. Even if that ever changes, false positives only + * cause an optimization to be missed; they do not affect + * correctness. + */ + + /* + * Start with the cheap checks that don't require old + * reference values to be read: + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + if (update->flags & REF_HAVE_OLD) + /* Have to check the old value -> needed. */ + return 1; + + if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid)) + /* Have to set a new value -> needed. */ + return 1; + } + + /* + * The transaction isn't checking any old values nor is it + * setting any nonzero new values, so it still might be able + * to be skipped. Now do the more expensive check: the update + * is needed if any of the updates is a delete, and the old + * `packed-refs` file contains a value for that reference. + */ + ret = 0; + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + unsigned int type; + struct object_id oid; + + if (!(update->flags & REF_HAVE_NEW)) + /* + * This reference isn't being deleted -> not + * needed. + */ + continue; + + if (!refs_read_raw_ref(ref_store, update->refname, + &oid, &referent, &type) || + errno != ENOENT) { + /* + * We have to actually delete that reference + * -> this transaction is needed. + */ + ret = 1; + break; + } + } + + strbuf_release(&referent); + return ret; +} + struct packed_transaction_backend_data { /* True iff the transaction owns the packed-refs lock. */ int own_lock; diff --git a/refs/packed-backend.h b/refs/packed-backend.h index 61687e408..640245d3b 100644 --- a/refs/packed-backend.h +++ b/refs/packed-backend.h @@ -23,4 +23,13 @@ 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); +/* + * Return true if `transaction` really needs to be carried out against + * the specified packed_ref_store, or false if it can be skipped + * (i.e., because it is an obvious NOOP). `ref_store` must be locked + * before calling this function. + */ +int is_packed_transaction_needed(struct ref_store *ref_store, + struct ref_transaction *transaction); + #endif /* REFS_PACKED_BACKEND_H */ diff --git a/refs/ref-cache.c b/refs/ref-cache.c index 043eb8374..82c1cf90a 100644 --- a/refs/ref-cache.c +++ b/refs/ref-cache.c @@ -260,8 +260,8 @@ int add_ref_entry(struct ref_dir *dir, struct ref_entry *ref) /* * Emit a warning and return true iff ref1 and ref2 have the same name - * and the same sha1. Die if they have the same name but different - * sha1s. + * and the same oid. Die if they have the same name but different + * oids. */ static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2) { diff --git a/refs/refs-internal.h b/refs/refs-internal.h index b0f3e300c..dd834314b 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -8,58 +8,22 @@ */ /* - * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken - * refs (i.e., because the reference is about to be deleted anyway). + * The following flags can appear in `ref_update::flags`. Their + * numerical values must not conflict with those of REF_NO_DEREF and + * REF_FORCE_CREATE_REFLOG, which are also stored in + * `ref_update::flags`. */ -#define REF_DELETING 0x02 /* - * Used as a flag in ref_update::flags when a loose ref is being - * pruned. This flag must only be used when REF_NODEREF is set. + * The reference should be updated to new_oid. */ -#define REF_ISPRUNING 0x04 +#define REF_HAVE_NEW (1 << 2) /* - * Used as a flag in ref_update::flags when the reference should be - * updated to new_sha1. + * The current reference's value should be checked to make sure that + * it agrees with old_oid. */ -#define REF_HAVE_NEW 0x08 - -/* - * Used as a flag in ref_update::flags when old_sha1 should be - * checked. - */ -#define REF_HAVE_OLD 0x10 - -/* - * Used as a flag in ref_update::flags when the lockfile needs to be - * committed. - */ -#define REF_NEEDS_COMMIT 0x20 - -/* - * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a - * value to ref_update::flags - */ - -/* - * Used as a flag in ref_update::flags when we want to log a ref - * update but not actually perform it. This is used when a symbolic - * ref update is split up. - */ -#define REF_LOG_ONLY 0x80 - -/* - * Internal flag, meaning that the containing ref_update was via an - * update to HEAD. - */ -#define REF_UPDATE_VIA_HEAD 0x100 - -/* - * Used as a flag in ref_update::flags when the loose reference has - * been deleted. - */ -#define REF_DELETED_LOOSE 0x200 +#define REF_HAVE_OLD (1 << 3) /* * Return the length of time to retry acquiring a loose reference lock @@ -122,7 +86,7 @@ enum peel_status { * tag recursively until a non-tag is found. If successful, store the * result to oid and return PEEL_PEELED. If the object is not a tag * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively, - * and leave sha1 unchanged. + * and leave oid unchanged. */ enum peel_status peel_object(const struct object_id *name, struct object_id *oid); @@ -134,30 +98,29 @@ enum peel_status peel_object(const struct object_id *name, struct object_id *oid int copy_reflog_msg(char *buf, const char *msg); /** - * Information needed for a single ref update. Set new_sha1 to the new - * value or to null_sha1 to delete the ref. To check the old value - * while the ref is locked, set (flags & REF_HAVE_OLD) and set - * old_sha1 to the old value, or to null_sha1 to ensure the ref does - * not exist before update. + * Information needed for a single ref update. Set new_oid to the new + * value or to null_oid to delete the ref. To check the old value + * while the ref is locked, set (flags & REF_HAVE_OLD) and set old_oid + * to the old value, or to null_oid to ensure the ref does not exist + * before update. */ struct ref_update { - /* - * If (flags & REF_HAVE_NEW), set the reference to this value: + * If (flags & REF_HAVE_NEW), set the reference to this value + * (or delete it, if `new_oid` is `null_oid`). */ struct object_id new_oid; /* * If (flags & REF_HAVE_OLD), check that the reference - * previously had this value: + * previously had this value (or didn't previously exist, if + * `old_oid` is `null_oid`). */ struct object_id old_oid; /* - * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF, - * REF_DELETING, REF_ISPRUNING, REF_LOG_ONLY, - * REF_UPDATE_VIA_HEAD, REF_NEEDS_COMMIT, and - * REF_DELETED_LOOSE: + * One or more of REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, + * REF_HAVE_NEW, REF_HAVE_OLD, or backend-specific flags. */ unsigned int flags; @@ -195,7 +158,7 @@ int ref_update_reject_duplicates(struct string_list *refnames, /* * Add a ref_update with the specified properties to transaction, and * return a pointer to the new object. This function does not verify - * that refname is well-formed. new_sha1 and old_sha1 are only + * that refname is well-formed. new_oid and old_oid are only * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits, * respectively, are set in flags. */ |