From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Haggerty Subject: [PATCH v2 19/27] refs: Add a concept of a reference transaction Date: Mon, 24 Mar 2014 18:56:52 +0100 Message-ID: <1395683820-17304-20-git-send-email-mhagger@alum.mit.edu> References: <1395683820-17304-1-git-send-email-mhagger@alum.mit.edu> Cc: Brad King , Johan Herland , Jeff King , Vicent Marti , git@vger.kernel.org, Michael Haggerty To: Junio C Hamano X-From: git-owner@vger.kernel.org Mon Mar 24 18:58:53 2014 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WS997-0002Oo-JE for gcvg-git-2@plane.gmane.org; Mon, 24 Mar 2014 18:58:50 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753833AbaCXR5t (ORCPT ); Mon, 24 Mar 2014 13:57:49 -0400 Received: from alum-mailsec-scanner-8.mit.edu ([18.7.68.20]:58420 "EHLO alum-mailsec-scanner-8.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753829AbaCXR5s (ORCPT ); Mon, 24 Mar 2014 13:57:48 -0400 X-AuditID: 12074414-f79d96d000002d2b-29-5330721bf576 Received: from outgoing-alum.mit.edu (OUTGOING-ALUM.MIT.EDU [18.7.68.33]) by alum-mailsec-scanner-8.mit.edu (Symantec Messaging Gateway) with SMTP id 3E.8E.11563.B1270335; Mon, 24 Mar 2014 13:57:47 -0400 (EDT) Received: from michael.fritz.box (p57A25F6C.dip0.t-ipconnect.de [87.162.95.108]) (authenticated bits=0) (User authenticated as mhagger@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.13.8/8.12.4) with ESMTP id s2OHv4xp028070 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 24 Mar 2014 13:57:45 -0400 X-Mailer: git-send-email 1.9.0 In-Reply-To: <1395683820-17304-1-git-send-email-mhagger@alum.mit.edu> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrAIsWRmVeSWpSXmKPExsUixO6iqCtdZBBs8HuqvMXOdRIWXVe6mSwa eq8wW8y7u4vJ4vaK+cwWP1p6mC0+di5gdmD3+Pv+A5PHzll32T0uvfzO5vHx2XJ2j2e9exg9 Ll5S9vi8SS6APYrbJimxpCw4Mz1P3y6BO+PEtxdMBb+MK86/u8rawHhVs4uRk0NCwETizrKD bBC2mMSFe+uBbC4OIYHLjBJLu5YzgySEBE4wSTx67gNiswnoSizqaWYCsUUE1CQmth1iAWlg FrjCKHHl43YWkISwgIfEq/cn2EFsFgFViQPnpoHZvAKuEpNuP2GG2CYnMeX3ArA4J1B8a/th qGUuEjs+9jJNYORdwMiwilEuMac0Vzc3MTOnODVZtzg5MS8vtUjXQi83s0QvNaV0EyMk9ER2 MB45KXeIUYCDUYmHN8LYIFiINbGsuDL3EKMkB5OSKC9bLlCILyk/pTIjsTgjvqg0J7X4EKME B7OSCK9lOFCONyWxsiq1KB8mJc3BoiTO+22xup+QQHpiSWp2ampBahFMVoaDQ0mCd2ohUKNg UWp6akVaZk4JQpqJgxNkOJeUSHFqXkpqUWJpSUY8KDbii4HRAZLiAdpbC9LOW1yQmAsUhWg9 xagoJc57rQAoIQCSyCjNgxsLSyivGMWBvhTmnQ/SzgNMRnDdr4AGMwENDm/SAxlckoiQkmpg 9HS5nPlK5sV++W8vXavvrEtieJgu8Wmm4j62fTWTDn9yCn/NMS/HMWSGCseT/itLld5tdtT9 ce32Gg71pM8rPr1yNZ952uX8twpx3h+Xs/IkuA8ozn5031riy5qFG5nmH69leTL9 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Build out the API for dealing with a bunch of reference checks and changes within a transaction. Define an opaque ref_transaction type that is managed entirely within refs.c. Introduce functions for beginning a transaction, adding updates to a transaction, and committing/rolling back a transaction. This API will soon replace update_refs(). Signed-off-by: Michael Haggerty --- refs.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ refs.h | 65 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 161 insertions(+) diff --git a/refs.c b/refs.c index 1305eb1..e788c27 100644 --- a/refs.c +++ b/refs.c @@ -3267,6 +3267,93 @@ static int update_ref_write(const char *action, const char *refname, return 0; } +/* + * Data structure for holding a reference transaction, which can + * consist of checks and updates to multiple references, carried out + * as atomically as possible. This structure is opaque to callers. + */ +struct ref_transaction { + struct ref_update **updates; + size_t alloc; + size_t nr; +}; + +struct ref_transaction *ref_transaction_begin(void) +{ + return xcalloc(1, sizeof(struct ref_transaction)); +} + +static void ref_transaction_free(struct ref_transaction *transaction) +{ + int i; + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + free((char *)update->ref_name); + free(update); + } + + free(transaction->updates); + free(transaction); +} + +void ref_transaction_rollback(struct ref_transaction *transaction) +{ + ref_transaction_free(transaction); +} + +static struct ref_update *add_update(struct ref_transaction *transaction, + const char *refname) +{ + struct ref_update *update = xcalloc(1, sizeof(*update)); + + update->ref_name = xstrdup(refname); + ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc); + transaction->updates[transaction->nr++] = update; + return update; +} + +void ref_transaction_update(struct ref_transaction *transaction, + const char *refname, + unsigned char *new_sha1, unsigned char *old_sha1, + int flags, int have_old) +{ + struct ref_update *update = add_update(transaction, refname); + + hashcpy(update->new_sha1, new_sha1); + update->flags = flags; + update->have_old = have_old; + if (have_old) + hashcpy(update->old_sha1, old_sha1); +} + +void ref_transaction_create(struct ref_transaction *transaction, + const char *refname, + unsigned char *new_sha1, + int flags) +{ + struct ref_update *update = add_update(transaction, refname); + + hashcpy(update->new_sha1, new_sha1); + hashclr(update->old_sha1); + update->flags = flags; + update->have_old = 1; +} + +void ref_transaction_delete(struct ref_transaction *transaction, + const char *refname, + unsigned char *old_sha1, + int flags, int have_old) +{ + struct ref_update *update = add_update(transaction, refname); + + update->flags = flags; + update->have_old = have_old; + if (have_old) + hashcpy(update->old_sha1, old_sha1); +} + int update_ref(const char *action, const char *refname, const unsigned char *sha1, const unsigned char *oldval, int flags, enum action_on_err onerr) @@ -3378,6 +3465,15 @@ cleanup: return ret; } +int ref_transaction_commit(struct ref_transaction *transaction, + const char *msg, enum action_on_err onerr) +{ + int ret = update_refs(msg, transaction->updates, transaction->nr, + onerr); + ref_transaction_free(transaction); + return ret; +} + char *shorten_unambiguous_ref(const char *refname, int strict) { int i; diff --git a/refs.h b/refs.h index 08e60ac..476a923 100644 --- a/refs.h +++ b/refs.h @@ -24,6 +24,8 @@ struct ref_update { int have_old; /* 1 if old_sha1 is valid, 0 otherwise */ }; +struct ref_transaction; + /* * Bit values set in the flags argument passed to each_ref_fn(): */ @@ -220,6 +222,69 @@ enum action_on_err { UPDATE_REFS_QUIET_ON_ERR }; +/* + * Begin a reference transaction. The reference transaction must + * eventually be commited using ref_transaction_commit() or rolled + * back using ref_transaction_rollback(). + */ +struct ref_transaction *ref_transaction_begin(void); + +/* + * Roll back a ref_transaction and free all associated data. + */ +void ref_transaction_rollback(struct ref_transaction *transaction); + + +/* + * The following functions add a reference check or update to a + * ref_transaction. In all of them, refname is the name of the + * reference to be affected. The functions make internal copies of + * refname, so the caller retains ownership of the parameter. flags + * can be REF_NODEREF; it is passed to update_ref_lock(). + */ + + +/* + * Add a reference update to transaction. new_sha1 is the value that + * the reference should have after the update, or zeros if it should + * be deleted. If have_old is true, then old_sha1 holds the value + * that the reference should have had before the update, or zeros if + * it must not have existed beforehand. + */ +void ref_transaction_update(struct ref_transaction *transaction, + const char *refname, + unsigned char *new_sha1, unsigned char *old_sha1, + int flags, int have_old); + +/* + * Add a reference creation to transaction. new_sha1 is the value + * that the reference should have after the update, or zeros if it + * should be deleted. It is verified that the reference does not + * exist already. + */ +void ref_transaction_create(struct ref_transaction *transaction, + const char *refname, + unsigned char *new_sha1, + int flags); + +/* + * Add a reference deletion to transaction. If have_old is true, then + * old_sha1 holds the value that the reference should have had before + * the update. + */ +void ref_transaction_delete(struct ref_transaction *transaction, + const char *refname, + unsigned char *old_sha1, + int flags, int have_old); + +/* + * Commit all of the changes that have been queued in transaction, as + * atomically as possible. Return a nonzero value if there is a + * problem. The ref_transaction is freed by this function. + */ +int ref_transaction_commit(struct ref_transaction *transaction, + const char *msg, enum action_on_err onerr); + /** Lock a ref and then write its file */ int update_ref(const char *action, const char *refname, const unsigned char *sha1, const unsigned char *oldval, -- 1.9.0