From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Haggerty Subject: [PATCH v3 19/27] refs: add a concept of a reference transaction Date: Mon, 7 Apr 2014 15:48:10 +0200 Message-ID: <1396878498-19887-20-git-send-email-mhagger@alum.mit.edu> References: <1396878498-19887-1-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 Apr 07 15:49:32 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 1WX9vV-00034G-BW for gcvg-git-2@plane.gmane.org; Mon, 07 Apr 2014 15:49:29 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755400AbaDGNtZ (ORCPT ); Mon, 7 Apr 2014 09:49:25 -0400 Received: from alum-mailsec-scanner-6.mit.edu ([18.7.68.18]:65450 "EHLO alum-mailsec-scanner-6.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755381AbaDGNtC (ORCPT ); Mon, 7 Apr 2014 09:49:02 -0400 X-AuditID: 12074412-f79d46d000002e58-84-5342accd6bc8 Received: from outgoing-alum.mit.edu (OUTGOING-ALUM.MIT.EDU [18.7.68.33]) by alum-mailsec-scanner-6.mit.edu (Symantec Messaging Gateway) with SMTP id A0.ED.11864.DCCA2435; Mon, 7 Apr 2014 09:49:01 -0400 (EDT) Received: from michael.fritz.box (p5B156B1D.dip0.t-ipconnect.de [91.21.107.29]) (authenticated bits=0) (User authenticated as mhagger@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.13.8/8.12.4) with ESMTP id s37DmJaQ026029 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 7 Apr 2014 09:48:59 -0400 X-Mailer: git-send-email 1.9.1 In-Reply-To: <1396878498-19887-1-git-send-email-mhagger@alum.mit.edu> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrAIsWRmVeSWpSXmKPExsUixO6iqHt2jVOwwcIHPBY710lYdF3pZrJo 6L3CbDHv7i4mi9sr5jNb/GjpYbb42LmA2YHd4+/7D0weO2fdZfe49PI7m8fHZ8vZPZ717mH0 uHhJ2ePzJrkA9ihum6TEkrLgzPQ8fbsE7owDNy4xF7wwqTh2dCJrA+NGrS5GTg4JAROJBQtm s0LYYhIX7q1n62Lk4hASuMwo0bVzFjNIQkjgGJPEh9tmIDabgK7Eop5mJhBbREBNYmLbIRaQ BmaBK4wSVz5uZwFJCAt4SLxqmMEOYrMIqEo8+HeJDcTmFXCVWPlqEgvENjmJk8cmg23mBIrP OHSLEWKZi8T9NcdYJjDyLmBkWMUol5hTmqubm5iZU5yarFucnJiXl1qka6aXm1mil5pSuokR EnpCOxjXn5Q7xCjAwajEw7vikGOwEGtiWXFl7iFGSQ4mJVHe58ucgoX4kvJTKjMSizPii0pz UosPMUpwMCuJ8HKtBsrxpiRWVqUW5cOkpDlYlMR5fy5W9xMSSE8sSc1OTS1ILYLJynBwKEnw NoI0ChalpqdWpGXmlCCkmTg4QYZzSYkUp+alpBYllpZkxINiI74YGB0gKR6gvXPB9hYXJOYC RSFaTzEqSonzloAkBEASGaV5cGNhCeUVozjQl8K8BSBVPMBkBNf9CmgwE9BgQ1ewwSWJCCmp Bkb2czfXbTwQsaRMvIbbmvFg0OUlIi8uLD65c8n6tW+na3hd3O7DYGteuais/JPkdPOsfA/t awwHtkX9tX10PPKnhMDHy4uYbsyROlGYoMWZdnRj1bGieO97n/bfNzu/z+jAaQft 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 | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ refs.h | 65 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 164 insertions(+) diff --git a/refs.c b/refs.c index 1305eb1..f0b5764 100644 --- a/refs.c +++ b/refs.c @@ -3267,6 +3267,96 @@ 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); + + assert(!is_null_sha1(new_sha1)); + 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) { + assert(!is_null_sha1(old_sha1)); + 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 +3468,15 @@ 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..0518dd5 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; it must not be the + * null SHA-1. 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 (which must not be the null SHA-1). + */ +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, -- 1.9.1