From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 10 Apr 2018 10:57:42 +0300 From: Vladimir Davydov Subject: Re: [PATCH 05/12] alter: allocate triggers before the point of no return Message-ID: <20180410075742.gh7wv7beff4h772a@esperanza> References: <55a4b2ee61c194074a98f03c5f42306662a3d9e9.1523105106.git.vdavydov.dev@gmail.com> <20180409203602.GF4527@atlas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180409203602.GF4527@atlas> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: On Mon, Apr 09, 2018 at 11:36:02PM +0300, Konstantin Osipov wrote: > * Vladimir Davydov [18/04/09 10:33]: > > Trigger allocation, as any other memory allocation, is allowed to fail. > > If this happens in alter_space_do, the space will be left in an > > inconsistent state. Let's move trigger allocation to the beginning of > > alter_space_do and add a comment denoting the point of no return. > > Previously we would reference the allocated trigger immediately > in txn_on_commit() /txn_on_rollback(), the changed code leaks > memory in case of any exception between allocation and "point of no > return". > > Please add guards. We don't need guards for the triggers, because they are allocated on region - see txn_alter_trigger_new(). > > > --- > > src/box/alter.cc | 14 ++++++++++---- > > 1 file changed, 10 insertions(+), 4 deletions(-) > > > > diff --git a/src/box/alter.cc b/src/box/alter.cc > > index 36310f1c..9d0c4c23 100644 > > --- a/src/box/alter.cc > > +++ b/src/box/alter.cc > > @@ -803,6 +803,11 @@ alter_space_rollback(struct trigger *trigger, void * /* event */) > > static void > > alter_space_do(struct txn *txn, struct alter_space *alter) > > { > > + /* Prepare triggers while we may fail. */ > > + struct trigger *on_commit, *on_rollback; > > + on_commit = txn_alter_trigger_new(alter_space_commit, alter); > > + on_rollback = txn_alter_trigger_new(alter_space_rollback, alter); > > + > > /* Create a definition of the new space. */ > > space_dump_def(alter->old_space, &alter->key_list); > > class AlterSpaceOp *op; > > @@ -853,6 +858,11 @@ alter_space_do(struct txn *txn, struct alter_space *alter) > > throw; > > } > > > > + /* > > + * This function must not throw exceptions or yield after > > + * this point. > > + */ > > + > > /* Rebuild index maps once for all indexes. */ > > space_fill_index_map(alter->old_space); > > space_fill_index_map(alter->new_space); > > @@ -873,11 +883,7 @@ alter_space_do(struct txn *txn, struct alter_space *alter) > > * finish or rollback the DDL depending on the results of > > * writing to WAL. > > */ > > - struct trigger *on_commit = > > - txn_alter_trigger_new(alter_space_commit, alter); > > txn_on_commit(txn, on_commit); > > - struct trigger *on_rollback = > > - txn_alter_trigger_new(alter_space_rollback, alter); > > txn_on_rollback(txn, on_rollback); > > }