From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 10 Apr 2018 14:54:35 +0300 From: Vladimir Davydov Subject: Re: [PATCH 05/12] alter: allocate triggers before the point of no return Message-ID: <20180410115435.cogcxwgw6jxi7y2y@esperanza> References: <55a4b2ee61c194074a98f03c5f42306662a3d9e9.1523105106.git.vdavydov.dev@gmail.com> <20180409203602.GF4527@atlas> <20180410075742.gh7wv7beff4h772a@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180410075742.gh7wv7beff4h772a@esperanza> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: On Tue, Apr 10, 2018 at 10:57:42AM +0300, Vladimir Davydov wrote: > 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(). Added a comment, as discussed: (not on the branch, don't push) >From d0467518750a6d7aaaf0eb80842ecd6ccc6b2219 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Wed, 4 Apr 2018 18:48:13 +0300 Subject: [PATCH] alter: allocate triggers before the point of no return 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. diff --git a/src/box/alter.cc b/src/box/alter.cc index 96143b95..c4141145 100644 --- a/src/box/alter.cc +++ b/src/box/alter.cc @@ -803,6 +803,15 @@ 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. Note, we don't have to + * free them in case of failure, because they are allocated on + * the region. + */ + 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 +862,11 @@ 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 +887,7 @@ 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); }