From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 10 Apr 2018 14:45:21 +0300 From: Vladimir Davydov Subject: Re: [PATCH 03/12] alter: move dictionary update from ModifySpace::alter_def to alter Message-ID: <20180410114521.hgpz6d3ypxbzq422@esperanza> References: <8f209a2a0dd9b9e6f2e3100a8331906189442f3d.1523105106.git.vdavydov.dev@gmail.com> <20180409203240.GD4527@atlas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180409203240.GD4527@atlas> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: On Mon, Apr 09, 2018 at 11:32:40PM +0300, Konstantin Osipov wrote: > * Vladimir Davydov [18/04/09 10:33]: > > - struct tuple_dictionary *new_dict; > > - /** > > - * Old tuple dictionary stored to rollback in destructor, > > - * if an exception had been raised after alter_def(), but > > - * before alter(). > > - */ > > - struct tuple_dictionary *old_dict; > > + struct tuple_dictionary *dict; > > Please provide a comment. > > > /* > > - * Move new names into an old dictionary, which already is > > - * referenced by existing tuple formats. New dictionary > > - * object is deleted later, in destructor. > > + * Use the old dictionary for the new space, because > > + * it is already referenced by existing tuple formats. > > + * We will update it in place in ModifySpace::alter. > > */ > > I don't understand this comment. Naming the variable "dict" didn't > help. Not having a comment for the variable where it was declared > didn't help :( > > I do understand that your strategy is to swap the new space' dict > with the old space dict and hold the new space dict in a temp > variable until possible rollback. But I don't understand why you > had to change it. The changeset comment says nothing about > changing the way you modify the format, it only mentions changes > in the timing. > > > - new_dict = def->dict; > > - old_dict = alter->old_space->def->dict; > > - tuple_dictionary_swap(new_dict, old_dict); > > - def->dict = old_dict; > > - tuple_dictionary_ref(old_dict); > > + dict = def->dict; > > + def->dict = alter->old_space->def->dict; > > + tuple_dictionary_ref(def->dict); > > > > space_def_delete(alter->space_def); > > alter->space_def = def; Fixed as discussed f2f. Please take a look. Note, the patch hasn't been updated on the branch yet, don't push it. >From 71e9dff0d3666a9ac02739d5754bd8d028134c9f Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Wed, 4 Apr 2018 16:02:07 +0300 Subject: [PATCH] alter: move dictionary update from ModifySpace::alter_def to alter We may yield while rebuilding a vinyl index hence we must not modify the old space before we are done building all indexes, otherwise the user might see an inconsistent state while a space is being altered. Currently, this requirement doesn't hold - we both modify the old space and build the new indexes in AlterSpaceOp::alter. We need to introduce AlterSpaceOp::prepare method that would perform all yielding operations and forbid yielding in AlterSpaceOp::alter. Dictionary update, which is currently done by ModifySpace::alter_def, modifies the old space hence it should live in ModifySpace::alter. Let's move it there. While we are at it, let's also rename ModifySpace::def to new_def, because it denotes the new space definition. diff --git a/src/box/alter.cc b/src/box/alter.cc index 0af4ac09..6e351cf5 100644 --- a/src/box/alter.cc +++ b/src/box/alter.cc @@ -916,24 +916,19 @@ CheckSpaceFormat::alter(struct alter_space *alter) class ModifySpace: public AlterSpaceOp { public: - ModifySpace(struct alter_space *alter, struct space_def *def_arg) - :AlterSpaceOp(alter), def(def_arg) {} + ModifySpace(struct alter_space *alter, struct space_def *def) + :AlterSpaceOp(alter), new_def(def) {} /** * Newely created field dictionary. When new space_def is * created, it allocates new dictionary. Alter moves new * names into an old dictionary and deletes new one. */ struct tuple_dictionary *new_dict; - /** - * Old tuple dictionary stored to rollback in destructor, - * if an exception had been raised after alter_def(), but - * before alter(). - */ - struct tuple_dictionary *old_dict; /* New space definition. */ - struct space_def *def; + struct space_def *new_def; virtual void alter_def(struct alter_space *alter); - virtual void commit(struct alter_space *alter, int64_t signature); + virtual void alter(struct alter_space *alter); + virtual void rollback(struct alter_space *alter); virtual ~ModifySpace(); }; @@ -942,40 +937,43 @@ void ModifySpace::alter_def(struct alter_space *alter) { /* - * Move new names into an old dictionary, which already is - * referenced by existing tuple formats. New dictionary - * object is deleted later, in destructor. + * Use the old dictionary for the new space, because + * it is already referenced by existing tuple formats. + * We will update it in place in ModifySpace::alter. */ - new_dict = def->dict; - old_dict = alter->old_space->def->dict; - tuple_dictionary_swap(new_dict, old_dict); - def->dict = old_dict; - tuple_dictionary_ref(old_dict); + new_dict = new_def->dict; + new_def->dict = alter->old_space->def->dict; + tuple_dictionary_ref(new_def->dict); space_def_delete(alter->space_def); - alter->space_def = def; + alter->space_def = new_def; /* Now alter owns the def. */ - def = NULL; + new_def = NULL; +} + +void +ModifySpace::alter(struct alter_space *alter) +{ + /* + * Move new names into an old dictionary, which already is + * referenced by existing tuple formats. New dictionary + * object is deleted later, in destructor. + */ + tuple_dictionary_swap(alter->new_space->def->dict, new_dict); } void -ModifySpace::commit(struct alter_space *alter, int64_t signature) +ModifySpace::rollback(struct alter_space *alter) { - (void) alter; - (void) signature; - old_dict = NULL; + tuple_dictionary_swap(alter->new_space->def->dict, new_dict); } ModifySpace::~ModifySpace() { - if (new_dict != NULL) { - /* Return old names into the old dict. */ - if (old_dict != NULL) - tuple_dictionary_swap(new_dict, old_dict); + if (new_dict != NULL) tuple_dictionary_unref(new_dict); - } - if (def != NULL) - space_def_delete(def); + if (new_def != NULL) + space_def_delete(new_def); } /** DropIndex - remove an index from space. */ diff --git a/src/box/tuple_format.c b/src/box/tuple_format.c index d3a7702d..11481473 100644 --- a/src/box/tuple_format.c +++ b/src/box/tuple_format.c @@ -262,8 +262,6 @@ tuple_format_new(struct tuple_format_vtab *vtab, struct key_def * const *keys, const struct field_def *space_fields, uint32_t space_field_count, struct tuple_dictionary *dict) { - assert((dict == NULL && space_field_count == 0) || - (dict != NULL && space_field_count == dict->name_count)); struct tuple_format *format = tuple_format_alloc(keys, key_count, space_field_count, dict); if (format == NULL)