[PATCH 03/12] alter: move dictionary update from ModifySpace::alter_def to alter
Konstantin Osipov
kostja at tarantool.org
Mon Apr 9 23:32:40 MSK 2018
* Vladimir Davydov <vdavydov.dev at gmail.com> [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;
> @@ -959,21 +952,21 @@ ModifySpace::alter_def(struct alter_space *alter)
> }
>
> void
> -ModifySpace::commit(struct alter_space *alter, int64_t signature)
> +ModifySpace::alter(struct alter_space *alter)
> {
> - (void) alter;
> - (void) signature;
> - old_dict = NULL;
> + tuple_dictionary_swap(alter->new_space->def->dict, dict);
> +}
> +
> +void
> +ModifySpace::rollback(struct alter_space *alter)
> +{
> + tuple_dictionary_swap(alter->new_space->def->dict, 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);
> - tuple_dictionary_unref(new_dict);
> - }
> + if (dict != NULL)
> + tuple_dictionary_unref(dict);
> if (def != NULL)
> space_def_delete(def);
> }
> 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)
> --
> 2.11.0
>
--
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov
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