[PATCH 03/12] alter: move dictionary update from ModifySpace::alter_def to alter
Vladimir Davydov
vdavydov.dev at gmail.com
Tue Apr 10 14:45:21 MSK 2018
On Mon, Apr 09, 2018 at 11:32:40PM +0300, Konstantin Osipov wrote:
> * 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;
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 <vdavydov.dev at gmail.com>
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)
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