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- implement inheritance of sp_instr: public Query_arena.

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We need every instruction to have its own arena, because we want to
  track instruction's state (INITIALIZED_FOR_SP -> EXECUTED). Because of 
  `if' statements and other conditional instructions used in stored 
  procedures, not every instruction of a stored procedure gets executed 
  during the first (or even subsequent) execution of the procedure. 
  So it's better if we track the execution state of every instruction 
  independently.
  All instructions of a given procedure now also share sp_head's 
  mem_root, but keep their own free_list.
  This simplifies juggling with free Item lists in sp_head::execute.
- free_items() moved to be a member of Query_arena. 
- logic of 'backup_arena' debug member of Query_arena has been
  changed to support
  multi-backups. Until now, TRUE 'backup_arena' meant that there is
  exactly one active backup of the THD arena. Now it means simply that
  the arena is used for backup, so that we can't accidentally overwrite an 
  existing backup. This allows doing multiple backups, e.g. in
  sp_head::execute and Cursor::fetch, when THD arena is already backed up
  but we want to set yet another arena (usually the 'permanent' arena,
  to save permanent transformations/optimizations of a parsed tree).
This commit is contained in:
konstantin@mysql.com
2005-06-23 20:22:08 +04:00
parent 23a2643cb6
commit 4c4079430d
6 changed files with 65 additions and 58 deletions
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27
sql/sql_class.cc
View File

@ -171,9 +171,6 @@ THD::THD()
spcont(NULL)
{
current_arena= this;
#ifndef DBUG_OFF
backup_arena= 0;
#endif
host= user= priv_user= db= ip= 0;
catalog= (char*)"std"; // the only catalog we have for now
host_or_ip= "connecting host";
@ -528,7 +525,7 @@ void THD::cleanup_after_query()
next_insert_id= 0;
}
/* Free Items that were created during this execution */
free_items(free_list);
free_items();
/*
In the rest of code we assume that free_list never points to garbage:
Keep this predicate true.
@ -1485,6 +1482,21 @@ Query_arena::Type Query_arena::type() const
}
void Query_arena::free_items()
{
Item *next;
DBUG_ENTER("Query_arena::free_items");
/* This works because items are allocated with sql_alloc() */
for (; free_list; free_list= next)
{
next= free_list->next;
free_list->delete_self();
}
/* Postcondition: free_list is 0 */
DBUG_VOID_RETURN;
}
/*
Statement functions
*/
@ -1556,11 +1568,11 @@ void THD::end_statement()
void Query_arena::set_n_backup_item_arena(Query_arena *set, Query_arena *backup)
{
DBUG_ENTER("Query_arena::set_n_backup_item_arena");
DBUG_ASSERT(backup_arena == 0);
DBUG_ASSERT(backup->is_backup_arena == FALSE);
backup->set_item_arena(this);
set_item_arena(set);
#ifndef DBUG_OFF
backup_arena= 1;
backup->is_backup_arena= TRUE;
#endif
DBUG_VOID_RETURN;
}
@ -1569,10 +1581,11 @@ void Query_arena::set_n_backup_item_arena(Query_arena *set, Query_arena *backup)
void Query_arena::restore_backup_item_arena(Query_arena *set, Query_arena *backup)
{
DBUG_ENTER("Query_arena::restore_backup_item_arena");
DBUG_ASSERT(backup->is_backup_arena);
set->set_item_arena(this);
set_item_arena(backup);
#ifndef DBUG_OFF
backup_arena= 0;
backup->is_backup_arena= FALSE;
#endif
DBUG_VOID_RETURN;
}