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Bug#45523 "Objects of class base_ilist should not be copyable".
               
Suppress the compiler-generated public copy constructor
and assignment operator of class base_ilist; instead, implement
move_elements_to() function which transfers ownership of elements
from one list to another.
This commit is contained in:
Tor Didriksen 2010-01-12 12:32:55 +01:00
parent 0bce0c9041
commit 6766c0d676
4 changed files with 38 additions and 18 deletions
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7
sql/sp_head.cc
View File

@ -1171,8 +1171,7 @@ sp_head::execute(THD *thd)
We should also save Item tree change list to avoid rollback something
too early in the calling query.
*/
old_change_list= thd->change_list;
thd->change_list.empty();
thd->change_list.move_elements_to(&old_change_list);
/*
Cursors will use thd->packet, so they may corrupt data which was prepared
for sending by upper level. OTOH cursors in the same routine can share this
@ -1318,9 +1317,7 @@ sp_head::execute(THD *thd)
/* Restore all saved */
old_packet.swap(thd->packet);
DBUG_ASSERT(thd->change_list.is_empty());
thd->change_list= old_change_list;
/* To avoid wiping out thd->change_list on old_change_list destruction */
old_change_list.empty();
old_change_list.move_elements_to(&thd->change_list);
thd->lex= old_lex;
thd->query_id= old_query_id;
DBUG_ASSERT(!thd->derived_tables);

9
sql/sql_cursor.cc
View File

@ -321,7 +321,7 @@ Sensitive_cursor::post_open(THD *thd)
lock= thd->lock;
query_id= thd->query_id;
free_list= thd->free_list;
change_list= thd->change_list;
thd->change_list.move_elements_to(&change_list);
reset_thd(thd);
/* Now we have an active cursor and can cause a deadlock */
thd->lock_info.n_cursors++;
@ -437,7 +437,7 @@ Sensitive_cursor::fetch(ulong num_rows)
thd->open_tables= open_tables;
thd->lock= lock;
thd->query_id= query_id;
thd->change_list= change_list;
change_list.move_elements_to(&thd->change_list);
/* save references to memory allocated during fetch */
thd->set_n_backup_active_arena(this, &backup_arena);
@ -459,7 +459,7 @@ Sensitive_cursor::fetch(ulong num_rows)
/* Grab free_list here to correctly free it in close */
thd->restore_active_arena(this, &backup_arena);
change_list= thd->change_list;
thd->change_list.move_elements_to(&change_list);
reset_thd(thd);
for (info= ht_info; info->read_view; info++)
@ -506,7 +506,7 @@ Sensitive_cursor::close()
info->ht= 0;
}
thd->change_list= change_list;
change_list.move_elements_to(&thd->change_list);
{
/*
XXX: Another hack: we need to set THD state as if in a fetch to be
@ -532,7 +532,6 @@ Sensitive_cursor::close()
join= 0;
stmt_arena= 0;
free_items();
change_list.empty();
DBUG_VOID_RETURN;
}

36
sql/sql_list.h
View File

@ -504,15 +504,12 @@ public:
template <class T> class I_List_iterator;
/*
WARNING: copy constructor of this class does not create a usable
copy, as its members may point at each other.
*/
class base_ilist
{
struct ilink *first;
struct ilink last;
public:
struct ilink *first,last;
inline void empty() { first= &last; last.prev= &first; }
base_ilist() { empty(); }
inline bool is_empty() { return first == &last; }
@ -540,7 +537,31 @@ public:
{
return (first != &last) ? first : 0;
}
friend class base_list_iterator;
/**
Moves list elements to new owner, and empties current owner (i.e. this).
@param[in,out] new_owner The new owner of the list elements.
Should be empty in input.
*/
void move_elements_to(base_ilist *new_owner)
{
DBUG_ASSERT(new_owner->is_empty());
new_owner->first= first;
new_owner->last= last;
empty();
}
friend class base_ilist_iterator;
private:
/*
We don't want to allow copying of this class, as that would give us
two list heads containing the same elements.
So we declare, but don't define copy CTOR and assignment operator.
*/
base_ilist(const base_ilist&);
void operator=(const base_ilist&);
};
@ -573,6 +594,9 @@ public:
inline void push_back(T* a) { base_ilist::push_back(a); }
inline T* get() { return (T*) base_ilist::get(); }
inline T* head() { return (T*) base_ilist::head(); }
inline void move_elements_to(I_List<T>* new_owner) {
base_ilist::move_elements_to(new_owner);
}
#ifndef _lint
friend class I_List_iterator<T>;
#endif

4
sql/sql_prepare.cc
View File

@ -3407,7 +3407,7 @@ Prepared_statement::execute_server_runnable(Server_runnable *server_runnable)
bool error;
Query_arena *save_stmt_arena= thd->stmt_arena;
Item_change_list save_change_list;
thd->change_list= save_change_list;
thd->change_list.move_elements_to(&save_change_list);
state= CONVENTIONAL_EXECUTION;
@ -3431,7 +3431,7 @@ Prepared_statement::execute_server_runnable(Server_runnable *server_runnable)
thd->restore_backup_statement(this, &stmt_backup);
thd->stmt_arena= save_stmt_arena;
save_change_list= thd->change_list;
save_change_list.move_elements_to(&thd->change_list);
/* Items and memory will freed in destructor */