changes based on partial revie of task 577 (SCRUM)

sql/item.cc:
  Fixed Item usual constructor to call current_thd only once.
  Fixed copy constructor to receive THD pointer via arguments.
  added comments
  removed counter-1 and unnessesary initializaton of counter
sql/item.h:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_cmpfunc.cc:
  fixed layout
  fixed direct call of destructor
sql/item_func.cc:
  fiex layout
  THD pointetr added to get_tmp_table_item.
sql/item_func.h:
  THD pointetr added to get_tmp_table_item.
sql/item_sum.cc:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_sum.h:
  fixed layout
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_uniq.h:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/sql_base.cc:
  count from 0
sql/sql_select.cc:
  removed counter-1 and unnessesary initializaton of counter
  THD pointetr added to get_tmp_table_item and change_to_use_tmp_fields.

sql/item.cc

@@ -37,16 +37,22 @@ void item_init(void)
 Item::Item():
   fixed(0)
 {
-  marker=0;
+  marker= 0;
   maybe_null=null_value=with_sum_func=unsigned_flag=0;
-  name=0;
-  decimals=0; max_length=0;
-  next=current_thd->free_list;			// Put in free list
-  current_thd->free_list=this;
+  name= 0;
+  decimals= 0; max_length= 0;
+  THD *thd= current_thd;
+  next= thd->free_list;			// Put in free list
+  thd->free_list= this;
   loop_id= 0;
 }
 
-Item::Item(Item &item):
+/*
+  Constructor used by Item_field, Item_ref & agregate (sum) functions.
+  Used for duplicating lists in processing queries with temporary
+  tables
+*/
+Item::Item(THD *thd, Item &item):
   loop_id(0),
   str_value(item.str_value),
   name(item.name),
@@ -59,12 +65,13 @@ Item::Item(Item &item):
   with_sum_func(item.with_sum_func),
   fixed(item.fixed)
 {
-  next=current_thd->free_list;			// Put in free list
-  current_thd->free_list= this;
+  next=thd->free_list;			// Put in free list
+  thd->free_list= this;
 }
 
-Item_ident::Item_ident(Item_ident &item):
-  Item(item),
+// Constructor used by Item_field & Item_ref (see Item comment)
+Item_ident::Item_ident(THD *thd, Item_ident &item):
+  Item(thd, item),
   db_name(item.db_name),
   table_name(item.table_name),
   field_name(item.field_name),
@@ -165,8 +172,9 @@ Item_field::Item_field(Field *f) :Item_ident(NullS,f->table_name,f->field_name)
   fixed= 1; // This item is not needed in fix_fields
 }
 
-Item_field::Item_field(Item_field &item):
-  Item_ident(item),
+// Constructor need to process subselect with temporary tables (see Item)
+Item_field::Item_field(THD *thd, Item_field &item):
+  Item_ident(thd, item),
   field(item.field),
   result_field(item.result_field)
 {}
@@ -281,9 +289,9 @@ table_map Item_field::used_tables() const
   return (depended_from? RAND_TABLE_BIT : field->table->map);
 }
 
-Item * Item_field::get_tmp_table_item()
+Item *Item_field::get_tmp_table_item(THD *thd)
 {
-  Item_field *new_item= new Item_field(*this);
+  Item_field *new_item= new Item_field(thd, *this);
   if (new_item)
     new_item->field= new_item->result_field;
   return new_item;
@@ -617,7 +625,7 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       thd->net.last_errno= 0;
 #endif
       Item **refer= (Item **)not_found_item;
-      uint counter= 0;
+      uint counter;
       // Prevent using outer fields in subselects, that is not supported now
       SELECT_LEX *cursel=(SELECT_LEX *) thd->lex.current_select;
       if (outer_resolving ||
@@ -658,19 +666,21 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 	}
 
 	Item_ref *r;
-	*ref= r= new Item_ref(last->ref_pointer_array + counter-1
+	*ref= r= new Item_ref(last->ref_pointer_array + counter
 			      , (char *)table_name,
 			   (char *)field_name);
 	if (!r)
 	  return 1;
 	if (r->fix_fields(thd, tables, ref) || r->check_cols(1))
 	  return 1;
+	// store pointer on SELECT_LEX from wich item is dependent
 	r->depended_from= last;
 	cursel->mark_as_dependent(last);
 	return 0;
       }
       else
       {
+	// store pointer on SELECT_LEX from wich item is dependent
 	depended_from= last;
 	/*
 	  Mark all selects from resolved to 1 before select where was 
@@ -1071,7 +1081,7 @@ bool Item_field::send(Protocol *protocol, String *buffer)
 
 bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 {
-  uint counter= 0;
+  uint counter;
   if (!ref)
   {
     TABLE_LIST *where= 0;
@@ -1142,6 +1152,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	Item_field* f;
 	if (!((*reference)= f= new Item_field(tmp)))
 	  return 1;
+	// store pointer on SELECT_LEX from wich item is dependent
 	f->depended_from= last;
 	thd->lex.current_select->mark_as_dependent(last);
 	return 0;
@@ -1154,7 +1165,10 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 		   "forward reference in item list");
 	  return -1;
 	}
-	ref= (depended_from= last)->ref_pointer_array + counter-1;
+        /*
+	  depended_from: pointer on SELECT_LEX from wich item is dependent
+	*/
+	ref= (depended_from= last)->ref_pointer_array + counter;
 	thd->lex.current_select->mark_as_dependent(last);
       }
     }
@@ -1168,7 +1182,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 		 "forward reference in item list");
 	return -1;
       }
-      ref= thd->lex.current_select->ref_pointer_array + counter-1;
+      ref= thd->lex.current_select->ref_pointer_array + counter;
     }
   }
 

sql/item.h

@@ -53,8 +53,12 @@ public:
 
   // alloc & destruct is done as start of select using sql_alloc
   Item();
-  // copy constructor used by Item_field, Item_ref & agregate (sum) functions
-  Item(Item &item);
+  /*
+     Constructor used by Item_field, Item_ref & agregate (sum) functions.
+     Used for duplicating lists in processing queries with temporary
+     tables
+  */
+  Item(THD *thd, Item &item);
   virtual ~Item() { name=0; }		/*lint -e1509 */
   void set_name(const char *str,uint length=0);
   void init_make_field(Send_field *tmp_field,enum enum_field_types type);
@@ -93,8 +97,8 @@ public:
   virtual bool get_time(TIME *ltime);
   virtual bool is_null() { return 0; };
   virtual void top_level_item() {}
-  virtual Item * get_same() { return this; }
-  virtual Item * get_tmp_table_item() { return get_same(); }
+  virtual Item *copy_or_same(THD *thd) { return this; }
+  virtual Item *get_tmp_table_item(THD *thd) { return copy_or_same(thd); }
 
   virtual bool binary() const
   { return str_value.charset()->state & MY_CS_BINSORT ? 1 : 0 ; }
@@ -129,8 +133,8 @@ public:
     :db_name(db_name_par), table_name(table_name_par),
      field_name(field_name_par), depended_from(0), outer_resolving(0)
     { name = (char*) field_name_par; }
-  // copy constructor used by Item_field & Item_ref
-  Item_ident(Item_ident &item);
+  // Constructor used by Item_field & Item_ref (see Item comment)
+  Item_ident(THD *thd, Item_ident &item);
   const char *full_name() const;
   void set_outer_resolving() { outer_resolving= 1; }
 };
@@ -147,8 +151,8 @@ public:
 	     const char *field_name_par)
     :Item_ident(db_par,table_name_par,field_name_par),field(0),result_field(0)
   {}
-  // copy constructor need to process subselect with temporary tables
-  Item_field(Item_field &item);
+  // Constructor need to process subselect with temporary tables (see Item)
+  Item_field(THD *thd, Item_field &item);
   Item_field(Field *field);
   enum Type type() const { return FIELD_ITEM; }
   bool eq(const Item *item, bool binary_cmp) const;
@@ -177,7 +181,7 @@ public:
   bool get_date(TIME *ltime,bool fuzzydate);  
   bool get_time(TIME *ltime);  
   bool is_null() { return field->is_null(); }
-  Item * get_tmp_table_item();
+  Item *get_tmp_table_item(THD *thd);
   friend class Item_default_value;
 };
 
@@ -437,10 +441,10 @@ class Item_result_field :public Item	/* Item with result field */
 public:
   Field *result_field;				/* Save result here */
   Item_result_field() :result_field(0) {}
-  Item_result_field(Item_result_field &item): Item(item)
-  {
-    result_field= item.result_field;
-  }
+  // Constructor used for Item_sum (see Item comment)
+  Item_result_field(THD *thd, Item_result_field &item):
+    Item(thd, item), result_field(item.result_field)
+  {}
   ~Item_result_field() {}			/* Required with gcc 2.95 */
   Field *tmp_table_field() { return result_field; }
   Field *tmp_table_field(TABLE *t_arg) { return result_field; }
@@ -457,8 +461,9 @@ public:
     :Item_ident(db_par,table_name_par,field_name_par),ref(0) {}
   Item_ref(Item **item, char *table_name_par,char *field_name_par)
     :Item_ident(NullS,table_name_par,field_name_par),ref(item) {}
-  // copy constructor need to process subselect with temporary tables
-  Item_ref(Item_ref &item): Item_ident(item), ref(item.ref) {}
+  // Constructor need to process subselect with temporary tables (see Item)
+  Item_ref(THD *thd, Item_ref &item)
+    :Item_ident(thd, item), ref(item.ref) {}
   enum Type type() const		{ return REF_ITEM; }
   bool eq(const Item *item, bool binary_cmp) const
   { return ref && (*ref)->eq(item, binary_cmp); }
@@ -527,6 +532,12 @@ public:
 class Item_ref_on_list_position: public Item_ref_null_helper
 {
 protected:
+  /* 
+     select_lex used for:
+     1) receiving expanded variant of item list (to check max possible 
+        nunber of elements);
+     2) to have access to  ref_pointer_array, via wich item will refered.
+  */
   st_select_lex *select_lex;
   uint pos;
 public:

sql/item_cmpfunc.cc

@@ -1063,7 +1063,8 @@ int in_vector::find(Item *item)
 }
 
 in_string::in_string(uint elements,qsort_cmp cmp_func)
-  :in_vector(elements,sizeof(String),cmp_func),tmp(buff,sizeof(buff),default_charset_info)
+  :in_vector(elements, sizeof(String), cmp_func),
+   tmp(buff, sizeof(buff), default_charset_info)
 {}
 
 in_string::~in_string()
@@ -1102,11 +1103,7 @@ in_row::in_row(uint elements, Item * item)
 in_row::~in_row()
 {
   if (base)
-  {
-    cmp_item_row *arr= (cmp_item_row *) base;
-    for (uint i=0 ; i < count ; i++)
-      arr[i].~cmp_item_row();
-  }
+    delete [] (cmp_item_row*) base;
 }
 
 byte *in_row::get_value(Item *item)

sql/item_func.cc

@@ -294,14 +294,11 @@ void Item_func::fix_num_length_and_dec()
   max_length=float_length(decimals);
 }
 
-Item * Item_func::get_tmp_table_item()
+Item *Item_func::get_tmp_table_item(THD *thd)
 {
   if (!with_sum_func && !const_item())
-  {
     return new Item_field(result_field);
-  }
-  else
-    return get_same();
+  return copy_or_same(thd);
 }
 
 String *Item_int_func::val_str(String *str)

sql/item_func.h

@@ -134,7 +134,7 @@ public:
   Field *tmp_table_field() { return result_field; }
   Field *tmp_table_field(TABLE *t_arg);
   void set_outer_resolving();
-  Item * get_tmp_table_item();
+  Item *get_tmp_table_item(THD *thd);
 };
 
 

sql/item_sum.cc

@@ -41,8 +41,9 @@ Item_sum::Item_sum(List<Item> &list)
   list.empty();					// Fields are used
 }
 
-Item_sum::Item_sum(Item_sum &item):
-  Item_result_field(item), quick_group(item.quick_group)
+// Constructor used in processing select with temporary tebles
+Item_sum::Item_sum(THD *thd, Item_sum &item):
+  Item_result_field(thd, item), quick_group(item.quick_group)
 {
   arg_count= item.arg_count;
   if (arg_count <= 2)
@@ -96,9 +97,9 @@ void Item_sum::fix_num_length_and_dec()
   max_length=float_length(decimals);
 }
 
-Item * Item_sum::get_tmp_table_item()
+Item *Item_sum::get_tmp_table_item(THD *thd)
 {
-  Item_sum* sum_item= (Item_sum *) get_same();
+  Item_sum* sum_item= (Item_sum *) copy_or_same(thd);
   if (sum_item && sum_item->result_field)	   // If not a const sum func
   {
     Field *result_field= sum_item->result_field;

sql/item_uniq.h

@@ -37,7 +37,8 @@ class Item_sum_unique_users :public Item_sum_num
 public:
   Item_sum_unique_users(Item *name_arg,int start,int end,Item *item_arg)
     :Item_sum_num(item_arg) {}
-  Item_sum_unique_users(Item_sum_unique_users &item): Item_sum_num(item) {}
+  Item_sum_unique_users(THD *thd, Item_sum_unique_users &item)
+    :Item_sum_num(thd, item) {}
   double val() { return 0.0; }  
   enum Sumfunctype sum_func () const {return UNIQUE_USERS_FUNC;}
   void reset() {}
@@ -49,5 +50,8 @@ public:
     fixed= 1;
     return 0;
   }
-  Item_sum * get_same() { return new Item_sum_unique_users(*this); }
+  Item_sum *copy_or_same(THD* thd)
+  {
+    return new Item_sum_unique_users(thd, *this);
+  }
 };

sql/sql_base.cc

@@ -1845,10 +1845,8 @@ find_item_in_list(Item *find, List<Item> &items, uint *counter,
     table_name= ((Item_ident*) find)->table_name;
   }
 
-  uint i= 0;
-  while ((item=li++))
+  for (uint i= 0; (item=li++); i++)
   {
-    i++;
     if (field_name && item->type() == Item::FIELD_ITEM)
     {
       if (!my_strcasecmp(system_charset_info,

sql/sql_select.cc

@@ -140,7 +140,7 @@ static void calc_group_buffer(JOIN *join,ORDER *group);
 static bool alloc_group_fields(JOIN *join,ORDER *group);
 static bool make_sum_func_list(JOIN *join,List<Item> &fields);
 // Create list for using with tempory table
-static bool change_to_use_tmp_fields(Item **ref_pointer_array,
+static bool change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
 				     List<Item> &new_list1,
 				     List<Item> &new_list2,
 				     uint elements, List<Item> &items);
@@ -968,7 +968,7 @@ JOIN::exec()
       items1= items0 + all_fields.elements;
       if (sort_and_group || curr_tmp_table->group)
       {
-	if (change_to_use_tmp_fields(items1,
+	if (change_to_use_tmp_fields(thd, items1,
 				     tmp_fields_list1, tmp_all_fields1,
 				     fields_list.elements, all_fields))
 	  DBUG_VOID_RETURN;
@@ -1088,7 +1088,7 @@ JOIN::exec()
       if (!items2)
       {
 	items2= items1 + all_fields.elements;
-	if (change_to_use_tmp_fields(items2,
+	if (change_to_use_tmp_fields(thd, items2,
 				     tmp_fields_list2, tmp_all_fields2, 
 				     fields_list.elements, tmp_all_fields1))
 	  DBUG_VOID_RETURN;
@@ -7069,12 +7069,12 @@ find_order_in_list(THD *thd, Item **ref_pointer_array,
     order->in_field_list= 1;
     return 0;
   }
-  uint counter= 0;
+  uint counter;
   Item **item= find_item_in_list(*order->item, fields, &counter,
 				 IGNORE_ERRORS);
   if (item)
   {
-    order->item= ref_pointer_array + counter-1;
+    order->item= ref_pointer_array + counter;
     order->in_field_list=1;
     return 0;
   }
@@ -7192,7 +7192,7 @@ setup_new_fields(THD *thd,TABLE_LIST *tables,List<Item> &fields,
   DBUG_ENTER("setup_new_fields");
 
   thd->set_query_id=1;				// Not really needed, but...
-  uint counter= 0;
+  uint counter;
   for (; new_field ; new_field= new_field->next)
   {
     if ((item= find_item_in_list(*new_field->item, fields, &counter,
@@ -7471,7 +7471,7 @@ setup_copy_fields(THD *thd, TMP_TABLE_PARAM *param,
     if (pos->type() == Item::FIELD_ITEM)
     {
       Item_field *item;
-      if (!(item= new Item_field(*((Item_field*) pos))))
+      if (!(item= new Item_field(thd, *((Item_field*) pos))))
 	goto err;
       pos= item;
       if (item->field->flags & BLOB_FLAG)
@@ -7590,7 +7590,7 @@ make_sum_func_list(JOIN *join,List<Item> &fields)
 */
 
 static bool
-change_to_use_tmp_fields(Item **ref_pointer_array,
+change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
 			 List<Item> &new_list1, List<Item> &new_list2,
 			 uint elements, List<Item> &items)
 {
@@ -7609,7 +7609,7 @@ change_to_use_tmp_fields(Item **ref_pointer_array,
     else
       if (item->type() == Item::FIELD_ITEM)
       {
-	item_field= item->get_tmp_table_item();
+	item_field= item->get_tmp_table_item(thd);
       }
       else if ((field= item->tmp_table_field()))
       {
@@ -7665,7 +7665,7 @@ change_refs_to_tmp_fields(THD *thd, Item **ref_pointer_array,
   uint i, border= items.elements - elements;
   for (i= 0; (item= it++); i++)
   {
-    new_list2.push_back(new_item= item->get_tmp_table_item());
+    new_list2.push_back(new_item= item->get_tmp_table_item(thd));
     ref_pointer_array[((i < border)? items.elements-i-1 : i-border)]=
       new_item;
   }