thd pointer storing moved to fix_fields() (WL#1254) (SCRUM)

sql/item_subselect.cc:
  thd pointer storing moved to fix_fields()
sql/item_subselect.h:
  thd pointer storing moved to fix_fields()
sql/sql_yacc.yy:
  thd pointer storing moved to fix_fields()

sql/item_subselect.cc

@@ -46,7 +46,7 @@ Item_subselect::Item_subselect():
   null_value= 1;
 }
 
-void Item_subselect::init(THD *thd, st_select_lex *select_lex,
+void Item_subselect::init(st_select_lex *select_lex,
 			  select_subselect *result)
 {
 
@@ -54,11 +54,10 @@ void Item_subselect::init(THD *thd, st_select_lex *select_lex,
   DBUG_PRINT("subs", ("select_lex 0x%xl", (ulong) select_lex));
 
   if (select_lex->next_select())
-    engine= new subselect_union_engine(thd, select_lex->master_unit(), result,
+    engine= new subselect_union_engine(select_lex->master_unit(), result,
 				       this);
   else
-    engine= new subselect_single_select_engine(thd, select_lex, result,
-					       this);
+    engine= new subselect_single_select_engine(select_lex, result, this);
   DBUG_VOID_RETURN;
 }
 
@@ -78,7 +77,7 @@ Item_subselect::select_transformer(JOIN *join)
 
 bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
 {
-  thd= thd_param;
+  engine->set_thd((thd= thd_param));
 
   char const *save_where= thd->where;
   int res= engine->prepare();
@@ -151,12 +150,11 @@ inline table_map Item_subselect::used_tables() const
 		      (engine->uncacheable() ? RAND_TABLE_BIT : 0L));
 }
 
-Item_singlerow_subselect::Item_singlerow_subselect(THD *thd,
-						   st_select_lex *select_lex):
+Item_singlerow_subselect::Item_singlerow_subselect(st_select_lex *select_lex):
   Item_subselect(), value(0)
 {
   DBUG_ENTER("Item_singlerow_subselect::Item_singlerow_subselect");
-  init(thd, select_lex, new select_singlerow_subselect(this));
+  init(select_lex, new select_singlerow_subselect(this));
   max_columns= 1;
   maybe_null= 1;
   max_columns= UINT_MAX;
@@ -325,12 +323,11 @@ String *Item_singlerow_subselect::val_str (String *str)
   }
 }
 
-Item_exists_subselect::Item_exists_subselect(THD *thd,
-					     st_select_lex *select_lex):
+Item_exists_subselect::Item_exists_subselect(st_select_lex *select_lex):
   Item_subselect()
 {
   DBUG_ENTER("Item_exists_subselect::Item_exists_subselect");
-  init(thd, select_lex, new select_exists_subselect(this));
+  init(select_lex, new select_exists_subselect(this));
   max_columns= UINT_MAX;
   null_value= 0; //can't be NULL
   maybe_null= 0; //can't be NULL
@@ -355,13 +352,13 @@ bool Item_in_subselect::test_limit(SELECT_LEX_UNIT *unit)
   return(0);
 }
 
-Item_in_subselect::Item_in_subselect(THD *thd, Item * left_exp,
+Item_in_subselect::Item_in_subselect(Item * left_exp,
 				     st_select_lex *select_lex):
   Item_exists_subselect()
 {
   DBUG_ENTER("Item_in_subselect::Item_in_subselect");
   left_expr= left_exp;
-  init(thd, select_lex, new select_exists_subselect(this));
+  init(select_lex, new select_exists_subselect(this));
   max_columns= UINT_MAX;
   maybe_null= 1;
   abort_on_null= 0;
@@ -371,7 +368,7 @@ Item_in_subselect::Item_in_subselect(THD *thd, Item * left_exp,
   DBUG_VOID_RETURN;
 }
 
-Item_allany_subselect::Item_allany_subselect(THD *thd, Item * left_exp,
+Item_allany_subselect::Item_allany_subselect(Item * left_exp,
 					     compare_func_creator fn,
 					     st_select_lex *select_lex):
   Item_in_subselect()
@@ -379,7 +376,7 @@ Item_allany_subselect::Item_allany_subselect(THD *thd, Item * left_exp,
   DBUG_ENTER("Item_in_subselect::Item_in_subselect");
   left_expr= left_exp;
   func= fn;
-  init(thd, select_lex, new select_exists_subselect(this));
+  init(select_lex, new select_exists_subselect(this));
   max_columns= 1;
   abort_on_null= 0;
   reset();
@@ -708,12 +705,12 @@ Item_allany_subselect::select_transformer(JOIN *join)
   return single_value_transformer(join, left_expr, func);
 }
 
-subselect_single_select_engine::subselect_single_select_engine(THD *thd, 
-							       st_select_lex *select,
-							       select_subselect *result,
-							       Item_subselect *item):
-  subselect_engine(thd, item, result),
-    prepared(0), optimized(0), executed(0)
+subselect_single_select_engine::
+subselect_single_select_engine(st_select_lex *select,
+			       select_subselect *result,
+			       Item_subselect *item)
+  :subselect_engine(item, result),
+   prepared(0), optimized(0), executed(0), join(0)
 {
   select_lex= select;
   SELECT_LEX_UNIT *unit= select_lex->master_unit();
@@ -724,24 +721,19 @@ subselect_single_select_engine::subselect_single_select_engine(THD *thd,
     unit->select_limit_cnt= HA_POS_ERROR;		// no limit
   if (unit->select_limit_cnt == HA_POS_ERROR)
     select_lex->options&= ~OPTION_FOUND_ROWS;
-  join= new JOIN(thd, select_lex->item_list, select_lex->options, result);
-  if (!join || !result)
-    //out of memory
-    thd->fatal_error();
   unit->item= item;
   this->select_lex= select_lex;
 }
 
-subselect_union_engine::subselect_union_engine(THD *thd,
-					       st_select_lex_unit *u,
+subselect_union_engine::subselect_union_engine(st_select_lex_unit *u,
 					       select_subselect *result,
-					       Item_subselect *item):
-  subselect_engine(thd, item, result)
+					       Item_subselect *item)
+  :subselect_engine(item, result)
 {
   unit= u;
   if (!result)
     //out of memory
-    thd->fatal_error();
+    current_thd->fatal_error();
   unit->item= item;
 }
 
@@ -749,6 +741,13 @@ int subselect_single_select_engine::prepare()
 {
   if (prepared)
     return 0;
+  join= new JOIN(thd, select_lex->item_list, select_lex->options, result);
+  if (!join || !result)
+  {
+    //out of memory
+    thd->fatal_error();
+    return 1;
+  }
   prepared= 1;
   SELECT_LEX *save_select= thd->lex.current_select;
   thd->lex.current_select= select_lex;

sql/item_subselect.h

@@ -75,7 +75,7 @@ public:
      pointer in constructor initialization list, but we need pass pointer
      to subselect Item class to select_subselect classes constructor.
   */
-  virtual void init (THD *thd, st_select_lex *select_lex, 
+  virtual void init (st_select_lex *select_lex, 
 		     select_subselect *result);
 
   ~Item_subselect();
@@ -122,7 +122,7 @@ class Item_singlerow_subselect :public Item_subselect
 protected:
   Item_cache *value, **row;
 public:
-  Item_singlerow_subselect(THD *thd, st_select_lex *select_lex);
+  Item_singlerow_subselect(st_select_lex *select_lex);
   Item_singlerow_subselect(Item_singlerow_subselect *item):
     Item_subselect(item)
   {
@@ -161,7 +161,7 @@ protected:
   longlong value; /* value of this item (boolean: exists/not-exists) */
 
 public:
-  Item_exists_subselect(THD *thd, st_select_lex *select_lex);
+  Item_exists_subselect(st_select_lex *select_lex);
   Item_exists_subselect(Item_exists_subselect *item):
     Item_subselect(item)
   {
@@ -202,7 +202,7 @@ protected:
   bool was_null;
   bool abort_on_null;
 public:
-  Item_in_subselect(THD *thd, Item * left_expr, st_select_lex *select_lex);
+  Item_in_subselect(Item * left_expr, st_select_lex *select_lex);
   Item_in_subselect(Item_in_subselect *item);
   Item_in_subselect(): Item_exists_subselect(), abort_on_null(0) {}
 
@@ -237,7 +237,7 @@ protected:
   compare_func_creator func;
 
 public:
-  Item_allany_subselect(THD *thd, Item * left_expr, compare_func_creator f,
+  Item_allany_subselect(Item * left_expr, compare_func_creator f,
 		     st_select_lex *select_lex);
   Item_allany_subselect(Item_allany_subselect *item);
   subs_type substype() { return ALLANY_SUBS; }
@@ -254,16 +254,19 @@ protected:
   bool maybe_null; /* may be null (first item in select) */
 public:
 
-  subselect_engine(THD *thd, Item_subselect *si, select_subselect *res) 
+  subselect_engine(Item_subselect *si, select_subselect *res)
+    :thd(0)
   {
     result= res;
     item= si;
-    this->thd= thd;
     res_type= STRING_RESULT;
     maybe_null= 0;
   }
   virtual ~subselect_engine() {}; // to satisfy compiler
-
+  
+  // set_thd should be called before prepare()
+  void set_thd(THD *thd) { this->thd= thd; }
+  THD * get_thd() { return thd; }
   virtual int prepare()= 0;
   virtual void fix_length_and_dec(Item_cache** row)= 0;
   virtual int exec()= 0;
@@ -283,7 +286,7 @@ class subselect_single_select_engine: public subselect_engine
   st_select_lex *select_lex; /* corresponding select_lex */
   JOIN * join; /* corresponding JOIN structure */
 public:
-  subselect_single_select_engine(THD *thd, st_select_lex *select,
+  subselect_single_select_engine(st_select_lex *select,
 				 select_subselect *result,
 				 Item_subselect *item);
   int prepare();
@@ -299,8 +302,7 @@ class subselect_union_engine: public subselect_engine
 {
   st_select_lex_unit *unit;  /* corresponding unit structure */
 public:
-  subselect_union_engine(THD *thd,
-			 st_select_lex_unit *u,
+  subselect_union_engine(st_select_lex_unit *u,
 			 select_subselect *result,
 			 Item_subselect *item);
   int prepare();
@@ -320,10 +322,13 @@ protected:
   Item *cond;
 public:
 
+  // constructor can assign THD because it will be called after JOIN::prepare
   subselect_uniquesubquery_engine(THD *thd, st_join_table *tab_arg,
 				  Item_subselect *subs, Item *where)
-    :subselect_engine(thd, subs, 0), tab(tab_arg), cond(where)
-  {}
+    :subselect_engine(subs, 0), tab(tab_arg), cond(where)
+  {
+    set_thd(thd);
+  }
     
   int prepare();
   void fix_length_and_dec(Item_cache** row);
@@ -339,6 +344,8 @@ class subselect_indexsubquery_engine: public subselect_uniquesubquery_engine
 {
   bool check_null;
 public:
+
+  // constructor can assign THD because it will be called after JOIN::prepare
   subselect_indexsubquery_engine(THD *thd, st_join_table *tab_arg,
 				 Item_subselect *subs, Item *where,
 				 bool chk_null)

sql/sql_yacc.yy

@@ -2238,10 +2238,10 @@ expr_expr:
 	| expr NOT IN_SYM '(' expr_list ')'
 	  { $5->push_front($1); $$= new Item_func_not(new Item_func_in(*$5)); }
         | expr IN_SYM in_subselect
-          { $$= new Item_in_subselect(YYTHD, $1, $3); }
+          { $$= new Item_in_subselect($1, $3); }
 	| expr NOT IN_SYM in_subselect
           {
-            $$= new Item_func_not(new Item_in_subselect(YYTHD, $1, $4));
+            $$= new Item_func_not(new Item_in_subselect($1, $4));
           }
 	| expr BETWEEN_SYM no_and_expr AND expr
 	  { $$= new Item_func_between($1,$3,$5); }
@@ -2263,7 +2263,7 @@ expr_expr:
 	| expr comp_op all_or_any in_subselect %prec EQ
 	{
 	  Item_allany_subselect *it=
-	    new Item_allany_subselect(YYTHD, $1, (*$2)($3), $4);
+	    new Item_allany_subselect($1, (*$2)($3), $4);
 	  if ($3)
 	    $$ = new Item_func_not(it);	/* ALL */
 	  else
@@ -2309,7 +2309,7 @@ no_in_expr:
 	| no_in_expr comp_op all_or_any in_subselect %prec EQ
 	{
 	  Item_allany_subselect *it=
-	    new Item_allany_subselect(YYTHD, $1, (*$2)($3), $4);
+	    new Item_allany_subselect($1, (*$2)($3), $4);
 	  if ($3)
 	    $$ = new Item_func_not(it);	/* ALL */
 	  else
@@ -2340,10 +2340,10 @@ no_and_expr:
 	| no_and_expr NOT IN_SYM '(' expr_list ')'
 	  { $5->push_front($1); $$= new Item_func_not(new Item_func_in(*$5)); }
         | no_and_expr IN_SYM in_subselect
-          { $$= new Item_in_subselect(YYTHD, $1, $3); }
+          { $$= new Item_in_subselect($1, $3); }
 	| no_and_expr NOT IN_SYM in_subselect
           {
-            $$= new Item_func_not(new Item_in_subselect(YYTHD, $1, $4));
+            $$= new Item_func_not(new Item_in_subselect($1, $4));
           }
 	| no_and_expr BETWEEN_SYM no_and_expr AND expr
 	  { $$= new Item_func_between($1,$3,$5); }
@@ -2364,7 +2364,7 @@ no_and_expr:
 	| no_and_expr comp_op all_or_any in_subselect %prec EQ
 	{
 	  Item_allany_subselect *it=
-	    new Item_allany_subselect(YYTHD, $1, (*$2)($3), $4);
+	    new Item_allany_subselect($1, (*$2)($3), $4);
 	  if ($3)
 	    $$ = new Item_func_not(it);	/* ALL */
 	  else
@@ -5349,9 +5349,8 @@ singlerow_subselect:
 singlerow_subselect_init:
 	select_init2
 	{
-	  $$= new Item_singlerow_subselect(YYTHD,
-					   Lex->current_select->master_unit()->
-                                             first_select());
+	  $$= new Item_singlerow_subselect(Lex->current_select->
+					   master_unit()->first_select());
 	};
 
 exists_subselect:
@@ -5364,9 +5363,8 @@ exists_subselect:
 exists_subselect_init:
 	select_init2
 	{
-	  $$= new Item_exists_subselect(YYTHD,
-					Lex->current_select->master_unit()->
-					  first_select());
+	  $$= new Item_exists_subselect(Lex->current_select->master_unit()->
+					first_select());
 	};
 
 in_subselect: