In the handlerton, cursor creation function don't have an argument

and so the engine calls current_thd to derive transaction information;
instead we now pass THD to those functions, it looks more logical
(it makes the implicit current_thd parameter more visible).
Approved by Brian and Monty.


sql/handler.h:
  cursor's creation functions in the handlerton need a THD,
  it's better than have the engine call current_thd
sql/sql_cursor.cc:
  pass the THD instead of letting the engine call current_thd
storage/innobase/handler/ha_innodb.cc:
  use the passed THD instead of current_thd
storage/innobase/handler/ha_innodb.h:
  use the passed THD instead of current_thd

sql/handler.h

@@ -630,9 +630,9 @@ struct handlerton
    int  (*recover)(XID *xid_list, uint len);
    int  (*commit_by_xid)(XID *xid);
    int  (*rollback_by_xid)(XID *xid);
-   void *(*create_cursor_read_view)();
+   void *(*create_cursor_read_view)(THD *thd);
-   void (*set_cursor_read_view)(void *);
+   void (*set_cursor_read_view)(THD *thd, void *read_view);
-   void (*close_cursor_read_view)(void *);
+   void (*close_cursor_read_view)(THD *thd, void *read_view);
    handler *(*create)(TABLE_SHARE *table, MEM_ROOT *mem_root);
    void (*drop_database)(char* path);
    int (*panic)(enum ha_panic_function flag);

sql/sql_cursor.cc

@@ -323,7 +323,7 @@ Sensitive_cursor::post_open(THD *thd)
     if (ht->create_cursor_read_view)
     {
       info->ht= ht;
-      info->read_view= (ht->create_cursor_read_view)();
+      info->read_view= (ht->create_cursor_read_view)(thd);
       ++info;
     }
   }
@@ -433,7 +433,7 @@ Sensitive_cursor::fetch(ulong num_rows)
   thd->set_n_backup_active_arena(this, &backup_arena);
 
   for (info= ht_info; info->read_view ; info++)
-    (info->ht->set_cursor_read_view)(info->read_view);
+    (info->ht->set_cursor_read_view)(thd, info->read_view);
 
   join->fetch_limit+= num_rows;
 
@@ -454,7 +454,7 @@ Sensitive_cursor::fetch(ulong num_rows)
   reset_thd(thd);
 
   for (info= ht_info; info->read_view; info++)
-    (info->ht->set_cursor_read_view)(0);
+    (info->ht->set_cursor_read_view)(thd, 0);
 
   if (error == NESTED_LOOP_CURSOR_LIMIT)
   {
@@ -487,7 +487,7 @@ Sensitive_cursor::close()
 
   for (Engine_info *info= ht_info; info->read_view; info++)
   {
-    (info->ht->close_cursor_read_view)(info->read_view);
+    (info->ht->close_cursor_read_view)(thd, info->read_view);
     info->read_view= 0;
     info->ht= 0;
   }

storage/innobase/handler/ha_innodb.cc

@@ -7529,12 +7529,14 @@ This consistent view is then used inside of MySQL when accessing records
 using a cursor. */
 
 void*
-innobase_create_cursor_view(void)
+innobase_create_cursor_view(
-/*=============================*/
+/*========================*/
-			/* out: Pointer to cursor view or NULL */
+						/* out: pointer to cursor
+						view or NULL */
+	THD*			thd)		/* in: user thread handle */
 {
 	return(read_cursor_view_create_for_mysql(
-					check_trx_exists(current_thd)));
+					check_trx_exists(thd)));
 }
 
 /***********************************************************************
@@ -7545,6 +7547,7 @@ corresponding MySQL thread still lacks one. */
 void
 innobase_close_cursor_view(
 /*=======================*/
+	THD*	thd,	/* in: user thread handle */
 	void*	curview)/* in: Consistent read view to be closed */
 {
 	read_cursor_view_close_for_mysql(check_trx_exists(current_thd),
@@ -7560,6 +7563,7 @@ restored to a transaction read view. */
 void
 innobase_set_cursor_view(
 /*=====================*/
+	THD*	thd,	/* in: user thread handle */
 	void*	curview)/* in: Consistent cursor view to be set */
 {
 	read_cursor_set_for_mysql(check_trx_exists(current_thd),

storage/innobase/handler/ha_innodb.h

@@ -313,9 +313,11 @@ This consistent view is then used inside of MySQL when accessing records
 using a cursor. */
 
 void*
-innobase_create_cursor_view(void);
+innobase_create_cursor_view(
-/*=============================*/
+/*========================*/
-				/* out: Pointer to cursor view or NULL */
+						/* out: pointer to cursor
+						view or NULL */
+	THD*			thd);		/* in: user thread handle */
 
 /***********************************************************************
 Close the given consistent cursor view of a transaction and restore
@@ -325,8 +327,10 @@ corresponding MySQL thread still lacks one. */
 void
 innobase_close_cursor_view(
 /*=======================*/
+	THD*	thd,		/* in: user thread handle */
 	void*	curview);	/* in: Consistent read view to be closed */
 
+
 /***********************************************************************
 Set the given consistent cursor view to a transaction which is created
 if the corresponding MySQL thread still lacks one. If the given
@@ -336,4 +340,5 @@ restored to a transaction read view. */
 void
 innobase_set_cursor_view(
 /*=====================*/
+	THD*	thd,		/* in: user thread handle */
 	void*	curview);	/* in: Consistent read view to be set */