MDEV-34171: Memory leakage is detected on running the test versioning.partition

One of possible use cases that reproduces the memory leakage listed below:

  set timestamp= unix_timestamp('2000-01-01 00:00:00');
  create or replace table t1 (x int) with system versioning
    partition by system_time interval 1 hour auto
    partitions 3;

  create table t2 (x int);

  create trigger tr after insert on t2 for each row update t1 set x= 11;
  create or replace procedure sp2() insert into t2 values (5);

  set timestamp= unix_timestamp('2000-01-01 04:00:00');
  call sp2;

  set timestamp= unix_timestamp('2000-01-01 13:00:00');
  call sp2; # <<=== Memory leak happens there. In case MariaDB server is built
                    with the option -DWITH_PROTECT_STATEMENT_MEMROOT,
                    the second execution would hit assert failure.

The reason of leaking a memory is that once a new partition be created
the table should be closed and re-opened. It results in calling the function
extend_table_list() that indirectly invokes the function sp_add_used_routine()
to add routines implicitly used by the statement that makes a new memory
allocation.

To fix it, don't remove routines and tables the statement implicitly depends
on when a table being closed for subsequent re-opening.

sql/sql_base.cc

@@ -4656,7 +4656,8 @@ bool open_tables(THD *thd, const DDL_options_st &options,
             have failed to open since closing tables can trigger removal of
             elements from the table list (if MERGE tables are involved),
           */
-          close_tables_for_reopen(thd, start, ot_ctx.start_of_statement_svp());
+          close_tables_for_reopen(thd, start, ot_ctx.start_of_statement_svp(),
+                                  ot_ctx.remove_implicitly_used_deps());
 
           /*
             Here we rely on the fact that 'tables' still points to the valid
@@ -4724,10 +4725,10 @@ bool open_tables(THD *thd, const DDL_options_st &options,
           /* F.ex. deadlock happened */
           if (ot_ctx.can_recover_from_failed_open())
           {
-            DBUG_ASSERT(ot_ctx.get_action() !=
-                        Open_table_context::OT_ADD_HISTORY_PARTITION);
+            DBUG_ASSERT(ot_ctx.remove_implicitly_used_deps());
             close_tables_for_reopen(thd, start,
-                                    ot_ctx.start_of_statement_svp());
+                                    ot_ctx.start_of_statement_svp(),
+                                    ot_ctx.remove_implicitly_used_deps());
             if (ot_ctx.recover_from_failed_open())
               goto error;
 
@@ -6017,27 +6018,34 @@ bool restart_trans_for_tables(THD *thd, TABLE_LIST *table)
                          trying to reopen tables. NULL if no metadata locks
                          were held and thus all metadata locks should be
                          released.
+  @param[in] remove_implicit_deps  True in case routines and tables implicitly
+                                   used by a statement should be removed.
 */
 
 void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
-                             const MDL_savepoint &start_of_statement_svp)
+                             const MDL_savepoint &start_of_statement_svp,
+                             bool remove_implicit_deps)
 {
   TABLE_LIST *first_not_own_table= thd->lex->first_not_own_table();
   TABLE_LIST *tmp;
 
-  /*
-    If table list consists only from tables from prelocking set, table list
-    for new attempt should be empty, so we have to update list's root pointer.
-  */
-  if (first_not_own_table == *tables)
-    *tables= 0;
-  thd->lex->chop_off_not_own_tables();
-  /* Reset MDL tickets for procedures/functions */
-  for (Sroutine_hash_entry *rt=
-         (Sroutine_hash_entry*)thd->lex->sroutines_list.first;
-       rt; rt= rt->next)
-    rt->mdl_request.ticket= NULL;
-  sp_remove_not_own_routines(thd->lex);
+  if (remove_implicit_deps)
+  {
+    /*
+      If table list consists only from tables from prelocking set, table list
+      for new attempt should be empty, so we have to update list's root pointer.
+    */
+    if (first_not_own_table == *tables)
+      *tables= 0;
+    thd->lex->chop_off_not_own_tables();
+
+    /* Reset MDL tickets for procedures/functions */
+    for (Sroutine_hash_entry *rt=
+        (Sroutine_hash_entry*)thd->lex->sroutines_list.first;
+        rt; rt= rt->next)
+      rt->mdl_request.ticket= NULL;
+    sp_remove_not_own_routines(thd->lex);
+  }
   for (tmp= *tables; tmp; tmp= tmp->next_global)
   {
     tmp->table= 0;

sql/sql_base.h

@@ -156,7 +156,8 @@ thr_lock_type read_lock_type_for_table(THD *thd,
 
 my_bool mysql_rm_tmp_tables(void);
 void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
-                             const MDL_savepoint &start_of_statement_svp);
+                             const MDL_savepoint &start_of_statement_svp,
+                             bool remove_implicit_dependencies);
 bool table_already_fk_prelocked(TABLE_LIST *tl, LEX_CSTRING *db,
                                 LEX_CSTRING *table, thr_lock_type lock_type);
 TABLE_LIST *find_table_in_list(TABLE_LIST *table,
@@ -566,9 +567,21 @@ class Open_table_context
     return m_timeout;
   }
 
-  enum_open_table_action get_action() const
+  /**
+    Return true in case tables and routines the statement implicilty
+    dependent on should be removed, else return false.
+
+    @note The use case when routines and tables the statement implicitly
+    dependent on shouldn't be removed is the one when a new partition be
+    created on handling the INSERT statement against a versioning partitioned
+    table. For this case re-opening a versioning table would result in adding
+    implicitly dependent routines (e.g. table's triggers) that lead to
+    allocation of memory on PS mem_root and so leaking a memory until the PS
+    statement be deallocated.
+  */
+  bool remove_implicitly_used_deps() const
   {
-    return m_action;
+    return m_action != OT_ADD_HISTORY_PARTITION;
   }
 
   uint get_flags() const { return m_flags; }

sql/sql_parse.cc

@@ -2945,7 +2945,7 @@ lock_tables_open_and_lock_tables(THD *thd, TABLE_LIST *tables)
             Deadlock occurred during upgrade of metadata lock.
             Let us restart acquring and opening tables for LOCK TABLES.
           */
-          close_tables_for_reopen(thd, &tables, mdl_savepoint);
+          close_tables_for_reopen(thd, &tables, mdl_savepoint, true);
           if (thd->open_temporary_tables(tables))
             goto err;
           goto retry;