MDEV-17349 Assertion `!table || (!table->read_set ||...

MDEV-17349 Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index))' failed on concurrent SELECT and DELETE after RENAME from table with index on virtual column

Race condition. field->flags were copied from s->field->flags during
field->clone(), early in open_table_from_share(). But s->field->flags
were getting their PART_INDIRECT_KEY_FLAG bit much later in
TABLE::mark_columns_used_by_virtual_fields() and only once per share.

If two threads were executing the code between field->clone()
and mark_columns_used_by_virtual_fields() at the same time, only
one would get PART_INDIRECT_KEY_FLAG bits in field[].

mysql-test/suite/vcol/r/races.result

+create table t1 (f text, vf tinytext as (f), key (vf(64))) engine=innodb;
+insert t1 (f) values ('foo');
+flush tables;
+connect con1,localhost,root,,test;
+set debug_sync='TABLE_after_field_clone WAIT_FOR go';
+delete from t1;
+connection default;
+select * from t1;
+f	vf
+foo	foo
+set debug_sync='now SIGNAL go';
+connection con1;
+disconnect con1;
+connection default;
+drop table t1;
+set debug_sync='reset';

mysql-test/suite/vcol/t/races.test

+#
+# MDEV-17349 Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index))' failed on concurrent SELECT and DELETE after RENAME from table with index on virtual column
+#
+source include/have_innodb.inc;
+source include/have_debug_sync.inc;
+create table t1 (f text, vf tinytext as (f), key (vf(64))) engine=innodb;
+insert t1 (f) values ('foo');
+flush tables;
+connect con1,localhost,root,,test;
+set debug_sync='TABLE_after_field_clone WAIT_FOR go';
+send delete from t1;
+connection default;
+let $wait_condition= select state like 'debug sync point%' from information_schema.processlist;
+source include/wait_condition.inc;
+select * from t1;
+set debug_sync='now SIGNAL go';
+connection con1;
+reap;
+disconnect con1;
+connection default;
+drop table t1;
+set debug_sync='reset';

sql/table.cc

@@ -3013,6 +3013,7 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
   uchar *record, *bitmaps;
   Field **field_ptr;
   uint8 save_context_analysis_only= thd->lex->context_analysis_only;
+  TABLE_SHARE::enum_v_keys check_set_initialized= share->check_set_initialized;
   DBUG_ENTER("open_table_from_share");
   DBUG_PRINT("enter",("name: '%s.%s'  form: %p", share->db.str,
                       share->table_name.str, outparam));
@@ -3116,6 +3117,8 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
   }
   (*field_ptr)= 0;                              // End marker
 
+  DEBUG_SYNC(thd, "TABLE_after_field_clone");
+
   if (share->found_next_number_field)
     outparam->found_next_number_field=
       outparam->field[(uint) (share->found_next_number_field - share->field)];
@@ -3371,6 +3374,16 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
   }
 
   outparam->mark_columns_used_by_virtual_fields();
+  if (!check_set_initialized &&
+      share->check_set_initialized == TABLE_SHARE::V_KEYS)
+  {
+    // copy PART_INDIRECT_KEY_FLAG that was set meanwhile by *some* thread
+    for (uint i= 0 ; i < share->fields ; i++)
+    {
+      if (share->field[i]->flags & PART_INDIRECT_KEY_FLAG)
+        outparam->field[i]->flags|= PART_INDIRECT_KEY_FLAG;
+    }
+  }
 
   if (share->table_category == TABLE_CATEGORY_LOG)
   {
@@ -6708,6 +6721,7 @@ void TABLE::mark_columns_used_by_virtual_fields(void)
 {
   MY_BITMAP *save_read_set;
   Field **vfield_ptr;
+  TABLE_SHARE::enum_v_keys v_keys= TABLE_SHARE::NO_V_KEYS;
 
   /* If there is virtual fields are already initialized */
   if (s->check_set_initialized)
@@ -6748,12 +6762,12 @@ void TABLE::mark_columns_used_by_virtual_fields(void)
       if (bitmap_is_set(&tmp_set, i))
       {
         s->field[i]->flags|= PART_INDIRECT_KEY_FLAG;
-        field[i]->flags|= PART_INDIRECT_KEY_FLAG;
+        v_keys= TABLE_SHARE::V_KEYS;
       }
     }
     bitmap_clear_all(&tmp_set);
   }
-  s->check_set_initialized= 1;
+  s->check_set_initialized= v_keys;
   if (s->tmp_table == NO_TMP_TABLE)
     mysql_mutex_unlock(&s->LOCK_share);
 }

sql/table.h

@@ -695,6 +695,9 @@ struct TABLE_SHARE
   uint column_bitmap_size;
   uchar frm_version;
 
+  enum enum_v_keys { NOT_INITIALIZED=0, NO_V_KEYS, V_KEYS };
+  enum_v_keys check_set_initialized;
+
   bool use_ext_keys;                    /* Extended keys can be used */
   bool null_field_first;
   bool system;                          /* Set if system table (one record) */
@@ -705,7 +708,6 @@ struct TABLE_SHARE
   bool table_creation_was_logged;
   bool non_determinstic_insert;
   bool vcols_need_refixing;
-  bool check_set_initialized;
   bool has_update_default_function;
   ulong table_map_id;                   /* for row-based replication */