Fix of query cache bug in Aria

MDEV-5817 query cache bug (returning inconsistent/old result
set) with aria table parallel inserts, row format = page

The problem is that for transactional aria tables
(row_type=PAGE and transactional=1), maria_lock_database()
didn't flush the state or the query cache.
Not flushing the state is correct for transactional tables as
this is done by checkpoint, but not flushing the query cache
was wrong and could cause concurrent SELECT queries to not
be deleted from the cache.

Fixed by introducing a flush of the query cache as part of commit, if the table has changed.
t for transactional aria tables (row_type=PAGE and transactional=1), maria_lock_table() didn't flush their state or the query cache.

storage/maria/ha_maria.cc

@@ -2859,7 +2859,20 @@ static void reset_thd_trn(THD *thd, MARIA_HA *first_table)
   THD_TRN= NULL;
   for (MARIA_HA *table= first_table; table ;
        table= table->trn_next)
+  {
     _ma_reset_trn_for_table(table);
+
+    /*
+      If table has changed by this statement, invalidate it from the query
+      cache
+    */
+    if (table->row_changes != table->start_row_changes)
+    {
+      table->start_row_changes= table->row_changes;
+      DBUG_ASSERT(table->s->chst_invalidator != NULL);
+      (*table->s->chst_invalidator)(table->s->data_file_name.str);
+    }
+  }
   DBUG_VOID_RETURN;
 }
 
@@ -3325,7 +3338,10 @@ static int maria_commit(handlerton *hton __attribute__ ((unused)),
                         THD *thd, bool all)
 {
   TRN *trn= THD_TRN;
+  int res;
+  MARIA_HA *used_instances= (MARIA_HA*) trn->used_instances;
   DBUG_ENTER("maria_commit");
+
   trnman_reset_locked_tables(trn, 0);
   trnman_set_flags(trn, trnman_get_flags(trn) & ~TRN_STATE_INFO_LOGGED);
 
@@ -3333,8 +3349,9 @@ static int maria_commit(handlerton *hton __attribute__ ((unused)),
   if ((thd->variables.option_bits & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)) &&
       !all)
     DBUG_RETURN(0); // end of statement
-  reset_thd_trn(thd, (MARIA_HA*) trn->used_instances);
-  DBUG_RETURN(ma_commit(trn)); // end of transaction
+  res= ma_commit(trn);
+  reset_thd_trn(thd, used_instances);
+  DBUG_RETURN(res);
 }
 
 

storage/maria/maria_def.h

@@ -640,6 +640,7 @@ struct st_maria_handler
   invalidator_by_filename invalidator;	/* query cache invalidator */
   ulonglong last_auto_increment;        /* auto value at start of statement */
   ulonglong row_changes;                /* Incremented for each change */
+  ulonglong start_row_changes;          /* Row changes since start trans */
   ulong this_unique;			/* uniq filenumber or thread */
   ulong last_unique;			/* last unique number */
   ulong this_loop;			/* counter for this open */