MDEV-4605: Failing to load GTID slave position from rpl.gtid_slave_pos

There were several cases where the slave GTID position was not loaded
correctly before being used. This caused various failures such as
corrupting the position at slave start and empty values of
@@gtid_slave_pos and @@gtid_current_pos.

Fixed by adding more checks for loaded position, and by always loading
the position at server startup.

1 files changed, 15 insertions, 1 deletions

diff --git a/sql/rpl_rli.cc b/sql/rpl_rli.cc
index 03ec77e1433..9cb210f398f 100644
--- a/sql/rpl_rli.cc
+++ b/sql/rpl_rli.cc
@@ -1425,7 +1425,10 @@ rpl_load_gtid_slave_state(THD *thd)
 
   bitmap_set_all(table->read_set);
   if ((err= table->file->ha_rnd_init_with_error(1)))
+  {
+    table->file->print_error(err, MYF(0));
     goto end;
+  }
   table_scanned= true;
   for (;;)
   {
@@ -1440,7 +1443,10 @@ rpl_load_gtid_slave_state(THD *thd)
       else if (err == HA_ERR_END_OF_FILE)
         break;
       else
+      {
+        table->file->print_error(err, MYF(0));
         goto end;
+      }
     }
     domain_id= (ulonglong)table->field[0]->val_int();
     sub_id= (ulonglong)table->field[1]->val_int();
@@ -1465,6 +1471,7 @@ rpl_load_gtid_slave_state(THD *thd)
       if (!(entry= (struct local_element *)my_malloc(sizeof(*entry),
                                                      MYF(MY_WME))))
       {
+        my_error(ER_OUTOFMEMORY, MYF(0), (int)sizeof(*entry));
         err= 1;
         goto end;
       }
@@ -1475,12 +1482,18 @@ rpl_load_gtid_slave_state(THD *thd)
       if ((err= my_hash_insert(&hash, (uchar *)entry)))
       {
         my_free(entry);
+        my_error(ER_OUT_OF_RESOURCES, MYF(0));
         goto end;
       }
     }
   }
 
   rpl_global_gtid_slave_state.lock();
+  if (rpl_global_gtid_slave_state.loaded)
+  {
+    rpl_global_gtid_slave_state.unlock();
+    goto end;
+  }
   for (i= 0; i < hash.records; ++i)
   {
     entry= (struct local_element *)my_hash_element(&hash, i);
@@ -1490,14 +1503,15 @@ rpl_load_gtid_slave_state(THD *thd)
                                                  entry->gtid.seq_no)))
     {
       rpl_global_gtid_slave_state.unlock();
+      my_error(ER_OUT_OF_RESOURCES, MYF(0));
       goto end;
     }
     if (opt_bin_log &&
         mysql_bin_log.bump_seq_no_counter_if_needed(entry->gtid.domain_id,
                                                     entry->gtid.seq_no))
     {
-      my_error(ER_OUT_OF_RESOURCES, MYF(0));
       rpl_global_gtid_slave_state.unlock();
+      my_error(ER_OUT_OF_RESOURCES, MYF(0));
       goto end;
     }
   }