MDEV-12012/MDEV-11969 Can't remove GTIDs for a stale GTID Domain ID

As reported in MDEV-11969 "there's no way to ditch knowledge" about some
domain that is no longer updated on a server. Besides being of annoyance to
clutter output in DBA console stale domains can prevent the slave
to connect the master as MDEV-12012 witnesses.
What domain is obsolete must be evaluated by the user (DBA) according
to whether the domain info is still relevant and will the domain ever
receive any update.

This patch introduces a method to discard obsolete gtid domains from
the server binlog state. The removal requires no event group from such
domain present in existing binlog files though. If there are any the
containing logs must be first PURGEd in order for

  FLUSH BINARY LOGS DELETE_DOMAIN_ID=(list-of-domains)

succeed. Otherwise the command returns an error.

The list of obsolete domains can be computed through
intersecting two sets - the earliest (first) binlog's Gtid_list
and the current value of @@global.gtid_binlog_state - and extracting
the domain id components from the intersection list items.
The new DELETE_DOMAIN_ID featured FLUSH continues to rotate binlog
omitting the deleted domains from the active binlog file's Gtid_list.
Notice though when the command is ineffective - that none of requested to delete
domain exists in the binlog state - rotation does not occur.

Obsolete domain deletion is not harmful for connected slaves as long
as master side binlog files *purge* is synchronized with FLUSH-DELETE_DOMAIN_ID.
The slaves must have the last event from purged files processed as usual,
in order not to bump later into requesting a gtid from a file which
was already gone.
While the command is not replicated (as ordinary FLUSH BINLOG LOGS is)
slaves, even though having extra domains, won't suffer from reconnection errors
thanks to master-slave gtid connection protocol allowing the master
to be ignorant about a gtid domain.
Should at failover such slave to be promoted into master role it may run
the ex-master's

 FLUSH BINARY LOGS DELETE_DOMAIN_ID=(list-of-domains)

to clean its own binlog state.

NOTES.
  suite/perfschema/r/start_server_low_digest.result
is re-recorded as consequence of internal parser codes changes.

1 files changed, 6 insertions, 1 deletions

diff --git a/sql/log.h b/sql/log.h
index bf076fae31d..3026ca11e31 100644
--- a/sql/log.h
+++ b/sql/log.h
@@ -755,7 +755,7 @@ public:
   int update_log_index(LOG_INFO* linfo, bool need_update_threads);
   int rotate(bool force_rotate, bool* check_purge);
   void checkpoint_and_purge(ulong binlog_id);
-  int rotate_and_purge(bool force_rotate);
+  int rotate_and_purge(bool force_rotate, DYNAMIC_ARRAY* drop_gtid_domain= NULL);
   /**
      Flush binlog cache and synchronize to disk.
 
@@ -1165,4 +1165,9 @@ static inline TC_LOG *get_tc_log_implementation()
   return &tc_log_mmap;
 }
 
+
+class Gtid_list_log_event;
+const char *
+get_gtid_list_event(IO_CACHE *cache, Gtid_list_log_event **out_gtid_list);
+
 #endif /* LOG_H */