Added checking that row events ends with a proper end block

Problems --------

The slave io thread did not conduct integrity check
for a group of row-based events. Specifically it tolerates missed
terminal block event that must be flagged with STMT_END. Failure to
react on its loss can confuse the applier thread in various ways.
Another potential issue was that there were no check of impossible
second in row Gtid-log-event while the slave io thread is receiving
to be skipped events after reconnect.

Fixes
-----
The slave io thread is made by this patch to track the rows event
STMT_END status.
Whenever at next event reading the IO thread finds out that a preceding
Rows event did not actually had the flag, an
explicit error is issued.

Replication can be resumed after the source of failure is eliminated,
see a provided test.

Note that currently the row-based group integrity check excludes
the compressed version 2 Rows events (which are not generated by MariaDB
master).
Its uncompressed counterpart is manually tested.

The 2nd issue is covered to produce an error in case the io thread
receives a successive Gtid_log_event while it is post-reconnect
skipping.

1 files changed, 21 insertions, 0 deletions

diff --git a/sql/rpl_mi.h b/sql/rpl_mi.h
index ccc1be6e5ce..b304e45f86a 100644
--- a/sql/rpl_mi.h
+++ b/sql/rpl_mi.h
@@ -133,6 +133,19 @@ public:
 
 extern TYPELIB slave_parallel_mode_typelib;
 
+typedef struct st_rows_event_tracker
+{
+  char binlog_file_name[FN_REFLEN];
+  my_off_t first_seen;
+  my_off_t last_seen;
+  bool stmt_end_seen;
+  void update(const char* file_name, size_t pos,
+              const char* buf,
+              const Format_description_log_event *fdle);
+  void reset();
+  bool check_and_report(const char* file_name, size_t pos);
+} Rows_event_tracker;
+
 /*****************************************************************************
   Replication IO Thread
 
@@ -301,6 +314,14 @@ class Master_info : public Slave_reporting_capability
   uint64 gtid_reconnect_event_skip_count;
   /* gtid_event_seen is false until we receive first GTID event from master. */
   bool gtid_event_seen;
+  /**
+    The struct holds some history of Rows- log-event reading/queuing
+    by the receiver thread. Its fields are updated per each such event
+    at time of queue_event(), and they are checked to detect
+    the Rows- event group integrity violation at time of first non-Rows-
+    event gets handled.
+  */
+  Rows_event_tracker rows_event_tracker;
   bool in_start_all_slaves, in_stop_all_slaves;
   bool in_flush_all_relay_logs;
   uint users;                                   /* Active user for object */