BUG#28618 (Skipping into the middle of a group with

SQL_SLAVE_SKIP_COUNTER is possible):

By setting the SQL_SLAVE_SKIP_COUNTER it was possible to start the
from the middle of a group. This patch adds code so that events that
do not end a statement are ignored instead of skip counted when the
slave skip counter is 1.


sql/log_event.cc:
  Adding code so that for rows log events where the STMT_END_F is clear
  and for table map events, the event is ignored when the slave skip
  counter is 1 instead of skip counted, or described another way, the
  slave skip counter can only be decreased from 1 to 0 when the
  STMT_END_F flag is set.
sql/log_event.h:
  Adding functions Table_map_log_event::do_shall_skip() and
  Rows_log_event::do_shall_skip().

sql/log_event.cc

@@ -6127,6 +6127,20 @@ int Rows_log_event::do_apply_event(RELAY_LOG_INFO const *rli)
   DBUG_RETURN(0);
 }
 
+Log_event::enum_skip_reason
+Rows_log_event::do_shall_skip(RELAY_LOG_INFO *rli)
+{
+  /*
+    If the slave skip counter is 1 and this event does not end a
+    statement, then we should not start executing on the next event.
+    Otherwise, we defer the decision to the normal skipping logic.
+  */
+  if (rli->slave_skip_counter == 1 && !get_flags(STMT_END_F))
+    return Log_event::EVENT_SKIP_IGNORE;
+  else
+    return Log_event::do_shall_skip(rli);
+}
+
 int
 Rows_log_event::do_update_pos(RELAY_LOG_INFO *rli)
 {
@@ -6599,6 +6613,19 @@ int Table_map_log_event::do_apply_event(RELAY_LOG_INFO const *rli)
   DBUG_RETURN(error);
 }
 
+Log_event::enum_skip_reason
+Table_map_log_event::do_shall_skip(RELAY_LOG_INFO *rli)
+{
+  /*
+    If the slave skip counter is 1, then we should not start executing
+    on the next event.
+  */
+  if (rli->slave_skip_counter == 1)
+    return Log_event::EVENT_SKIP_IGNORE;
+  else
+    return Log_event::do_shall_skip(rli);
+}
+
 int Table_map_log_event::do_update_pos(RELAY_LOG_INFO *rli)
 {
   rli->inc_event_relay_log_pos();

sql/log_event.h

@@ -2066,6 +2066,7 @@ class Table_map_log_event : public Log_event
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
   virtual int do_apply_event(RELAY_LOG_INFO const *rli);
   virtual int do_update_pos(RELAY_LOG_INFO *rli);
+  virtual enum_skip_reason do_shall_skip(RELAY_LOG_INFO *rli);
 #endif
 
 #ifndef MYSQL_CLIENT
@@ -2244,6 +2245,7 @@ class Rows_log_event : public Log_event
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
   virtual int do_apply_event(RELAY_LOG_INFO const *rli);
   virtual int do_update_pos(RELAY_LOG_INFO *rli);
+  virtual enum_skip_reason do_shall_skip(RELAY_LOG_INFO *rli);
 
   /*
     Primitive to prepare for a sequence of row executions.