BUG#43407 SET GLOBAL SQL_SLAVE_SKIP_COUNTER should log previous state in error log

      
When issuing a 'SET GLOBAL SQL_SLAVE_SKIP_COUNTER' statement, the previous
position along with the new position is dumped into the error log. Namely,
the following information is printed out: skip_counter, group_relay_log_name
and group_relay_log_pos.

sql/slave.cc

@@ -2883,6 +2883,11 @@ pthread_handler_t handle_slave_sql(void *arg)
 {
   THD *thd;                     /* needs to be first for thread_stack */
   char llbuff[22],llbuff1[22];
+  char saved_log_name[FN_REFLEN];
+  char saved_master_log_name[FN_REFLEN];
+  my_off_t saved_log_pos;
+  my_off_t saved_master_log_pos;
+  my_off_t saved_skip= 0;
 
   Relay_log_info* rli = &((Master_info*)arg)->rli;
   const char *errmsg;
@@ -3028,6 +3033,17 @@ log '%s' at position %s, relay log '%s' position: %s", RPL_LOG_NAME,
     do not want to wait for next event in this case.
   */
   pthread_mutex_lock(&rli->data_lock);
+  if (rli->slave_skip_counter)
+  {
+    char *pos;
+    pos= strmake(saved_log_name, rli->group_relay_log_name, FN_REFLEN - 1);
+    pos= '\0';
+    pos= strmake(saved_master_log_name, rli->group_master_log_name, FN_REFLEN - 1);
+    pos= '\0';
+    saved_log_pos= rli->group_relay_log_pos;
+    saved_master_log_pos= rli->group_master_log_pos;
+    saved_skip= rli->slave_skip_counter;
+  }
   if (rli->until_condition != Relay_log_info::UNTIL_NONE &&
       rli->is_until_satisfied(thd, NULL))
   {
@@ -3046,6 +3062,21 @@ log '%s' at position %s, relay log '%s' position: %s", RPL_LOG_NAME,
     thd_proc_info(thd, "Reading event from the relay log");
     DBUG_ASSERT(rli->sql_thd == thd);
     THD_CHECK_SENTRY(thd);
+
+    if (saved_skip && rli->slave_skip_counter == 0)
+    {
+      sql_print_information("'SQL_SLAVE_SKIP_COUNTER=%ld' executed at "
+        "relay_log_file='%s', relay_log_pos='%ld', master_log_name='%s', "
+        "master_log_pos='%ld' and new position at "
+        "relay_log_file='%s', relay_log_pos='%ld', master_log_name='%s', "
+        "master_log_pos='%ld' ",
+        (ulong) saved_skip, saved_log_name, (ulong) saved_log_pos,
+        saved_master_log_name, (ulong) saved_master_log_pos,
+        rli->group_relay_log_name, (ulong) rli->group_relay_log_pos,
+        rli->group_master_log_name, (ulong) rli->group_master_log_pos);
+      saved_skip= 0;
+    }
+    
     if (exec_relay_log_event(thd,rli))
     {
       DBUG_PRINT("info", ("exec_relay_log_event() failed"));