BUG#44270: RESET SLAVE does not reset Last_IO_Error or Last_IO_Errno

The server was not cleaning the last IO error and error number when
resetting slave.

This patch addresses this issue by backporting into 5.1 part of the
patch in BUG 34654. A fix for this issue had already been pushed into
6.0 as part of the aforementioned bug, however the patch also included
some refactoring. The fix for 5.1 does not take into account the
refactoring part.

mysql-test/extra/rpl_tests/rpl_reset_slave.test:
  Backported the test case and improved with deploying include/start_slave.inc
  in relevant spots.
sql/slave.cc:
  Backported part of patch from 6.0 that includes cleaning 
  mi->clear_error() at:
    1. beginning of handle_slave_io
    2. on successful connection
  
  Also, backported the assertion added in the original patch.
sql/sql_repl.cc:
  Backported the call to mi->clear_error() on reset_slave().

mysql-test/extra/rpl_tests/rpl_reset_slave.test

@@ -41,3 +41,57 @@ reset slave;
 start slave;
 sync_with_master;
 show status like 'slave_open_temp_tables';
+
+#
+#Bug#34654  	RESET SLAVE does not clear LAST_IO_Err* 
+#
+
+# clearing the status
+stop slave;
+reset slave;
+let $last_io_errno= query_get_value(SHOW SLAVE STATUS, Last_IO_Errno, 1);
+echo *** errno must be zero: $last_io_errno ***;
+
+#
+# verifying start slave resets Last_IO_Error and Last_IO_Errno.
+#
+
+change master to master_user='impossible_user_name';
+start slave;
+source include/wait_for_slave_io_to_stop.inc;
+let $last_io_errno= query_get_value(SHOW SLAVE STATUS, Last_IO_Errno, 1);
+--disable_query_log
+eval SELECT $last_io_errno > 0 as ONE;
+--enable_query_log
+
+source include/stop_slave.inc;
+change master to master_user='root';
+source include/start_slave.inc;
+let $last_io_errno= query_get_value(SHOW SLAVE STATUS, Last_IO_Errno, 1);
+let $last_io_error= query_get_value(SHOW SLAVE STATUS, Last_IO_Error, 1);
+--echo *** last errno must be  zero: $last_io_errno ***
+--echo *** last error must be blank: $last_io_error ***
+
+#
+# verifying reset slave resets Last_{IO,SQL}_Err{or,no}
+#
+
+source include/stop_slave.inc;
+change master to master_user='impossible_user_name';
+start slave;
+source include/wait_for_slave_io_to_stop.inc;
+let $last_io_errno= query_get_value(SHOW SLAVE STATUS, Last_IO_Errno, 1);
+--disable_query_log
+eval SELECT $last_io_errno > 0 as ONE;
+--enable_query_log
+
+source include/stop_slave.inc;
+reset slave;
+let $last_io_errno= query_get_value(SHOW SLAVE STATUS, Last_IO_Errno, 1);
+let $last_io_error= query_get_value(SHOW SLAVE STATUS, Last_IO_Error, 1);
+let $last_sql_errno= query_get_value(SHOW SLAVE STATUS, Last_SQL_Errno, 1);
+let $last_sql_error= query_get_value(SHOW SLAVE STATUS, Last_SQL_Error, 1);
+--echo *** io  last errno must be  zero: $last_io_errno  ***
+--echo *** io  last error must be blank: $last_io_error  ***
+--echo *** sql last errno must be  zero: $last_sql_errno ***
+--echo *** sql last error must be blank: $last_sql_error ***

mysql-test/suite/rpl/r/rpl_row_reset_slave.result

@@ -174,3 +174,26 @@ start slave;
 show status like 'slave_open_temp_tables';
 Variable_name	Value
 Slave_open_temp_tables	0
+stop slave;
+reset slave;
+*** errno must be zero: 0 ***
+change master to master_user='impossible_user_name';
+start slave;
+ONE
+1
+include/stop_slave.inc
+change master to master_user='root';
+include/start_slave.inc
+*** last errno must be  zero: 0 ***
+*** last error must be blank:  ***
+include/stop_slave.inc
+change master to master_user='impossible_user_name';
+start slave;
+ONE
+1
+include/stop_slave.inc
+reset slave;
+*** io  last errno must be  zero: 0  ***
+*** io  last error must be blank:   ***
+*** sql last errno must be  zero: 0 ***
+*** sql last error must be blank:  ***

mysql-test/suite/rpl/r/rpl_stm_reset_slave.result

@@ -174,3 +174,26 @@ start slave;
 show status like 'slave_open_temp_tables';
 Variable_name	Value
 Slave_open_temp_tables	1
+stop slave;
+reset slave;
+*** errno must be zero: 0 ***
+change master to master_user='impossible_user_name';
+start slave;
+ONE
+1
+include/stop_slave.inc
+change master to master_user='root';
+include/start_slave.inc
+*** last errno must be  zero: 0 ***
+*** last error must be blank:  ***
+include/stop_slave.inc
+change master to master_user='impossible_user_name';
+start slave;
+ONE
+1
+include/stop_slave.inc
+reset slave;
+*** io  last errno must be  zero: 0  ***
+*** io  last error must be blank:   ***
+*** sql last errno must be  zero: 0 ***
+*** sql last error must be blank:  ***

sql/slave.cc

@@ -2397,6 +2397,7 @@ pthread_handler_t handle_slave_io(void *arg)
 
   pthread_detach_this_thread();
   thd->thread_stack= (char*) &thd; // remember where our stack is
+  mi->clear_error();
   if (init_slave_thread(thd, SLAVE_THD_IO))
   {
     pthread_cond_broadcast(&mi->start_cond);
@@ -2511,6 +2512,7 @@ requesting master dump") ||
         goto connected;
       });
 
+    DBUG_ASSERT(mi->last_error().number == 0);
     while (!io_slave_killed(thd,mi))
     {
       ulong event_len;
@@ -3710,6 +3712,7 @@ static int connect_to_master(THD* thd, MYSQL* mysql, Master_info* mi,
 
   if (!slave_was_killed)
   {
+    mi->clear_error(); // clear possible left over reconnect error
     if (reconnect)
     {
       if (!suppress_warnings && global_system_variables.log_warnings)

sql/sql_repl.cc

@@ -1043,6 +1043,7 @@ int reset_slave(THD *thd, Master_info* mi)
      Reset errors (the idea is that we forget about the
      old master).
   */
+  mi->clear_error();
   mi->rli.clear_error();
   mi->rli.clear_until_condition();