BUG#11809016 - NO WAY TO DISCOVER AN INSTANCE IS NO LONGER A SLAVE FOLLOWING MYSQL BUG#28796

Before BUG#28796, an empty host was used to identify that an instance was no
longer a slave. However, BUG#28796 changed this behavior and one cannot set
an empty host. Besides, a RESET SLAVE only cleans up information on the next
event to retrieve from the master, disables ssl and resets heartbeat period.
So a call to SHOW SLAVE STATUS after issuing a RESET SLAVE still returns some
valid information, such as host, port, user and password.

To fix this problem, we have introduced the command RESET SLAVE ALL that does
what a regular RESET SLAVE does and also clears host, port, user and password
information thus allowing users to identify when an instance is no longer a
slave.

mysql-test/extra/rpl_tests/rpl_reset_slave.test

@@ -77,5 +77,31 @@ reset slave;
 source include/check_slave_no_error.inc;
 change master to master_user='root';
 
---let $rpl_only_running_threads= 1
+
+#
+# BUG#11809016 - NO WAY TO DISCOVER AN INSTANCE IS NO LONGER A SLAVE FOLLOWING MYSQL BUG#28796
+#
+
+reset slave;
+--source include/start_slave.inc
+
+--source include/stop_slave.inc
+--let $_slave_master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1)
+--let $_slave_master_user= query_get_value(SHOW SLAVE STATUS, Master_User, 1)
+--let $_slave_master_port= query_get_value(SHOW SLAVE STATUS, Master_Port, 1)
+
+reset slave all;
+--error ER_BAD_SLAVE
+start slave;
+
+--let $_show_master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1)
+if ($_show_master_host != No such row)
+{
+  die;
+}
+
+--replace_result $_slave_master_host MASTER_HOST $_slave_master_user MASTER_USER $_slave_master_port MASTER_PORT
+--eval CHANGE MASTER TO MASTER_HOST= '$_slave_master_host', MASTER_USER= '$_slave_master_user', MASTER_PORT= $_slave_master_port
+--source include/start_slave.inc
+
 --source include/rpl_end.inc

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

@@ -41,4 +41,12 @@ include/stop_slave_sql.inc
 reset slave;
 include/check_slave_no_error.inc
 change master to master_user='root';
+reset slave;
+include/start_slave.inc
+include/stop_slave.inc
+reset slave all;
+start slave;
+ERROR HY000: The server is not configured as slave; fix in config file or with CHANGE MASTER TO
+CHANGE MASTER TO MASTER_HOST= 'MASTER_HOST', MASTER_USER= 'MASTER_USER', MASTER_PORT= MASTER_PORT;
+include/start_slave.inc
 include/rpl_end.inc

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

@@ -41,4 +41,12 @@ include/stop_slave_sql.inc
 reset slave;
 include/check_slave_no_error.inc
 change master to master_user='root';
+reset slave;
+include/start_slave.inc
+include/stop_slave.inc
+reset slave all;
+start slave;
+ERROR HY000: The server is not configured as slave; fix in config file or with CHANGE MASTER TO
+CHANGE MASTER TO MASTER_HOST= 'MASTER_HOST', MASTER_USER= 'MASTER_USER', MASTER_PORT= MASTER_PORT;
+include/start_slave.inc
 include/rpl_end.inc

sql/rpl_mi.cc

@@ -31,6 +31,8 @@ int init_strvar_from_file(char *var, int max_size, IO_CACHE *f,
 int init_floatvar_from_file(float* var, IO_CACHE* f, float default_val);
 int init_dynarray_intvar_from_file(DYNAMIC_ARRAY* arr, IO_CACHE* f);
 
+static void init_master_log_pos(Master_info* mi);
+
 Master_info::Master_info(bool is_slave_recovery)
   :Slave_reporting_capability("I/O"),
    ssl(0), ssl_verify_server_cert(0), fd(-1), io_thd(0), 
@@ -100,6 +102,16 @@ bool Master_info::shall_ignore_server_id(ulong s_id)
       != NULL;
 }
 
+void Master_info::clear_in_memory_info(bool all)
+{
+  init_master_log_pos(this);
+  if (all)
+  {
+    port= MYSQL_PORT;
+    host[0] = 0; user[0] = 0; password[0] = 0;
+  }
+}
+
 void init_master_log_pos(Master_info* mi)
 {
   DBUG_ENTER("init_master_log_pos");
@@ -234,7 +246,7 @@ file '%s')", fname);
     }
 
     mi->fd = fd;
-    init_master_log_pos(mi);
+    mi->clear_in_memory_info(false);
 
   }
   else // file exists

sql/rpl_mi.h

@@ -62,6 +62,7 @@ class Master_info : public Slave_reporting_capability
   Master_info(bool is_slave_recovery);
   ~Master_info();
   bool shall_ignore_server_id(ulong s_id);
+  void clear_in_memory_info(bool all);
 
   /* the variables below are needed because we can change masters on the fly */
   char master_log_name[FN_REFLEN];
@@ -113,7 +114,6 @@ class Master_info : public Slave_reporting_capability
   DYNAMIC_ARRAY ignore_server_ids;
   ulong master_id;
 };
-void init_master_log_pos(Master_info* mi);
 int init_master_info(Master_info* mi, const char* master_info_fname,
 		     const char* slave_info_fname,
 		     bool abort_if_no_master_info_file,

sql/sql_lex.h

@@ -294,6 +294,10 @@ typedef struct st_lex_master_info
   DYNAMIC_ARRAY repl_ignore_server_ids;
 } LEX_MASTER_INFO;
 
+typedef struct st_lex_reset_slave
+{
+  bool all;
+} LEX_RESET_SLAVE;
 
 enum sub_select_type
 {
@@ -2232,6 +2236,7 @@ struct LEX: public Query_tables_list
   LEX_MASTER_INFO mi;				// used by CHANGE MASTER
   LEX_SERVER_OPTIONS server_options;
   USER_RESOURCES mqh;
+  LEX_RESET_SLAVE reset_slave_info;
   ulong type;
   /*
     This variable is used in post-parse stage to declare that sum-functions,

sql/sql_repl.cc

@@ -1285,8 +1285,9 @@ int reset_slave(THD *thd, Master_info* mi)
     goto err;
   }
 
-  /* Clear master's log coordinates */
-  init_master_log_pos(mi);
+  /* Clear master's log coordinates and associated information */
+  mi->clear_in_memory_info(thd->lex->reset_slave_info.all);
+
   /*
      Reset errors (the idea is that we forget about the
      old master).

sql/sql_yacc.yy

@@ -11337,10 +11337,16 @@ reset_options:
 
 reset_option:
           SLAVE               { Lex->type|= REFRESH_SLAVE; }
+          slave_reset_options { }
         | MASTER_SYM          { Lex->type|= REFRESH_MASTER; }
         | QUERY_SYM CACHE_SYM { Lex->type|= REFRESH_QUERY_CACHE;}
         ;
 
+slave_reset_options:
+          /* empty */ { Lex->reset_slave_info.all= false; }
+        | ALL         { Lex->reset_slave_info.all= true; }
+        ;
+
 purge:
           PURGE
           {