Bug#13437900 - VALGRIND REPORTS A LEAK FOR REPL_IGNORE_SERVER_IDS

There was memory leak when running some tests on PB2.
The reason of the failure is an early return from change_master()
that was supposed to deallocate a dyn-array.

Fixed with relocating the dyn-array's destructor at ~LEX() that is
the end of the session, per Gleb's patch idea.
Two optimizations were done: the static buffer for the dyn-array to base on,
and the array initialization is called precisely when it's necessary rather than
per each CHANGE-MASTER as before.
 

mysql-test/suite/rpl/t/rpl_empty_master_host.test

@@ -17,6 +17,7 @@
 #   working when expected.
 
 --source include/master-slave.inc
+--source include/have_binlog_format_mixed.inc
 
 connection slave;
 STOP SLAVE;

sql/sql_lex.cc

@@ -2352,6 +2352,7 @@ LEX::LEX()
                          INITIAL_LEX_PLUGIN_LIST_SIZE, 
                          INITIAL_LEX_PLUGIN_LIST_SIZE);
   reset_query_tables_list(TRUE);
+  repl_ignore_server_ids_inited= false;
 }
 
 

sql/sql_lex.h

@@ -291,7 +291,9 @@ typedef struct st_lex_master_info
   char *ssl_key, *ssl_cert, *ssl_ca, *ssl_capath, *ssl_cipher;
   char *relay_log_name;
   ulong relay_log_pos;
+  bool repl_ignore_server_ids_inited;
   DYNAMIC_ARRAY repl_ignore_server_ids;
+  typeof(::server_id) repl_ignore_server_ids_static_buffer[4];
 } LEX_MASTER_INFO;
 
 typedef struct st_lex_reset_slave
@@ -2455,6 +2457,11 @@ struct LEX: public Query_tables_list
     destroy_query_tables_list();
     plugin_unlock_list(NULL, (plugin_ref *)plugins.buffer, plugins.elements);
     delete_dynamic(&plugins);
+    if (mi.repl_ignore_server_ids_inited)
+    {
+      delete_dynamic(&mi.repl_ignore_server_ids);
+      mi.repl_ignore_server_ids_inited= false;
+    }
   }
 
   inline bool is_ps_or_view_context_analysis()

sql/sql_repl.cc

@@ -1689,7 +1689,6 @@ bool change_master(THD* thd, Master_info* mi)
   thd_proc_info(thd, 0);
   if (ret == FALSE)
     my_ok(thd);
-  delete_dynamic(&lex_mi->repl_ignore_server_ids); //freeing of parser-time alloc
   DBUG_RETURN(ret);
 }
 

sql/sql_yacc.yy

@@ -1863,12 +1863,7 @@ change:
             LEX *lex = Lex;
             lex->sql_command = SQLCOM_CHANGE_MASTER;
             bzero((char*) &lex->mi, sizeof(lex->mi));
-            /*
-              resetting flags that can left from the previous CHANGE MASTER
-            */
             lex->mi.repl_ignore_server_ids_opt= LEX_MASTER_INFO::LEX_MI_UNCHANGED;
-            my_init_dynamic_array(&Lex->mi.repl_ignore_server_ids,
-                                  sizeof(::server_id), 16, 16);
           }
           master_defs
           {}
@@ -1965,7 +1960,7 @@ master_def:
         | IGNORE_SERVER_IDS_SYM EQ '(' ignore_server_id_list ')'
           {
             Lex->mi.repl_ignore_server_ids_opt= LEX_MASTER_INFO::LEX_MI_ENABLE;
-           }
+          }
         |
         master_file_def
         ;
@@ -1979,6 +1974,15 @@ ignore_server_id_list:
 ignore_server_id:
           ulong_num
           {
+            if (!Lex->mi.repl_ignore_server_ids_inited)
+            {
+              my_init_dynamic_array2(&Lex->mi.repl_ignore_server_ids,
+                                     sizeof(::server_id),
+                                     Lex->mi.repl_ignore_server_ids_static_buffer,
+                                     array_elements(Lex->mi.repl_ignore_server_ids_static_buffer),
+                                     16);
+              Lex->mi.repl_ignore_server_ids_inited= true;
+            }
             insert_dynamic(&Lex->mi.repl_ignore_server_ids, (uchar*) &($1));
           }