Fix for BUG#1086. Now we don't preserve event's log_pos through

log-slave-updates since this causes unexpected values in 
Exec_master_log_pos in A->B->C replication setup, synchronization
 problems in master_pos_wait()... 
Still this brokes some functionality in sql/repl_failsafe.cc 
(but this file is not used now)

mysql-test/r/rpl_log.result

@@ -85,15 +85,15 @@ slave-bin.001	263	Query	1	263	use test; drop table t1
 slave-bin.001	311	Query	1	311	use test; create table t1 (word char(20) not null)
 slave-bin.001	386	Create_file	1	386	db=test;table=t1;file_id=1;block_len=581
 slave-bin.001	1065	Exec_load	1	1056	;file_id=1
-slave-bin.001	1088	Query	1	1079	use test; drop table t1
-slave-bin.001	1136	Query	1	4	use test; create table t5 (a int)
-slave-bin.001	1194	Query	1	62	use test; drop table t5
+slave-bin.001	1088	Query	1	1088	use test; drop table t1
+slave-bin.001	1136	Query	1	1136	use test; create table t5 (a int)
+slave-bin.001	1194	Query	1	1194	use test; drop table t5
 slave-bin.001	1242	Rotate	2	1242	slave-bin.002;pos=4
 show binlog events in 'slave-bin.002' from 4;
 Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
-slave-bin.002	4	Query	1	110	use test; create table t1 (n int)
-slave-bin.002	62	Query	1	168	use test; insert into t1 values (1)
-slave-bin.002	122	Query	1	228	use test; drop table t1
+slave-bin.002	4	Query	1	4	use test; create table t1 (n int)
+slave-bin.002	62	Query	1	62	use test; insert into t1 values (1)
+slave-bin.002	122	Query	1	122	use test; drop table t1
 show slave status;
 Master_Host	Master_User	Master_Port	Connect_retry	Master_Log_File	Read_Master_Log_Pos	Relay_Log_File	Relay_Log_Pos	Relay_Master_Log_File	Slave_IO_Running	Slave_SQL_Running	Replicate_do_db	Replicate_ignore_db	Last_errno	Last_error	Skip_counter	Exec_master_log_pos	Relay_log_space
 127.0.0.1	root	MASTER_PORT	1	master-bin.002	276	slave-relay-bin.003	211	master-bin.002	Yes	Yes			0		0	276	211

sql/log_event.cc

@@ -119,12 +119,11 @@ const char* Log_event::get_type_str()
 
 #ifndef MYSQL_CLIENT
 Log_event::Log_event(THD* thd_arg, uint16 flags_arg, bool using_trans)
-  :temp_buf(0), exec_time(0), cached_event_len(0), flags(flags_arg), 
-   thd(thd_arg)
+  :log_pos(0), temp_buf(0), exec_time(0), cached_event_len(0), 
+   flags(flags_arg), thd(thd_arg)
 {
   server_id = thd->server_id;
   when = thd->start_time;
-  log_pos = thd->log_pos;
   cache_stmt= (using_trans &&
 	       (thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)));
 }

sql/repl_failsafe.cc

@@ -249,6 +249,18 @@ static int find_target_pos(LEX_MASTER_INFO *mi, IO_CACHE *log, char *errmsg)
   /* Impossible */
 }
 
+/* 
+  Before 4.0.15 we had a member of THD called log_pos, it was meant for
+  failsafe replication code in repl_failsafe.cc which is disabled until
+  it is reworked. Event's log_pos used to be preserved through 
+  log-slave-updates to make code in repl_failsafe.cc work (this 
+  function, SHOW NEW MASTER); but on the other side it caused unexpected
+  values in Exec_master_log_pos in A->B->C replication setup, 
+  synchronization problems in master_pos_wait(), ... So we 
+  (Dmitri & Guilhem) removed it.
+  
+  So for now this function is broken. 
+*/
 
 int translate_master(THD* thd, LEX_MASTER_INFO* mi, char* errmsg)
 {
@@ -414,6 +426,9 @@ static Slave_log_event* find_slave_event(IO_CACHE* log,
   return (Slave_log_event*)ev;
 }
 
+/*
+   This function is broken now. See comment for translate_master().
+ */
 
 int show_new_master(THD* thd)
 {

sql/slave.cc

@@ -2253,7 +2253,6 @@ static int exec_relay_log_event(THD* thd, RELAY_LOG_INFO* rli)
     if (!ev->when)
       ev->when = time(NULL);
     ev->thd = thd;
-    thd->log_pos = ev->log_pos;
     exec_res = ev->exec_event(rli);
     DBUG_ASSERT(rli->sql_thd==thd);
     delete ev;

sql/sql_class.cc

@@ -125,7 +125,6 @@ THD::THD():user_time(0),fatal_error(0),last_insert_id_used(0),
   where="field list";
   server_id = ::server_id;
   slave_net = 0;
-  log_pos = 0;
   command=COM_CONNECT;
   set_query_id=1;
   db_access=NO_ACCESS;

sql/sql_class.h

@@ -472,7 +472,6 @@ public:
   */
   ulong	     slave_proxy_id;
   NET*       slave_net;			// network connection from slave -> m.
-  my_off_t   log_pos;
    
   /* Used by the sys_var class to store temporary values */
   union

sql/sql_parse.cc

@@ -1458,6 +1458,7 @@ mysql_execute_command(void)
   {
     if (check_global_access(thd, REPL_SLAVE_ACL))
       goto error;
+    /* This query don't work now. See comment in repl_failsafe.cc */
 #ifndef WORKING_NEW_MASTER
     net_printf(&thd->net, ER_NOT_SUPPORTED_YET, "SHOW NEW MASTER");
     res= 1;