WL#912 (more user control on relay logs):

FLUSH LOGS now rotates relay logs,
and a new variable max_relay_log_size.
Plus a very small bit of code cleaning.

libmysqld/lib_sql.cc

@@ -511,17 +511,17 @@ int STDCALL mysql_server_init(int argc, char **argv, char **groups)
   /* Setup log files */
   if (opt_log)
     open_log(&mysql_log, glob_hostname, opt_logname, ".log", NullS,
-	     LOG_NORMAL);
+	     LOG_NORMAL, 0, 0, 0);
   if (opt_update_log)
   {
     open_log(&mysql_update_log, glob_hostname, opt_update_logname, "",
-	     NullS, LOG_NEW);
+	     NullS, LOG_NEW, 0, 0, 0);
     using_update_log=1;
   }
 
   if (opt_slow_log)
     open_log(&mysql_slow_log, glob_hostname, opt_slow_logname, "-slow.log",
-	     NullS, LOG_NORMAL);
+	     NullS, LOG_NORMAL, 0, 0, 0);
   if (ha_init())
   {
     sql_print_error("Can't init databases");
@@ -586,7 +586,7 @@ int STDCALL mysql_server_init(int argc, char **argv, char **groups)
       opt_bin_logname=my_strdup(tmp,MYF(MY_WME));
     }
     open_log(&mysql_bin_log, glob_hostname, opt_bin_logname, "-bin",
-	     opt_binlog_index_name, LOG_BIN);
+	     opt_binlog_index_name, LOG_BIN, 0, 0, max_binlog_size);
     using_update_log=1;
   }
 

mysql-test/r/rpl_flush_log_loop.result

@@ -14,4 +14,4 @@ slave start;
 flush logs;
 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	SLAVE_PORT	60	slave-bin.001	79	relay-log.001	119	slave-bin.001	Yes	Yes			0		0	79	119
+127.0.0.1	root	SLAVE_PORT	60	slave-bin.001	79	relay-log.002	119	slave-bin.001	Yes	Yes			0		0	79	119

mysql-test/r/rpl_log.result

@@ -93,6 +93,6 @@ 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
 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.002	1563	master-bin.002	Yes	Yes			0		0	276	1563
+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
 show binlog events in 'slave-bin.005' from 4;
 Error when executing command SHOW BINLOG EVENTS: Could not find target log

mysql-test/r/rpl_max_relay_size.result

+slave stop;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+slave start;
+stop slave;
+create table t1 (a int);
+drop table t1;
+reset slave;
+set global max_binlog_size=8192;
+set global max_relay_log_size=8192-1;
+select @@global.max_relay_log_size;
+@@global.max_relay_log_size
+4096
+start slave;
+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	9306	1	master-bin.001	50477	slave-relay-bin.014	1221	master-bin.001	Yes	Yes			0		0	50477	1221
+stop slave;
+reset slave;
+set global max_relay_log_size=(5*4096);
+select @@global.max_relay_log_size;
+@@global.max_relay_log_size
+20480
+start slave;
+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	9306	1	master-bin.001	50477	slave-relay-bin.004	9457	master-bin.001	Yes	Yes			0		0	50477	9457
+stop slave;
+reset slave;
+set global max_relay_log_size=0;
+select @@global.max_relay_log_size;
+@@global.max_relay_log_size
+0
+start slave;
+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	9306	1	master-bin.001	50477	slave-relay-bin.008	1283	master-bin.001	Yes	Yes			0		0	50477	1283
+stop slave;
+reset slave;
+flush logs;
+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	9306	1		4	slave-relay-bin.001	4		No	No			0		0	0	4
+reset slave;
+start slave;
+flush logs;
+create table t1 (a int);
+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	9306	1	master-bin.001	50535	slave-relay-bin.009	62	master-bin.001	Yes	Yes			0		0	50535	62
+flush logs;
+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	9306	1	master-bin.001	50583	slave-relay-bin.010	52	master-bin.001	Yes	Yes			0		0	50583	52
+flush logs;
+show master status;
+File	Position	Binlog_do_db	Binlog_ignore_db
+master-bin.002	4		

mysql-test/r/rpl_rotate_logs.result

@@ -65,17 +65,15 @@ show master logs;
 Log_name
 master-bin.003
 master-bin.004
-master-bin.005
-master-bin.006
 show master status;
 File	Position	Binlog_do_db	Binlog_ignore_db
-master-bin.006	838		
+master-bin.004	2886		
 select * from t4;
 a
 testing temporary tables part 2
 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	60	master-bin.006	838	slave-relay-bin.001	8034	master-bin.006	Yes	Yes			0		0	838	8034
+127.0.0.1	root	MASTER_PORT	60	master-bin.004	2886	slave-relay-bin.001	7870	master-bin.004	Yes	Yes			0		0	2886	7870
 lock tables t3 read;
 select count(*) from t3 where n >= 4;
 count(*)

mysql-test/t/rpl_max_relay_size.test

+# Test of options max_binlog_size and max_relay_log_size and
+# how they act (if max_relay_log_size == 0, use max_binlog_size 
+# for relay logs too).
+# Test of manual relay log rotation with FLUSH LOGS.
+
+source include/master-slave.inc;
+connection slave;
+stop slave;
+connection master;
+# Generate a big enough master's binlog to cause relay log rotations
+create table t1 (a int);
+let $1=800;
+disable_query_log;
+begin;
+while ($1)
+{
+# eval means expand $ expressions
+ eval insert into t1 values( $1 );
+ dec $1;
+}
+enable_query_log;
+drop table t1;
+save_master_pos;
+connection slave;
+reset slave;
+set global max_binlog_size=8192;
+set global max_relay_log_size=8192-1; # mapped to 4096
+select @@global.max_relay_log_size;
+start slave;
+sync_with_master;
+show slave status;
+stop slave;
+reset slave;
+set global max_relay_log_size=(5*4096);
+select @@global.max_relay_log_size;
+start slave;
+sync_with_master;
+show slave status;
+stop slave;
+reset slave;
+set global max_relay_log_size=0;
+select @@global.max_relay_log_size;
+start slave;
+sync_with_master;
+show slave status;
+
+# Tests below are mainly to ensure that we have not coded with wrong assumptions
+
+stop slave;
+reset slave;
+# test of relay log rotation when the slave is stopped
+# (to make sure it does not crash).
+flush logs;
+show slave status;
+
+reset slave;
+start slave;
+sync_with_master;
+# test of relay log rotation when the slave is started
+flush logs;
+# We have now easy way to be sure that the SQL thread has now deleted the
+# log we just closed. But a trick to achieve this is do an update on the master.
+connection master;
+create table t1 (a int);
+save_master_pos;
+connection slave;
+sync_with_master;
+show slave status;
+# one more rotation, to be sure Relay_log_space is correctly updated
+flush logs;
+connection master;
+drop table t1;
+save_master_pos;
+connection slave;
+sync_with_master;
+show slave status;
+
+connection master;
+# test that the absence of relay logs does not make a master crash
+flush logs;
+show master status;

mysql-test/t/rpl_rotate_logs-master.opt

--O max_binlog_size=2048
+-O max_binlog_size=4096

sql/log.cc

@@ -133,11 +133,15 @@ int MYSQL_LOG::generate_new_name(char *new_name, const char *log_name)
 
 void MYSQL_LOG::init(enum_log_type log_type_arg,
 		     enum cache_type io_cache_type_arg,
-		     bool no_auto_events_arg)
+		     bool no_auto_events_arg,
+                     ulong max_size_arg)
 {
+  DBUG_ENTER("MYSQL_LOG::init");
   log_type = log_type_arg;
   io_cache_type = io_cache_type_arg;
   no_auto_events = no_auto_events_arg;
+  max_size=max_size_arg;
+  DBUG_PRINT("info",("log_type=%d max_size=%lu", log_type, max_size));
   if (!inited)
   {
     inited= 1;
@@ -145,6 +149,7 @@ void MYSQL_LOG::init(enum_log_type log_type_arg,
     (void) pthread_mutex_init(&LOCK_index, MY_MUTEX_INIT_SLOW);
     (void) pthread_cond_init(&update_cond, 0);
   }
+  DBUG_VOID_RETURN;
 }
 
 
@@ -165,7 +170,8 @@ void MYSQL_LOG::init(enum_log_type log_type_arg,
 bool MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
 		     const char *new_name, const char *index_file_name_arg,
 		     enum cache_type io_cache_type_arg,
-		     bool no_auto_events_arg)
+		     bool no_auto_events_arg,
+                     ulong max_size)
 {
   char buff[512];
   File file= -1, index_file_nr= -1;
@@ -178,7 +184,7 @@ bool MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
 
   if (!inited && log_type_arg == LOG_BIN && *fn_ext(log_name))
     no_rotate = 1;
-  init(log_type_arg,io_cache_type_arg,no_auto_events_arg);
+  init(log_type_arg,io_cache_type_arg,no_auto_events_arg,max_size);
   
   if (!(name=my_strdup(log_name,MYF(MY_WME))))
     goto err;
@@ -577,7 +583,7 @@ bool MYSQL_LOG::reset_logs(THD* thd)
   if (!thd->slave_thread)
     need_start_event=1;
   open(save_name, save_log_type, 0, index_file_name,
-       io_cache_type, no_auto_events);
+       io_cache_type, no_auto_events, max_size);
   my_free((gptr) save_name, MYF(0));
 
 err:  
@@ -802,8 +808,12 @@ void MYSQL_LOG::new_file(bool need_lock)
   char new_name[FN_REFLEN], *new_name_ptr, *old_name;
   enum_log_type save_log_type;
 
+  DBUG_ENTER("MYSQL_LOG::new_file");
   if (!is_open())
-    return;					// Should never happen
+  {
+    DBUG_PRINT("info",("log is closed"));
+    DBUG_VOID_RETURN;
+  }
 
   if (need_lock)
   {
@@ -865,8 +875,16 @@ void MYSQL_LOG::new_file(bool need_lock)
   save_log_type=log_type;
   name=0;				// Don't free name
   close();
+/*
+  if (save_log_type == LOG_BIN)
+  {
+    printf("after close, before open; I wait for 20 seconds\n");
+    sleep(20);
+    printf("sleep finished, opening\n");
+  }
+*/
   open(old_name, save_log_type, new_name_ptr, index_file_name, io_cache_type,
-       no_auto_events);
+       no_auto_events, max_size);
   my_free(old_name,MYF(0));
 
 end:
@@ -875,6 +893,7 @@ void MYSQL_LOG::new_file(bool need_lock)
     pthread_mutex_unlock(&LOCK_index);
     pthread_mutex_unlock(&LOCK_log);
   }
+  DBUG_VOID_RETURN;
 }
 
 
@@ -882,6 +901,7 @@ bool MYSQL_LOG::append(Log_event* ev)
 {
   bool error = 0;
   pthread_mutex_lock(&LOCK_log);
+  DBUG_ENTER("MYSQL_LOG::append");
 
   DBUG_ASSERT(log_file.type == SEQ_READ_APPEND);
   /*
@@ -894,7 +914,8 @@ bool MYSQL_LOG::append(Log_event* ev)
     goto err;
   }
   bytes_written += ev->get_event_len();
-  if ((uint) my_b_append_tell(&log_file) > max_binlog_size)
+  DBUG_PRINT("info",("max_size=%lu",max_size));
+  if ((uint) my_b_append_tell(&log_file) > max_size)
   {
     pthread_mutex_lock(&LOCK_index);
     new_file(0);
@@ -904,13 +925,14 @@ bool MYSQL_LOG::append(Log_event* ev)
 err:  
   pthread_mutex_unlock(&LOCK_log);
   signal_update();				// Safe as we don't call close
-  return error;
+  DBUG_RETURN(error);
 }
 
 
 bool MYSQL_LOG::appendv(const char* buf, uint len,...)
 {
   bool error= 0;
+  DBUG_ENTER("MYSQL_LOG::appendv");
   va_list(args);
   va_start(args,len);
   
@@ -926,8 +948,8 @@ bool MYSQL_LOG::appendv(const char* buf, uint len,...)
     }
     bytes_written += len;
   } while ((buf=va_arg(args,const char*)) && (len=va_arg(args,uint)));
-  
-  if ((uint) my_b_append_tell(&log_file) > max_binlog_size)
+  DBUG_PRINT("info",("max_size=%lu",max_size));
+  if ((uint) my_b_append_tell(&log_file) > max_size)
   {
     pthread_mutex_lock(&LOCK_index);
     new_file(0);
@@ -938,7 +960,7 @@ bool MYSQL_LOG::appendv(const char* buf, uint len,...)
   pthread_mutex_unlock(&LOCK_log);
   if (!error)
     signal_update();
-  return error;
+  DBUG_RETURN(error);
 }
 
 
@@ -1188,8 +1210,9 @@ bool MYSQL_LOG::write(Log_event* event_info)
           called_handler_commit=1;
         }
       }
-      /* we wrote to the real log, check automatic rotation */
-      should_rotate= (my_b_tell(file) >= (my_off_t) max_binlog_size); 
+      /* We wrote to the real log, check automatic rotation; */
+      DBUG_PRINT("info",("max_size=%lu",max_size));      
+      should_rotate= (my_b_tell(file) >= (my_off_t) max_size); 
     }
     error=0;
 
@@ -1319,7 +1342,8 @@ bool MYSQL_LOG::write(THD *thd, IO_CACHE *cache)
 					    log_file.pos_in_file)))
       goto err;
     signal_update();
-    if (my_b_tell(&log_file) >= (my_off_t) max_binlog_size)
+    DBUG_PRINT("info",("max_size=%lu",max_size));
+    if (my_b_tell(&log_file) >= (my_off_t) max_size)
     {
       pthread_mutex_lock(&LOCK_index);
       new_file(0); // inside mutex
@@ -1563,6 +1587,24 @@ void MYSQL_LOG::close(bool exiting)
   DBUG_VOID_RETURN;
 }
 
+void MYSQL_LOG::set_max_size(ulong max_size_arg)
+{
+  /*
+    We need to take locks, otherwise this may happen:
+    new_file() is called, calls open(old_max_size), then before open() starts,
+    set_max_size() sets max_size to max_size_arg, then open() starts and
+    uses the old_max_size argument, so max_size_arg has been overwritten and
+    it's like if the SET command was never run.
+  */
+  if (is_open())
+  {
+    pthread_mutex_lock(&LOCK_log);
+    pthread_mutex_lock(&LOCK_index);
+    max_size= max_size_arg;
+    pthread_mutex_unlock(&LOCK_index);
+    pthread_mutex_unlock(&LOCK_log);
+  }
+}
 
 /*
   Check if a string is a valid number

sql/mysql_priv.h

@@ -606,8 +606,8 @@ bool fn_format_relative_to_data_home(my_string to, const char *name,
 bool open_log(MYSQL_LOG *log, const char *hostname,
 	      const char *opt_name, const char *extension,
 	      const char *index_file_name,
-	      enum_log_type type, bool read_append = 0,
-	      bool no_auto_events = 0);
+	      enum_log_type type, bool read_append,
+	      bool no_auto_events, ulong max_size);
 /* mysqld.cc */
 void clear_error_message(THD *thd);
 
@@ -654,7 +654,8 @@ extern ulong max_insert_delayed_threads, max_user_connections;
 extern ulong long_query_count, what_to_log,flush_time,opt_sql_mode;
 extern ulong query_buff_size, thread_stack,thread_stack_min;
 extern ulong binlog_cache_size, max_binlog_cache_size, open_files_limit;
-extern ulong max_binlog_size, rpl_recovery_rank, thread_cache_size;
+extern ulong max_binlog_size, max_relay_log_size;
+extern ulong rpl_recovery_rank, thread_cache_size;
 extern ulong com_stat[(uint) SQLCOM_END], com_other, back_log;
 extern ulong specialflag, current_pid;
 

sql/mysqld.cc

@@ -354,7 +354,7 @@ ulong table_cache_size,
       query_buff_size,
       slow_launch_time = 2L,
       slave_open_temp_tables=0,
-      open_files_limit=0, max_binlog_size;
+      open_files_limit=0, max_binlog_size, max_relay_log_size;
 ulong com_stat[(uint) SQLCOM_END], com_other;
 ulong slave_net_timeout;
 ulong thread_cache_size=0, binlog_cache_size=0, max_binlog_cache_size=0;
@@ -1950,7 +1950,7 @@ bool open_log(MYSQL_LOG *log, const char *hostname,
 	      const char *opt_name, const char *extension,
 	      const char *index_file_name,
 	      enum_log_type type, bool read_append,
-	      bool no_auto_events)
+	      bool no_auto_events, ulong max_size)
 {
   char tmp[FN_REFLEN];
   if (!opt_name || !opt_name[0])
@@ -1976,7 +1976,7 @@ bool open_log(MYSQL_LOG *log, const char *hostname,
   }
   return log->open(opt_name, type, 0, index_file_name,
 		   (read_append) ? SEQ_READ_APPEND : WRITE_CACHE,
-		   no_auto_events);
+		   no_auto_events, max_size);
 }
 
 
@@ -2196,17 +2196,17 @@ int main(int argc, char **argv)
   /* Setup log files */
   if (opt_log)
     open_log(&mysql_log, glob_hostname, opt_logname, ".log", NullS,
-	     LOG_NORMAL);
+	     LOG_NORMAL, 0, 0, 0);
   if (opt_update_log)
   {
     open_log(&mysql_update_log, glob_hostname, opt_update_logname, "",
-	     NullS, LOG_NEW);
+	     NullS, LOG_NEW, 0, 0, 0);
     using_update_log=1;
   }
  
   if (opt_slow_log)
     open_log(&mysql_slow_log, glob_hostname, opt_slow_logname, "-slow.log",
-	     NullS, LOG_NORMAL);
+	     NullS, LOG_NORMAL, 0, 0, 0);
 
   if (opt_error_log)
   {
@@ -2321,7 +2321,7 @@ The server will not act as a slave.");
   if (opt_bin_log)
   {
     open_log(&mysql_bin_log, glob_hostname, opt_bin_logname, "-bin",
-	     opt_binlog_index_name,LOG_BIN);
+	     opt_binlog_index_name, LOG_BIN, 0, 0, max_binlog_size);
     using_update_log=1;
   }
   else if (opt_log_slave_updates)
@@ -3156,8 +3156,8 @@ enum options {
   OPT_MAX_BINLOG_CACHE_SIZE, OPT_MAX_BINLOG_SIZE,
   OPT_MAX_CONNECTIONS, OPT_MAX_CONNECT_ERRORS,
   OPT_MAX_DELAYED_THREADS, OPT_MAX_HEP_TABLE_SIZE,
-  OPT_MAX_JOIN_SIZE, OPT_MAX_SORT_LENGTH, OPT_MAX_SEEKS_FOR_KEY,
-  OPT_MAX_TMP_TABLES, OPT_MAX_USER_CONNECTIONS,
+  OPT_MAX_JOIN_SIZE, OPT_MAX_RELAY_LOG_SIZE, OPT_MAX_SORT_LENGTH, 
+  OPT_MAX_SEEKS_FOR_KEY, OPT_MAX_TMP_TABLES, OPT_MAX_USER_CONNECTIONS,
   OPT_MAX_WRITE_LOCK_COUNT, OPT_BULK_INSERT_BUFFER_SIZE,
   OPT_MYISAM_BLOCK_SIZE, OPT_MYISAM_MAX_EXTRA_SORT_FILE_SIZE,
   OPT_MYISAM_MAX_SORT_FILE_SIZE, OPT_MYISAM_SORT_BUFFER_SIZE,
@@ -3809,9 +3809,11 @@ replicating a LOAD DATA INFILE command",
    (gptr*) &max_binlog_cache_size, (gptr*) &max_binlog_cache_size, 0,
    GET_ULONG, REQUIRED_ARG, ~0L, IO_SIZE, ~0L, 0, IO_SIZE, 0},
   {"max_binlog_size", OPT_MAX_BINLOG_SIZE,
-   "Binary log will be rotated automatically when the size crosses the limit.",
+   "Binary log will be rotated automatically when the size exceeds this \
+value. Will also apply to relay logs if max_relay_log_size is 0. \
+The minimum value for this variable is 4096.",
    (gptr*) &max_binlog_size, (gptr*) &max_binlog_size, 0, GET_ULONG,
-   REQUIRED_ARG, 1024*1024L*1024L, 1024, 1024*1024L*1024L, 0, 1, 0},
+   REQUIRED_ARG, 1024*1024L*1024L, IO_SIZE, 1024*1024L*1024L, 0, IO_SIZE, 0},
   {"max_connections", OPT_MAX_CONNECTIONS,
    "The number of simultaneous clients allowed.", (gptr*) &max_connections,
    (gptr*) &max_connections, 0, GET_ULONG, REQUIRED_ARG, 100, 1, 16384, 0, 1,
@@ -3834,6 +3836,12 @@ replicating a LOAD DATA INFILE command",
    (gptr*) &global_system_variables.max_join_size,
    (gptr*) &max_system_variables.max_join_size, 0, GET_HA_ROWS, REQUIRED_ARG,
    ~0L, 1, ~0L, 0, 1, 0},
+  {"max_relay_log_size", OPT_MAX_RELAY_LOG_SIZE,
+   "If non-zero: relay log will be rotated automatically when the size exceeds \
+this value; if zero (the default): when the size exceeds max_binlog_size. \
+0 expected, the minimum value for this variable is 4096.",
+   (gptr*) &max_relay_log_size, (gptr*) &max_relay_log_size, 0, GET_ULONG,
+   REQUIRED_ARG, 0L, 0L, 1024*1024L*1024L, 0, IO_SIZE, 0},
   { "max_seeks_for_key", OPT_MAX_SEEKS_FOR_KEY,
     "Limit assumed max number of seeks when looking up rows based on a key",
     (gptr*) &global_system_variables.max_seeks_for_key,

sql/set_var.cc

@@ -84,6 +84,8 @@ static void fix_query_cache_size(THD *thd, enum_var_type type);
 static void fix_key_buffer_size(THD *thd, enum_var_type type);
 static void fix_myisam_max_extra_sort_file_size(THD *thd, enum_var_type type);
 static void fix_myisam_max_sort_file_size(THD *thd, enum_var_type type);
+static void fix_max_binlog_size(THD *thd, enum_var_type type);
+static void fix_max_relay_log_size(THD *thd, enum_var_type type);
 
 /*
   Variable definition list
@@ -142,7 +144,8 @@ sys_var_thd_ulong	sys_max_allowed_packet("max_allowed_packet",
 sys_var_long_ptr	sys_max_binlog_cache_size("max_binlog_cache_size",
 						  &max_binlog_cache_size);
 sys_var_long_ptr	sys_max_binlog_size("max_binlog_size",
-					    &max_binlog_size);
+					    &max_binlog_size,
+                                            fix_max_binlog_size);
 sys_var_long_ptr	sys_max_connections("max_connections",
 					    &max_connections);
 sys_var_long_ptr	sys_max_connect_errors("max_connect_errors",
@@ -161,6 +164,9 @@ sys_var_thd_ha_rows	sys_sql_max_join_size("sql_max_join_size",
 					      &SV::max_join_size,
 					      fix_max_join_size);
 #endif
+sys_var_long_ptr	sys_max_relay_log_size("max_relay_log_size",
+                                               &max_relay_log_size,
+                                               fix_max_relay_log_size);
 sys_var_thd_ulong	sys_max_sort_length("max_sort_length",
 					    &SV::max_sort_length);
 sys_var_long_ptr	sys_max_user_connections("max_user_connections",
@@ -350,6 +356,7 @@ sys_var *sys_variables[]=
   &sys_max_delayed_threads,
   &sys_max_heap_table_size,
   &sys_max_join_size,
+  &sys_max_relay_log_size,
   &sys_max_seeks_for_key,
   &sys_max_sort_length,
   &sys_max_tmp_tables,
@@ -495,6 +502,7 @@ struct show_var_st init_vars[]= {
   {sys_max_delayed_threads.name,(char*) &sys_max_delayed_threads,   SHOW_SYS},
   {sys_max_heap_table_size.name,(char*) &sys_max_heap_table_size,   SHOW_SYS},
   {sys_max_join_size.name,	(char*) &sys_max_join_size,	    SHOW_SYS},
+  {sys_max_relay_log_size.name, (char*) &sys_max_relay_log_size,    SHOW_SYS},
   {sys_max_seeks_for_key.name,  (char*) &sys_max_seeks_for_key,	    SHOW_SYS},
   {sys_max_sort_length.name,	(char*) &sys_max_sort_length,	    SHOW_SYS},
   {sys_max_user_connections.name,(char*) &sys_max_user_connections, SHOW_SYS},
@@ -697,6 +705,26 @@ void fix_delay_key_write(THD *thd, enum_var_type type)
   }
 }
 
+void fix_max_binlog_size(THD *thd, enum_var_type type)
+{
+  DBUG_ENTER("fix_max_binlog_size");
+  DBUG_PRINT("info",("max_binlog_size=%lu max_relay_log_size=%lu",
+                     max_binlog_size, max_relay_log_size));
+  mysql_bin_log.set_max_size(max_binlog_size);
+  if (!max_relay_log_size)
+    active_mi->rli.relay_log.set_max_size(max_binlog_size);
+  DBUG_VOID_RETURN;
+}
+
+void fix_max_relay_log_size(THD *thd, enum_var_type type)
+{
+  DBUG_ENTER("fix_max_relay_log_size");
+  DBUG_PRINT("info",("max_binlog_size=%lu max_relay_log_size=%lu",
+                     max_binlog_size, max_relay_log_size));
+  active_mi->rli.relay_log.set_max_size(max_relay_log_size ?
+                                        max_relay_log_size: max_binlog_size);
+  DBUG_VOID_RETURN;
+}
 
 bool sys_var_long_ptr::update(THD *thd, set_var *var)
 {

sql/slave.cc

@@ -1235,7 +1235,17 @@ int init_relay_log_info(RELAY_LOG_INFO* rli, const char* info_fname)
   if (open_log(&rli->relay_log, glob_hostname, opt_relay_logname,
 	       "-relay-bin", opt_relaylog_index_name,
 	       LOG_BIN, 1 /* read_append cache */,
-	       1 /* no auto events */))
+	       1 /* no auto events */,
+               /*
+                 For the maximum size, we choose max_relay_log_size if it is
+                 non-zero, max_binlog_size otherwise. If later the user does SET
+                 GLOBAL on one of these variables, fix_max_binlog_size and
+                 fix_max_relay_log_size will reconsider the choice (for example
+                 if the user changes max_relay_log_size to zero, we have to
+                 switch to using max_binlog_size for the relay log) and update
+                 rli->relay_log.max_size (and mysql_bin_log.max_size).
+               */
+               max_relay_log_size ? max_relay_log_size : max_binlog_size))
   {
     sql_print_error("Failed in open_log() called from init_relay_log_info()");
     DBUG_RETURN(1);
@@ -3421,6 +3431,46 @@ event(errno: %d  cur_log->error: %d)",
   DBUG_RETURN(0);
 }
 
+/*
+  Rotate a relay log (this is used only by FLUSH LOGS; the automatic rotation
+  because of size is simpler because when we do it we already have all relevant
+  locks; here we don't, so this function is mainly taking locks). 
+  Returns nothing as we cannot catch any error (MYSQL_LOG::new_file() is void).
+*/
+
+void rotate_relay_log(MASTER_INFO* mi)
+{
+  DBUG_ENTER("rotate_relay_log");
+  RELAY_LOG_INFO* rli= &mi->rli;
+  /* If this server is not a slave (or RESET SLAVE has just been run) */
+  if (!rli->inited)
+  {
+    DBUG_PRINT("info", ("rli->inited=0"));
+    DBUG_VOID_RETURN;
+  }
+  lock_slave_threads(mi);
+  pthread_mutex_lock(&rli->data_lock);
+  /* If the relay log is closed, new_file() will do nothing. */
+  rli->relay_log.new_file(1);
+  /*
+    We harvest now, because otherwise BIN_LOG_HEADER_SIZE will not immediately
+    be counted, so imagine a succession of FLUSH LOGS  and assume the slave
+    threads are started:
+    relay_log_space decreases by the size of the deleted relay log, but does not
+    increase, so flush-after-flush we may become negative, which is wrong.
+    Even if this will be corrected as soon as a query is replicated on the slave
+    (because the I/O thread will then call harvest_bytes_written() which will
+    harvest all these BIN_LOG_HEADER_SIZE we forgot), it may give strange output
+    in SHOW SLAVE STATUS meanwhile. So we harvest now.
+    If the log is closed, then this will just harvest the last writes, probably
+    0 as they probably have been harvested.
+  */
+  rli->relay_log.harvest_bytes_written(&rli->log_space_total);
+  pthread_mutex_unlock(&rli->data_lock);
+  unlock_slave_threads(mi);
+  DBUG_VOID_RETURN;
+}
+
 
 #ifdef __GNUC__
 template class I_List_iterator<i_string>;

sql/slave.h

@@ -403,6 +403,7 @@ int init_relay_log_pos(RELAY_LOG_INFO* rli,const char* log,ulonglong pos,
 
 int purge_relay_logs(RELAY_LOG_INFO* rli, THD *thd, bool just_reset,
 		     const char** errmsg);
+void rotate_relay_log(MASTER_INFO* mi);
 
 extern "C" pthread_handler_decl(handle_slave_io,arg);
 extern "C" pthread_handler_decl(handle_slave_sql,arg);

sql/sql_class.h

@@ -84,6 +84,17 @@ class MYSQL_LOG {
   bool no_rotate;
   bool need_start_event;
   bool no_auto_events; // for relay binlog
+  /* 
+     The max size before rotation (usable only if log_type == LOG_BIN: binary
+     logs and relay logs).
+     For a binlog, max_size should be max_binlog_size.
+     For a relay log, it should be max_relay_log_size if this is non-zero,
+     max_binlog_size otherwise.
+     max_size is set in init(), and dynamically changed (when one does SET
+     GLOBAL MAX_BINLOG_SIZE|MAX_RELAY_LOG_SIZE) by fix_max_binlog_size and
+     fix_max_relay_log_size). 
+  */
+  ulong max_size;
   friend class Log_event;
 
 public:
@@ -105,17 +116,18 @@ class MYSQL_LOG {
     bytes_written=0;
     DBUG_VOID_RETURN;
   }
+  void set_max_size(ulong max_size_arg);
   void signal_update() { pthread_cond_broadcast(&update_cond);}
   void wait_for_update(THD* thd);
   void set_need_start_event() { need_start_event = 1; }
   void init(enum_log_type log_type_arg,
-	    enum cache_type io_cache_type_arg = WRITE_CACHE,
-	    bool no_auto_events_arg = 0);
+	    enum cache_type io_cache_type_arg,
+	    bool no_auto_events_arg, ulong max_size);
   void cleanup();
   bool open(const char *log_name,enum_log_type log_type,
 	    const char *new_name, const char *index_file_name_arg,
 	    enum cache_type io_cache_type_arg,
-	    bool no_auto_events_arg);
+	    bool no_auto_events_arg, ulong max_size);
   void new_file(bool need_lock= 1);
   bool write(THD *thd, enum enum_server_command command,
 	     const char *format,...);

sql/sql_parse.cc

@@ -3571,10 +3571,18 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables)
   }
   if (options & REFRESH_LOG)
   {
+    /*
+      Flush the normal query log, the update log, the binary log, the slow query
+      log, and the relay log (if it exists).
+    */
     mysql_log.new_file(1);
     mysql_update_log.new_file(1);
     mysql_bin_log.new_file(1);
     mysql_slow_log.new_file(1);
+    LOCK_ACTIVE_MI;
+    rotate_relay_log(active_mi);
+    UNLOCK_ACTIVE_MI;
+
     if (ha_flush_logs())
       result=1;
     if (flush_error_log())