Hi Alfranio
Thank you for your work!
Here is my thoughts about these two approaches:
1) The first approach (BUG#35542, BUG#31665) introduces
--sync-relay-log, which fsync the relay-log and master.info for every
sync_relay_log events, and fsync the relay-log.info every sync_relay_log
transactions.
2) The second approach (BUG#40337) introduces --relay-log-throw, which
fsync the relay-log.info for EVERY transaction, and when restart from
server crash, the slave purges any relay-logs after the executed master
log position recorded in relay-log.info and re-fetch master binlogs from
that position.
I think most part of these two approaches are orthogonal, except that we
have to make sure when both are enabled, the relay-log.info is only
flushed once for every transaction.
So I think you do not need to base your patch on mine (actually
Sinisa's), I think your approach and the approach proposed by Sinisa can
be seperate. It should be possible that we only add your approach to the
code. So I think your approach should only depend on option
--relay-log-throw, and should not have dependency on option
--sync-relay-log.
BTW, since the performance of previous approach is acceptable if we turn
on hard drive cache, and it won't delete the relay-log that's already
been saved on slave, which some users may prefer, so I think the first
approach still has its use case. So I think we can have both and the
users can choose any one of them or both of them.
There are also some inline comments.
Alfranio Correia wrote:
> #At file:///home/acorreia/workspace.sun/playground.mysql/mysql-5.0.68-custom_build/
>
> 2704 Alfranio Correia 2008-10-27
> Merged patch that was proposed by Sinisa and modified by He Zhenxing to fix
> bugs: BUG#35542 and BUG#31665. This is an update to BUG#40337.
> And introduced a new recovery process that disregards old relay-log.bin(s) and
> starts
> re-fetching from the master based on the information in relay-log.info which
> may be flushed and synced after each transaction commit.
> modified:
> mysql-test/r/rpl_flush_log_loop.result
> sql/log.cc
> sql/mysql_priv.h
> sql/mysqld.cc
> sql/set_var.cc
> sql/set_var.h
> sql/slave.cc
> sql/sql_class.h
>
> per-file messages:
> mysql-test/r/rpl_flush_log_loop.result
> Changed result file for a test case affected by fix proposed for BUG#40337
> sql/log.cc
> Added support to the checkpoint interval through the parameter --sync-relay-log.
> sql/mysql_priv.h
> Created parameter --relay_log_throw, default = 0 thus keeping the original
> behavior. And added support to the checkpoint interval through the parameter
> --sync-relay-log, default = 0 thus keeping the original behavior.
Usually, we use hyphen (-) instead of underscore (_) in option names,
but the corresponding parameter name will use unserscore.
> sql/mysqld.cc
> Created parameter --relay_log_throw, default = 0 thus keeping the original
> behavior. And added support to the checkpoint interval through the parameter
> --sync-relay-log, default = 0 thus keeping the original behavior.
> sql/set_var.cc
> Created parameter --relay_log_throw, default = 0 thus keeping the original
> behavior. And added support to the checkpoint interval through the parameter
> --sync-relay-log, default = 0 thus keeping the original behavior.
> sql/set_var.h
> Added support to the checkpoint interval through the parameter --sync-relay-log.
> sql/slave.cc
> Introduced the function init_recovery that is fired right after the startup and
> updates the master.info according to the relay-log.info and throws away (i.e.
> ignores)the old relay-log.bin. And also added support to the checkpoint interval through
> the parameter --sync-relay-log.
>
> Note that the when --sync-relay-log is on the relay-info is flushed and synced
> per transaction commit:
>
> if (sync_relaylog_period &&
> !error)
> {
> if (my_sync(rli->info_fd, MYF(MY_WME)))
> error=1;
> }
>
> This is a bit different from the patch proposed for BUG#35542 and BUG#31665.
> sql/sql_class.h
> Created sync_period that determines how often the master.info and relay-log.bin
> are flushed and synch. This parameter should be seen as a checkpoint based on number of
> events.
> === modified file 'mysql-test/r/rpl_flush_log_loop.result'
> --- a/mysql-test/r/rpl_flush_log_loop.result 2007-10-10 07:21:11 +0000
> +++ b/mysql-test/r/rpl_flush_log_loop.result 2008-10-27 15:09:43 +0000
> @@ -10,6 +10,7 @@ relay_log MYSQLTEST_VARDIR/master-data/r
> relay_log_index
> relay_log_info_file relay-log.info
> relay_log_purge ON
> +relay_log_throw OFF
> relay_log_space_limit 0
> stop slave;
> change master to master_host='127.0.0.1',master_user='root',
>
> === modified file 'sql/log.cc'
> --- a/sql/log.cc 2008-07-24 12:28:21 +0000
> +++ b/sql/log.cc 2008-10-27 15:09:43 +0000
> @@ -32,8 +32,7 @@
> #include "message.h"
> #endif
>
> -MYSQL_LOG mysql_log, mysql_slow_log, mysql_bin_log;
> -ulong sync_binlog_counter= 0;
> +MYSQL_LOG mysql_log, mysql_slow_log, mysql_bin_log(&sync_binlog_period);
>
> static Muted_query_log_event invisible_commit;
>
> @@ -402,10 +401,11 @@ static int find_uniq_filename(char *name
> }
>
>
> -MYSQL_LOG::MYSQL_LOG()
> +MYSQL_LOG::MYSQL_LOG(uint *sync_period)
> :bytes_written(0), last_time(0), query_start(0), name(0),
> prepared_xids(0), log_type(LOG_CLOSED), file_id(1), open_count(1),
> write_error(FALSE), inited(FALSE), need_start_event(TRUE),
> + sync_period_ptr(sync_period),
> description_event_for_exec(0), description_event_for_queue(0)
> {
> /*
> @@ -1622,6 +1622,8 @@ bool MYSQL_LOG::append(Log_event* ev)
> }
> bytes_written+= ev->data_written;
> DBUG_PRINT("info",("max_size: %lu",max_size));
> + if (flush_and_sync())
> + goto err;
> if ((uint) my_b_append_tell(&log_file) > max_size)
> new_file(0);
>
> @@ -1652,6 +1654,8 @@ bool MYSQL_LOG::appendv(const char* buf,
> bytes_written += len;
> } while ((buf=va_arg(args,const char*)) && (len=va_arg(args,uint)));
> DBUG_PRINT("info",("max_size: %lu",max_size));
> + if (flush_and_sync())
> + goto err;
> if ((uint) my_b_append_tell(&log_file) > max_size)
> new_file(0);
>
> @@ -1758,9 +1762,10 @@ bool MYSQL_LOG::flush_and_sync()
> safe_mutex_assert_owner(&LOCK_log);
> if (flush_io_cache(&log_file))
> return 1;
> - if (++sync_binlog_counter >= sync_binlog_period && sync_binlog_period)
> + uint sync_period= get_sync_period();
> + if (sync_period && ++sync_counter >= sync_period)
> {
> - sync_binlog_counter= 0;
> + sync_counter= 0;
> err=my_sync(fd, MYF(MY_WME));
> }
> return err;
>
> === modified file 'sql/mysql_priv.h'
> --- a/sql/mysql_priv.h 2008-10-02 11:57:52 +0000
> +++ b/sql/mysql_priv.h 2008-10-27 15:09:43 +0000
> @@ -1310,10 +1310,11 @@ extern ulong max_binlog_size, max_relay_
> extern ulong rpl_recovery_rank, thread_cache_size;
> extern ulong back_log;
> extern ulong specialflag, current_pid;
> -extern ulong expire_logs_days, sync_binlog_period, sync_binlog_counter;
> +extern ulong expire_logs_days;
> +extern uint sync_binlog_period, sync_relaylog_period;
> extern ulong opt_tc_log_size, tc_log_max_pages_used, tc_log_page_size;
> extern ulong tc_log_page_waits;
> -extern my_bool relay_log_purge, opt_innodb_safe_binlog, opt_innodb;
> +extern my_bool relay_log_purge, relay_log_throw, opt_innodb_safe_binlog,
> opt_innodb;
> extern uint test_flags,select_errors,ha_open_options;
> extern uint protocol_version, mysqld_port, dropping_tables;
> extern uint delay_key_write_options, lower_case_table_names;
>
> === modified file 'sql/mysqld.cc'
> --- a/sql/mysqld.cc 2008-08-26 08:32:43 +0000
> +++ b/sql/mysqld.cc 2008-10-27 15:09:43 +0000
> @@ -404,7 +404,7 @@ ulong opt_ndb_cache_check_time;
> const char *opt_ndb_mgmd;
> ulong opt_ndb_nodeid;
> #endif
> -my_bool opt_readonly, use_temp_pool, relay_log_purge;
> +my_bool opt_readonly, use_temp_pool, relay_log_purge, relay_log_throw;
> my_bool opt_sync_frm, opt_allow_suspicious_udfs;
> my_bool opt_secure_auth= 0;
> char* opt_secure_file_priv= 0;
> @@ -466,7 +466,8 @@ ulong max_prepared_stmt_count;
> */
> ulong prepared_stmt_count=0;
> ulong thread_id=1L,current_pid;
> -ulong slow_launch_threads = 0, sync_binlog_period;
> +ulong slow_launch_threads = 0;
> +uint sync_binlog_period= 0, sync_relaylog_period= 0;
> ulong expire_logs_days = 0;
> ulong rpl_recovery_rank=0;
>
> @@ -4918,6 +4919,7 @@ enum options_mysqld
> OPT_QUERY_CACHE_TYPE, OPT_QUERY_CACHE_WLOCK_INVALIDATE, OPT_RECORD_BUFFER,
> OPT_RECORD_RND_BUFFER, OPT_DIV_PRECINCREMENT, OPT_RELAY_LOG_SPACE_LIMIT,
> OPT_RELAY_LOG_PURGE,
> + OPT_RELAY_LOG_THROW,
> OPT_SLAVE_NET_TIMEOUT, OPT_SLAVE_COMPRESSED_PROTOCOL, OPT_SLOW_LAUNCH_TIME,
> OPT_SLAVE_TRANS_RETRIES, OPT_READONLY, OPT_DEBUGGING,
> OPT_SORT_BUFFER, OPT_TABLE_CACHE,
> @@ -4995,7 +4997,8 @@ enum options_mysqld
> OPT_SECURE_FILE_PRIV,
> OPT_KEEP_FILES_ON_CREATE,
> OPT_INNODB_ADAPTIVE_HASH_INDEX,
> - OPT_FEDERATED
> + OPT_FEDERATED,
> + OPT_SYNC_RELAY_LOG
> };
>
>
> @@ -6302,6 +6305,11 @@ The minimum value for this variable is 4
> (gptr*) &relay_log_purge,
> (gptr*) &relay_log_purge, 0, GET_BOOL, NO_ARG,
> 1, 0, 1, 0, 1, 0},
> + {"relay_log_throw", OPT_RELAY_LOG_THROW,
> + "0 = do not ignore retrieved relay logs. 1 = ignore retrieved relay logs.",
> + (gptr*) &relay_log_throw,
> + (gptr*) &relay_log_throw, 0, GET_BOOL, NO_ARG,
> + 0, 0, 1, 0, 1, 0},
> {"relay_log_space_limit", OPT_RELAY_LOG_SPACE_LIMIT,
> "Maximum space to use for all relay logs.",
> (gptr*) &relay_log_space_limit,
> @@ -6342,8 +6350,13 @@ The minimum value for this variable is 4
> {"sync-binlog", OPT_SYNC_BINLOG,
> "Synchronously flush binary log to disk after every #th event. "
> "Use 0 (default) to disable synchronous flushing.",
> - (gptr*) &sync_binlog_period, (gptr*) &sync_binlog_period, 0, GET_ULONG,
> - REQUIRED_ARG, 0, 0, ULONG_MAX, 0, 1, 0},
> + (gptr*) &sync_binlog_period, (gptr*) &sync_binlog_period, 0, GET_UINT,
> + REQUIRED_ARG, 0, 0, UINT_MAX, 0, 1, 0},
> + {"sync-relay-log", OPT_SYNC_RELAY_LOG,
> + "Synchronously flush relay log to disk after every #th event. "
> + "Use 0 (default) to disable synchronous flushing.",
> + (gptr *) &sync_relaylog_period, (gptr *) &sync_relaylog_period, 0,
> GET_UINT,
> + REQUIRED_ARG, 0, 0, UINT_MAX, 0, 1, 0},
> {"sync-frm", OPT_SYNC_FRM, "Sync .frm to disk on create. Enabled by default.",
> (gptr*) &opt_sync_frm, (gptr*) &opt_sync_frm, 0, GET_BOOL, NO_ARG, 1, 0,
> 0, 0, 0, 0},
>
> === modified file 'sql/set_var.cc'
> --- a/sql/set_var.cc 2008-08-25 12:11:59 +0000
> +++ b/sql/set_var.cc 2008-10-27 15:09:43 +0000
> @@ -323,6 +323,8 @@ sys_var_thd_ulong sys_div_precincrement(
> #ifdef HAVE_REPLICATION
> sys_var_bool_ptr sys_relay_log_purge("relay_log_purge",
> &relay_log_purge);
> +sys_var_bool_ptr sys_relay_log_throw("relay_log_throw",
> + &relay_log_throw);
> #endif
> sys_var_long_ptr sys_rpl_recovery_rank("rpl_recovery_rank",
> &rpl_recovery_rank);
> @@ -402,7 +404,8 @@ sys_var_thd_table_type sys_table_type("
> sys_var_thd_storage_engine sys_storage_engine("storage_engine",
> &SV::table_type);
> #ifdef HAVE_REPLICATION
> -sys_var_sync_binlog_period sys_sync_binlog_period("sync_binlog",
> &sync_binlog_period);
> +sys_var_int_ptr sys_sync_binlog_period("sync_binlog", &sync_binlog_period);
> +sys_var_int_ptr sys_sync_relaylog_period("sync_relay_log",
> &sync_relaylog_period);
> #endif
> sys_var_bool_ptr sys_sync_frm("sync_frm", &opt_sync_frm);
> sys_var_const_str sys_system_time_zone("system_time_zone",
> @@ -733,6 +736,7 @@ sys_var *sys_variables[]=
> &sys_read_rnd_buff_size,
> #ifdef HAVE_REPLICATION
> &sys_relay_log_purge,
> + &sys_relay_log_throw,
> #endif
> &sys_rpl_recovery_rank,
> &sys_safe_updates,
> @@ -762,6 +766,7 @@ sys_var *sys_variables[]=
> &sys_storage_engine,
> #ifdef HAVE_REPLICATION
> &sys_sync_binlog_period,
> + &sys_sync_relaylog_period,
> #endif
> &sys_sync_frm,
> &sys_system_time_zone,
> @@ -1052,6 +1057,7 @@ struct show_var_st init_vars[]= {
> {"relay_log_index", (char*) &opt_relaylog_index_name, SHOW_CHAR_PTR},
> {"relay_log_info_file", (char*) &relay_log_info_file, SHOW_CHAR_PTR},
> {sys_relay_log_purge.name, (char*) &sys_relay_log_purge, SHOW_SYS},
> + {sys_relay_log_throw.name, (char*) &sys_relay_log_throw, SHOW_SYS},
> {"relay_log_space_limit", (char*) &relay_log_space_limit,
> SHOW_LONGLONG},
> #endif
> {sys_rpl_recovery_rank.name,(char*) &sys_rpl_recovery_rank, SHOW_SYS},
> @@ -1090,6 +1096,7 @@ struct show_var_st init_vars[]= {
> {sys_storage_engine.name, (char*) &sys_storage_engine, SHOW_SYS},
> #ifdef HAVE_REPLICATION
> {sys_sync_binlog_period.name,(char*) &sys_sync_binlog_period, SHOW_SYS},
> + {sys_sync_relaylog_period.name,(char*) &sys_sync_relaylog_period,
> SHOW_SYS},
> #endif
> {sys_sync_frm.name, (char*) &sys_sync_frm, SHOW_SYS},
> #ifdef HAVE_TZNAME
> @@ -1486,6 +1493,23 @@ static bool get_unsigned(THD *thd, set_v
> }
>
>
> +bool sys_var_int_ptr::check(THD *thd, set_var *var)
> +{
> + var->save_result.ulong_value= (ulong) var->value->val_int();
> + return 0;
> +}
> +
> +bool sys_var_int_ptr::update(THD *thd, set_var *var)
> +{
> + *value= (uint) var->save_result.ulong_value;
> + return 0;
> +}
> +
> +void sys_var_int_ptr::set_default(THD *thd, enum_var_type type)
> +{
> + *value= (uint) option_limits->def_value;
> +}
> +
> sys_var_long_ptr::
> sys_var_long_ptr(const char *name_arg, ulong *value_ptr_arg,
> sys_after_update_func after_update_arg)
> @@ -2759,13 +2783,6 @@ bool sys_var_slave_skip_counter::update(
> pthread_mutex_unlock(&LOCK_active_mi);
> return 0;
> }
> -
> -
> -bool sys_var_sync_binlog_period::update(THD *thd, set_var *var)
> -{
> - sync_binlog_period= (ulong) var->save_result.ulonglong_value;
> - return 0;
> -}
> #endif /* HAVE_REPLICATION */
>
> bool sys_var_rand_seed1::update(THD *thd, set_var *var)
>
> === modified file 'sql/set_var.h'
> --- a/sql/set_var.h 2008-01-23 15:03:58 +0000
> +++ b/sql/set_var.h 2008-10-27 15:09:43 +0000
> @@ -110,6 +110,26 @@ public:
> { return (byte*) value; }
> };
>
> +/**
> + Unsigned int system variable class
> + */
> +class sys_var_int_ptr :public sys_var
> +{
> +public:
> + sys_var_int_ptr(const char *name_arg, uint *value_ptr_arg,
> + sys_after_update_func after_update_arg= NULL)
> + :sys_var(name_arg, after_update_arg),
> + value(value_ptr_arg)
> + {}
> + bool check(THD *thd, set_var *var);
> + bool update(THD *thd, set_var *var);
> + void set_default(THD *thd, enum_var_type type);
> + SHOW_TYPE show_type() { return SHOW_INT; }
> + byte *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base)
> + { return (byte*) value; }
> +private:
> + uint *value;
> +};
>
> /*
> A global ulong variable that is protected by LOCK_global_system_variables
> @@ -550,11 +570,11 @@ public:
> */
> };
>
> -class sys_var_sync_binlog_period :public sys_var_long_ptr
> +class sys_var_sync_binlog_period :public sys_var_int_ptr
> {
> public:
> - sys_var_sync_binlog_period(const char *name_arg, ulong *value_ptr_arg)
> - :sys_var_long_ptr(name_arg,value_ptr_arg) {}
> + sys_var_sync_binlog_period(const char *name_arg, uint *value_ptr_arg)
> + :sys_var_int_ptr(name_arg,value_ptr_arg) {}
> bool update(THD *thd, set_var *var);
> };
> #endif
>
> === modified file 'sql/slave.cc'
> --- a/sql/slave.cc 2008-03-28 20:01:05 +0000
> +++ b/sql/slave.cc 2008-10-27 15:09:43 +0000
> @@ -66,6 +66,7 @@ static bool wait_for_relay_log_space(REL
> static inline bool io_slave_killed(THD* thd,MASTER_INFO* mi);
> static inline bool sql_slave_killed(THD* thd,RELAY_LOG_INFO* rli);
> static int count_relay_log_space(RELAY_LOG_INFO* rli);
> +static int init_recovery(MASTER_INFO* mi);
> static int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type);
> static int safe_connect(THD* thd, MYSQL* mysql, MASTER_INFO* mi);
> static int safe_reconnect(THD* thd, MYSQL* mysql, MASTER_INFO* mi,
> @@ -174,6 +175,9 @@ int init_slave()
> if (server_id && !master_host && active_mi->host[0])
> master_host= active_mi->host;
>
> + if (init_recovery(active_mi))
> + goto err;
> +
> /* If server id is not set, start_slave_thread() will say it */
>
> if (master_host && !opt_skip_slave_start)
> @@ -197,6 +201,48 @@ err:
> DBUG_RETURN(1);
> }
>
> +static int init_recovery(MASTER_INFO* mi)
> +{
> + const char* errmsg=0;
> + DBUG_ENTER("recovery_init");
> +
A typo, should be "init_recovery"
> + RELAY_LOG_INFO* rli = &mi->rli;
> + if (relay_log_throw && rli->group_master_log_name[0])
> + {
> + mi->master_log_pos = max(BIN_LOG_HEADER_SIZE,
> + rli->group_master_log_pos);
> + strmake(mi->master_log_name, rli->group_master_log_name,
> + sizeof(mi->master_log_name)-1);
> +
> + strmake(rli->group_relay_log_name, rli->relay_log.get_log_fname(),
> + sizeof(rli->group_relay_log_name)-1);
> + strmake(rli->event_relay_log_name, rli->relay_log.get_log_fname(),
> + sizeof(mi->rli.event_relay_log_name)-1);
> +
> + rli->group_relay_log_pos = rli->group_relay_log_pos =
> BIN_LOG_HEADER_SIZE;
> +
> + if (init_relay_log_pos(rli,
> + rli->group_relay_log_name,
> + rli->group_relay_log_pos,
> + 0 /*no data lock*/,
> + &errmsg, 0))
> + DBUG_RETURN(1);
> +
> + if (flush_master_info(mi, 0))
> + {
> + sql_print_error("Failed to flush master info file");
> + DBUG_RETURN(1);
> + }
> + if (flush_relay_log_info(rli))
> + {
> + sql_print_error("Failed to flush master info file");
> + DBUG_RETURN(1);
> + }
I think you need to purge the discarded relay-log files here.
> + }
> +
> + DBUG_RETURN(0);
> +}
> +
>
> static void free_table_ent(TABLE_RULE_ENT* e)
> {
> @@ -2582,6 +2628,7 @@ int flush_master_info(MASTER_INFO* mi, b
> {
> IO_CACHE* file = &mi->file;
> char lbuf[22];
> + int err= 0;
> DBUG_ENTER("flush_master_info");
> DBUG_PRINT("enter",("master_pos: %ld", (long) mi->master_log_pos));
>
> @@ -2597,9 +2644,12 @@ int flush_master_info(MASTER_INFO* mi, b
> When we come to this place in code, relay log may or not be initialized;
> the caller is responsible for setting 'flush_relay_log_cache' accordingly.
> */
> - if (flush_relay_log_cache &&
> - flush_io_cache(mi->rli.relay_log.get_log_file()))
> - DBUG_RETURN(2);
> + if (flush_relay_log_cache)
> + {
> + IO_CACHE *log_file= mi->rli.relay_log.get_log_file();
> + if (flush_io_cache(log_file))
> + DBUG_RETURN(2);
> + }
>
> /*
> We flushed the relay log BEFORE the master.info file, because if we crash
> @@ -2626,12 +2676,21 @@ int flush_master_info(MASTER_INFO* mi, b
> mi->password, mi->port, mi->connect_retry,
> (int)(mi->ssl), mi->ssl_ca, mi->ssl_capath, mi->ssl_cert,
> mi->ssl_cipher, mi->ssl_key);
> - DBUG_RETURN(-flush_io_cache(file));
> + err= flush_io_cache(file);
> + static unsigned int count=1;
> + if (sync_relaylog_period && !err && count >
> sync_relaylog_period)
> + {
> + err= my_sync(mi->fd, MYF(MY_WME));
> + count= 1;
> + }
> + count++;
> + DBUG_RETURN(-err);
> }
>
>
> st_relay_log_info::st_relay_log_info()
> - :info_fd(-1), cur_log_fd(-1), save_temporary_tables(0),
> + :info_fd(-1), cur_log_fd(-1), relay_log(&sync_relaylog_period),
> + save_temporary_tables(0),
> cur_log_old_open_count(0), group_master_log_pos(0), log_space_total(0),
> ignore_log_space_limit(0), last_master_timestamp(0), slave_skip_counter(0),
> abort_pos_wait(0), slave_run_id(0), sql_thd(0), last_slave_errno(0),
> @@ -4872,6 +4931,14 @@ bool flush_relay_log_info(RELAY_LOG_INFO
> error=1;
> if (flush_io_cache(file))
> error=1;
> + static unsigned int count= 1;
> + if (sync_relaylog_period &&
> + !error)
> + {
> + if (my_sync(rli->info_fd, MYF(MY_WME)))
> + error=1;
> + }
> + count++;
> /* Flushing the relay log is done by the slave I/O thread */
> return error;
> }
>
> === modified file 'sql/sql_class.h'
> --- a/sql/sql_class.h 2008-09-17 06:34:00 +0000
> +++ b/sql/sql_class.h 2008-10-27 15:09:43 +0000
> @@ -238,6 +238,18 @@ class MYSQL_LOG: public TC_LOG
> bool no_auto_events;
> friend class Log_event;
>
> + /* pointer to the sync period variable, for binlog this will be
> + sync_binlog_period, for relay log this will be
> + sync_relay_log_period
> + */
> + uint *sync_period_ptr;
> + uint sync_counter;
> +
> + inline uint get_sync_period()
> + {
> + return *sync_period_ptr;
> + }
> +
> public:
> /*
> These describe the log's format. This is used only for relay logs.
> @@ -250,7 +262,7 @@ public:
> Format_description_log_event *description_event_for_exec,
> *description_event_for_queue;
>
> - MYSQL_LOG();
> + MYSQL_LOG(uint *sync_period=0);
> /*
> note that there's no destructor ~MYSQL_LOG() !
> The reason is that we don't want it to be automatically called
>
