mariadb/sql/rpl_mi.h

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/* Copyright (C) 2000-2003 MySQL AB, 2008-2009 Sun Microsystems, Inc
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef RPL_MI_H
#define RPL_MI_H
#ifdef HAVE_REPLICATION
#include "rpl_rli.h"
#include "rpl_reporting.h"
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#include "my_sys.h"
typedef struct st_mysql MYSQL;
/*****************************************************************************
Replication IO Thread
Master_info contains:
- information about how to connect to a master
- current master log name
- current master log offset
- misc control variables
Master_info is initialized once from the master.info file if such
exists. Otherwise, data members corresponding to master.info fields
are initialized with defaults specified by master-* options. The
initialization is done through init_master_info() call.
The format of master.info file:
log_name
log_pos
master_host
master_user
master_pass
master_port
master_connect_retry
To write out the contents of master.info file to disk ( needed every
time we read and queue data from the master ), a call to
flush_master_info() is required.
To clean up, call end_master_info()
*****************************************************************************/
class Master_info : public Slave_reporting_capability
{
public:
BUG#40337 Fsyncing master and relay log to disk after every event is too slow NOTE: Backporting the patch to next-mr. The fix proposed in BUG#35542 and BUG#31665 introduces a performance issue when fsyncing the master.info, relay.info and relay-log.bin* after #th events. Although such solution has been proposed to reduce the probability of corrupted files due to a slave-crash, the performance penalty introduced by it has made the approach impractical for highly intensive workloads. In a nutshell, the option --syn-relay-log proposed in BUG#35542 and BUG#31665 simultaneously fsyncs master.info, relay-log.info and relay-log.bin* and this is the main source of performance issues. This patch introduces new options that give more control to the user on what should be fsynced and how often: 1) (--sync-master-info, integer) which syncs the master.info after #th event; 2) (--sync-relay-log, integer) which syncs the relay-log.bin* after #th events. 3) (--sync-relay-log-info, integer) which syncs the relay.info after #th transactions. To provide both performance and increased reliability, we recommend the following setup: 1) --sync-master-info = 0 eventually the operating system will fsync it; 2) --sync-relay-log = 0 eventually the operating system will fsync it; 3) --sync-relay-log-info = 1 fsyncs it after every transaction; Notice, that the previous setup does not reduce the probability of corrupted master.info and relay-log.bin*. To overcome the issue, this patch also introduces a recovery mechanism that right after restart throws away relay-log.bin* retrieved from a master and updates the master.info based on the relay.info: 4) (--relay-log-recovery, boolean) which enables a recovery mechanism that throws away relay-log.bin* after a crash. However, it can only recover the incorrect binlog file and position in master.info, if other informations (host, port password, etc) are corrupted or incorrect, then this recovery mechanism will fail to work.
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Master_info(bool is_slave_recovery);
~Master_info();
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bool shall_ignore_server_id(ulong s_id);
/* the variables below are needed because we can change masters on the fly */
char master_log_name[FN_REFLEN];
char host[HOSTNAME_LENGTH+1];
char user[USERNAME_LENGTH+1];
char password[MAX_PASSWORD_LENGTH+1];
my_bool ssl; // enables use of SSL connection if true
char ssl_ca[FN_REFLEN], ssl_capath[FN_REFLEN], ssl_cert[FN_REFLEN];
char ssl_cipher[FN_REFLEN], ssl_key[FN_REFLEN];
my_bool ssl_verify_server_cert;
my_off_t master_log_pos;
File fd; // we keep the file open, so we need to remember the file pointer
IO_CACHE file;
mysql_mutex_t data_lock, run_lock;
mysql_cond_t data_cond, start_cond, stop_cond;
THD *io_thd;
MYSQL* mysql;
uint32 file_id; /* for 3.23 load data infile */
Relay_log_info rli;
uint port;
uint connect_retry;
#ifndef DBUG_OFF
int events_till_disconnect;
#endif
bool inited;
volatile bool abort_slave;
volatile uint slave_running;
volatile ulong slave_run_id;
/*
The difference in seconds between the clock of the master and the clock of
the slave (second - first). It must be signed as it may be <0 or >0.
clock_diff_with_master is computed when the I/O thread starts; for this the
I/O thread does a SELECT UNIX_TIMESTAMP() on the master.
"how late the slave is compared to the master" is computed like this:
clock_of_slave - last_timestamp_executed_by_SQL_thread - clock_diff_with_master
*/
long clock_diff_with_master;
BUG#40337 Fsyncing master and relay log to disk after every event is too slow NOTE: Backporting the patch to next-mr. The fix proposed in BUG#35542 and BUG#31665 introduces a performance issue when fsyncing the master.info, relay.info and relay-log.bin* after #th events. Although such solution has been proposed to reduce the probability of corrupted files due to a slave-crash, the performance penalty introduced by it has made the approach impractical for highly intensive workloads. In a nutshell, the option --syn-relay-log proposed in BUG#35542 and BUG#31665 simultaneously fsyncs master.info, relay-log.info and relay-log.bin* and this is the main source of performance issues. This patch introduces new options that give more control to the user on what should be fsynced and how often: 1) (--sync-master-info, integer) which syncs the master.info after #th event; 2) (--sync-relay-log, integer) which syncs the relay-log.bin* after #th events. 3) (--sync-relay-log-info, integer) which syncs the relay.info after #th transactions. To provide both performance and increased reliability, we recommend the following setup: 1) --sync-master-info = 0 eventually the operating system will fsync it; 2) --sync-relay-log = 0 eventually the operating system will fsync it; 3) --sync-relay-log-info = 1 fsyncs it after every transaction; Notice, that the previous setup does not reduce the probability of corrupted master.info and relay-log.bin*. To overcome the issue, this patch also introduces a recovery mechanism that right after restart throws away relay-log.bin* retrieved from a master and updates the master.info based on the relay.info: 4) (--relay-log-recovery, boolean) which enables a recovery mechanism that throws away relay-log.bin* after a crash. However, it can only recover the incorrect binlog file and position in master.info, if other informations (host, port password, etc) are corrupted or incorrect, then this recovery mechanism will fail to work.
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/*
Keeps track of the number of events before fsyncing.
The option --sync-master-info determines how many
events should happen before fsyncing.
*/
uint sync_counter;
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float heartbeat_period; // interface with CHANGE MASTER or master.info
ulonglong received_heartbeats; // counter of received heartbeat events
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,
int thread_mask);
void end_master_info(Master_info* mi);
int flush_master_info(Master_info* mi,
bool flush_relay_log_cache,
bool need_lock_relay_log);
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int change_master_server_id_cmp(ulong *id1, ulong *id2);
#endif /* HAVE_REPLICATION */
#endif /* RPL_MI_H */