mariadb/sql/semisync_slave.h

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2011-06-30 17:46:53 +02:00
/* Copyright (c) 2006 MySQL AB, 2009 Sun Microsystems, Inc.
Use is subject to license terms.
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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef SEMISYNC_SLAVE_H
#define SEMISYNC_SLAVE_H
#include "semisync.h"
#include "my_global.h"
#include "sql_priv.h"
#include "rpl_mi.h"
#include "mysql.h"
MDEV-11853: semisync thread can be killed after sync binlog but before ACK in the sync state Problem: ======== If a primary is shutdown during an active semi-sync connection during the period when the primary is awaiting an ACK, the primary hard kills the active communication thread and does not ensure the transaction was received by a replica. This can lead to an inconsistent replication state. Solution: ======== During shutdown, the primary should wait for an ACK or timeout before hard killing a thread which is awaiting a communication. We extend the `SHUTDOWN WAIT FOR SLAVES` logic to identify and ignore any threads waiting for a semi-sync ACK in phase 1. Then, before stopping the ack receiver thread, the shutdown is delayed until all waiting semi-sync connections receive an ACK or time out. The connections are then killed in phase 2. Notes: 1) There remains an unresolved corner case that affects this patch. MDEV-28141: Slave crashes with Packets out of order when connecting to a shutting down master. Specifically, If a slave is connecting to a master which is actively shutting down, the slave can crash with a "Packets out of order" assertion error. To get around this issue in the MTR tests, the primary will wait a small amount of time before phase 1 killing threads to let the replicas safely stop (if applicable). 2) This patch also fixes MDEV-28114: Semi-sync Master ACK Receiver Thread Can Error on COM_QUIT Reviewed By ============ Andrei Elkin <andrei.elkin@mariadb.com>
2021-10-21 04:13:45 +02:00
#include <sql_common.h>
class Master_info;
/**
The extension class for the slave of semi-synchronous replication
*/
class Repl_semi_sync_slave
:public Repl_semi_sync_base {
public:
Repl_semi_sync_slave() :m_slave_enabled(false) {}
~Repl_semi_sync_slave() = default;
void set_trace_level(unsigned long trace_level) {
m_trace_level = trace_level;
}
/* Initialize this class after MySQL parameters are initialized. this
* function should be called once at bootstrap time.
*/
int init_object();
bool get_slave_enabled() {
return m_slave_enabled;
}
void set_slave_enabled(bool enabled) {
m_slave_enabled = enabled;
}
bool is_delay_master(){
return m_delay_master;
}
void set_delay_master(bool enabled) {
m_delay_master = enabled;
}
void set_kill_conn_timeout(unsigned int timeout) {
m_kill_conn_timeout = timeout;
}
/* A slave reads the semi-sync packet header and separate the metadata
* from the payload data.
*
* Input:
* header - (IN) packet header pointer
* total_len - (IN) total packet length: metadata + payload
* semi_flags - (IN) store flags: SEMI_SYNC_SLAVE_DELAY_SYNC and
SEMI_SYNC_NEED_ACK
* payload - (IN) payload: the replication event
* payload_len - (IN) payload length
*
* Return:
* 0: success; non-zero: error
*/
int slave_read_sync_header(const char *header, unsigned long total_len,
int *semi_flags,
const char **payload, unsigned long *payload_len);
/* A slave replies to the master indicating its replication process. It
* indicates that the slave has received all events before the specified
* binlog position.
*/
int slave_reply(Master_info* mi);
int slave_start(Master_info *mi);
int slave_stop(Master_info *mi);
int request_transmit(Master_info*);
void kill_connection(MYSQL *mysql);
int reset_slave(Master_info *mi);
private:
/* True when init_object has been called */
bool m_init_done;
bool m_slave_enabled; /* semi-sycn is enabled on the slave */
bool m_delay_master;
unsigned int m_kill_conn_timeout;
};
/* System and status variables for the slave component */
extern my_bool rpl_semi_sync_slave_enabled;
extern my_bool rpl_semi_sync_slave_status;
extern ulong rpl_semi_sync_slave_trace_level;
extern Repl_semi_sync_slave repl_semisync_slave;
extern char rpl_semi_sync_slave_delay_master;
extern unsigned int rpl_semi_sync_slave_kill_conn_timeout;
extern unsigned long long rpl_semi_sync_slave_send_ack;
#endif /* SEMISYNC_SLAVE_H */