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`@@rpl_semi_sync_slave_enabled` can be changed without stopping replication, because it takes effect when a connection is established. But when it takes effect, it applies to *all* replication connections. This means that starting an async connection will switch any ongoing semi-sync connections to async as well, and vice versa, which will cause those connections to fail to replicate in the wrong mode. This fix resolves this oversight by changing the value application to be specific to only the establishing connection (technically, moving the singleton’s field `Repl_semi_sync_slave::m_slave_enabled` to the instance variable `Master_info::semi_sync_enabled`). This design builds toward MDEV-40941, which proposes migrating `@@rpl_semi_sync_slave_enabled` to a proper per-connection config. Note, `Master_info::semi_sync_reply_enabled` must remain separate, because it only disables ACK replying in async slave fallback, whereas the semi-sync slave setting also controls whether the IO thread should expect additional semi-sync flags in event packets. To maintain backward compatibility until MDEV-40941, the status variable `Rpl_semi_sync_slave_status` is kept showing the applied `@@rpl_semi_sync_slave_enabled` for the most recent START SLAVE in any connection; that is, not yet made per-connection. Reviewed-by: Brandon Nesterenko <brandon.nesterenko@mariadb.com>
122 lines
3.8 KiB
C++
122 lines
3.8 KiB
C++
/* Copyright (c) 2006 MySQL AB, 2009 Sun Microsystems, Inc.
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Use is subject to license terms.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef SEMISYNC_SLAVE_H
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#define SEMISYNC_SLAVE_H
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#ifdef HAVE_REPLICATION
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#include "semisync.h"
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#include "my_global.h"
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#include "sql_priv.h"
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#include "rpl_mi.h"
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#include "mysql.h"
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#include <sql_common.h>
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class Master_info;
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/**
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The extension class for the slave of semi-synchronous replication
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*/
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class Repl_semi_sync_slave
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:public Repl_semi_sync_base {
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public:
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Repl_semi_sync_slave() :m_slave_enabled(false) {}
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~Repl_semi_sync_slave() = default;
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void set_trace_level(unsigned long trace_level) {
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m_trace_level = trace_level;
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}
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/* Initialize this class after MySQL parameters are initialized. this
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* function should be called once at bootstrap time.
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*/
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int init_object();
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inline bool get_slave_enabled(Master_info *mi) {
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return mi->semi_sync_enabled;
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}
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void set_slave_enabled(Master_info *mi, bool enabled) {
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m_slave_enabled= mi->semi_sync_enabled= enabled;
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}
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inline bool is_delay_master(){
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return m_delay_master;
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}
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void set_delay_master(bool enabled) {
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m_delay_master = enabled;
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}
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void set_kill_conn_timeout(unsigned int timeout) {
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m_kill_conn_timeout = timeout;
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}
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/* A slave reads the semi-sync packet header and separate the metadata
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* from the payload data.
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*
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* Input:
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* header - (IN) packet header pointer
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* total_len - (IN) total packet length: metadata + payload
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* mi - (IN) store flags: SEMI_SYNC_SLAVE_DELAY_SYNC and
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SEMI_SYNC_NEED_ACK, to Master_info::semi_ack
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* payload - (IN) payload: the replication event
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* payload_len - (IN) payload length
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*
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* Return:
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* 0: success; non-zero: error
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*/
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int slave_read_sync_header(const uchar *header, unsigned long total_len,
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Master_info *mi,
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const uchar **payload, unsigned long *payload_len);
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/* A slave replies to the master indicating its replication process. It
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* indicates that the slave has received all events before the specified
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* binlog position.
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*/
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int slave_reply(Master_info* mi);
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void slave_start(Master_info *mi);
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void slave_stop(Master_info *mi);
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void slave_reconnect(Master_info *mi);
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int request_transmit(Master_info *mi);
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void kill_connection(Master_info *mi);
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/// @deprecated For `Rpl_semi_sync_slave_status` compatibility only
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bool m_slave_enabled;
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private:
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/* True when init_object has been called */
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bool m_init_done;
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bool m_delay_master;
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unsigned int m_kill_conn_timeout;
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};
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/* System and status variables for the slave component */
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extern my_bool global_rpl_semi_sync_slave_enabled;
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extern ulong rpl_semi_sync_slave_trace_level;
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extern Repl_semi_sync_slave repl_semisync_slave;
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extern char rpl_semi_sync_slave_delay_master;
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extern unsigned int rpl_semi_sync_slave_kill_conn_timeout;
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extern unsigned long long rpl_semi_sync_slave_send_ack;
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extern int rpl_semi_sync_enabled(THD *thd, SHOW_VAR *var, void *buff,
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system_status_var *status_var,
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enum_var_type scope);
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#endif /* HAVE_REPLICATION */
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#endif /* SEMISYNC_SLAVE_H */
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