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一、主库修改时机
(2) binlog打开
mysql.gtid_executed表修改时机
在binlog发生切换(rotate)的时候保存直到上一个binlog文件执行过的全部Gtid，它不是实时更新的。
栈帧如下:
#0 Gtid_table_persistor::save (this=0x2f9f9c0, gtid_set=0x7ffff03595a0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_persist.cc:425
#1 0x0000000001803dbe in Gtid_state::save (this=0x2ff8bb0, gtid_set=0x7ffff03595a0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:796
#2 0x0000000001803f62 in Gtid_state::save_gtids_of_last_binlog_into_table (this=0x2ff8bb0, on_rotation=true)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:835
#3 0x000000000185266d in MYSQL_BIN_LOG::new_file_impl (this=0x2dffc80, need_lock_log=false, extra_description_event=0x0)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:6751
#4 0x00000000018520a7 in MYSQL_BIN_LOG::new_file_without_locking (this=0x2dffc80, extra_description_event=0x0)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:6636
#5 0x0000000001853e67 in MYSQL_BIN_LOG::rotate (this=0x2dffc80, force_rotate=true, check_purge=0x7ffff0359c4b)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:7292其主要逻辑在Gtid_state::save_gtids_of_last_binlog_into_table 中我们在随后的部分讨论这个函数逻辑。
gtid_executed变量修改时机
如前文所述ordered_commit flush阶段生成Gtid，在commit阶段才计入gtid_executed变量，它是实时更新的。
栈帧如下：
#0 Gtid_set::_add_gtid (this=0x2ff8d38, sidno=1, gno=16) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid.h:1135
#1 0x0000000001804576 in Gtid_set::_add_gtid (this=0x2ff8d38, gtid=...) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid.h:1166
#2 0x00000000018024ba in Gtid_state::update_gtids_impl (this=0x2ff8bb0, thd=0x7fff2c000b70, is_commit=true)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:304
#3 0x00000000018020df in Gtid_state::update_on_commit (this=0x2ff8bb0, thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:148
#4 0x00000000018573d4 in MYSQL_BIN_LOG::process_commit_stage_queue (this=0x2dffc80, thd=0x7fff2c000b70, first=0x7fff2c000b70)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:8646
#5 0x0000000001858b51 in MYSQL_BIN_LOG::ordered_commit (this=0x2dffc80, thd=0x7fff2c000b70, all=false, skip_commit=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:9304其主要逻辑在Gtid_state::update_gtids_impl中我们在随后的部分讨论这个函数逻辑。
gtid_purged变量修改时机
在Mysql触发的清理binlog的情况下，比如purge binary logs to或者超过参数expire_logs_days设置的天数后自动删除，需要将丢失的Gtid计入这个变量中。
栈帧如下:
#0 MYSQL_BIN_LOG::init_gtid_sets (this=0x2e00280, all_gtids=0x0, lost_gtids=0x2fcaee8, verify_checksum=false, need_lock=false, trx_parser=0x0, gtid_partial_trx=0x0, is_server_starting=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:4333
#1 0x0000000001850b8e in MYSQL_BIN_LOG::purge_logs (this=0x2e00280, to_log=0x7fff57a74ad0 "/root/mysql5.7.14/percona-server-5.7.14-7/mysql-test/var/mysqld.1/test.000202", included=false, need_lock_index=true,
need_update_threads=true, decrease_log_space=0x0, auto_purge=false) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:6036
#2 0x0000000001848ecf in purge_master_logs (thd=0x7fff49200dc0, to_log=0x7fff492051a8 "test.000202") at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:2815其主要逻辑在MYSQL_BIN_LOG::purge_logs中，我们随后查看其代码片段，同时MYSQL_BIN_LOG::init_gtid_sets函数是一个及其重要的函数，主要用在：
Mysql启动时候初始化整个Gtid_state中的各种Gtid_set。
Mysql删除binlog(如purge binary logfiles或者超过expire_logs_days设置)后需要确认gtid_purged变量(及Gtid_state.lost_gtids)的值的时候。
随后我会单独一节来讲解Mysql Gtid模块的初始化还会讲解这个函数。
二、主库修改时机源码函数分析
这里就对上面提到的主要逻辑函数进行分析
Gtid_state::save_gtids_of_last_binlog_into_table函数逻辑
logged_gtids_last_binlog.add_interval_memory(PREALLOCATED_INTERVAL_COUNT, iv); //这里构建一个logged_gtids_last_binlog集合来保存切换后需要写入表和previous_gtids_logged的Gtid
global_sid_lock->wrlock();//
ret= (logged_gtids_last_binlog.add_gtid_set(&executed_gtids) != //将当前执行过的Gtid全部加入logged_gtids_last_binlog 列如:executed_gtids start=1, end=27
RETURN_STATUS_OK);
if (!ret)
{
logged_gtids_last_binlog.remove_gtid_set(&previous_gtids_logged); //获得上一个binlog文件包含的全部Gtid，并且做一个差集 列如:previous_gtids_logged 为start=1, end=25
//做完差集后logged_gtids_last_binlog为start=26, end=27
logged_gtids_last_binlog.remove_gtid_set(>ids_only_in_table);//此处主库一定为空，除非异常情况
if (!logged_gtids_last_binlog.is_empty())
{
if (on_rotation)
ret= previous_gtids_logged.add_gtid_set(&logged_gtids_last_binlog);//将这个start=26, end=27的Gtid集合加入到previous_gtids_logged中，这样previous_gtids_logged也完整了
global_sid_lock->unlock();
if (!ret)
ret= save(&logged_gtids_last_binlog);//将这个start=26, end=27的Gtid集合写入到表mysql.gtid_executed表中
}Gtid_state::update_gtids_impl函数代码片段
while (g.sidno != 0)
{
if (g.sidno != prev_sidno)
sid_locks.lock(g.sidno);
owned_gtids.remove_gtid(g); //从owned_gtid中去掉
git.next();
g= git.get();
if (is_commit)
executed_gtids._add_gtid(g);//将这个Gtid加入到executed_gtids
}MYSQL_BIN_LOG::purge_logs函数代码片段
if (!is_relay_log)
{
global_sid_lock->wrlock();
error= init_gtid_sets(NULL,
const_cast<Gtid_set *>(gtid_state->get_lost_gtids()),
opt_master_verify_checksum,
false,
NULL, NULL);//这里我看到将gtid_state->lost_gtids直接传入给了init_gtid_sets
//init_gtid_sets会做正向查找获得gtid_state->lost_gtids这个函数稍后
//详细讨论
global_sid_lock->unlock();
if (error)
goto err;
}三、从库修改时机
(2)binlog开启同时参数log_slave_updates开启的情况
这种情况sql_thread执行过的Gtid事物可以通过binlog进行维护，所以mysql.gtid_executed表和gtid_purged变量不需要实时更新。
mysql.gtid_executed表修改时机
和主库一致。及在进行日志切换的时候进行更新，不做讨论
gtid_executed变量修改时机
和主库一样实时更新，不做讨论
gtid_purged变量修改时机
和主库一致，binlog删除时更新，不做讨论
四、从库修改时机源码函数分析
commit_owned_gtids函数逻辑：
//如果 binlog 没有开启包括(log_bin=0 和 sql_log_bin =0 )或者 开启了binlog 但是slave线程并且slave update 没有开启,都会记录gtid到表
//但是这里要注意一点在主库上如果binlog不开启那么thd->owned_gtid.sidno ==0 因为这个时候Gtid都没有生成,生成阶段为order_commit的commit阶段
if ((!opt_bin_log || (thd->slave_thread && !opt_log_slave_updates)) &&
(all || !thd->in_multi_stmt_transaction_mode()) && //all 代表是否是显示begin 事物 in_multi_stmt_transaction_mode则相反
!thd->is_operating_gtid_table_implicitly && //是否是GTID_NEXT方式 flase
!thd->is_operating_substatement_implicitly)//是否是子语句 flase
{
if (thd->owned_gtid.sidno > 0)
{
error= gtid_state->save(thd);//就是这里进行了mysql.gtid_executed表的实时更新
*need_clear_owned_gtid_ptr= true;
}
else if (thd->owned_gtid.sidno == THD::OWNED_SIDNO_ANONYMOUS)
*need_clear_owned_gtid_ptr= true;
}Gtid_state::update_gtids_impl_own_gtid 函数逻辑片段
这个函数是5.7.17的，5.7.14没有逻辑放到了Gtid_state::update_gtids_impl中
if (is_commit)
{
DBUG_EXECUTE_IF(
"rpl_gtid_update_on_commit_simulate_out_of_memory",
DBUG_SET("+d,rpl_gtid_get_free_interval_simulate_out_of_memory"););
executed_gtids._add_gtid(thd->owned_gtid); //加入executed_gtids集合
thd->rpl_thd_ctx.session_gtids_ctx().
notify_after_gtid_executed_update(thd);
if (thd->slave_thread && opt_bin_log && !opt_log_slave_updates)//如果是slave线程同时binlog开启了并且log_slave_updates关闭了
//如果binlog关闭则使用 executed_gtids这样提高性能前面的注释说了
{
lost_gtids._add_gtid(thd->owned_gtid); //写入lost_gtids也就是更新参数gtid_purged变量
gtids_only_in_table._add_gtid(thd->owned_gtid);
}
}五、通用更改时机
mysql.gtid_executed表修改时机
在reset master的时候清空本表
栈帧如下：
#0 Gtid_table_persistor::delete_all (this=0x2f9f9c0, table=0x7fff2c0116a0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_persist.cc:795
#1 0x000000000180a4ef in Gtid_table_persistor::reset (this=0x2f9f9c0, thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_persist.cc:689
#2 0x0000000001801f2e in Gtid_state::clear (this=0x2ff8bb0, thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:36
#3 0x000000000184fee6 in MYSQL_BIN_LOG::reset_logs (this=0x2dffe80, thd=0x7fff2c000b70, delete_only=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:5586
#4 0x0000000001872308 in reset_master (thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_master.cc:587其主要逻辑在Gtid_state::clear中。
在set global gitd_purged的时候，设置本表
栈帧如下：
#0 Gtid_table_persistor::save (this=0x2f9f9c0, gtid_set=0x7ffff0359a70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_persist.cc:425
#1 0x000000000180400a in Gtid_state::save (this=0x2ff8bb0, gtid_set=0x7ffff0359a70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:796
#2 0x0000000001803c25 in Gtid_state::add_lost_gtids (this=0x2ff8bb0, gtid_set=0x7ffff0359a70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:737
#3 0x00000000016778f3 in Sys_var_gtid_purged::global_update (this=0x2de9fe0, thd=0x7fff2c000b70, var=0x7fff2c006630)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sys_vars.cc:5888
#4 0x00000000014d5cd1 in sys_var::update (this=0x2de9fe0, thd=0x7fff2c000b70, var=0x7fff2c006630) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/set_var.cc:184
#5 0x00000000014d74ee in set_var::update (this=0x7fff2c006630, thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/set_var.cc:812
#6 0x00000000014d6d1a in sql_set_variables (thd=0x7fff2c000b70, var_list=0x7fff2c003528) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/set_var.cc:669其主要逻辑在Gtid_state::add_lost_gtids中。
gtid_executed变量修改时机
在reset master的时候清空本变量
栈帧同上在set global gitd_purged的时候，设置本变量
栈帧同上在mysql启动的时候初始化设置gtid_executed变量，这个将在后面章节详细描述描述步骤。
gtid_purged变量修改时机
在reset master的时候清空本变量
栈帧同上在set global gitd_purged的时候，设置本变量
栈帧同上在mysql启动的时候初始化设置gtid_executed变量，这个将在后面章节详细描述描述步骤。
六、通用更改时机源码函数分析
Gtid_state::clear函数逻辑
int Gtid_state::clear(THD *thd)
{
....
// the wrlock implies that no other thread can hold any of the mutexes
sid_lock->assert_some_wrlock();
lost_gtids.clear();//此处清空gtid_purged变量
executed_gtids.clear();//此处清空gtid_executed变量
gtids_only_in_table.clear();//清空only in table Gtid set
previous_gtids_logged.clear();//清空 previous gtids logged Gtid set
if ((ret= gtid_table_persistor->reset(thd)) == 1)//此处清空mysql.gtid_executed表
{
thd->clear_error();
ret= 0;
}
next_free_gno= 1;
DBUG_RETURN(ret);
}Gtid_state::add_lost_gtids函数逻辑
enum_return_status Gtid_state::add_lost_gtids(const Gtid_set *gtid_set)
{
......
if (save(gtid_set)) //此处将set gtid_purge的值加入到mysql.gtid_executed表中
RETURN_REPORTED_ERROR;
PROPAGATE_REPORTED_ERROR(gtids_only_in_table.add_gtid_set(gtid_set));
PROPAGATE_REPORTED_ERROR(lost_gtids.add_gtid_set(gtid_set));//此处将set gtid_purge的值加入到gtid_purge变量中
PROPAGATE_REPORTED_ERROR(executed_gtids.add_gtid_set(gtid_set));//此处将set gtid_purge的值加入到gtid_executed变量中
lock_sidnos(gtid_set);
broadcast_sidnos(gtid_set);
unlock_sidnos(gtid_set);
DBUG_RETURN(RETURN_STATUS_OK);
}“Mysql 5.7中mysql.gtid_executed表及其他变量更改时机是什么”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注亿速云网站，小编将为大家输出更多高质量的实用文章！
