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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:

#0Gtid_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#10x0000000001803dbeinGtid_state::save(this=0x2ff8bb0,gtid_set=0x7ffff03595a0)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:796#20x0000000001803f62inGtid_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#30x000000000185266dinMYSQL_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#40x00000000018520a7inMYSQL_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#50x0000000001853e67inMYSQL_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：

#0Gtid_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#10x0000000001804576inGtid_set::_add_gtid(this=0x2ff8d38,gtid=...)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid.h:1166#20x00000000018024bainGtid_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#30x00000000018020dfinGtid_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#40x00000000018573d4inMYSQL_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#50x0000000001858b51inMYSQL_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:

#0MYSQL_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#10x0000000001850b8einMYSQL_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#20x0000000001848ecfinpurge_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。

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/*logged_gtids_last_binlog=executed_gtids-previous_gtids_logged-gtids_only_in_table*/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_gtidsstart=1,end=27RETURN_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=27logged_gtids_last_binlog.remove_gtid_set(&gtids_only_in_table);//此处主库一定为空，除非异常情况if(!logged_gtids_last_binlog.is_empty()){/*Prepareprevious_gtids_loggedfornextbinlogonbinlogrotation*/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();/*SavesetofGTIDsofthelastbinlogintogtid_executedtable*/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/*false=don'tneedlock*/,NULL/*trx_parser*/,NULL/*gtid_partial_trx*/);//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)gotoerr;}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

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slaveupdate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{/*Ifthebinarylogisdisabledforthisthread(eitherbylog_bin=0orsql_log_bin=0orbylog_slave_updates=0foraslavethread),thenthestatementwillnotbewrittentothebinarylog.Inthiscase,weshouldsaveitsGTIDintomysql.gtid_executedtableand@@GLOBAL.GTID_EXECUTEDasitdidwhenbinlogisenabled.*/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;}elseif(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"););/*AnysessionaddstransactionownedGTIDintoglobalexecuted_gtids.Ifbinlogisdisabled,wereport@@GLOBAL.GTID_PURGEDfromexecuted_gtids,since@@GLOBAL.GTID_PURGEDand@@GLOBAL.GTID_EXECUTEDarealwayssame,sowedidnotsavegtidintolost_gtidsforeverytransactionforimprovingperformance.Ifbinlogisenabledandlog_slave_updatesisdisabled,slaveSQLthreadorslaveworkerthreadaddstransactionownedGTIDintoglobalexecuted_gtids,lost_gtidsandgtids_only_in_table.*/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：

#0Gtid_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#10x000000000180a4efinGtid_table_persistor::reset(this=0x2f9f9c0,thd=0x7fff2c000b70)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_persist.cc:689#20x0000000001801f2einGtid_state::clear(this=0x2ff8bb0,thd=0x7fff2c000b70)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:36#30x000000000184fee6inMYSQL_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#40x0000000001872308inreset_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：

#0Gtid_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#10x000000000180400ainGtid_state::save(this=0x2ff8bb0,gtid_set=0x7ffff0359a70)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/rpl_gtid_state.cc:796#20x0000000001803c25inGtid_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#30x00000000016778f3inSys_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#40x00000000014d5cd1insys_var::update(this=0x2de9fe0,thd=0x7fff2c000b70,var=0x7fff2c006630)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/set_var.cc:184#50x00000000014d74eeinset_var::update(this=0x7fff2c006630,thd=0x7fff2c000b70)at/root/mysql5.7.14/percona-server-5.7.14-7/sql/set_var.cc:812#60x00000000014d6d1ainsql_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。

Gtid_state::clear函数逻辑

intGtid_state::clear(THD*thd){....//thewrlockimpliesthatnootherthreadcanholdanyofthemutexessid_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onlyintableGtidsetprevious_gtids_logged.clear();//清空previousgtidsloggedGtidset/*Resetgtid_executedtable.*/if((ret=gtid_table_persistor->reset(thd))==1)//此处清空mysql.gtid_executed表{/*Gtidtableisnotreadytobeused,sofailedtoopenit.Ignoretheerror.*/thd->clear_error();ret=0;}next_free_gno=1;DBUG_RETURN(ret);}

Gtid_state::add_lost_gtids函数逻辑

enum_return_statusGtid_state::add_lost_gtids(constGtid_set*gtid_set){......if(save(gtid_set))//此处将setgtid_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setgtid_purge的值加入到gtid_purge变量中PROPAGATE_REPORTED_ERROR(executed_gtids.add_gtid_set(gtid_set));//此处将setgtid_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);}

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