- It turns out, there are statements that will call lex_start(thd->lex)
after parsing has been finished. lex_start() will set lex->explain=NULL,
which will lose the pointer to already allocated Explain_plan object.
- To get rid of this, switch to lazy creation of lex->explain. Now, it is
created only when we get a part ot query plan.
- Made slaves temporary table multi-thread slave safe by adding mutex around save_temporary_table usage.
- rli->save_temporary_tables is the active list of all used temporary tables
- This is copied to THD->temporary_tables when temporary tables are opened and updated when temporary tables are closed
- Added THD->lock_temporary_tables() and THD->unlock_temporary_tables() to simplify this.
- Relay_log_info->sql_thd renamed to Relay_log_info->sql_driver_thd to avoid wrong usage for merged code.
- Added is_part_of_group() to mark functions that are part of the next function. This replaces setting IN_STMT when events are executed.
- Added is_begin(), is_commit() and is_rollback() functions to Query_log_event to simplify code.
- If slave_skip_counter is set run things in single threaded mode. This simplifies code for skipping events.
- Updating state of relay log (IN_STMT and IN_TRANSACTION) is moved to one single function: update_state_of_relay_log()
We can't use OPTION_BEGIN to check for the state anymore as the sql_driver and sql execution threads may be different.
Clear IN_STMT and IN_TRANSACTION in init_relay_log_pos() and Relay_log_info::cleanup_context() to ensure the flags doesn't survive slave restarts
is_in_group() is now independent of state of executed transaction.
- Reset thd->transaction.all.modified_non_trans_table() if we did set it for single table row events.
This was mainly for keeping the flag as documented.
- Changed slave_open_temp_tables to uint32 to be able to use atomic operators on it.
- Relay_log_info::sleep_lock -> rpl_group_info::sleep_lock
- Relay_log_info::sleep_cond -> rpl_group_info::sleep_cond
- Changed some functions to take rpl_group_info instead of Relay_log_info to make them multi-slave safe and to simplify usage
- do_shall_skip()
- continue_group()
- sql_slave_killed()
- next_event()
- Simplifed arguments to io_salve_killed(), check_io_slave_killed() and sql_slave_killed(); No reason to supply THD as this is part of the given structure.
- set_thd_in_use_temporary_tables() removed as in_use is set on usage
- Added information to thd_proc_info() which thread is waiting for slave mutex to exit.
- In open_table() reuse code from find_temporary_table()
Other things:
- More DBUG statements
- Fixed the rpl_incident.test can be run with --debug
- More comments
- Disabled not used function rpl_connect_master()
mysql-test/suite/perfschema/r/all_instances.result:
Moved sleep_lock and sleep_cond to rpl_group_info
mysql-test/suite/rpl/r/rpl_incident.result:
Updated result
mysql-test/suite/rpl/t/rpl_incident-master.opt:
Not needed anymore
mysql-test/suite/rpl/t/rpl_incident.test:
Fixed that test can be run with --debug
sql/handler.cc:
More DBUG_PRINT
sql/log.cc:
More comments
sql/log_event.cc:
Added DBUG statements
do_shall_skip(), continue_group() now takes rpl_group_info param
Use is_begin(), is_commit() and is_rollback() functions instead of inspecting query string
We don't have set slaves temporary tables 'in_use' as this is now done when tables are opened.
Removed IN_STMT flag setting. This is now done in update_state_of_relay_log()
Use IN_TRANSACTION flag to test state of relay log.
In rows_event_stmt_cleanup() reset thd->transaction.all.modified_non_trans_table if we had set this before.
sql/log_event.h:
do_shall_skip(), continue_group() now takes rpl_group_info param
Added is_part_of_group() to mark events that are part of the next event. This replaces setting IN_STMT when events are executed.
Added is_begin(), is_commit() and is_rollback() functions to Query_log_event to simplify code.
sql/log_event_old.cc:
Removed IN_STMT flag setting. This is now done in update_state_of_relay_log()
do_shall_skip(), continue_group() now takes rpl_group_info param
sql/log_event_old.h:
Added is_part_of_group() to mark events that are part of the next event.
do_shall_skip(), continue_group() now takes rpl_group_info param
sql/mysqld.cc:
Changed slave_open_temp_tables to uint32 to be able to use atomic operators on it.
Relay_log_info::sleep_lock -> Rpl_group_info::sleep_lock
Relay_log_info::sleep_cond -> Rpl_group_info::sleep_cond
sql/mysqld.h:
Updated types and names
sql/rpl_gtid.cc:
More DBUG
sql/rpl_parallel.cc:
Updated TODO section
Set thd for event that is execution
Use new is_begin(), is_commit() and is_rollback() functions.
More comments
sql/rpl_rli.cc:
sql_thd -> sql_driver_thd
Relay_log_info::sleep_lock -> rpl_group_info::sleep_lock
Relay_log_info::sleep_cond -> rpl_group_info::sleep_cond
Clear IN_STMT and IN_TRANSACTION in init_relay_log_pos() and Relay_log_info::cleanup_context() to ensure the flags doesn't survive slave restarts.
Reset table->in_use for temporary tables as the table may have been used by another THD.
Use IN_TRANSACTION instead of OPTION_BEGIN to check state of relay log.
Removed IN_STMT flag setting. This is now done in update_state_of_relay_log()
sql/rpl_rli.h:
Changed relay log state flags to bit masks instead of bit positions (most other code we have uses bit masks)
Added IN_TRANSACTION to mark if we are in a BEGIN ... COMMIT section.
save_temporary_tables is now thread safe
Relay_log_info::sleep_lock -> rpl_group_info::sleep_lock
Relay_log_info::sleep_cond -> rpl_group_info::sleep_cond
Relay_log_info->sql_thd renamed to Relay_log_info->sql_driver_thd to avoid wrong usage for merged code
is_in_group() is now independent of state of executed transaction.
sql/slave.cc:
Simplifed arguments to io_salve_killed(), sql_slave_killed() and check_io_slave_killed(); No reason to supply THD as this is part of the given structure.
set_thd_in_use_temporary_tables() removed as in_use is set on usage in sql_base.cc
sql_thd -> sql_driver_thd
More DBUG
Added update_state_of_relay_log() which will calculate the IN_STMT and IN_TRANSACTION state of the relay log after the current element is executed.
If slave_skip_counter is set run things in single threaded mode.
Simplifed arguments to io_salve_killed(), check_io_slave_killed() and sql_slave_killed(); No reason to supply THD as this is part of the given structure.
Added information to thd_proc_info() which thread is waiting for slave mutex to exit.
Disabled not used function rpl_connect_master()
Updated argument to next_event()
sql/sql_base.cc:
Added mutex around usage of slave's temporary tables. The active list is always kept up to date in sql->rgi_slave->save_temporary_tables.
Clear thd->temporary_tables after query (safety)
More DBUG
When using temporary table, set table->in_use to current thd as the THD may be different for slave threads.
Some code is ifdef:ed with REMOVE_AFTER_MERGE_WITH_10 as the given code in 10.0 is not yet in this tree.
In open_table() reuse code from find_temporary_table()
sql/sql_binlog.cc:
rli->sql_thd -> rli->sql_driver_thd
Remove duplicate setting of rgi->rli
sql/sql_class.cc:
Added helper functions rgi_lock_temporary_tables() and rgi_unlock_temporary_tables()
Would have been nicer to have these inline, but there was no easy way to do that
sql/sql_class.h:
Added functions to protect slaves temporary tables
sql/sql_parse.cc:
Added DBUG_PRINT
sql/transaction.cc:
Added comment
- Run probes like MYSQL_INSERT_SELECT_START or
MYSQL_MULTI_DELETE_START for EXPLAIN, too.
We should run them, because 1. EXPLAIN SELECT does it, and
2. MySQL also does it.
- Make EXPLAIN UPDATE/DELETE work inside SPs
- Return correct error code from mysql_delete()
- EXPLAIN <multi-DELETE> will create a multi_delete object (as it
affects the optimization). select_result will be only used for
producing EXPLAIN output.
- merged test cases for MySQL bug#27480
- fixed that LOCK TABLES was unable to open temporary table
(covered by grant2 test, merged appropriate code from 5.6)
- commented lines that cause server crash in merge test, reported
MDEV-5042 (not relevant to bug#27480)
It is now possible to kill query by query id. KILL syntax was extended to:
KILL [HARD | SOFT] [CONNECTION | QUERY [ID query_id]] [thread_id | USER user_name]
Added QUERY_ID column to INFORMATION_SCHEMA.PROCESSLIST.
Fixed tests affected by this change:
- added PROCESSLIST.QUERY_ID column
- ID is now keyword and is quoted in SHOW CREATE TABLE output
- PFS statement digest is calculated basing on token id
(not token text). Token id has shifted for keywords residing
after ID in keywords array.
- YYPARSE_PARAM and YYLEX_PARAM are removed in Bison 3.0. Deprecated
since Bison 1.875 in favor of %lex-param, %parse-param.
- %parse-param adds an argument to yyerror() as well, updated
MYSQLerror() accordingly.
- %parse-param allows to declare proper type for argument. That's
what 99% of this patch is about.
"SHOW PROCESSLIST"
Analysis:
----------
The problem here is, if one connection changes its
default db and at the same time another connection executes
"SHOW PROCESSLIST", when it wants to read db of the another
connection then there is a chance of accessing the invalid
memory.
The db name stored in THD is not guarded while changing user
DB and while reading the user DB in "SHOW PROCESSLIST".
So, if THD.db is freed by thd "owner" thread and if another
thread executing "SHOW PROCESSLIST" statement tries to read
and copy THD.db at the same time then we may endup in the issue
reported here.
Fix:
----------
Used mutex "LOCK_thd_data" to guard THD.db while freeing it
and while copying it to processlist.
"SHOW PROCESSLIST"
Analysis:
----------
The problem here is, if one connection changes its
default db and at the same time another connection executes
"SHOW PROCESSLIST", when it wants to read db of the another
connection then there is a chance of accessing the invalid
memory.
The db name stored in THD is not guarded while changing user
DB and while reading the user DB in "SHOW PROCESSLIST".
So, if THD.db is freed by thd "owner" thread and if another
thread executing "SHOW PROCESSLIST" statement tries to read
and copy THD.db at the same time then we may endup in the issue
reported here.
Fix:
----------
Used mutex "LOCK_thd_data" to guard THD.db while freeing it
and while copying it to processlist.
