Revert MDEV-18464 and MDEV-12009

This reverts commit 21b2fad and commit 81d71ee. The MDEV-18464 change introduces a few data race issues. Contrary to the documentation, the field trx_t::victim is not always being protected by lock_sys_t::mutex and trx_t::mutex. Most importantly, it seems that KILL QUERY could wrongly avoid acquiring both mutexes when invoking lock_trx_handle_wait_low(), in case another thread had already set trx->victim=true. We also revert MDEV-12009, because it should depend on the MDEV-18464 fix being present.

Author: dr-m

include/mysql/service_wsrep.h

@@ -112,7 +112,6 @@ extern struct wsrep_service_st {
  int (*wsrep_trx_order_before_func)(MYSQL_THD, MYSQL_THD);
  void (*wsrep_unlock_rollback_func)();
  void (*wsrep_set_data_home_dir_func)(const char *data_dir);
- my_bool (*wsrep_thd_is_applier_func)(THD *thd);
 } *wsrep_service;
 
 #ifdef MYSQL_DYNAMIC_PLUGIN
@@ -156,7 +155,6 @@ extern struct wsrep_service_st {
 #define wsrep_trx_order_before(T1,T2) wsrep_service->wsrep_trx_order_before_func(T1,T2)
 #define wsrep_unlock_rollback() wsrep_service->wsrep_unlock_rollback_func()
 #define wsrep_set_data_home_dir(A) wsrep_service->wsrep_set_data_home_dir_func(A)
-#define wsrep_thd_is_applier(T) wsrep_service->wsrep_thd_is_applier_func(T)
 
 #define wsrep_debug get_wsrep_debug()
 #define wsrep_log_conflicts get_wsrep_log_conflicts()
@@ -216,7 +214,6 @@ void wsrep_thd_set_conflict_state(THD *thd, enum wsrep_conflict_state state);
 bool wsrep_thd_ignore_table(THD *thd);
 void wsrep_unlock_rollback();
 void wsrep_set_data_home_dir(const char *data_dir);
-my_bool wsrep_thd_is_applier(THD *thd);
 
 #endif
 

mysql-test/suite/galera/r/galera_kill_applier.result

@@ -1,8 +1,4 @@
-CREATE USER foo@localhost;
-GRANT SELECT on test.* TO foo@localhost;
-# Open connection to the 1st node using 'test_user1' user.
 Got one of the listed errors
 Got one of the listed errors
 Got one of the listed errors
 Got one of the listed errors
-DROP USER foo@localhost;

mysql-test/suite/galera/t/galera_kill_applier.cnf

@@ -1,74 +1,26 @@
 #
 # This test checks that applier threads are immune to KILL QUERY and KILL STATEMENT
-# when USER is not SUPER
 #
 
 --source include/galera_cluster.inc
+--source include/have_innodb.inc
 
 --connection node_1
 
-CREATE USER foo@localhost;
-GRANT SELECT on test.* TO foo@localhost;
-
 --let $applier_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE != 'wsrep aborter idle' OR STATE IS NULL LIMIT 1`
 
---let $aborter_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE = 'wsrep aborter idle' LIMIT 1`
-
---echo # Open connection to the 1st node using 'test_user1' user.
---let $port_1= \$NODE_MYPORT_1
---connect(foo_node_1,localhost,foo,,test,$port_1,)
-
---connection foo_node_1
-
 --disable_query_log
 --error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
 --eval KILL $applier_thread
 
 --error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
 --eval KILL QUERY $applier_thread
 
---error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
---eval KILL $aborter_thread
-
---error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
---eval KILL QUERY $aborter_thread
---enable_query_log
-
-#
-# SUPER can kill applier threads
-#
---connection node_2
-
---let $applier_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE != 'wsrep aborter idle' OR STATE IS NULL LIMIT 1`
-
---disable_query_log
---eval KILL $applier_thread
---enable_query_log
-
 --let $aborter_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE = 'wsrep aborter idle' LIMIT 1`
 
---disable_query_log
+--error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
 --eval KILL $aborter_thread
---enable_query_log
-
---source include/restart_mysqld.inc
 
---connection node_2
---let $applier_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE != 'wsrep aborter idle' OR STATE IS NULL LIMIT 1`
-
---disable_query_log
---eval KILL QUERY $applier_thread
---enable_query_log
-
---let $aborter_thread = `SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user' AND STATE = 'wsrep aborter idle' LIMIT 1`
-
---disable_query_log
+--error ER_KILL_DENIED_ERROR,ER_KILL_DENIED_ERROR
 --eval KILL QUERY $aborter_thread
 --enable_query_log
-
---source include/restart_mysqld.inc
-
---connection node_1
---disconnect foo_node_1
-DROP USER foo@localhost;
-

mysql-test/suite/galera/t/galera_kill_applier.test

@@ -8292,19 +8292,11 @@ kill_one_thread(THD *thd, longlong id, killed_state kill_signal, killed_type typ
  It's ok to also kill DELAYED threads with KILL_CONNECTION instead of
  KILL_SYSTEM_THREAD; The difference is that KILL_CONNECTION may be
  faster and do a harder kill than KILL_SYSTEM_THREAD;
-
- Note that if thread is wsrep Brute Force or applier thread we
- allow killing it only when we're SUPER.
  */
 
- if ((thd->security_ctx->master_access & SUPER_ACL) ||
-(thd->security_ctx->user_matches(tmp->security_ctx)
-#ifdef WITH_WSREP
- &&
- !tmp->wsrep_applier &&
- !wsrep_thd_is_BF(tmp, false)
-#endif
-))
+ if (((thd->security_ctx->master_access & SUPER_ACL) ||
+ thd->security_ctx->user_matches(tmp->security_ctx)) &&
+!wsrep_thd_is_BF(tmp, false))
  {
  tmp->awake(kill_signal);
  error=0;

sql/sql_parse.cc

@@ -181,8 +181,7 @@ static struct wsrep_service_st wsrep_handler = {
  wsrep_trx_is_aborting,
  wsrep_trx_order_before,
  wsrep_unlock_rollback,
- wsrep_set_data_home_dir,
- wsrep_thd_is_applier,
+ wsrep_set_data_home_dir
 };
 
 static struct thd_specifics_service_st thd_specifics_handler=

sql/sql_plugin_services.ic

@@ -20,9 +20,6 @@
 my_bool wsrep_thd_is_BF(THD *, my_bool)
 { return 0; }
 
-my_bool wsrep_thd_is_applier(THD *)
-{ return 0; }
-
 int wsrep_trx_order_before(THD *, THD *)
 { return 0; }
 

sql/wsrep_dummy.cc

@@ -2470,6 +2470,7 @@ extern "C" void wsrep_thd_set_exec_mode(THD *thd, enum wsrep_exec_mode mode)
  thd->wsrep_exec_mode= mode;
 }
 
+
 extern "C" void wsrep_thd_set_query_state(
 THD *thd, enum wsrep_query_state state)
 {

sql/wsrep_mysqld.cc

@@ -596,15 +596,6 @@ my_bool wsrep_thd_is_BF(THD *thd, my_bool sync)
  return status;
 }
 
-my_bool wsrep_thd_is_applier(THD *thd)
-{
- my_bool ret = FALSE;
- if (thd) {
- ret = thd->wsrep_applier;
- }
- return ret;
-}
-
 extern "C"
 my_bool wsrep_thd_is_BF_or_commit(void *thd_ptr, my_bool sync)
 {

sql/wsrep_thd.cc

@@ -37,7 +37,6 @@ int wsrep_abort_thd(void *bf_thd_ptr, void *victim_thd_ptr,
 */
 extern void wsrep_thd_set_PA_safe(void *thd_ptr, my_bool safe);
 extern my_bool wsrep_thd_is_BF(THD *thd, my_bool sync);
-extern my_bool wsrep_thd_is_applier(THD *thd);
 extern my_bool wsrep_thd_is_wsrep(void *thd_ptr);
 
 enum wsrep_conflict_state wsrep_thd_conflict_state(void *thd_ptr, my_bool sync);
@@ -48,7 +47,6 @@ extern "C" int wsrep_thd_in_locking_session(void *thd_ptr);
 #else /* WITH_WSREP */
 
 #define wsrep_thd_is_BF(T, S) (0)
-#define wsrep_thd_is_applier(T) (0)
 #define wsrep_abort_thd(X,Y,Z) do { } while(0)
 #define wsrep_create_appliers(T) do { } while(0)