MDEV-22203: WSREP_ON is unnecessarily expensive to evaluate

This is a backport of the applicable part of
commit 93475af and
commit 2c39f69
from 10.4.

Before 10.4 and Galera 4, WSREP_ON is a macro that points to
a global Boolean variable, so it is not that expensive to
evaluate, but we will add an unlikely() hint around it.

WSREP_ON_NEW: Remove. This macro was introduced in
commit c863159
when reverting WSREP_ON to its previous definition.

We replace some use of WSREP_ON with WSREP(thd), like it was done
in 93475af. Note: the macro
WSREP() in 10.1 is equivalent to WSREP_NNULL() in 10.4.

Item_func_rand::seed_random(): Avoid invoking current_thd
when WSREP is not enabled.

Author: dr-m

mysql-test/suite/galera/t/MW-86-wait1.test

@@ -5,6 +5,7 @@
 #
 --source include/galera_cluster.inc
 --source include/have_binlog_format_row.inc
+--source include/have_debug.inc
 --source include/have_debug_sync.inc
 
 --connection node_2

sql/item_func.cc

@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2015, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2017, MariaDB
+   Copyright (c) 2009, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -2650,19 +2650,20 @@ void Item_func_rand::seed_random(Item *arg)
     TODO: do not do reinit 'rand' for every execute of PS/SP if
     args[0] is a constant.
   */
-  uint32 tmp;
+  uint32 tmp= (uint32) arg->val_int();
 #ifdef WITH_WSREP
-  THD *thd= current_thd;
-  if (WSREP(thd))
+  if (WSREP_ON)
   {
-    if (thd->wsrep_exec_mode==REPL_RECV)
-      tmp= thd->wsrep_rand;
-    else
-      tmp= thd->wsrep_rand= (uint32) arg->val_int();
-   }
-  else
+    THD *thd= current_thd;
+    if (thd->variables.wsrep_on)
+    {
+      if (thd->wsrep_exec_mode==REPL_RECV)
+        tmp= thd->wsrep_rand;
+      else
+        thd->wsrep_rand= tmp;
+    }
+  }
 #endif /* WITH_WSREP */
-    tmp= (uint32) arg->val_int();
 
   my_rnd_init(rand, (uint32) (tmp*0x10001L+55555555L),
              (uint32) (tmp*0x10000001L));

sql/log.cc

@@ -1791,7 +1791,7 @@ binlog_commit_flush_stmt_cache(THD *thd, bool all,
 #ifdef WITH_WSREP
   if (thd->wsrep_mysql_replicated > 0)
   {
-    DBUG_ASSERT(WSREP_ON);
+    DBUG_ASSERT(WSREP(thd));
     WSREP_DEBUG("avoiding binlog_commit_flush_trx_cache: %d",
                 thd->wsrep_mysql_replicated);
     return 0;
@@ -6612,14 +6612,15 @@ int MYSQL_BIN_LOG::rotate(bool force_rotate, bool* check_purge)
   int error= 0;
   DBUG_ENTER("MYSQL_BIN_LOG::rotate");
 
-  if (wsrep_to_isolation)
+#ifdef WITH_WSREP
+  if (WSREP_ON && wsrep_to_isolation)
   {
-    DBUG_ASSERT(WSREP_ON);
     *check_purge= false;
-    WSREP_DEBUG("avoiding binlog rotate due to TO isolation: %d", 
+    WSREP_DEBUG("avoiding binlog rotate due to TO isolation: %d",
                 wsrep_to_isolation);
     DBUG_RETURN(0);
   }
+#endif /* WITH_WSREP */
 
   //todo: fix the macro def and restore safe_mutex_assert_owner(&LOCK_log);
   *check_purge= false;

sql/log_event.cc

@@ -1,6 +1,6 @@
 /*
    Copyright (c) 2000, 2019, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2019, MariaDB
+   Copyright (c) 2009, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -4770,7 +4770,7 @@ Query_log_event::do_shall_skip(rpl_group_info *rgi)
     }
   }
 #ifdef WITH_WSREP
-  else if (WSREP_ON && wsrep_mysql_replication_bundle && opt_slave_domain_parallel_threads == 0 &&
+  else if (WSREP(thd) && wsrep_mysql_replication_bundle && opt_slave_domain_parallel_threads == 0 &&
            thd->wsrep_mysql_replicated > 0 &&
            (is_begin() || is_commit()))
   {
@@ -4784,7 +4784,7 @@ Query_log_event::do_shall_skip(rpl_group_info *rgi)
       thd->wsrep_mysql_replicated = 0;
     }
   }
-#endif
+#endif /* WITH_WSREP */
   DBUG_RETURN(Log_event::do_shall_skip(rgi));
 }
 
@@ -7755,7 +7755,7 @@ Xid_log_event::do_shall_skip(rpl_group_info *rgi)
     DBUG_RETURN(Log_event::EVENT_SKIP_COUNT);
   }
 #ifdef WITH_WSREP
-  else if (wsrep_mysql_replication_bundle && WSREP_ON &&
+  else if (WSREP(thd) && wsrep_mysql_replication_bundle &&
            opt_slave_domain_parallel_threads == 0)
   {
     if (++thd->wsrep_mysql_replicated < (int)wsrep_mysql_replication_bundle)

sql/mysqld.cc

@@ -5781,8 +5781,10 @@ int mysqld_main(int argc, char **argv)
       set_user(mysqld_user, user_info);
   }
 
+#ifdef WITH_WSREP
   if (WSREP_ON && wsrep_check_opts())
     global_system_variables.wsrep_on= 0;
+#endif
 
   if (opt_bin_log && !global_system_variables.server_id)
   {

sql/slave.cc

@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2017, MariaDB Corporation
+   Copyright (c) 2009, 2020, MariaDB Corporation
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -4998,8 +4998,10 @@ pthread_handler_t handle_slave_sql(void *arg)
       if (!sql_slave_killed(serial_rgi))
       {
         slave_output_error_info(serial_rgi, thd);
-        if (WSREP_ON && rli->last_error().number == ER_UNKNOWN_COM_ERROR)
+        if (WSREP(thd) && rli->last_error().number == ER_UNKNOWN_COM_ERROR)
+        {
           wsrep_node_dropped= TRUE;
+        }
       }
       goto err;
     }
@@ -5131,7 +5133,7 @@ pthread_handler_t handle_slave_sql(void *arg)
     If slave stopped due to node going non primary, we set global flag to
     trigger automatic restart of slave when node joins back to cluster.
   */
-  if (WSREP_ON && wsrep_node_dropped && wsrep_restart_slave)
+  if (WSREP(thd) && wsrep_node_dropped && wsrep_restart_slave)
   {
     if (wsrep_ready_get())
     {

sql/sql_base.cc

@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2016, Oracle and/or its affiliates.
-   Copyright (c) 2010, 2016, MariaDB
+   Copyright (c) 2010, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -4784,7 +4784,7 @@ bool open_tables(THD *thd, const DDL_options_st &options,
     }
   }
 
-  if (WSREP_ON                                         &&
+  if (WSREP(thd)                                       &&
       wsrep_replicate_myisam                           &&
       (*start)                                         &&
       (*start)->table                                  &&

sql/sql_parse.cc

@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2017, Oracle and/or its affiliates.
-   Copyright (c) 2008, 2019, MariaDB
+   Copyright (c) 2008, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1493,7 +1493,7 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     if (parser_state.init(thd, thd->query(), thd->query_length()))
       break;
 
-    if (WSREP_ON)
+    if (WSREP(thd))
       wsrep_mysql_parse(thd, thd->query(), thd->query_length(), &parser_state);
     else
       mysql_parse(thd, thd->query(), thd->query_length(), &parser_state);
@@ -1574,13 +1574,13 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
       */
       statistic_increment(thd->status_var.questions, &LOCK_status);
 
-      if(!WSREP(thd))
+      if (!WSREP(thd))
 	thd->set_time(); /* Reset the query start time. */
 
       parser_state.reset(beginning_of_next_stmt, length);
       /* TODO: set thd->lex->sql_command to SQLCOM_END here */
 
-      if (WSREP_ON)
+      if (WSREP(thd))
         wsrep_mysql_parse(thd, beginning_of_next_stmt, length, &parser_state);
       else
         mysql_parse(thd, beginning_of_next_stmt, length, &parser_state);

sql/sql_table.cc

@@ -1,6 +1,6 @@
 /*
    Copyright (c) 2000, 2019, Oracle and/or its affiliates.
-   Copyright (c) 2010, 2019, MariaDB
+   Copyright (c) 2010, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -5338,7 +5338,7 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
   DBUG_ENTER("mysql_create_like_table");
 
 #ifdef WITH_WSREP
-  if (WSREP_ON && !thd->wsrep_applier &&
+  if (WSREP(thd) && !thd->wsrep_applier &&
       wsrep_create_like_table(thd, table, src_table, create_info))
     DBUG_RETURN(res);
 #endif

sql/wsrep_mysqld.h

@@ -179,13 +179,7 @@ extern void wsrep_prepend_PATH (const char* path);
 /* Other global variables */
 extern wsrep_seqno_t wsrep_locked_seqno;
 
-#define WSREP_ON                         \
-  (global_system_variables.wsrep_on)
-
-#define WSREP_ON_NEW                     \
-  ((global_system_variables.wsrep_on) && \
-   wsrep_provider                     && \
-   strcmp(wsrep_provider, WSREP_NONE))
+#define WSREP_ON unlikely(global_system_variables.wsrep_on)
 
 #define WSREP(thd) \
   (WSREP_ON && thd->variables.wsrep_on)