MDEV-34071: Failure during the galera_3nodes_sr.GCF-336 test

This commit fixes sporadic failures in galera_3nodes_sr.GCF-336
test. The following changes have been made here:

1) A small addition to the test itself which should make
   it more deterministic by waiting for non-primary state
   before COMMIT;
2) More careful handling of the wsrep_ready variable in
   the server code (it should always be protected with mutex).

No additional tests are required.

mysql-test/suite/galera_3nodes_sr/r/GCF-336.result

@@ -25,6 +25,8 @@ SET SESSION wsrep_sync_wait=0;
 connection node_2;
 INSERT INTO t1 VALUES (2);
 ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+connection node_2a;
+connection node_2;
 COMMIT;
 ERROR 08S01: WSREP has not yet prepared node for application use
 connection node_2a;

mysql-test/suite/galera_3nodes_sr/t/GCF-336.test

@@ -27,6 +27,12 @@ SET SESSION wsrep_sync_wait=0;
 --connection node_2
 --error ER_LOCK_DEADLOCK
 INSERT INTO t1 VALUES (2);
+
+--connection node_2a
+--let $wait_condition = SELECT VARIABLE_VALUE = 'non-Primary' FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_status';
+--source include/wait_condition.inc
+
+--connection node_2
 --error ER_UNKNOWN_COM_ERROR
 COMMIT;
 

sql/slave.cc

@@ -3895,7 +3895,7 @@ apply_event_and_update_pos_apply(Log_event* ev, THD* thd, rpl_group_info *rgi,
           if (thd->system_thread == SYSTEM_THREAD_SLAVE_SQL &&
               ((rli->mi->using_parallel() &&
                 rli->mi->parallel_mode <= SLAVE_PARALLEL_CONSERVATIVE) ||
-               wsrep_ready == 0)) {
+                !wsrep_ready_get())) {
             rli->abort_slave= 1;
             rli->report(ERROR_LEVEL, ER_UNKNOWN_COM_ERROR, rgi->gtid_info(),
                         "Node has dropped from cluster");

sql/wsrep_mysqld.cc

@@ -3456,7 +3456,7 @@ void wsrep_ready_set(bool ready_value)
   mysql_mutex_lock(&LOCK_wsrep_ready);
   wsrep_ready= ready_value;
   // Signal if we have reached ready state
-  if (wsrep_ready)
+  if (ready_value)
     mysql_cond_signal(&COND_wsrep_ready);
   mysql_mutex_unlock(&LOCK_wsrep_ready);
 }

sql/wsrep_notify.cc

@@ -24,7 +24,7 @@ void wsrep_notify_status(enum wsrep::server_state::state status,
   if (!view)
   {
     WSREP_DEBUG("wsrep_notify_status server not yet ready : wsrep_ready=%d status %d",
-		wsrep_ready, (int)status);
+		(int) wsrep_ready_get(), (int)status);
     return;
   }
 

sql/wsrep_server_service.cc

@@ -340,7 +340,6 @@ void Wsrep_server_service::log_state_change(
   switch (current_state)
   {
   case Wsrep_server_state::s_synced:
-    wsrep_ready= TRUE;
     WSREP_INFO("Synchronized with group, ready for connections");
     wsrep_ready_set(true);
     /* fall through */