MDEV-25319 : Long BF log wait turns on InnoDB Monitor output without telling, never turns it off

Removed explicit InnoDB monitor startup and used just functions
to print current lock information.

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

+CREATE TABLE t1(id int not null primary key, b int) engine=InnoDB;
+INSERT INTO t1 VALUES (0,0),(1,1),(2,2),(3,3);
+BEGIN;
+UPDATE t1 set b = 100 where id between 1 and 2;;
+connect node_1b, 127.0.0.1, root, , test, $NODE_MYPORT_1;
+connection node_1b;
+SET @save_dbug = @@SESSION.debug_dbug;
+SET @@SESSION.innodb_lock_wait_timeout=2;
+SET @@SESSION.debug_dbug = '+d,wsrep_instrument_BF_lock_wait';
+UPDATE t1 set b = 200 WHERE id = 1;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
+SET @@SESSION.debug_dbug = @save_dbug;
+connection node_1;
+COMMIT;
+SELECT * FROM t1;
+id	b
+0	0
+1	100
+2	100
+3	3
+disconnect node_1b;
+DROP TABLE t1;

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

+--source include/galera_cluster.inc
+--source include/have_debug.inc
+--source include/have_debug_sync.inc
+
+CREATE TABLE t1(id int not null primary key, b int) engine=InnoDB;
+INSERT INTO t1 VALUES (0,0),(1,1),(2,2),(3,3);
+
+BEGIN;
+--send UPDATE t1 set b = 100 where id between 1 and 2;
+
+--connect node_1b, 127.0.0.1, root, , test, $NODE_MYPORT_1
+--connection node_1b
+SET @save_dbug = @@SESSION.debug_dbug;
+SET @@SESSION.innodb_lock_wait_timeout=2;
+SET @@SESSION.debug_dbug = '+d,wsrep_instrument_BF_lock_wait';
+--error ER_LOCK_WAIT_TIMEOUT
+UPDATE t1 set b = 200 WHERE id = 1;
+SET @@SESSION.debug_dbug = @save_dbug;
+
+--connection node_1
+--reap
+COMMIT;
+SELECT * FROM t1;
+--disconnect node_1b
+DROP TABLE t1;

storage/innobase/lock/lock0wait.cc

@@ -192,28 +192,33 @@ wsrep_is_BF_lock_timeout(
 	const trx_t*	trx,
 	bool		locked = true)
 {
-	if (trx->is_wsrep() && wsrep_thd_is_BF(trx->mysql_thd, FALSE)
-	    && trx->error_state != DB_DEADLOCK) {
-		ib::info() << "WSREP: BF lock wait long for trx:" << ib::hex(trx->id)
+	bool long_wait= (trx->error_state != DB_DEADLOCK &&
+			 trx->is_wsrep() &&
+			 wsrep_thd_is_BF(trx->mysql_thd, false));
+	bool was_wait= true;
+
+	DBUG_EXECUTE_IF("wsrep_instrument_BF_lock_wait",
+			was_wait=false; long_wait=true;);
+
+	if (long_wait) {
+		ib::info() << "WSREP: BF lock wait long for trx:" << trx->id
 			   << " query: " << wsrep_thd_query(trx->mysql_thd);
-		if (!locked) {
+
+		if (!locked)
 			lock_mutex_enter();
-		}
 
 		ut_ad(lock_mutex_own());
 
 		wsrep_trx_print_locking(stderr, trx, 3000);
+		/* Note this will release lock_sys mutex */
+		lock_print_info_all_transactions(stderr);
 
-		if (!locked) {
-			lock_mutex_exit();
-		}
+		if (locked)
+			lock_mutex_enter();
 
-		srv_print_innodb_monitor 	= TRUE;
-		srv_print_innodb_lock_monitor 	= TRUE;
-		os_event_set(srv_monitor_event);
-		return true;
-	}
-	return false;
+		return was_wait;
+	} else
+		return false;
 }
 #endif /* WITH_WSREP */