Bug #40221 Replication failure on RBR + UPDATE the primary key

A transaction could result in having an extra event after a query that
errored e.g because of a dup key. Such a query is rolled back in
innodb, as specified, but has not been in binlog.
It appeares that the binlog engine did not always register for a query
(statement) because the previous query had not reset at its statement
commit time. Because of that fact there was no roll-back to the
trx_data->before_stmt_pos position and a the pending event of the
errorred query could become flushed to the binlog file.

Fixed with deploying the reset of trx_data->before_stmt_pos at the end
of the query processing.

mysql-test/suite/binlog/r/binlog_innodb_row.result

+CREATE TABLE t1 (pk int auto_increment primary key) ENGINE=innodb;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `pk` int(11) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`pk`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+reset master;
+begin;
+insert into t1 values (1),(2);
+*** the following UPDATE query wont generate any updates for the binlog ***
+update t1 set pk = 3 where pk < 3;
+ERROR 23000: Duplicate entry '3' for key 'PRIMARY'
+commit;
+*** Results of the test: the binlog must have only Write_rows events not any Update_rows ***
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	#	#	use `test`; BEGIN
+master-bin.000001	#	Table_map	#	#	table_id: # (test.t1)
+master-bin.000001	#	Write_rows	#	#	table_id: # flags: STMT_END_F
+master-bin.000001	#	Xid	#	#	COMMIT /* XID */
+drop table t1;

mysql-test/suite/binlog/t/binlog_innodb_row.test

+#
+# Tests of innodb/binlog with the row binlog format
+# 
+source include/have_innodb.inc;
+source include/have_log_bin.inc;
+source include/have_binlog_format_row.inc;
+
+#
+# Bug #40221 Replication failure on RBR + UPDATE the primary key
+#
+
+CREATE TABLE t1 (pk int auto_increment primary key) ENGINE=innodb;
+show create table t1;
+reset master;
+
+begin;
+insert into t1 values (1),(2);
+--echo *** the following UPDATE query wont generate any updates for the binlog ***
+--error ER_DUP_ENTRY
+update t1 set pk = 3 where pk < 3;
+commit;
+
+--echo *** Results of the test: the binlog must have only Write_rows events not any Update_rows ***
+source include/show_binlog_events.inc;
+
+drop table t1;

sql/log.cc

@@ -207,6 +207,7 @@ public:
       truncate(0);
     before_stmt_pos= MY_OFF_T_UNDEF;
     trans_log.end_of_file= max_binlog_cache_size;
+    DBUG_ASSERT(empty());
   }
 
   Rows_log_event *pending() const
@@ -1377,8 +1378,6 @@ binlog_end_trans(THD *thd, binlog_trx_data *trx_data,
                       FLAGSTR(thd->options, OPTION_NOT_AUTOCOMMIT),
                       FLAGSTR(thd->options, OPTION_BEGIN)));
 
-  thd->binlog_flush_pending_rows_event(TRUE);
-
   /*
     NULL denotes ROLLBACK with nothing to replicate: i.e., rollback of
     only transactional tables.  If the transaction contain changes to
@@ -1387,6 +1386,7 @@ binlog_end_trans(THD *thd, binlog_trx_data *trx_data,
   */
   if (end_ev != NULL)
   {
+    thd->binlog_flush_pending_rows_event(TRUE);
     /*
       Doing a commit or a rollback including non-transactional tables,
       i.e., ending a transaction where we might write the transaction
@@ -1435,6 +1435,7 @@ binlog_end_trans(THD *thd, binlog_trx_data *trx_data,
     mysql_bin_log.update_table_map_version();
   }
 
+  DBUG_ASSERT(thd->binlog_get_pending_rows_event() == NULL);
   DBUG_RETURN(error);
 }
 
@@ -1466,6 +1467,7 @@ static int binlog_prepare(handlerton *hton, THD *thd, bool all)
 */
 static int binlog_commit(handlerton *hton, THD *thd, bool all)
 {
+  int error= 0;
   DBUG_ENTER("binlog_commit");
   binlog_trx_data *const trx_data=
     (binlog_trx_data*) thd_get_ha_data(thd, binlog_hton);
@@ -1552,10 +1554,14 @@ static int binlog_commit(handlerton *hton, THD *thd, bool all)
   {
     Query_log_event qev(thd, STRING_WITH_LEN("COMMIT"), TRUE, FALSE);
     qev.error_code= 0; // see comment in MYSQL_LOG::write(THD, IO_CACHE)
-    int error= binlog_end_trans(thd, trx_data, &qev, all);
-    DBUG_RETURN(error);
+    error= binlog_end_trans(thd, trx_data, &qev, all);
+    goto end;
   }
-  DBUG_RETURN(0);
+
+end:
+  if (!all)
+    trx_data->before_stmt_pos = MY_OFF_T_UNDEF; // part of the stmt commit
+  DBUG_RETURN(error);
 }
 
 /**
@@ -1615,6 +1621,8 @@ static int binlog_rollback(handlerton *hton, THD *thd, bool all)
      */
     error= binlog_end_trans(thd, trx_data, 0, all);
   }
+  if (!all)
+    trx_data->before_stmt_pos = MY_OFF_T_UNDEF; // part of the stmt rollback
   DBUG_RETURN(error);
 }