write "COMMIT" into binlog if there's no Xid at the end of transaction

new tests

mysql-test/r/binlog.result

+drop table if exists t1, t2;
+create table t1 (a int) engine=bdb;
+create table t2 (a int) engine=innodb;
+begin;
+insert t1 values (5);
+commit;
+begin;
+insert t2 values (5);
+commit;
+show binlog events from 96;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	96	Query	1	187	use `test`; drop table if exists t1, t2
+master-bin.000001	187	Query	1	285	use `test`; create table t1 (a int) engine=bdb
+master-bin.000001	285	Query	1	386	use `test`; create table t2 (a int) engine=innodb
+master-bin.000001	386	Query	1	455	use `test`; BEGIN
+master-bin.000001	455	Query	1	84	use `test`; insert t1 values (5)
+master-bin.000001	539	Query	1	154	use `test`; COMMIT
+master-bin.000001	609	Query	1	678	use `test`; BEGIN
+master-bin.000001	678	Query	1	84	use `test`; insert t2 values (5)
+master-bin.000001	762	Xid	1	111	COMMIT /* xid=10 */
+reset master;
+drop table t1,t2;

mysql-test/r/innodb.result

@@ -272,6 +272,10 @@ n
 7
 rollback to savepoint `my_savepoint`;
 ERROR 42000: SAVEPOINT my_savepoint does not exist
+insert into t1 values (8);
+savepoint sv;
+commit;
+savepoint sv;
 set autocommit=1;
 rollback;
 drop table t1;
@@ -1717,7 +1721,7 @@ Variable_name	Value
 Innodb_rows_deleted	2070
 show status like "Innodb_rows_inserted";
 Variable_name	Value
-Innodb_rows_inserted	31708
+Innodb_rows_inserted	31709
 show status like "Innodb_rows_updated";
 Variable_name	Value
 Innodb_rows_updated	29530

mysql-test/t/binlog.test

+#
+# misc binlogging tests that do not require a slave running
+#
+-- source include/have_bdb.inc
+-- source include/have_innodb.inc
+
+--disable_warnings
+drop table if exists t1, t2;
+--enable_warnings
+
+create table t1 (a int) engine=bdb;
+create table t2 (a int) engine=innodb;
+begin;
+insert t1 values (5);
+commit;
+begin;
+insert t2 values (5);
+commit;
+# first COMMIT must be Query_log_event, second - Xid_log_event
+show binlog events from 96;
+reset master;
+drop table t1,t2;
+

mysql-test/t/innodb.test

@@ -141,6 +141,10 @@ release savepoint `my_savepoint`;
 select n from t1;
 -- error 1305
 rollback to savepoint `my_savepoint`;
+insert into t1 values (8);
+savepoint sv;
+commit;
+savepoint sv;
 set autocommit=1;
 # nop
 rollback;

sql/log.cc

@@ -103,11 +103,21 @@ static int binlog_prepare(THD *thd, bool all)
   return 0;
 }
 
-static int binlog_commit(THD *thd, bool all)
+static int binlog_real_commit(THD *thd, IO_CACHE *trans_log)
 {
   int error;
+  DBUG_ENTER("binlog_real_commit");
+
+  /* Update the binary log as we have cached some queries */
+  error= mysql_bin_log.write(thd, trans_log);
+  binlog_cleanup_trans(trans_log);
+  DBUG_RETURN(error);
+}
+
+static int binlog_commit(THD *thd, bool all)
+{
   IO_CACHE *trans_log= (IO_CACHE*)thd->ha_data[binlog_hton.slot];
-  DBUG_ENTER("binlog_commit");
+  DBUG_ENTER("binlog_real_commit");
   DBUG_ASSERT(mysql_bin_log.is_open() &&
      (all || !(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN))));
 
@@ -116,11 +126,10 @@ static int binlog_commit(THD *thd, bool all)
     // we're here because trans_log was flushed in MYSQL_LOG::log()
     DBUG_RETURN(0);
   }
+  Query_log_event qev(thd, "COMMIT", 6, TRUE, FALSE);
+  qev.write(trans_log);
 
-  /* Update the binary log as we have cached some queries */
-  error= mysql_bin_log.write(thd, trans_log);
-  binlog_cleanup_trans(trans_log);
-  DBUG_RETURN(error);
+  DBUG_RETURN(binlog_real_commit(thd, trans_log));
 }
 
 static int binlog_rollback(THD *thd, bool all)
@@ -2985,10 +2994,11 @@ void TC_LOG_BINLOG::close()
 int TC_LOG_BINLOG::log(THD *thd, my_xid xid)
 {
   Xid_log_event xle(thd, xid);
-  if (xle.write((IO_CACHE*)thd->ha_data[binlog_hton.slot]))
+  IO_CACHE *trans_log= (IO_CACHE*)thd->ha_data[binlog_hton.slot];
+  if (xle.write(trans_log))
     return 0;
   thread_safe_increment(prepared_xids, &LOCK_prep_xids);
-  return !binlog_commit(thd,1);                 // invert return value
+  return !binlog_real_commit(thd, trans_log);     // invert return value
 }
 
 void TC_LOG_BINLOG::unlog(ulong cookie, my_xid xid)