The patch looks good, but I have some minor comments:
1) Are you planning to add a test case?
2) It would be easier to review this patch if the documentation of
ddl_blocker.cc#check_DDL_blocker mentioned that it has the side effect
that it blocks the ddl blocker until end_ddl is called.
3) I do not think the current variable name (backup_wait_timeout) is
good. However, since the name has been discussed and approved previously
by the team and an architect, I don't consider this a patch blocker.
Jørgen
Chuck Bell wrote:
> #At file:///C:/source/bzr/mysql-6.0-bug-33414/
>
> 2673 Chuck Bell 2008-07-25
> BUG#33414 : Backup: DDL hangs indefinitely if ongoing backup
>
> Added ability to set a timeout for blocked DDL operations. The
> timeout is the number of seconds a blocked DDL operation will
> wait before aborting with an error message. The variable can be
> set only as a session variable.
>
> Note: timeout must be set before DDL is executed.
> modified:
> sql/ddl_blocker.cc
> sql/set_var.cc
> sql/set_var.h
> sql/share/errmsg.txt
> sql/sql_class.cc
> sql/sql_class.h
> sql/sql_parse.cc
