On 12/03/2012 01:57 AM, Roald van Loon wrote:
Hi list, ceph devs,
I've been doing some toying with Ceph lately in my spare time and one
of the things I'm doing is trying to refactor some of the
configuration handling / argument parsing. I had some trouble finding
specific runtime options and configuration settings, so I thought this
was a good way to get to know the code somewhat better :-) Because
boost was already used in some places, and some tests also used
boost::program_options, I've created a new config framework based on
this. This framework allows for more advanced configuration files in
the future, beter command line handling, and reduces the amount of
code in argument parsing somewhat. I also created a different observer
system, where different parts of the code base can subscribe to
changes in specific parameters and get notified on changes.
Awesome! We've needed better command line parsing and usage for a while.
It looks like boost::program_options does a lot of nice things there.
To allow somewhat of a smoother transition and backwards
compatibility, I've made the new configuration class inherit from the
one one (md_config_t) and switched all references (like g_conf) to the
new class. There were also some small changes in files with references
directly to md_config_t, like pidfile_write. Global_init and
common_init were duplicated such that it 'injects' the new
configuration class in the ceph_context object. Most config entries
are read directly from the md_config_t class (e.g. g_conf->pid_file),
so it will take some more changes to allow my configuration framework
to function properly.
This seems like a nice way to allow it to be used gradually by more
and more tools.
Of course it's an extremely long long long way from ready, but maybe
you're interested. Maybe you think this is not needed at all... I'd
love to have some feedback on it either way.
It looks like you've got a good start on integrating it into the main
ceph infrastructure. Skimming over it, the general structure makes sense
to me. One part that might be a bit tricky is making the new parsing
backwards compatible with the old parsing.
1) For config options in general, '-', '_', and ' ' are all equivalent.
2) In ceph's config file format, we treat ';' as a comment in addition
to '#'.
I'm not sure how difficult those are to handle with the built-in
boost::program_options parsers.
Converting some of the individual command line tools that use
subcommands might be a little cumbersome too, but I think they'll
be better off once it's done.
Josh
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