Re: More "store" questions

[Roland McGrath]

>    1) In the network block device client, nbd.c, it 
>        seems very reasonable to set the "handle" on a 
>        request and match this "handle" when receiving 
>        a reply. It doesn't seem like it is set. Is 
>        this because you have not implemented the 
>        notion of queued requests in nbd.c, i.e. 
>        handles definitely make sense when there are
>        several outstanding requests.

Yes.  It would be some substantial more complexity to allow multiple
outstanding requests and match up their replies.  The existing libstore
interface doesn't really make this possible, since the caller is
responsible for locking around the blocking store_read call.

>    2) In ndbopen, where is the parameter "mod_flags" 
>         set?

It is not used.  

>    3) You have defined a set of instances of "struct 
>         store_class". What happens in the case where 
>         not all "store" operations are defined, e.g. 
>         store_part_class only defines open, not read, 
>         write, etc.

If you look at such classes, you will see it is not in fact possible to
have an actual struct store with that class.  Its `open' function creates
stores of different clases.

>    4) If I am writing a "store" server
>          that can handle an arbitrary "name" (i.e. 
>          I can't make an assumptions ahead of time 
>           about the syntax of "name", i.e. I don't 
>           in advance the type of store), what to I 
>           call from my server to invoke the correct
>           libstore functionality?

>    5) I still don't understand the purpose of the 
>         decode and encode functionality.

See the file_get_storage_info RPC.