[OpenAFS-devel] Adding an "estimate" function to vlserver

[Joseph V Moss]

> Moving to implementation details, our first thought was to call this
> new function "vos dump -estimate" and we've gone ahead and coded up
> a working implementation of this, but in hindsight we think perhaps
> this is not the best choice and we should make it "vos estimate"
> instead.  The "who really cares which way you do it?" answer turns out
> to be hiding in the coding details.
> 
> Adding a -estimate flag to vos dump required adding an extra parameter
> to the existing vos dump RPC call, which breaks backward compatibility
> with existing vlservers and vos command suites.  This seems like a bad
> thing to do when it can be easily avoided.
> 
> Adding a new vos command "vos estimate" leaves vos dump as is so it
> remains backward compatible.  Instead it requires adding a new RPC
> opcode.  We are currently inclined to proceed in this direction, but
> would like to pause for a moment and submit some questions and gather
> feedback before going any further with this.


If you're modifying vos to add a new command, couldn't you just code up
the change so that 'vos dump -estimate' sends the new RPC rather than
a modified version of the existing dump RPC call?

Or as a different possible interface, how about 'vos examine -dumpsize' to
get it to show the size you're looking for rather than the one it shows currently.