Re: [Qemu-devel] [PATCH v0] fsdev: QMP interface for throttling

[Eric Blake]

On 03/21/2017 04:44 AM, Pradeep Jagadeesh wrote:

>>
>> You're introducing this struct in 2.10, so this member is not since 1.7.
>>  Either that, or you're copying-and-pasting when you should be sharing
>> code and reusing an existing struct.
> Hmm..copied the block devices code, I will correct it.
> I thought of reusing the code, but the whole struct from block devices
> can not be used, as there is one member called "group" that is not used
> in case of 9p.

Then make a common base type with the common fields, and have the block
devices use a subtype that reuses the base type and adds the additional
field 'group'.

> Also this needs lot of changes even in case of block
> devices. Because I may need to rename the structure as IOThrottle or
> something like that.

Yes, type names may have a ripple effect. But when done as a series,
separating the mechanical changes from the semantic changes, it's still
fairly easy to review, and worth it in the long run.

> Shall I reuse the code and avoid setting the group member in case of 9p?
> What do you think?

Better than avoiding the group member by avoiding it is avoiding it by
not having it in the type, by using type inheritance to your advantage.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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