[Libguestfs] [PATCH] New API: btrfs_device_stats

[Richard W.M. Jones]

On Thu, Jun 18, 2015 at 10:41:56AM +0200, Pino Toscano wrote:
> Hi,
> 
> On Thursday 18 June 2015 11:01:37 Cao jin wrote:
> > > Speaking of this: you said that you have a colleague working on
> > > btrfs-progs? What about suggesting to create some machine-parseable
> > > output (csv, xml, yaml, json, whatever) so extracting the results of
> > > btrfs tools is a lot more easy?
> > >
> > 
> > Yes, I forward your suggestion and consult him, the result is not 
> > surprised:( Here is what I learned from him:
> >    For the btrfs-progs cmds who output strings, the output are plain, 
> > don`t have patterns. Seen some guys who want a formatted output, they do 
> > a filter by themself, it not reasonable to ask btrfs-progs to output 
> > formatted strings.
> 
> This is exactly the issue here: every btrfs command has a totally
> different formatting for its output. Just let him take a look at all
> the commands implemented so far in libguestfs, you can easily spot
> that:
> - btrfs subvolume list
> - btrfs subvolume show
> - btrfs qgroup show
> - btrfs balance status
> - btrfs scrub status
> - btrfs device stats
> all have different custom parsers for each of their outputs.
> 
> Compare that to e.g. the -m parameter for parted, so it outputs fields
> separated by semi-colon.

I have to agree with Pino T that btrfs-progs would be a lot better if
it had parseable output, like json/XML/etc, especially parseable
output that was stable over time.

Rich.

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