Hi Axel,
On 2015-10-05 17:04, Axel Burri wrote:
[...]
>
> A quick look at the code shows me that Goffredo is right here, as
> __list_subvol_search() always fetches ALL data from
> BTRFS_IOC_TREE_SEARCH, putting it into a rbtree for later processing
> (assemble full paths, sorting).
>
> While there is certainly room for improvements here (assuming that
> BTRFS_IOC_TREE_SEARCH returns objectid's in sorted order, it would
> definitively be possible to produce line-by-line output), the code looks
> pretty elegant the way it is.
>
> I still don't think it is wise to bloat things further just for printing
> nice tables. My impression is that "btrfs subvolume list" is
> human-readable enough without the '-t' flag, while the output with '-t'
> flag is much more machine-readable-friendly, and thus should have the
> highest possible performance. e.g.:
I disagree, the "-t" mode is for the human; the non '-t' mode would be for
machine (if you take the space as separator and the first word as key, with the
exception of the path which starts from the "path " word and ends to the end of
line); unfortunately "top level" is an exception. Anyway btrfs is not very
machine-friendly (sic).
Compare the two output below:
$ sudo btrfs sub list -a /
ID 257 gen 44309 top level 5 path <FS_TREE>/debian
ID 289 gen 17415 top level 257 path debian/var/lib/machines
ID 298 gen 35434 top level 5 path <FS_TREE>/debian-i32
ID 299 gen 43961 top level 5 path <FS_TREE>/boot
ID 300 gen 39452 top level 5 path <FS_TREE>/debian-jessie
$ sudo btrfs sub list -at /
ID gen top level path
-- --- --------- ----
257 44310 5 <FS_TREE>/debian
289 17415 257 debian/var/lib/machines
298 35434 5 <FS_TREE>/debian-i32
299 43961 5 <FS_TREE>/boot
300 39452 5 <FS_TREE>/debian-jessie
I think that is easy to declare the latter more "human" friendly.
BTW with the use of the table_* function the output become:
$ sudo ./btrfs sub list -at /
ID gen top level path
=== ===== ========= =======================
257 44311 5 <FS_TREE>/debian
289 17415 257 debian/var/lib/machines
298 35434 5 <FS_TREE>/debian-i32
299 43961 5 <FS_TREE>/boot
300 39452 5 <FS_TREE>/debian-jessie
$ sudo ./btrfs sub list -aptcguqR /
ID gen cgen parent top level parent_uuid received_uuid uuid
path
=== ===== ===== ====== ========= =========== =============
==================================== =======================
257 44313 7 5 5 - -
840c86cf-e78b-d54a-ab38-66662858812d <FS_TREE>/debian
289 17415 17415 257 257 - -
8b857250-3a3e-754d-810e-57342bbb2f56 debian/var/lib/machines
298 35434 35399 5 5 - -
1f38049b-b153-d741-b903-d2de6fd7b3fd <FS_TREE>/debian-i32
299 43961 35512 5 5 - -
f9d52b6b-a6d1-8c45-a6cd-ddb68cf58062 <FS_TREE>/boot
300 39452 37744 5 5 - -
026e44bd-66d4-e341-9a14-0124acf79793 <FS_TREE>/debian-jessie
I right aligned each field with the exception of the path (which is left
aligned).
I already prepared the patch which convert "btrfs sub list -t" to use the
table_* function. If you want I can send it to you to extend/replace your patch
#4.
BR
G.Baroncelli
>
> btrfs sub list -t / | (read th; while read $th ; do echo $gen; done)
> btrfs sub list -t | column -t
>
> Again, this is just my opinion, being a "unix-purist". Maybe a good
> compromise would be to use a single "\t" instead of " " as column delimiter.
>
--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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