On 01/19/2018 06:50 AM, Anton Nefedov wrote:
A block driver can provide a callback to report driver-specific
statistics.
file-posix driver now reports discard statistics
Signed-off-by: Anton Nefedov <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
+++ b/qapi/block-core.json
@@ -774,6 +774,40 @@
'timed_stats': ['BlockDeviceTimedStats'] } }
##
+# @BlockDriverStatsFile:
+#
+# File driver statistics
+#
+# @discard_nb_ok: The number of succeeded discard operations performed by
+# the driver.
+#
+# @discard_nb_failed: The number of failed discard operations performed by
+# the driver.
+#
+# @discard_bytes_ok: The number of bytes discarded by the driver.
+#
+# Since 2.12
+##
+{ 'struct': 'BlockDriverStatsFile',
+ 'data': {
+ 'discard_nb_ok': 'int',
+ 'discard_nb_failed': 'int',
+ 'discard_bytes_ok': 'int'
+ } }
New interfaces should prefer '-' over '_', where possible (a reason for
using '_' is if the fields are alongside pre-existing fields that
already used '_'). Let's see how this gets used...[1]
+
+##
+# @BlockDriverStats:
+#
+# Statistics of a block driver (driver-specific)
+#
+# Since: 2.12
+##
+{ 'union': 'BlockDriverStats',
+ 'data': {
+ 'file': 'BlockDriverStatsFile'
+ } }
Markus has been adamant that we add no new "simple unions" (unions with
a 'discriminator' field) - because they are anything but simple in the
long run.
+
+##
# @BlockStats:
#
# Statistics of a virtual block device or a block backing device.
@@ -785,6 +819,8 @@
#
# @stats: A @BlockDeviceStats for the device.
#
+# @driver-stats: Optional driver-specific statistics. (Since 2.12)
+#
# @parent: This describes the file block device if it has one.
# Contains recursively the statistics of the underlying
# protocol (e.g. the host file for a qcow2 image). If there is
@@ -798,6 +834,7 @@
{ 'struct': 'BlockStats',
'data': {'*device': 'str', '*node-name': 'str',
'stats': 'BlockDeviceStats',
+ '*driver-stats': 'BlockDriverStats',
...[1] You are using it alongside a struct that already uses '-'
(node-name), so you should use dashes.
So, the difference between your proposal (a simple union) and using a
"flat union", on the wire, is yours:
"return": { ..., "driver-stats": { "type": "file", "data": {
"discard_nb_ok: ... } } }
vs. a flat union:
"return": { ..., "driver-stats": { "driver": "file", "discard-nb-ok":
... } }
where you can benefit from less nesting and a saner discriminator name.