On Wed, Aug 22, 2018 at 09:54:58AM +0200, Ondrej Lichtner wrote:
On Tue, Aug 21, 2018 at 03:00:01PM +0200, Jan Tluka wrote:
Tue, Aug 21, 2018 at 02:11:06PM CEST, csfakian@redhat.com wrote:
m1.bond0 = BondDevice(mode="active-backup", name="my_bond0")m1.eth0.down()m1.eth1.down()m1.bond0.slave_add(m1.eth0)m1.bond0.slave_add(m1.eth1)Could we enhance the abstraction here? Probably we could completely remove: m1.eth0.down() m1.eth1.down()
and move it into BondDevice class when calling m1.bond0.slave_add(m1.eth0)
This is more of a generic "next" branch question... it's an interesting idea, but I'm not 100% convinced... the slave_{add, del} methods are shared by all devices inheriting from MasterDevice class. At the same time the rules to adding slaves can be slightly different based on the type of device, some types don't require first setting the slaves down, some do, some require the master to be down.
Hiding this inside the slave_{add, del} methods could become confusing and give testers false assumptions - e.g. adding a slave while some test is running will end up setting all other slaves and the master down, then add the slave and then set everything back up, whereas in the code it would just look like a slave was added.
So I think for now I prefer this to be explicit even if it leads to a couple more lines. But we can discuss this on an upstream meeting, see what others think...
-Ondrej
I've thought about this a little bit more and I want to record my thoughts somewhere so we don't forget to talk about this on an upstream meeting.
I definitely think that LNST should be able to provide the "smallest step possible" APIs in case they're needed for some test scenario. And at same time provide some nice abstractions that makes writing normal (no special scenarios) tests easy. And finally we want to have future version API stability at some point... This kind of leads to us supporting multiple APIs - some that do the smallest step and then some that combine multiple steps that are commonly used.
The question then is if we want to mix these in the same place (e.g. Device class and derivatives APIs) or if we want to separate them somewhere else and expose them to the tester in different ways.
In case of these slave_* methods, I think I changed my mind. I think I agree that they should take care of the up/down actions and abstract them for the tester. The reason for that is because the most important "smallest step possible" is really just setting device master (not adding a slave, that's an operation in the other direction). So in this case we already have "2" APIs that do the "same thing" - set master is the smallest step operation and slave_add is the abstracted operation for the tester.
In the slave_* case it's obvious that the higher abstraction is comfortable in the place that it's currently at, however I don't know if that's true for all the cases where we want to provide some level of abstraction... we should talk about that.
Thanks, -Ondrej