[systemd-devel] from dbus , how do i find if app went down

[Lennart Poettering]

On Fri, 03.07.15 15:29, Pradeepa Kumar (cdpradeepa at gmail.com) wrote:

> I am writing lib which will monitor apps and notify/callback higher level
>  if apps went down.
> How can I achieve this?
> I tried doing this using propertieschanged signal and reading
>  substate

We reserve the liberty to introduce new substates, and hence you
shouldn't check "Substate" anyway if you want to stay compatible with
future versions of systemd. Check the "State" instead, which is more
abstract and is considered API.

> property and that msg does not have old value and new value in the msg.
> I noticed that when app go down i get two signals and hence two substates -
> stop and stop-term.
> So it is difficult to call registered callbacks only when substate changes
> from running->stop.

> Do i need to maintain current state of app in my lib?

If you want to track these state changes, you'd have to cache the
states client-side.

> is there any other easier way for this ??

I fear not, sorry.

Lennart

-- 
Lennart Poettering, Red Hat