tree 1f9c3383e594b9ff0d467be0ddf74e5667da2796
parent d1d19210e7bbffd5a6d7512539d13f8ec7d14b2a
author Gunnar Mills <gmills@us.ibm.com> 1531492051 -0500
committer Adriana Kobylak <anoo@us.ibm.com> 1531759063 -0500

activation: Improve error handling in Subscribe

Handle exceptions from the sdbusplus method call_noreply API.

The Activation constructor was subscribing to systemd signals, which
would cause an "Already Subscribed" error when creating multiple
Activation instances because the bus is common.

There is no reason to subscribe to systemd signals in the constructor,
since the signals are only triggered during the activation process.
Move the Subscribe call to the activation process which calls
Unsubscribe at the end.

There's a scenario where there could still be an "Already Subscribed"
error if the activation fails, so add error handling there.

This is very similar to:
https://gerrit.openbmc-project.xyz/#/c/11428/

Tested: Code updated an image.
Change-Id: Ia35b7f2fc24c0b605692bc534c54e18742027061
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>