mstate: added agent alive methods

mstate: added agent alive methods

Machine provides AgentAlive(), WaitAgentAlive() and
SetAgentAlive() using the presence package.

https://code.launchpad.net/~themue/juju-core/go-mstate-machine-agent-alive/+merge/122819

Requires: https://code.launchpad.net/~themue/juju-core/go-mstate-unit-status/+merge/122500

(do not edit description out of merge proposal)

[TheMue, 2012-09-05 09:13:27]

Please take a look.

[niemeyer, 2012-09-05 21:28:27]

Nice, LGTM.

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go
File mstate/machine.go (right):

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode82
mstate/machine.go:82: func (m *Machine) WaitAgentAlive(timeout time.Duration)
error {
Nice implementation.

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode101
mstate/machine.go:101: panic(fmt.Sprintf("unexpected alive status of machine
%v", m))
"presence reported dead status twice in a row for machine %v"

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode109
mstate/machine.go:109: // by starting a pinger on its presence node. It returns
the
Please drop the "by starting a pinger on its presence node" part. This isn't
entirely true anymore, and isn't really necessary given the rest of the doc.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go
File mstate/machine_test.go (right):

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode31
mstate/machine_test.go:31: defer pinger.Kill()
s/Kill/Stop/

We only care that it's not running after the test is done.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode50
mstate/machine_test.go:50: c.Assert(pinger, Not(IsNil))
This check isn't necessary. We'd go crazy if we had to check everything that is
*not* nil when err is nil.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode60
mstate/machine_test.go:60: pinger.Kill()
err := pinger.Kill()
c.Assert(err, IsNil)

[TheMue, 2012-09-06 17:05:56]

*** Submitted:

mstate: added agent alive methods

Machine provides AgentAlive(), WaitAgentAlive() and
SetAgentAlive() using the presence package.

R=niemeyer
CC=
https://codereview.appspot.com/6498091

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go
File mstate/machine.go (right):

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode82
mstate/machine.go:82: func (m *Machine) WaitAgentAlive(timeout time.Duration)
error {
On 2012/09/05 21:28:28, niemeyer wrote:
> Nice implementation.

Thanks.

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode101
mstate/machine.go:101: panic(fmt.Sprintf("unexpected alive status of machine
%v", m))
On 2012/09/05 21:28:28, niemeyer wrote:
> "presence reported dead status twice in a row for machine %v"

Done.

https://codereview.appspot.com/6498091/diff/1/mstate/machine.go#newcode109
mstate/machine.go:109: // by starting a pinger on its presence node. It returns
the
On 2012/09/05 21:28:28, niemeyer wrote:
> Please drop the "by starting a pinger on its presence node" part. This isn't
> entirely true anymore, and isn't really necessary given the rest of the doc.

Done.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go
File mstate/machine_test.go (right):

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode31
mstate/machine_test.go:31: defer pinger.Kill()
On 2012/09/05 21:28:28, niemeyer wrote:
> s/Kill/Stop/
> 
> We only care that it's not running after the test is done.

Done.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode50
mstate/machine_test.go:50: c.Assert(pinger, Not(IsNil))
On 2012/09/05 21:28:28, niemeyer wrote:
> This check isn't necessary. We'd go crazy if we had to check everything that
is
> *not* nil when err is nil.

Done.

https://codereview.appspot.com/6498091/diff/1/mstate/machine_test.go#newcode60
mstate/machine_test.go:60: pinger.Kill()
On 2012/09/05 21:28:28, niemeyer wrote:
> err := pinger.Kill()
> c.Assert(err, IsNil)

Done.