Replaces agent infinite block with agent.Stop()

[danehans]

Which problem is this PR solving?

• The select {} statement to place agent in an infinite loop is uncommon and causes confusion for new contributors.

Short description of the changes

• The agent.Stop() method exists, so let's use it. Calling defer with the agent.Stop() method will stop agent only when the agent.Start go routine stops/fails and is easier for new contributors to understand.

Signed-off-by: Daneyon Hansen [email protected]

[sergeyklay]

@black-adder Aha! https://travis-ci.org/jaegertracing/jaeger/jobs/405032533#L3365
The same crossdock error I faced yesterday in the #933

[yurishkuro]

I think this will exit the app immediately, won't it?

[yurishkuro]

The select {} statement to place agent in an infinite loop is uncommon and causes confusion for new contributors.

It's not that uncommon. But in the other executables we trapped the interrupts:

jaeger/cmd/query/main.go

Lines 143 to 147 in 7919cd9

	select {
	case <-serverChannel:
	logger.Info("Jaeger Query is finishing")
	}
	return nil

[danehans]

@yurishkuro OK. I tested locally and the agent does exit immediately. Although it would be nice to defer the agent.Stop(), it's not required. I will close out this PR. Thank you.