Channel initialization span

[Aki-7]

close #41
ref #40

What I did

• Enable to collect Channel Initialization Span
  • Only for JNLP inbound connection
  • Channel Initialization Span is between the first TCP handshaking begins and the org.hudson.Channel is connected
  • Contains following the child spans
    • Jnlp Endpoint Resolving Span
    • Jnlp Initialization Span
      • between the JNLP starts and org.hudson.Channel is connected or the JNLP fails
  • According to the JIRA ticket survey, unexpected Jnlp endpoint resolution causes problems, especially under the special network environment, e.g., HTTP Proxy, SSH Tunnel. And that's why I create Jnlp Endpoint Resolving Span

Limitation

Some spans are not precise enough as I only use the already-existing listener functionality in the remoting module.
To collect more spans more precisely, I'm going to create a PR for the remoting modules.

Demo

I disconnected and reconnected the agent several times to produce Channel Initialization spans.

Jaeger

list

each span

details

Protocol, port and host can be seen

Zipkin

Checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your master branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• All follow-ups are documented as issues and-or TODO comments
• Ensure you have provided tests - that demonstrates feature works or fixes the issue
• Please update user documentation if needed
• Please update developer documentation if needed