Add metrics

[black-adder]

No description provided.

[coveralls]

Coverage decreased (-35.2%) to 64.807% when pulling 1da622b on add_metrics into 321ba1b on master.

[black-adder]

welllll, it looks like I missed a spot

[coveralls]

Coverage decreased (-15.5%) to 84.549% when pulling 8fe296b on add_metrics into 321ba1b on master.

[coveralls]

Coverage decreased (-10.7%) to 89.27% when pulling 916fa89 on add_metrics into 321ba1b on master.

[yurishkuro]

some easy wins for coverage is to exercise the noop impls. But the biggest unexercised chunk is reading from the timer channel. If you run it with high frequency, like 1ms, then you can also test it.

[yurishkuro]

btw, the actual build error is not about coverage (it does not block PRs), but from a test error

=== RUN   TestLocalMetrics
--- FAIL: TestLocalMetrics (0.00s)
    Error Trace:    local_test.go:15
            local_test.go:75
    Error:      Not equal: 3 (expected)
                    != 4 (actual)
    Messages:   Leaked at least one goroutine.

The class should have proper shutdown procedure when used in tests.

[yurishkuro]

remove pkg, this whole repo is the equivalent of pkg namespace.

[yurishkuro]

Please read up on good commit messages - http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html

I updated the PR title

[coveralls]

Coverage decreased (-3.4%) to 96.61% when pulling 3c48f28 on add_metrics into 321ba1b on master.

[yurishkuro]

nit: s/tick/collectionInterval/ and explain it in the doc string

[yurishkuro]

nit: move to a function, e.g. runLoop()

[yurishkuro]

The tags are ignored here. That will make it impossible to use this local backend in unit tests that are sensitive to the tags. We can address this in a different PR, basically by copying functionality from the metrics implementation in jaeger-client-go.

[coveralls]

Coverage decreased (-3.4%) to 96.624% when pulling 472809b on add_metrics into 321ba1b on master.