* Replace StatsD client library
The [Datadog package][1] is a StatsD compatible drop-in replacement for the
client library, but it seems to be [better maintained][2] and has support for
Datadog DogStatsD specific features, which will be made use of in a subsequent
commit.
The `count`, `time`, and `gauge` methods are actually exactly compatible with
the previous library and the modifications shouldn't be required, but EasyMock
seems to have a hard time dealing with the variable arguments added by the
DogStatsD library and causes tests to fail if no arguments are provided for the
last String vararg. Passing an empty array fixes the test failures.
[1]: https://github.com/DataDog/java-dogstatsd-client
[2]: https://github.com/tim-group/java-statsd-client/issues/37#issuecomment-248698856
* Retain dimension key information for StatsD metrics
This doesn't change behavior, but allows separating dimensions from the metric
name in subsequent commits.
There is a possible order change for values from
`dimsBuilder.build().values()`, but from the tests it looks like it doesn't
affect actual behavior and the order of user dimensions is also retained.
* Support DogStatsD style tags in statsd-emitter
Datadog [doesn't support name-encoded dimensions and uses a concept of _tags_
instead.][1] This change allows Datadog users to send the metrics without
having to encode the various dimensions in the metric names. This enables
building graphs and monitors with and without aggregation across various
dimensions from the same data.
As tests in this commit verify, the behavior remains the same for users who
don't enable the `druid.emitter.statsd.dogstatsd` configuration flag.
[1]: https://www.datadoghq.com/blog/the-power-of-tagged-metrics/#tags-decouple-collection-and-reporting
* Disable convertRange behavior for DogStatsD users
DogStatsD, unlike regular StatsD, supports floating-point values, so this
behavior is unnecessary. It would be possible to still support `convertRange`,
even with `dogstatsd` enabled, but that would mean that people using the
default mapping would have some of the gauges unnecessarily converted.
`time` is in milliseconds and doesn't support floating-point values.
David Lim
Vadim Ogievetsky
Deiwin Sarjas
chaoqiang
michaelschiff
michaelschiff