! all: refactor the core metric recording instruments and accomodate UserMetrics

This PR is including several changes to the kamon-core, most notably:
  - Formalize the interface for Histograms, Counters and MinMaxCounters. Making sure
    that the interfaces are as clean as possible.
  - Move away from the all Vector[Measurement] based Histogram snapshot to a new approach
    in which we use a single long to store both the index in the counts array and the
    frequency on that bucket. The leftmost 2 bytes of each long are used for storing the
    counts array index and the remaining 6 bytes are used for the actual count, and
    everything is put into a simple long array. This way only the buckets that actually
    have values will be included in the snapshot with the smallest possible memory
    footprint.
  - Introduce Gauges.
  - Reorganize the instrumentation for Akka and Scala and rewrite most of the tests
    of this components to avoid going through the subscription protocol to test.
  - Introduce trace tests and fixes on various tests.
  - Necessary changes on new relic, datadog and statsd modules to compile with the new
    codebase.

Pending:
  - Finish the upgrade of the new relic to the current model.
  - Introduce proper limit checks for histograms to ensure that we never pass the 2/6 bytes
    limits.
  - More testing, more testing, more testing.
  - Create the KamonStandalone module.

1 files changed, 3 insertions, 3 deletions

diff --git a/kamon-newrelic/src/main/scala/kamon/newrelic/CustomMetrics.scala b/kamon-newrelic/src/main/scala/kamon/newrelic/CustomMetrics.scala
index 08e0add3..44d9c605 100644
--- a/kamon-newrelic/src/main/scala/kamon/newrelic/CustomMetrics.scala
+++ b/kamon-newrelic/src/main/scala/kamon/newrelic/CustomMetrics.scala
@@ -17,16 +17,16 @@
 package kamon.newrelic
 
 import akka.actor.Actor
-import kamon.metrics._
+import kamon.metric._
 
 trait CustomMetrics {
   self: Actor ⇒
 
   def collectCustomMetrics(metrics: Map[MetricGroupIdentity, MetricGroupSnapshot]): Seq[NewRelic.Metric] = {
     metrics.collect {
-      case (CustomMetric(name), groupSnapshot) ⇒
+      case (UserMetrics, groupSnapshot) ⇒
         groupSnapshot.metrics collect {
-          case (_, snapshot) ⇒ toNewRelicMetric(Scale.Unit)(s"Custom/$name", None, snapshot)
+          case (name, snapshot) ⇒ toNewRelicMetric(Scale.Unit)(s"Custom/$name", None, snapshot)
         }
     }.flatten.toSeq
   }