! 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, 0 insertions, 78 deletions

diff --git a/kamon-core/src/test/scala/kamon/metrics/CustomMetricSpec.scala b/kamon-core/src/test/scala/kamon/metrics/CustomMetricSpec.scala
deleted file mode 100644
index 1e072f71..00000000
--- a/kamon-core/src/test/scala/kamon/metrics/CustomMetricSpec.scala
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013 the kamon project <http://kamon.io/>
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
- * except in compliance with the License. You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software distributed under the
- * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
- * either express or implied. See the License for the specific language governing permissions
- * and limitations under the License.
- * =========================================================================================
- */
-
-package kamon.metrics
-
-import akka.testkit.TestKitBase
-import org.scalatest.{ Matchers, WordSpecLike }
-import akka.actor.ActorSystem
-import scala.concurrent.duration._
-import com.typesafe.config.ConfigFactory
-import kamon.Kamon
-import kamon.metrics.Subscriptions.TickMetricSnapshot
-import kamon.metrics.MetricSnapshot.Measurement
-
-class CustomMetricSpec extends TestKitBase with WordSpecLike with Matchers {
-  implicit lazy val system: ActorSystem = ActorSystem("actor-metrics-spec", ConfigFactory.parseString(
-    """
-      |kamon.metrics {
-      |  filters = [
-      |    {
-      |      custom-metric {
-      |        includes = [ "test/*" ]
-      |        excludes = [ ]
-      |      }
-      |    }
-      |  ]
-      |}
-    """.stripMargin))
-
-  "the Kamon custom metrics support" should {
-    "allow registering a custom metric with the Metrics extension" in {
-      val recorder = Kamon(Metrics).register(CustomMetric("test/sample-counter"), CustomMetric.histogram(100, 2, Scale.Unit))
-
-      recorder should be('defined)
-    }
-
-    "allow subscriptions to custom metrics using the default subscription protocol" in {
-      val recorder = Kamon(Metrics).register(CustomMetric("test/sample-counter"), CustomMetric.histogram(100, 2, Scale.Unit))
-
-      recorder.map { r ⇒
-        r.record(100)
-        r.record(15)
-        r.record(0)
-        r.record(50)
-      }
-
-      Kamon(Metrics).subscribe(CustomMetric, "test/sample-counter", testActor)
-
-      val recordedValues = within(5 seconds) {
-        val snapshot = expectMsgType[TickMetricSnapshot]
-        snapshot.metrics(CustomMetric("test/sample-counter")).metrics(CustomMetric.RecordedValues)
-      }
-
-      recordedValues.min should equal(0)
-      recordedValues.max should equal(100)
-      recordedValues.numberOfMeasurements should equal(4)
-      recordedValues.measurements should contain allOf (
-        Measurement(0, 1),
-        Measurement(15, 1),
-        Measurement(50, 1),
-        Measurement(100, 1))
-    }
-  }
-
-}