! 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, 66 deletions

diff --git a/kamon-core/src/main/scala/kamon/metrics/TraceMetrics.scala b/kamon-core/src/main/scala/kamon/metrics/TraceMetrics.scala
deleted file mode 100644
index 5454edf5..00000000
--- a/kamon-core/src/main/scala/kamon/metrics/TraceMetrics.scala
+++ /dev/null
@@ -1,66 +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 org.HdrHistogram.HdrRecorder
-import scala.collection.concurrent.TrieMap
-import com.typesafe.config.Config
-
-case class TraceMetrics(name: String) extends MetricGroupIdentity {
-  val category = TraceMetrics
-}
-
-object TraceMetrics extends MetricGroupCategory {
-  val name = "trace"
-
-  case object ElapsedTime extends MetricIdentity { val name, tag = "elapsed-time" }
-  case class HttpClientRequest(name: String, tag: String) extends MetricIdentity
-
-  class TraceMetricRecorder(val elapsedTime: HdrRecorder, private val segmentRecorderFactory: () ⇒ HdrRecorder)
-      extends MetricGroupRecorder {
-
-    private val segments = TrieMap[MetricIdentity, HdrRecorder]()
-
-    def segmentRecorder(segmentIdentity: MetricIdentity): HdrRecorder =
-      segments.getOrElseUpdate(segmentIdentity, segmentRecorderFactory.apply())
-
-    def collect: MetricGroupSnapshot = TraceMetricSnapshot(elapsedTime.collect(),
-      segments.map { case (identity, recorder) ⇒ (identity, recorder.collect()) }.toMap)
-  }
-
-  case class TraceMetricSnapshot(elapsedTime: MetricSnapshotLike, segments: Map[MetricIdentity, MetricSnapshotLike])
-      extends MetricGroupSnapshot {
-
-    def metrics: Map[MetricIdentity, MetricSnapshotLike] = segments + (ElapsedTime -> elapsedTime)
-  }
-
-  val Factory = new MetricGroupFactory {
-    type GroupRecorder = TraceMetricRecorder
-
-    def create(config: Config): TraceMetricRecorder = {
-
-      val settings = config.getConfig("precision.trace")
-      val elapsedTimeConfig = extractPrecisionConfig(settings.getConfig("elapsed-time"))
-      val segmentConfig = extractPrecisionConfig(settings.getConfig("segment"))
-
-      new TraceMetricRecorder(
-        HdrRecorder(elapsedTimeConfig.highestTrackableValue, elapsedTimeConfig.significantValueDigits, Scale.Nano),
-        () ⇒ HdrRecorder(segmentConfig.highestTrackableValue, segmentConfig.significantValueDigits, Scale.Nano))
-    }
-  }
-
-}