! 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, 110 deletions

diff --git a/kamon-core/src/test/scala/kamon/metrics/instrument/MinMaxCounterSpec.scala b/kamon-core/src/test/scala/kamon/metrics/instrument/MinMaxCounterSpec.scala
deleted file mode 100644
index 14f1573f..00000000
--- a/kamon-core/src/test/scala/kamon/metrics/instrument/MinMaxCounterSpec.scala
+++ /dev/null
@@ -1,110 +0,0 @@
-/* =========================================================================================
- * Copyright © 2013-2014 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.instrument
-
-import org.scalatest.{ Matchers, WordSpecLike }
-import kamon.metrics.instruments.MinMaxCounter
-import kamon.metrics.instruments.MinMaxCounter.CounterMeasurement
-
-class MinMaxCounterSpec extends WordSpecLike with Matchers {
-
-  "the MinMaxCounter" should {
-    "increment" in {
-      val counter = MinMaxCounter()
-
-      counter.increment()
-      counter.increment()
-      counter.increment()
-      counter.increment()
-      counter.increment()
-
-      val CounterMeasurement(_, _, current) = counter.collect()
-
-      current should be(5)
-    }
-
-    "decrement" in {
-      val counter = MinMaxCounter()
-      counter.increment(5L)
-
-      counter.decrement()
-      counter.decrement()
-      counter.decrement()
-      counter.decrement()
-      counter.decrement()
-
-      val CounterMeasurement(_, _, current) = counter.collect()
-
-      current should be(0)
-    }
-
-    "reset the min and max with the sum value when the collect method is called" in {
-      val counter = MinMaxCounter()
-
-      counter.increment(10)
-      counter.increment(20)
-      counter.increment(30)
-      counter.increment(40)
-      counter.increment(50)
-
-      counter.collect() //only for check the last value after reset min max
-
-      val CounterMeasurement(min, max, current) = counter.collect()
-
-      min should be(current)
-      max should be(current)
-      current should be(150)
-    }
-  }
-
-  "track the min value" in {
-    val counter = MinMaxCounter()
-
-    counter.increment(10)
-    counter.increment(20)
-    counter.increment(30)
-    counter.increment(40)
-    counter.increment(50)
-
-    val CounterMeasurement(min, _, _) = counter.collect()
-
-    min should be(0)
-
-    counter.increment(50)
-
-    val CounterMeasurement(minAfterCollectAndAddSomeValues, _, _) = counter.collect()
-
-    minAfterCollectAndAddSomeValues should be(150)
-  }
-
-  "track the max value" in {
-    val counter = MinMaxCounter()
-    counter.increment(10)
-    counter.increment(20)
-    counter.increment(30)
-    counter.increment(40)
-    counter.increment(50)
-
-    val CounterMeasurement(_, max, _) = counter.collect()
-
-    max should be(150)
-
-    counter.increment(200)
-
-    val CounterMeasurement(_, maxAfterCollectAndAddSomeValues, _) = counter.collect()
-
-    maxAfterCollectAndAddSomeValues should be(350)
-  }
-}