! 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, 169 deletions

diff --git a/kamon-core/src/test/scala/kamon/trace/instrumentation/ActorSystemMessagePassingInstrumentationSpec.scala b/kamon-core/src/test/scala/kamon/trace/instrumentation/ActorSystemMessagePassingInstrumentationSpec.scala
deleted file mode 100644
index ed239b38..00000000
--- a/kamon-core/src/test/scala/kamon/trace/instrumentation/ActorSystemMessagePassingInstrumentationSpec.scala
+++ /dev/null
@@ -1,169 +0,0 @@
-package kamon.trace.instrumentation
-
-import akka.testkit.{ ImplicitSender, TestKit }
-import akka.actor._
-import org.scalatest.WordSpecLike
-import kamon.trace.TraceRecorder
-import scala.util.control.NonFatal
-import akka.actor.SupervisorStrategy.{ Escalate, Stop, Restart, Resume }
-import scala.concurrent.duration._
-
-class ActorSystemMessagePassingInstrumentationSpec extends TestKit(ActorSystem("actor-message-passing-tracing-spec")) with WordSpecLike with ImplicitSender {
-  implicit val executionContext = system.dispatcher
-
-  "the system message passing instrumentation" should {
-    "keep the TraceContext while processing the Create message in top level actors" in {
-      val testTraceContext = TraceRecorder.withNewTraceContext("creating-top-level-actor") {
-        system.actorOf(Props(new Actor {
-          testActor ! TraceRecorder.currentContext
-          def receive: Actor.Receive = { case any ⇒ }
-        }))
-
-        TraceRecorder.currentContext
-      }
-
-      expectMsg(testTraceContext)
-    }
-
-    "keep the TraceContext while processing the Create message in non top level actors" in {
-      val testTraceContext = TraceRecorder.withNewTraceContext("creating-non-top-level-actor") {
-        system.actorOf(Props(new Actor {
-          def receive: Actor.Receive = {
-            case any ⇒
-              context.actorOf(Props(new Actor {
-                testActor ! TraceRecorder.currentContext
-                def receive: Actor.Receive = { case any ⇒ }
-              }))
-          }
-        })) ! "any"
-
-        TraceRecorder.currentContext
-      }
-
-      expectMsg(testTraceContext)
-    }
-
-    "keep the TraceContext in the supervision cycle" when {
-      "the actor is resumed" in {
-        val supervisor = supervisorWithDirective(Resume)
-
-        val testTraceContext = TraceRecorder.withNewTraceContext("fail-and-resume") {
-          supervisor ! "fail"
-          TraceRecorder.currentContext
-        }
-
-        expectMsg(testTraceContext) // From the parent executing the supervision strategy
-
-        // Ensure we didn't tie the actor with the context
-        supervisor ! "context"
-        expectMsg(None)
-      }
-
-      "the actor is restarted" in {
-        val supervisor = supervisorWithDirective(Restart, sendPreRestart = true, sendPostRestart = true)
-
-        val testTraceContext = TraceRecorder.withNewTraceContext("fail-and-restart") {
-          supervisor ! "fail"
-          TraceRecorder.currentContext
-        }
-
-        expectMsg(testTraceContext) // From the parent executing the supervision strategy
-        expectMsg(testTraceContext) // From the preRestart hook
-        expectMsg(testTraceContext) // From the postRestart hook
-
-        // Ensure we didn't tie the actor with the context
-        supervisor ! "context"
-        expectMsg(None)
-      }
-
-      "the actor is stopped" in {
-        val supervisor = supervisorWithDirective(Stop, sendPostStop = true)
-
-        val testTraceContext = TraceRecorder.withNewTraceContext("fail-and-stop") {
-          supervisor ! "fail"
-          TraceRecorder.currentContext
-        }
-
-        expectMsg(testTraceContext) // From the parent executing the supervision strategy
-        expectMsg(testTraceContext) // From the postStop hook
-        expectNoMsg(1 second)
-      }
-
-      "the failure is escalated" in {
-        val supervisor = supervisorWithDirective(Escalate, sendPostStop = true)
-
-        val testTraceContext = TraceRecorder.withNewTraceContext("fail-and-escalate") {
-          supervisor ! "fail"
-          TraceRecorder.currentContext
-        }
-
-        expectMsg(testTraceContext) // From the parent executing the supervision strategy
-        expectMsg(testTraceContext) // From the grandparent executing the supervision strategy
-        expectMsg(testTraceContext) // From the postStop hook in the child
-        expectMsg(testTraceContext) // From the postStop hook in the parent
-        expectNoMsg(1 second)
-      }
-    }
-  }
-
-  def supervisorWithDirective(directive: SupervisorStrategy.Directive, sendPreRestart: Boolean = false, sendPostRestart: Boolean = false,
-                              sendPostStop: Boolean = false, sendPreStart: Boolean = false): ActorRef = {
-    class GrandParent extends Actor {
-      val child = context.actorOf(Props(new Parent))
-
-      override def supervisorStrategy: SupervisorStrategy = OneForOneStrategy() {
-        case NonFatal(throwable) ⇒ testActor ! TraceRecorder.currentContext; Stop
-      }
-
-      def receive = {
-        case any ⇒ child forward any
-      }
-    }
-
-    class Parent extends Actor {
-      val child = context.actorOf(Props(new Child))
-
-      override def supervisorStrategy: SupervisorStrategy = OneForOneStrategy() {
-        case NonFatal(throwable) ⇒ testActor ! TraceRecorder.currentContext; directive
-      }
-
-      def receive: Actor.Receive = {
-        case any ⇒ child forward any
-      }
-
-      override def postStop(): Unit = {
-        if (sendPostStop) testActor ! TraceRecorder.currentContext
-        super.postStop()
-      }
-    }
-
-    class Child extends Actor {
-      def receive = {
-        case "fail"    ⇒ 1 / 0
-        case "context" ⇒ sender ! TraceRecorder.currentContext
-      }
-
-      override def preRestart(reason: Throwable, message: Option[Any]): Unit = {
-        if (sendPreRestart) testActor ! TraceRecorder.currentContext
-        super.preRestart(reason, message)
-      }
-
-      override def postRestart(reason: Throwable): Unit = {
-        if (sendPostRestart) testActor ! TraceRecorder.currentContext
-        super.postRestart(reason)
-      }
-
-      override def postStop(): Unit = {
-        if (sendPostStop) testActor ! TraceRecorder.currentContext
-        super.postStop()
-      }
-
-      override def preStart(): Unit = {
-        if (sendPreStart) testActor ! TraceRecorder.currentContext
-        super.preStart()
-      }
-    }
-
-    system.actorOf(Props(new GrandParent))
-  }
-}