! 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, 146 deletions

diff --git a/kamon-core/src/main/scala/akka/instrumentation/ActorMessagePassingTracing.scala b/kamon-core/src/main/scala/akka/instrumentation/ActorMessagePassingTracing.scala
deleted file mode 100644
index 6db86828..00000000
--- a/kamon-core/src/main/scala/akka/instrumentation/ActorMessagePassingTracing.scala
+++ /dev/null
@@ -1,146 +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 akka.instrumentation
-
-import org.aspectj.lang.annotation._
-import org.aspectj.lang.ProceedingJoinPoint
-import akka.actor._
-import akka.dispatch.{ Envelope, MessageDispatcher }
-import kamon.trace._
-import kamon.metrics.{ ActorMetrics, Metrics }
-import kamon.Kamon
-import kamon.metrics.ActorMetrics.ActorMetricRecorder
-import kamon.metrics.instruments.MinMaxCounter
-import kamon.metrics.instruments.MinMaxCounter.CounterMeasurement
-
-@Aspect
-class BehaviourInvokeTracing {
-
-  @Pointcut("execution(akka.actor.ActorCell.new(..)) && this(cell) && args(system, ref, props, dispatcher, parent)")
-  def actorCellCreation(cell: ActorCell, system: ActorSystem, ref: ActorRef, props: Props, dispatcher: MessageDispatcher, parent: ActorRef): Unit = {}
-
-  @After("actorCellCreation(cell, system, ref, props, dispatcher, parent)")
-  def afterCreation(cell: ActorCell, system: ActorSystem, ref: ActorRef, props: Props, dispatcher: MessageDispatcher, parent: ActorRef): Unit = {
-
-    val metricsExtension = Kamon(Metrics)(system)
-    val metricIdentity = ActorMetrics(ref.path.elements.mkString("/"))
-    val cellWithMetrics = cell.asInstanceOf[ActorCellMetrics]
-
-    cellWithMetrics.metricIdentity = metricIdentity
-    cellWithMetrics.actorMetricsRecorder = metricsExtension.register(metricIdentity, ActorMetrics.Factory)
-
-    if (cellWithMetrics.actorMetricsRecorder.isDefined) {
-      cellWithMetrics.mailboxSizeCollectorCancellable = metricsExtension.scheduleGaugeRecorder {
-        cellWithMetrics.actorMetricsRecorder.map { am ⇒
-          import am.mailboxSize._
-          val CounterMeasurement(min, max, current) = cellWithMetrics.queueSize.collect()
-
-          record(min)
-          record(max)
-          record(current)
-        }
-      }
-    }
-  }
-
-  @Pointcut("(execution(* akka.actor.ActorCell.invoke(*)) || execution(* akka.routing.RoutedActorCell.sendMessage(*))) && this(cell) && args(envelope)")
-  def invokingActorBehaviourAtActorCell(cell: ActorCell, envelope: Envelope) = {}
-
-  @Around("invokingActorBehaviourAtActorCell(cell, envelope)")
-  def aroundBehaviourInvoke(pjp: ProceedingJoinPoint, cell: ActorCell, envelope: Envelope): Any = {
-    val timestampBeforeProcessing = System.nanoTime()
-    val contextAndTimestamp = envelope.asInstanceOf[TraceContextAware]
-    val cellWithMetrics = cell.asInstanceOf[ActorCellMetrics]
-
-    try {
-      TraceRecorder.withTraceContext(contextAndTimestamp.traceContext) {
-        pjp.proceed()
-      }
-    } finally {
-      cellWithMetrics.actorMetricsRecorder.map {
-        am ⇒
-          am.processingTime.record(System.nanoTime() - timestampBeforeProcessing)
-          am.timeInMailbox.record(timestampBeforeProcessing - contextAndTimestamp.captureNanoTime)
-          cellWithMetrics.queueSize.decrement()
-      }
-    }
-  }
-
-  @Pointcut("execution(* akka.actor.ActorCell.sendMessage(*)) && this(cell)")
-  def sendingMessageToActorCell(cell: ActorCell): Unit = {}
-
-  @After("sendingMessageToActorCell(cell)")
-  def afterSendMessageToActorCell(cell: ActorCell): Unit = {
-    val cellWithMetrics = cell.asInstanceOf[ActorCellMetrics]
-    cellWithMetrics.actorMetricsRecorder.map(am ⇒ cellWithMetrics.queueSize.increment())
-  }
-
-  @Pointcut("execution(* akka.actor.ActorCell.stop()) && this(cell)")
-  def actorStop(cell: ActorCell): Unit = {}
-
-  @After("actorStop(cell)")
-  def afterStop(cell: ActorCell): Unit = {
-    val cellWithMetrics = cell.asInstanceOf[ActorCellMetrics]
-
-    cellWithMetrics.actorMetricsRecorder.map { p ⇒
-      cellWithMetrics.mailboxSizeCollectorCancellable.cancel()
-      Kamon(Metrics)(cell.system).unregister(cellWithMetrics.metricIdentity)
-    }
-  }
-
-  @Pointcut("execution(* akka.actor.ActorCell.handleInvokeFailure(..)) && this(cell)")
-  def actorInvokeFailure(cell: ActorCell): Unit = {}
-
-  @Before("actorInvokeFailure(cell)")
-  def beforeInvokeFailure(cell: ActorCell): Unit = {
-    val cellWithMetrics = cell.asInstanceOf[ActorCellMetrics]
-
-    cellWithMetrics.actorMetricsRecorder.map {
-      am ⇒ am.errorCounter.record(1L)
-    }
-  }
-}
-
-trait ActorCellMetrics {
-  var metricIdentity: ActorMetrics = _
-  var actorMetricsRecorder: Option[ActorMetricRecorder] = _
-  var mailboxSizeCollectorCancellable: Cancellable = _
-  val queueSize = MinMaxCounter()
-}
-
-@Aspect
-class ActorCellMetricsMixin {
-
-  @DeclareMixin("akka.actor.ActorCell")
-  def mixinActorCellMetricsToActorCell: ActorCellMetrics = new ActorCellMetrics {}
-}
-
-@Aspect
-class EnvelopeTraceContextMixin {
-
-  @DeclareMixin("akka.dispatch.Envelope")
-  def mixinTraceContextAwareToEnvelope: TraceContextAware = TraceContextAware.default
-
-  @Pointcut("execution(akka.dispatch.Envelope.new(..)) && this(ctx)")
-  def envelopeCreation(ctx: TraceContextAware): Unit = {}
-
-  @After("envelopeCreation(ctx)")
-  def afterEnvelopeCreation(ctx: TraceContextAware): Unit = {
-    // Necessary to force the initialization of ContextAware at the moment of creation.
-    ctx.traceContext
-  }
-}
\ No newline at end of file