Merge branch 'wip/metrics-collection-refactor'

Conflicts:
	kamon-datadog/src/test/scala/kamon/datadog/DatadogMetricSenderSpec.scala

7 files changed, 486 insertions, 22 deletions

diff --git a/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorCellInstrumentation.scala b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorCellInstrumentation.scala
new file mode 100644
index 00000000..5fce4555
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorCellInstrumentation.scala
@@ -0,0 +1,130 @@
+/*
+ * =========================================================================================
+ * 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 akka.actor._
+import akka.dispatch.{ Envelope, MessageDispatcher }
+import kamon.Kamon
+import kamon.metric.ActorMetrics.ActorMetricsRecorder
+import kamon.metric.{ ActorMetrics, Metrics }
+import kamon.trace._
+import org.aspectj.lang.ProceedingJoinPoint
+import org.aspectj.lang.annotation._
+
+@Aspect
+class ActorCellInstrumentation {
+
+  @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)
+  }
+
+  @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)
+          am.mailboxSize.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 ⇒ am.mailboxSize.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.errors.increment()
+    }
+  }
+}
+
+trait ActorCellMetrics {
+  var metricIdentity: ActorMetrics = _
+  var actorMetricsRecorder: Option[ActorMetricsRecorder] = _
+  var mailboxSizeCollectorCancellable: Cancellable = _
+}
+
+@Aspect
+class ActorCellMetricsIntoActorCellMixin {
+
+  @DeclareMixin("akka.actor.ActorCell")
+  def mixinActorCellMetricsToActorCell: ActorCellMetrics = new ActorCellMetrics {}
+}
+
+@Aspect
+class TraceContextIntoEnvelopeMixin {
+
+  @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
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/ActorLoggingTracing.scala b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorLoggingInstrumentation.scala
index 85d39d3e..ee9d442f 100644
--- a/kamon-core/src/main/scala/kamon/instrumentation/ActorLoggingTracing.scala
+++ b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorLoggingInstrumentation.scala
@@ -1,11 +1,11 @@
 /*
  * =========================================================================================
- * Copyright © 2013 the kamon project <http://kamon.io/>
+ * 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
+ *   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,
@@ -14,14 +14,14 @@
  * =========================================================================================
  */
 
-package kamon.instrumentation
+package akka.instrumentation
 
-import org.aspectj.lang.annotation._
-import org.aspectj.lang.ProceedingJoinPoint
 import kamon.trace.{ TraceContextAware, TraceRecorder }
+import org.aspectj.lang.ProceedingJoinPoint
+import org.aspectj.lang.annotation._
 
 @Aspect
-class ActorLoggingTracing {
+class ActorLoggingInstrumentation {
 
   @DeclareMixin("akka.event.Logging.LogEvent+")
   def mixinTraceContextAwareToLogEvent: TraceContextAware = TraceContextAware.default
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorSystemMessageInstrumentation.scala b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorSystemMessageInstrumentation.scala
new file mode 100644
index 00000000..9b6b6866
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/akka/ActorSystemMessageInstrumentation.scala
@@ -0,0 +1,80 @@
+/*
+ * =========================================================================================
+ * 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 akka.dispatch.sysmsg.EarliestFirstSystemMessageList
+import kamon.trace.{ TraceContextAware, TraceRecorder }
+import org.aspectj.lang.ProceedingJoinPoint
+import org.aspectj.lang.annotation._
+
+@Aspect
+class ActorSystemMessageInstrumentation {
+
+  @Pointcut("execution(* akka.actor.ActorCell.invokeAll$1(..)) && args(messages, *)")
+  def systemMessageProcessing(messages: EarliestFirstSystemMessageList): Unit = {}
+
+  @Around("systemMessageProcessing(messages)")
+  def aroundSystemMessageInvoke(pjp: ProceedingJoinPoint, messages: EarliestFirstSystemMessageList): Any = {
+    if (messages.nonEmpty) {
+      val ctx = messages.head.asInstanceOf[TraceContextAware].traceContext
+      TraceRecorder.withTraceContext(ctx)(pjp.proceed())
+
+    } else pjp.proceed()
+  }
+}
+
+@Aspect
+class TraceContextIntoSystemMessageMixin {
+
+  @DeclareMixin("akka.dispatch.sysmsg.SystemMessage+")
+  def mixinTraceContextAwareToSystemMessage: TraceContextAware = TraceContextAware.default
+
+  @Pointcut("execution(akka.dispatch.sysmsg.SystemMessage+.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
+  }
+}
+
+@Aspect
+class TraceContextIntoRepointableActorRefMixin {
+
+  @DeclareMixin("akka.actor.RepointableActorRef")
+  def mixinTraceContextAwareToRepointableActorRef: TraceContextAware = TraceContextAware.default
+
+  @Pointcut("execution(akka.actor.RepointableActorRef.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
+  }
+
+  @Pointcut("execution(* akka.actor.RepointableActorRef.point(..)) && this(repointableActorRef)")
+  def repointableActorRefCreation(repointableActorRef: TraceContextAware): Unit = {}
+
+  @Around("repointableActorRefCreation(repointableActorRef)")
+  def afterRepointableActorRefCreation(pjp: ProceedingJoinPoint, repointableActorRef: TraceContextAware): Any = {
+    TraceRecorder.withTraceContext(repointableActorRef.traceContext) {
+      pjp.proceed()
+    }
+  }
+}
\ No newline at end of file
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/akka/AskPatternInstrumentation.scala b/kamon-core/src/main/scala/kamon/instrumentation/akka/AskPatternInstrumentation.scala
new file mode 100644
index 00000000..3bf13ce2
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/akka/AskPatternInstrumentation.scala
@@ -0,0 +1,55 @@
+/*
+ * =========================================================================================
+ * 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 akka.actor.ActorRefProvider
+import akka.event.Logging.Warning
+import akka.pattern.{ AskTimeoutException, PromiseActorRef }
+import kamon.Kamon
+import kamon.trace.Trace
+import org.aspectj.lang.annotation.{ AfterReturning, Aspect, Pointcut }
+
+import scala.compat.Platform.EOL
+
+@Aspect
+class AskPatternInstrumentation {
+
+  class StackTraceCaptureException extends Throwable
+
+  @Pointcut(value = "execution(* akka.pattern.PromiseActorRef$.apply(..)) && args(provider, *, *)", argNames = "provider")
+  def promiseActorRefApply(provider: ActorRefProvider): Unit = {}
+
+  @AfterReturning(pointcut = "promiseActorRefApply(provider)", returning = "promiseActor")
+  def hookAskTimeoutWarning(provider: ActorRefProvider, promiseActor: PromiseActorRef): Unit = {
+    val system = promiseActor.provider.guardian.underlying.system
+    val traceExtension = Kamon(Trace)(system)
+
+    if (traceExtension.enableAskPatternTracing) {
+      val future = promiseActor.result.future
+      implicit val ec = system.dispatcher
+      val stack = new StackTraceCaptureException
+
+      future onFailure {
+        case timeout: AskTimeoutException ⇒
+          val stackString = stack.getStackTrace.drop(3).mkString("", EOL, EOL)
+
+          system.eventStream.publish(Warning("AskPatternTracing", classOf[AskPatternInstrumentation],
+            "Timeout triggered for ask pattern registered at: " + stackString))
+      }
+    }
+  }
+}
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/akka/DispatcherInstrumentation.scala b/kamon-core/src/main/scala/kamon/instrumentation/akka/DispatcherInstrumentation.scala
new file mode 100644
index 00000000..db366e8c
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/akka/DispatcherInstrumentation.scala
@@ -0,0 +1,163 @@
+/*
+ * =========================================================================================
+ * 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 java.lang.reflect.Method
+import java.util.concurrent.ThreadPoolExecutor
+
+import akka.actor.{ ActorSystemImpl, Cancellable }
+import akka.dispatch.{ Dispatcher, Dispatchers, ExecutorServiceDelegate, MessageDispatcher }
+import akka.instrumentation.DispatcherMetricsCollector.DispatcherMetricsMeasurement
+import kamon.Kamon
+import kamon.metric.DispatcherMetrics.DispatcherMetricRecorder
+import kamon.metric.{ DispatcherMetrics, Metrics }
+import org.aspectj.lang.annotation._
+
+import scala.concurrent.forkjoin.ForkJoinPool
+
+@Aspect
+class DispatcherInstrumentation {
+
+  @Pointcut("execution(akka.dispatch.Dispatchers.new(..)) && this(dispatchers) && cflow(execution(akka.actor.ActorSystemImpl.new(..)) && this(system))")
+  def onActorSystemStartup(dispatchers: Dispatchers, system: ActorSystemImpl) = {}
+
+  @Before("onActorSystemStartup(dispatchers, system)")
+  def beforeActorSystemStartup(dispatchers: Dispatchers, system: ActorSystemImpl): Unit = {
+    val currentDispatchers = dispatchers.asInstanceOf[DispatchersWithActorSystem]
+    currentDispatchers.actorSystem = system
+  }
+
+  @Pointcut("execution(* akka.dispatch.Dispatchers.lookup(..)) && this(dispatchers)")
+  def onDispatchersLookup(dispatchers: Dispatchers) = {}
+
+  @AfterReturning(pointcut = "onDispatchersLookup(dispatchers)", returning = "dispatcher")
+  def afterReturningLookup(dispatchers: Dispatchers, dispatcher: Dispatcher): Unit = {
+    val dispatchersWithActorSystem = dispatchers.asInstanceOf[DispatchersWithActorSystem]
+    val dispatcherWithMetrics = dispatcher.asInstanceOf[DispatcherMetricCollectionInfo]
+
+    dispatcherWithMetrics.actorSystem = dispatchersWithActorSystem.actorSystem
+  }
+
+  @Pointcut("call(* akka.dispatch.ExecutorServiceFactory.createExecutorService(..))")
+  def onCreateExecutorService(): Unit = {}
+
+  @Pointcut("cflow((execution(* akka.dispatch.MessageDispatcher.registerForExecution(..)) || execution(* akka.dispatch.MessageDispatcher.executeTask(..))) && this(dispatcher))")
+  def onCflowMessageDispatcher(dispatcher: Dispatcher): Unit = {}
+
+  @Pointcut("onCreateExecutorService() && onCflowMessageDispatcher(dispatcher)")
+  def onDispatcherStartup(dispatcher: Dispatcher): Unit = {}
+
+  @After("onDispatcherStartup(dispatcher)")
+  def afterDispatcherStartup(dispatcher: MessageDispatcher): Unit = {
+
+    val dispatcherWithMetrics = dispatcher.asInstanceOf[DispatcherMetricCollectionInfo]
+    val metricsExtension = Kamon(Metrics)(dispatcherWithMetrics.actorSystem)
+    val metricIdentity = DispatcherMetrics(dispatcher.id)
+
+    dispatcherWithMetrics.metricIdentity = metricIdentity
+    dispatcherWithMetrics.dispatcherMetricsRecorder = metricsExtension.register(metricIdentity, DispatcherMetrics.Factory)
+
+    if (dispatcherWithMetrics.dispatcherMetricsRecorder.isDefined) {
+      dispatcherWithMetrics.dispatcherCollectorCancellable = metricsExtension.scheduleGaugeRecorder {
+        dispatcherWithMetrics.dispatcherMetricsRecorder.map {
+          dm ⇒
+            val DispatcherMetricsMeasurement(maximumPoolSize, runningThreadCount, queueTaskCount, poolSize) =
+              DispatcherMetricsCollector.collect(dispatcher)
+
+            dm.maximumPoolSize.record(maximumPoolSize)
+            dm.runningThreadCount.record(runningThreadCount)
+            dm.queueTaskCount.record(queueTaskCount)
+            dm.poolSize.record(poolSize)
+        }
+      }
+    }
+  }
+
+  @Pointcut("execution(* akka.dispatch.MessageDispatcher.shutdown(..)) && this(dispatcher)")
+  def onDispatcherShutdown(dispatcher: MessageDispatcher): Unit = {}
+
+  @After("onDispatcherShutdown(dispatcher)")
+  def afterDispatcherShutdown(dispatcher: MessageDispatcher): Unit = {
+    val dispatcherWithMetrics = dispatcher.asInstanceOf[DispatcherMetricCollectionInfo]
+
+    dispatcherWithMetrics.dispatcherMetricsRecorder.map {
+      dispatcher ⇒
+        dispatcherWithMetrics.dispatcherCollectorCancellable.cancel()
+        Kamon(Metrics)(dispatcherWithMetrics.actorSystem).unregister(dispatcherWithMetrics.metricIdentity)
+    }
+  }
+}
+
+@Aspect
+class DispatcherMetricCollectionInfoIntoDispatcherMixin {
+
+  @DeclareMixin("akka.dispatch.Dispatcher")
+  def mixinDispatcherMetricsToMessageDispatcher: DispatcherMetricCollectionInfo = new DispatcherMetricCollectionInfo {}
+
+  @DeclareMixin("akka.dispatch.Dispatchers")
+  def mixinDispatchersToDispatchersWithActorSystem: DispatchersWithActorSystem = new DispatchersWithActorSystem {}
+}
+
+trait DispatcherMetricCollectionInfo {
+  var metricIdentity: DispatcherMetrics = _
+  var dispatcherMetricsRecorder: Option[DispatcherMetricRecorder] = _
+  var dispatcherCollectorCancellable: Cancellable = _
+  var actorSystem: ActorSystemImpl = _
+}
+
+trait DispatchersWithActorSystem {
+  var actorSystem: ActorSystemImpl = _
+}
+
+object DispatcherMetricsCollector {
+
+  case class DispatcherMetricsMeasurement(maximumPoolSize: Long, runningThreadCount: Long, queueTaskCount: Long, poolSize: Long)
+
+  private def collectForkJoinMetrics(pool: ForkJoinPool): DispatcherMetricsMeasurement = {
+    DispatcherMetricsMeasurement(pool.getParallelism, pool.getActiveThreadCount,
+      (pool.getQueuedTaskCount + pool.getQueuedSubmissionCount), pool.getPoolSize)
+  }
+
+  private def collectExecutorMetrics(pool: ThreadPoolExecutor): DispatcherMetricsMeasurement = {
+    DispatcherMetricsMeasurement(pool.getMaximumPoolSize, pool.getActiveCount, pool.getQueue.size(), pool.getPoolSize)
+  }
+
+  private val executorServiceMethod: Method = {
+    // executorService is protected
+    val method = classOf[Dispatcher].getDeclaredMethod("executorService")
+    method.setAccessible(true)
+    method
+  }
+
+  def collect(dispatcher: MessageDispatcher): DispatcherMetricsMeasurement = {
+    dispatcher match {
+      case x: Dispatcher ⇒ {
+        val executor = executorServiceMethod.invoke(x) match {
+          case delegate: ExecutorServiceDelegate ⇒ delegate.executor
+          case other                             ⇒ other
+        }
+
+        executor match {
+          case fjp: ForkJoinPool       ⇒ collectForkJoinMetrics(fjp)
+          case tpe: ThreadPoolExecutor ⇒ collectExecutorMetrics(tpe)
+          case anything                ⇒ DispatcherMetricsMeasurement(0L, 0L, 0L, 0L)
+        }
+      }
+      case _ ⇒ new DispatcherMetricsMeasurement(0L, 0L, 0L, 0L)
+    }
+  }
+}
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/hdrhistogram/AtomicHistogramFieldsAccessor.scala b/kamon-core/src/main/scala/kamon/instrumentation/hdrhistogram/AtomicHistogramFieldsAccessor.scala
new file mode 100644
index 00000000..e79090a8
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/hdrhistogram/AtomicHistogramFieldsAccessor.scala
@@ -0,0 +1,35 @@
+/*
+ * =========================================================================================
+ * 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 org.HdrHistogram
+
+import java.util.concurrent.atomic.{ AtomicLongArray, AtomicLongFieldUpdater }
+
+trait AtomicHistogramFieldsAccessor {
+  self: AtomicHistogram ⇒
+
+  def countsArray(): AtomicLongArray = self.counts
+
+  def unitMagnitude(): Int = self.unitMagnitude
+
+  def subBucketHalfCount(): Int = self.subBucketHalfCount
+
+  def subBucketHalfCountMagnitude(): Int = self.subBucketHalfCountMagnitude
+}
+
+object AtomicHistogramFieldsAccessor {
+  def totalCountUpdater(): AtomicLongFieldUpdater[AtomicHistogram] = AtomicHistogram.totalCountUpdater
+}
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/FutureTracing.scala b/kamon-core/src/main/scala/kamon/instrumentation/scala/FutureInstrumentation.scala
index b9424579..bda2da78 100644
--- a/kamon-core/src/main/scala/kamon/instrumentation/FutureTracing.scala
+++ b/kamon-core/src/main/scala/kamon/instrumentation/scala/FutureInstrumentation.scala
@@ -1,26 +1,27 @@
-/* ===================================================
- * Copyright © 2013 the kamon project <http://kamon.io/>
+/*
+ * =========================================================================================
+ * 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
+ * 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
+ *   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.instrumentation
+ * 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.instrumentation.scala
 
-import org.aspectj.lang.annotation._
-import org.aspectj.lang.ProceedingJoinPoint
 import kamon.trace.{ TraceContextAware, TraceRecorder }
+import org.aspectj.lang.ProceedingJoinPoint
+import org.aspectj.lang.annotation._
 
 @Aspect
-class FutureTracing {
+class FutureInstrumentation {
 
   @DeclareMixin("scala.concurrent.impl.CallbackRunnable || scala.concurrent.impl.Future.PromiseCompletingRunnable")
   def mixinTraceContextAwareToFutureRelatedRunnable: TraceContextAware = TraceContextAware.default