! 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, 161 deletions

diff --git a/kamon-core/src/main/scala/akka/instrumentation/DispatcherTracing.scala b/kamon-core/src/main/scala/akka/instrumentation/DispatcherTracing.scala
deleted file mode 100644
index 60cc4ddf..00000000
--- a/kamon-core/src/main/scala/akka/instrumentation/DispatcherTracing.scala
+++ /dev/null
@@ -1,161 +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 akka.dispatch.{ Dispatchers, ExecutorServiceDelegate, Dispatcher, MessageDispatcher }
-import kamon.metrics.{ Metrics, DispatcherMetrics }
-import kamon.metrics.DispatcherMetrics.DispatcherMetricRecorder
-import kamon.Kamon
-import akka.actor.{ Cancellable, ActorSystemImpl }
-import scala.concurrent.forkjoin.ForkJoinPool
-import java.util.concurrent.ThreadPoolExecutor
-import java.lang.reflect.Method
-import akka.instrumentation.DispatcherMetricsCollector.DispatcherMetricsMeasurement
-
-@Aspect
-class DispatcherTracing {
-
-  @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[DispatcherMessageMetrics]
-
-    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[DispatcherMessageMetrics]
-    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[DispatcherMessageMetrics]
-
-    dispatcherWithMetrics.dispatcherMetricsRecorder.map {
-      dispatcher ⇒
-        dispatcherWithMetrics.dispatcherCollectorCancellable.cancel()
-        Kamon(Metrics)(dispatcherWithMetrics.actorSystem).unregister(dispatcherWithMetrics.metricIdentity)
-    }
-  }
-}
-
-@Aspect
-class DispatcherMetricsMixin {
-
-  @DeclareMixin("akka.dispatch.Dispatcher")
-  def mixinDispatcherMetricsToMessageDispatcher: DispatcherMessageMetrics = new DispatcherMessageMetrics {}
-
-  @DeclareMixin("akka.dispatch.Dispatchers")
-  def mixinDispatchersToDispatchersWithActorSystem: DispatchersWithActorSystem = new DispatchersWithActorSystem {}
-}
-
-trait DispatcherMessageMetrics {
-  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)
-    }
-  }
-}