! 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, 65 deletions

diff --git a/kamon-core/src/main/scala/akka/instrumentation/ActorSystemMessagePassingTracing.scala b/kamon-core/src/main/scala/akka/instrumentation/ActorSystemMessagePassingTracing.scala
deleted file mode 100644
index 7d03d946..00000000
--- a/kamon-core/src/main/scala/akka/instrumentation/ActorSystemMessagePassingTracing.scala
+++ /dev/null
@@ -1,65 +0,0 @@
-package akka.instrumentation
-
-import org.aspectj.lang.annotation._
-import akka.dispatch.sysmsg.EarliestFirstSystemMessageList
-import org.aspectj.lang.ProceedingJoinPoint
-import kamon.trace.{ TraceRecorder, TraceContextAware }
-
-@Aspect
-class SystemMessageTraceContextMixin {
-
-  @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 RepointableActorRefTraceContextMixin {
-
-  @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()
-    }
-  }
-
-}
-
-@Aspect
-class ActorSystemMessagePassingTracing {
-
-  @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()
-  }
-}