! 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, 66 deletions

diff --git a/kamon-core/src/test/scala/kamon/trace/instrumentation/AskPatternTracingSpec.scala b/kamon-core/src/test/scala/kamon/trace/instrumentation/AskPatternTracingSpec.scala
deleted file mode 100644
index fb886de6..00000000
--- a/kamon-core/src/test/scala/kamon/trace/instrumentation/AskPatternTracingSpec.scala
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013 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 kamon.trace.instrumentation
-
-import akka.testkit.TestKitBase
-import akka.actor.{ Props, Actor, ActorSystem }
-import org.scalatest.{ Matchers, WordSpecLike }
-import akka.event.Logging.Warning
-import scala.concurrent.duration._
-import akka.pattern.ask
-import akka.util.Timeout
-import kamon.trace.{ TraceContextAware, TraceRecorder }
-import com.typesafe.config.ConfigFactory
-
-class AskPatternTracingSpec extends TestKitBase with WordSpecLike with Matchers {
-  implicit lazy val system: ActorSystem = ActorSystem("ask-pattern-tracing-spec", ConfigFactory.parseString(
-    """
-      |kamon {
-      |  trace {
-      |    ask-pattern-tracing = on
-      |  }
-      |}
-    """.stripMargin))
-
-  "the AskPatternTracing" should {
-    "log a warning with a stack trace and TraceContext taken from the moment the ask was triggered" in {
-      implicit val ec = system.dispatcher
-      implicit val timeout = Timeout(10 milliseconds)
-      val noReply = system.actorOf(Props[NoReply])
-      system.eventStream.subscribe(testActor, classOf[Warning])
-
-      val testTraceContext = TraceRecorder.withNewTraceContext("ask-timeout-warning") {
-        noReply ? "hello"
-        TraceRecorder.currentContext
-      }
-
-      val warn = expectMsgPF() {
-        case warn: Warning if warn.message.toString.contains("Timeout triggered for ask pattern") ⇒ warn
-      }
-      val capturedCtx = warn.asInstanceOf[TraceContextAware].traceContext
-
-      capturedCtx should be('defined)
-      capturedCtx should equal(testTraceContext)
-    }
-  }
-}
-
-class NoReply extends Actor {
-  def receive = {
-    case any ⇒
-  }
-}