From becf6cac7142011cc478ab7ab15d51799b190951 Mon Sep 17 00:00:00 2001
From: Ivan Topolnjak <ivantopo@gmail.com>
Date: Sat, 24 Dec 2016 03:14:29 +0100
Subject: allow restarting Kamon in the same process.

taking some ideas from #395, this commit removes ConfigProviders and
allows Kamon to be used in "permissive" mode until it gets started.
---
 .../src/test/scala/kamon/KamonLifecycleSpec.scala  | 93 ++++++++++++++++++++++
 .../test/scala/kamon/testkit/BaseKamonSpec.scala   |  4 +-
 2 files changed, 95 insertions(+), 2 deletions(-)
 create mode 100644 kamon-core/src/test/scala/kamon/KamonLifecycleSpec.scala

(limited to 'kamon-core/src/test')

diff --git a/kamon-core/src/test/scala/kamon/KamonLifecycleSpec.scala b/kamon-core/src/test/scala/kamon/KamonLifecycleSpec.scala
new file mode 100644
index 00000000..2fbd1b71
--- /dev/null
+++ b/kamon-core/src/test/scala/kamon/KamonLifecycleSpec.scala
@@ -0,0 +1,93 @@
+package kamon
+
+import akka.actor.ActorSystem
+import akka.testkit.{TestKitBase, TestProbe}
+import com.typesafe.config.ConfigFactory
+import kamon.metric.SubscriptionsDispatcher.TickMetricSnapshot
+import kamon.metric.{EntitySnapshot, SubscriptionsDispatcher}
+import kamon.util.LazyActorRef
+import org.scalatest.{Matchers, WordSpecLike}
+import org.scalactic.TimesOnInt._
+
+import scala.concurrent.duration._
+
+class KamonLifecycleSpec extends TestKitBase with WordSpecLike with Matchers {
+  override implicit lazy val system: ActorSystem = ActorSystem("kamon-lifecycle-spec")
+
+  "The Kamon lifecycle" should {
+    "allow Kamon to be used before it gets started" in {
+      val someMetric = Kamon.metrics.histogram("allow-me-before-start")
+    }
+
+    "allow Kamon to be started/shutdown several times" in {
+      10 times {
+        Kamon.shutdown()
+        Kamon.start()
+        Kamon.start()
+        Kamon.shutdown()
+        Kamon.shutdown()
+      }
+    }
+
+    "not dispatch subscriptions before Kamon startup" in {
+      val subscriber = TestProbe()
+      Kamon.metrics.histogram("only-after-startup").record(100)
+      Kamon.metrics.subscribe("**", "**", subscriber.ref, permanently = true)
+
+      flushSubscriptions()
+      subscriber.expectNoMsg(300 millis)
+
+      Kamon.metrics.histogram("only-after-startup").record(100)
+      Kamon.start()
+      flushSubscriptions()
+      subscriber.expectMsgType[TickMetricSnapshot]
+      Kamon.shutdown()
+    }
+
+    "not dispatch subscriptions after Kamon shutdown" in {
+      val subscriber = TestProbe()
+      Kamon.start()
+      Kamon.metrics.histogram("only-before-shutdown").record(100)
+      Kamon.metrics.subscribe("**", "**", subscriber.ref, permanently = true)
+
+      flushSubscriptions()
+      subscriber.expectMsgType[TickMetricSnapshot]
+
+      Kamon.metrics.histogram("only-before-shutdown").record(100)
+      Kamon.shutdown()
+      Thread.sleep(500)
+      flushSubscriptions()
+      subscriber.expectNoMsg(300 millis)
+    }
+
+    "reconfigure filters after being started" in {
+      val customConfig = ConfigFactory.parseString(
+        """
+          |kamon.metric.filters.histogram {
+          |  includes = [ "**" ]
+          |  excludes = ["untracked-histogram"]
+          |}
+        """.stripMargin
+      )
+
+      Kamon.metrics.shouldTrack("untracked-histogram", "histogram") shouldBe true
+      Kamon.start(customConfig.withFallback(ConfigFactory.load()))
+      Kamon.metrics.shouldTrack("untracked-histogram", "histogram") shouldBe false
+
+    }
+  }
+
+  def takeSnapshotOf(name: String, category: String): EntitySnapshot = {
+    val collectionContext = Kamon.metrics.buildDefaultCollectionContext
+    val recorder = Kamon.metrics.find(name, category).get
+    recorder.collect(collectionContext)
+  }
+
+  def flushSubscriptions(): Unit = {
+    val subscriptionsField = Kamon.metrics.getClass.getDeclaredField("_subscriptions")
+    subscriptionsField.setAccessible(true)
+    val subscriptions = subscriptionsField.get(Kamon.metrics).asInstanceOf[LazyActorRef]
+
+    subscriptions.tell(SubscriptionsDispatcher.Tick)
+  }
+}
diff --git a/kamon-core/src/test/scala/kamon/testkit/BaseKamonSpec.scala b/kamon-core/src/test/scala/kamon/testkit/BaseKamonSpec.scala
index a869149b..49bcee68 100644
--- a/kamon-core/src/test/scala/kamon/testkit/BaseKamonSpec.scala
+++ b/kamon-core/src/test/scala/kamon/testkit/BaseKamonSpec.scala
@@ -32,9 +32,9 @@ abstract class BaseKamonSpec(actorSystemName: String) extends TestKitBase with W
     ActorSystem(actorSystemName, mergedConfig)
   }
 
-  def config: Config = Kamon.defaultConfig
+  def config: Config = Kamon.config
 
-  def mergedConfig: Config = config.withFallback(Kamon.defaultConfig)
+  def mergedConfig: Config = config.withFallback(Kamon.config)
 
   def newContext(name: String): TraceContext =
     Kamon.tracer.newContext(name)
-- 
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