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.

2 files changed, 8 insertions, 7 deletions

diff --git a/kamon-core/src/main/scala/kamon/trace/TraceSettings.scala b/kamon-core/src/main/scala/kamon/trace/TraceSettings.scala
index 06677314..c3a83e93 100644
--- a/kamon-core/src/main/scala/kamon/trace/TraceSettings.scala
+++ b/kamon-core/src/main/scala/kamon/trace/TraceSettings.scala
@@ -20,7 +20,7 @@ import kamon.util.ConfigTools.Syntax
 import com.typesafe.config.Config
 import kamon.util.NanoInterval
 
-case class TraceSettings(levelOfDetail: LevelOfDetail, sampler: Sampler, tokenGeneratorFQN: String)
+case class TraceSettings(levelOfDetail: LevelOfDetail, sampler: Sampler, tokenGenerator: () ⇒ String)
 
 object TraceSettings {
   def apply(config: Config): TraceSettings = {
@@ -42,8 +42,10 @@ object TraceSettings {
         case "clock"     ⇒ new ClockSampler(new NanoInterval(tracerConfig.getFiniteDuration("clock-sampler.pause").toNanos))
       }
 
+    val dynamic = new akka.actor.ReflectiveDynamicAccess(getClass.getClassLoader)
     val tokenGeneratorFQN = tracerConfig.getString("token-generator")
+    val tokenGenerator = dynamic.createInstanceFor[() ⇒ String](tokenGeneratorFQN, Nil).get // let's bubble up any problems.
 
-    TraceSettings(detailLevel, sampler, tokenGeneratorFQN)
+    TraceSettings(detailLevel, sampler, tokenGenerator)
   }
 }
\ No newline at end of file
diff --git a/kamon-core/src/main/scala/kamon/trace/TracerModule.scala b/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
index b7b6c17a..552962eb 100644
--- a/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
+++ b/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
@@ -117,14 +117,12 @@ object Tracer {
 }
 
 private[kamon] class TracerModuleImpl(metricsExtension: MetricsModule, config: Config) extends TracerModule {
-  private val _settings = TraceSettings(config)
+  @volatile private var _settings = TraceSettings(config)
 
   private val _subscriptions = new LazyActorRef
   private val _incubator = new LazyActorRef
-  private val _dynamic = new akka.actor.ReflectiveDynamicAccess(getClass.getClassLoader)
-  private val _tokenGenerator = _dynamic.createInstanceFor[() ⇒ String](_settings.tokenGeneratorFQN, Nil).get // let's bubble up any problems.
 
-  private def newToken: String = _tokenGenerator()
+  private def newToken: String = _settings.tokenGenerator()
 
   def newContext(name: String): TraceContext =
     createTraceContext(name, None)
@@ -180,7 +178,8 @@ private[kamon] class TracerModuleImpl(metricsExtension: MetricsModule, config: C
     _incubator.point(_system.actorOf(Incubator.props(subscriptions)))
   }
 
-  def start(system: ActorSystem): Unit = synchronized {
+  def start(system: ActorSystem, newConfig: Config): Unit = synchronized {
+    _settings = TraceSettings(newConfig)
     _system = system
     _logger = Logging(_system, "TracerModule")
     _start