= core: put the ModuleLoader back in place for auto-starting modules.

8 files changed, 112 insertions, 240 deletions

diff --git a/kamon-core/src/main/resources/META-INF/aop.xml b/kamon-core/src/main/resources/META-INF/aop.xml
index 2ffb8b09..b13f9aac 100644
--- a/kamon-core/src/main/resources/META-INF/aop.xml
+++ b/kamon-core/src/main/resources/META-INF/aop.xml
@@ -4,7 +4,7 @@
   <aspects>
 
     <!-- Notify that AspectJ is present -->
-    <aspect name="kamon.supervisor.AspectJPresent"/>
+    <aspect name="kamon.AspectJPresent"/>
 
   </aspects>
 
diff --git a/kamon-core/src/main/scala/kamon/Kamon.scala b/kamon-core/src/main/scala/kamon/Kamon.scala
index a6469039..f8253875 100644
--- a/kamon-core/src/main/scala/kamon/Kamon.scala
+++ b/kamon-core/src/main/scala/kamon/Kamon.scala
@@ -48,6 +48,7 @@ object Kamon {
 
       metrics.start(_system)
       tracer.start(_system)
+      _system.registerExtension(ModuleLoader)
 
     } else sys.error("Kamon has already been started.")
   }
diff --git a/kamon-core/src/main/scala/kamon/ModuleLoader.scala b/kamon-core/src/main/scala/kamon/ModuleLoader.scala
new file mode 100644
index 00000000..84d93943
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/ModuleLoader.scala
@@ -0,0 +1,109 @@
+package kamon
+
+import _root_.akka.actor
+import _root_.akka.actor._
+import _root_.akka.event.Logging
+import org.aspectj.lang.ProceedingJoinPoint
+import org.aspectj.lang.annotation.{Around, Pointcut, Aspect}
+
+
+private[kamon] object ModuleLoader extends ExtensionId[ModuleLoaderExtension] with ExtensionIdProvider {
+  def lookup(): ExtensionId[_ <: actor.Extension] = ModuleLoader
+  def createExtension(system: ExtendedActorSystem): ModuleLoaderExtension = new ModuleLoaderExtension(system)
+}
+
+private[kamon] class ModuleLoaderExtension(system: ExtendedActorSystem) extends Kamon.Extension {
+  val log = Logging(system, "ModuleLoader")
+  val settings = ModuleLoaderSettings(system)
+
+
+  if (settings.modulesRequiringAspectJ.nonEmpty && !isAspectJPresent && settings.showAspectJMissingWarning)
+    logAspectJWeaverMissing(settings.modulesRequiringAspectJ)
+
+  // Force initialization of all modules marked with auto-start.
+  settings.availableModules.filter(_.autoStart).foreach { module ⇒
+    if (module.extensionClass == "none")
+      log.debug("Ignoring auto start of the [{}] module with no extension class.")
+    else
+      system.dynamicAccess.getObjectFor[ExtensionId[Kamon.Extension]](module.extensionClass).map { moduleID ⇒
+        log.debug("Auto starting the [{}] module.", module.name)
+        moduleID.get(system)
+
+      } recover {
+        case th: Throwable ⇒ log.error(th, "Failed to auto start the [{}] module.", module.name)
+      }
+
+  }
+
+  // When AspectJ is present the kamon.supervisor.AspectJPresent aspect will make this return true.
+  def isAspectJPresent: Boolean = false
+
+  def logAspectJWeaverMissing(modulesRequiringAspectJ: List[AvailableModuleInfo]): Unit = {
+    val moduleNames = modulesRequiringAspectJ.map(_.name).mkString(", ")
+    val weaverMissingMessage =
+      """
+        |
+        |  ___                           _      ___   _    _                                 ___  ___ _            _
+        | / _ \                         | |    |_  | | |  | |                                |  \/  |(_)          (_)
+        |/ /_\ \ ___  _ __    ___   ___ | |_     | | | |  | |  ___   __ _ __   __ ___  _ __  | .  . | _  ___  ___  _  _ __    __ _
+        ||  _  |/ __|| '_ \  / _ \ / __|| __|    | | | |/\| | / _ \ / _` |\ \ / // _ \| '__| | |\/| || |/ __|/ __|| || '_ \  / _` |
+        || | | |\__ \| |_) ||  __/| (__ | |_ /\__/ / \  /\  /|  __/| (_| | \ V /|  __/| |    | |  | || |\__ \\__ \| || | | || (_| |
+        |\_| |_/|___/| .__/  \___| \___| \__|\____/   \/  \/  \___| \__,_|  \_/  \___||_|    \_|  |_/|_||___/|___/|_||_| |_| \__, |
+        |            | |                                                                                                      __/ |
+        |            |_|                                                                                                     |___/
+        |
+        | It seems like your application was not started with the -javaagent:/path-to-aspectj-weaver.jar option but Kamon detected
+        | the following modules which require AspecJ to work properly:
+        |
+      """.stripMargin + moduleNames +
+        """
+          |
+          | If you need help on setting up the aspectj weaver go to http://kamon.io/introduction/get-started/ for more info. On the
+          | other hand, if you are sure that you do not need or do not want to use the weaver then you can disable this error message
+          | by changing the kamon.show-aspectj-missing-warning setting in your configuration file.
+          |
+        """.stripMargin
+
+    log.error(weaverMissingMessage)
+  }
+}
+
+private[kamon] case class AvailableModuleInfo(name: String, extensionClass: String, requiresAspectJ: Boolean, autoStart: Boolean)
+private[kamon] case class ModuleLoaderSettings(showAspectJMissingWarning: Boolean, availableModules: List[AvailableModuleInfo]) {
+  val modulesRequiringAspectJ = availableModules.filter(_.requiresAspectJ)
+}
+
+private[kamon] object ModuleLoaderSettings {
+
+  def apply(system: ActorSystem): ModuleLoaderSettings = {
+    import kamon.util.ConfigTools.Syntax
+
+    val config = system.settings.config.getConfig("kamon.modules")
+    val showAspectJMissingWarning = system.settings.config.getBoolean("kamon.show-aspectj-missing-warning")
+
+    val modules = config.firstLevelKeys
+    val availableModules = modules.map { moduleName ⇒
+      val moduleConfig = config.getConfig(moduleName)
+
+      AvailableModuleInfo(
+        moduleName,
+        moduleConfig.getString("extension-id"),
+        moduleConfig.getBoolean("requires-aspectj"),
+        moduleConfig.getBoolean("auto-start"))
+
+    } toList
+
+    ModuleLoaderSettings(showAspectJMissingWarning, availableModules)
+  }
+}
+
+@Aspect
+private[kamon] class AspectJPresent {
+
+  @Pointcut("execution(* kamon.ModuleLoaderExtension.isAspectJPresent())")
+  def isAspectJPresentAtModuleSupervisor(): Unit = {}
+
+  @Around("isAspectJPresentAtModuleSupervisor()")
+  def aroundIsAspectJPresentAtModuleSupervisor(pjp: ProceedingJoinPoint): Boolean = true
+
+}
diff --git a/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala b/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala
deleted file mode 100644
index 4dc5ff41..00000000
--- a/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013-2015 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.instrumentation
-
-import _root_.akka.event.EventStream
-import org.aspectj.lang.ProceedingJoinPoint
-import org.aspectj.lang.annotation.{ Around, Pointcut, Aspect }
-
-@Aspect
-class AspectJWeaverMissingWarning {
-
-  @Pointcut("execution(* kamon.metric.MetricsExtension.printInitializationMessage(..)) && args(eventStream, *)")
-  def printInitializationMessage(eventStream: EventStream): Unit = {}
-
-  @Around("printInitializationMessage(eventStream)")
-  def aroundPrintInitializationMessage(pjp: ProceedingJoinPoint, eventStream: EventStream): Unit = {
-    pjp.proceed(Array[AnyRef](eventStream, Boolean.box(true)))
-  }
-}
diff --git a/kamon-core/src/main/scala/kamon/supervisor/AspectJPresent.scala b/kamon-core/src/main/scala/kamon/supervisor/AspectJPresent.scala
deleted file mode 100644
index 0df9539f..00000000
--- a/kamon-core/src/main/scala/kamon/supervisor/AspectJPresent.scala
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013-2015 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.supervisor
-
-import org.aspectj.lang.ProceedingJoinPoint
-import org.aspectj.lang.annotation.{ Around, Aspect, Pointcut }
-
-@Aspect
-class AspectJPresent {
-
-  @Pointcut("execution(* kamon.supervisor.KamonSupervisor.isAspectJPresent())")
-  def isAspectJPresentAtModuleSupervisor(): Unit = {}
-
-  @Around("isAspectJPresentAtModuleSupervisor()")
-  def aroundIsAspectJPresentAtModuleSupervisor(pjp: ProceedingJoinPoint): Boolean = true
-
-}
diff --git a/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorExtension.scala b/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorExtension.scala
deleted file mode 100644
index ddce63fb..00000000
--- a/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorExtension.scala
+++ /dev/null
@@ -1,125 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013-2015 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.supervisor
-
-import akka.actor
-import akka.actor._
-import kamon.Kamon
-import kamon.supervisor.KamonSupervisor.CreateModule
-
-import scala.concurrent.{ Promise, Future }
-import scala.util.Success
-
-object ModuleSupervisor extends ExtensionId[ModuleSupervisorExtension] with ExtensionIdProvider {
-  def lookup(): ExtensionId[_ <: actor.Extension] = ModuleSupervisor
-  def createExtension(system: ExtendedActorSystem): ModuleSupervisorExtension = new ModuleSupervisorExtensionImpl(system)
-}
-
-trait ModuleSupervisorExtension extends actor.Extension {
-  def createModule(name: String, props: Props): Future[ActorRef]
-}
-
-class ModuleSupervisorExtensionImpl(system: ExtendedActorSystem) extends ModuleSupervisorExtension {
-  import system.dispatcher
-
-  private val _settings = ModuleSupervisorSettings(system)
-  private val _supervisor = system.actorOf(KamonSupervisor.props(_settings, system.dynamicAccess), "kamon")
-
-  def createModule(name: String, props: Props): Future[ActorRef] = Future {} flatMap { _: Unit ⇒
-    val modulePromise = Promise[ActorRef]()
-    _supervisor ! CreateModule(name, props, modulePromise)
-    modulePromise.future
-  }
-}
-
-class KamonSupervisor(settings: ModuleSupervisorSettings, dynamicAccess: DynamicAccess) extends Actor with ActorLogging {
-
-  init()
-
-  def receive = {
-    case CreateModule(name, props, childPromise) ⇒ createChildModule(name, props, childPromise)
-  }
-
-  def createChildModule(name: String, props: Props, childPromise: Promise[ActorRef]): Unit =
-    context.child(name).map { alreadyAvailableModule ⇒
-      log.warning("Received a request to create module [{}] but the module is already available, returning the existent instance.")
-      childPromise.complete(Success(alreadyAvailableModule))
-
-    } getOrElse (childPromise.complete(Success(context.actorOf(props, name))))
-
-  def init(): Unit = {
-    if (settings.modulesRequiringAspectJ.nonEmpty && !isAspectJPresent && settings.showAspectJMissingWarning)
-      logAspectJWeaverMissing(settings.modulesRequiringAspectJ)
-
-    // Force initialization of all modules marked with auto-start.
-    settings.availableModules.filter(_.autoStart).foreach { module ⇒
-      if (module.extensionClass == "none")
-        log.debug("Ignoring auto start of the [{}] module with no extension class.")
-      else
-        dynamicAccess.getObjectFor[ExtensionId[Kamon.Extension]](module.extensionClass).map { moduleID ⇒
-          moduleID.get(context.system)
-          log.debug("Auto starting the [{}] module.", module.name)
-
-        } recover {
-          case th: Throwable ⇒ log.error(th, "Failed to auto start the [{}] module.", module.name)
-        }
-
-    }
-  }
-
-  // When AspectJ is present the kamon.supervisor.AspectJPresent aspect will make this return true.
-  def isAspectJPresent: Boolean = false
-
-  def logAspectJWeaverMissing(modulesRequiringAspectJ: List[AvailableModuleInfo]): Unit = {
-    val moduleNames = modulesRequiringAspectJ.map(_.name).mkString(", ")
-    val weaverMissingMessage =
-      """
-        |
-        |  ___                           _      ___   _    _                                 ___  ___ _            _
-        | / _ \                         | |    |_  | | |  | |                                |  \/  |(_)          (_)
-        |/ /_\ \ ___  _ __    ___   ___ | |_     | | | |  | |  ___   __ _ __   __ ___  _ __  | .  . | _  ___  ___  _  _ __    __ _
-        ||  _  |/ __|| '_ \  / _ \ / __|| __|    | | | |/\| | / _ \ / _` |\ \ / // _ \| '__| | |\/| || |/ __|/ __|| || '_ \  / _` |
-        || | | |\__ \| |_) ||  __/| (__ | |_ /\__/ / \  /\  /|  __/| (_| | \ V /|  __/| |    | |  | || |\__ \\__ \| || | | || (_| |
-        |\_| |_/|___/| .__/  \___| \___| \__|\____/   \/  \/  \___| \__,_|  \_/  \___||_|    \_|  |_/|_||___/|___/|_||_| |_| \__, |
-        |            | |                                                                                                      __/ |
-        |            |_|                                                                                                     |___/
-        |
-        | It seems like your application was not started with the -javaagent:/path-to-aspectj-weaver.jar option but Kamon detected
-        | the following modules which require AspecJ to work properly:
-        |
-      """.stripMargin + moduleNames +
-        """
-        |
-        | If you need help on setting up the aspectj weaver go to http://kamon.io/introduction/get-started/ for more info. On the
-        | other hand, if you are sure that you do not need or do not want to use the weaver then you can disable this error message
-        | by changing the kamon.show-aspectj-missing-warning setting in your configuration file.
-        |
-      """.stripMargin
-
-    log.error(weaverMissingMessage)
-  }
-
-}
-
-object KamonSupervisor {
-  case class CreateModule(name: String, props: Props, childPromise: Promise[ActorRef])
-
-  def props(settings: ModuleSupervisorSettings, dynamicAccess: DynamicAccess): Props =
-    Props(new KamonSupervisor(settings, dynamicAccess))
-
-}
-
diff --git a/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorSettings.scala b/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorSettings.scala
deleted file mode 100644
index c04157aa..00000000
--- a/kamon-core/src/main/scala/kamon/supervisor/ModuleSupervisorSettings.scala
+++ /dev/null
@@ -1,49 +0,0 @@
-/*
- * =========================================================================================
- * Copyright © 2013-2015 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.supervisor
-
-import akka.actor.ActorSystem
-
-case class AvailableModuleInfo(name: String, extensionClass: String, requiresAspectJ: Boolean, autoStart: Boolean)
-case class ModuleSupervisorSettings(showAspectJMissingWarning: Boolean, availableModules: List[AvailableModuleInfo]) {
-  val modulesRequiringAspectJ = availableModules.filter(_.requiresAspectJ)
-}
-
-object ModuleSupervisorSettings {
-
-  def apply(system: ActorSystem): ModuleSupervisorSettings = {
-    import kamon.util.ConfigTools.Syntax
-
-    val config = system.settings.config.getConfig("kamon.modules")
-    val showAspectJMissingWarning = system.settings.config.getBoolean("kamon.show-aspectj-missing-warning")
-
-    val modules = config.firstLevelKeys
-    val availableModules = modules.map { moduleName ⇒
-      val moduleConfig = config.getConfig(moduleName)
-
-      AvailableModuleInfo(
-        moduleName,
-        moduleConfig.getString("extension-id"),
-        moduleConfig.getBoolean("requires-aspectj"),
-        moduleConfig.getBoolean("auto-start"))
-
-    } toList
-
-    ModuleSupervisorSettings(showAspectJMissingWarning, availableModules)
-  }
-
-}
diff --git a/kamon-core/src/main/scala/kamon/util/MapMerge.scala b/kamon-core/src/main/scala/kamon/util/MapMerge.scala
index 64b4f7ae..8573358b 100644
--- a/kamon-core/src/main/scala/kamon/util/MapMerge.scala
+++ b/kamon-core/src/main/scala/kamon/util/MapMerge.scala
@@ -19,7 +19,7 @@ package kamon.util
 object MapMerge {
 
   /**
-   *  Merge to immutable maps with the same key and value types, using the provided valueMerge function.
+   *  Merge two immutable maps with the same key and value types, using the provided valueMerge function.
    */
   implicit class Syntax[K, V](val map: Map[K, V]) extends AnyVal {
     def merge(that: Map[K, V], valueMerge: (V, V) ⇒ V): Map[K, V] = {