+ core: log a configurable error message when the application was started with the AspectJ Weaver, closes #48

2 files changed, 45 insertions, 1 deletions

diff --git a/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala b/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala
new file mode 100644
index 00000000..d227404a
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/instrumentation/AspectJWeaverMissingWarning.scala
@@ -0,0 +1,17 @@
+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/metric/MetricsExtension.scala b/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
index 8c6d0359..3465fef9 100644
--- a/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
+++ b/kamon-core/src/main/scala/kamon/metric/MetricsExtension.scala
@@ -16,7 +16,8 @@
 
 package kamon.metric
 
-import java.nio.{ LongBuffer, ByteBuffer }
+import akka.event.Logging.Error
+import akka.event.EventStream
 
 import scala.collection.concurrent.TrieMap
 import akka.actor._
@@ -30,6 +31,7 @@ import java.util.concurrent.TimeUnit
 
 class MetricsExtension(system: ExtendedActorSystem) extends Kamon.Extension {
   val metricsExtConfig = system.settings.config.getConfig("kamon.metrics")
+  printInitializationMessage(system.eventStream, metricsExtConfig.getBoolean("disable-aspectj-weaver-missing-error"))
 
   /** Configured Dispatchers */
   val metricSubscriptionsDispatcher = system.dispatchers.lookup(metricsExtConfig.getString("dispatchers.metric-subscriptions"))
@@ -93,6 +95,31 @@ class MetricsExtension(system: ExtendedActorSystem) extends Kamon.Extension {
 
   def buildDefaultCollectionContext: CollectionContext =
     CollectionContext(metricsExtConfig.getInt("default-collection-context-buffer-size"))
+
+  def printInitializationMessage(eventStream: EventStream, disableWeaverMissingError: Boolean): Unit = {
+    if(!disableWeaverMissingError) {
+      val weaverMissingMessage =
+        """
+          |
+          |  ___                           _      ___   _    _                                 ___  ___ _            _
+          | / _ \                         | |    |_  | | |  | |                                |  \/  |(_)          (_)
+          |/ /_\ \ ___  _ __    ___   ___ | |_     | | | |  | |  ___   __ _ __   __ ___  _ __  | .  . | _  ___  ___  _  _ __    __ _
+          ||  _  |/ __|| '_ \  / _ \ / __|| __|    | | | |/\| | / _ \ / _` |\ \ / // _ \| '__| | |\/| || |/ __|/ __|| || '_ \  / _` |
+          || | | |\__ \| |_) ||  __/| (__ | |_ /\__/ / \  /\  /|  __/| (_| | \ V /|  __/| |    | |  | || |\__ \\__ \| || | | || (_| |
+          |\_| |_/|___/| .__/  \___| \___| \__|\____/   \/  \/  \___| \__,_|  \_/  \___||_|    \_|  |_/|_||___/|___/|_||_| |_| \__, |
+          |            | |                                                                                                      __/ |
+          |            |_|                                                                                                     |___/
+          |
+          | It seems like your application wasn't started with the -javaagent:/path-to-aspectj-weaver.jar option. Without that Kamon might
+          | not work properly, if you need help on setting up the weaver go to http://kamon.io/introduction/get-started/ for more info. If
+          | you are sure that you don't need the weaver (e.g. you are only using KamonStandalone) then you can disable this error message
+          | by changing the kamon.metrics.disable-aspectj-weaver-missing-error setting in your configuration file.
+          |
+        """.stripMargin
+
+      eventStream.publish(Error("MetricsExtension", classOf[MetricsExtension], weaverMissingMessage))
+    }
+  }
 }
 
 object Metrics extends ExtensionId[MetricsExtension] with ExtensionIdProvider {