OSGi EventHandler dynamically listen to LogService

More information in logging

Conflicts:

	project/AkkaBuild.scala

akka-osgi/src/main/scala/akka/osgi/ActorSystemActivator.scala

@@ -5,9 +5,8 @@ package akka.osgi
 
 import akka.actor.ActorSystem
 import java.util.{ Dictionary, Properties }
-import org.osgi.framework.{ ServiceRegistration, BundleContext, BundleActivator }
+import org.osgi.framework._
 import org.osgi.service.log.LogService
-import org.osgi.util.tracker.ServiceTracker
 
 /**
  * Abstract bundle activator implementation to bootstrap and configure an actor system in an
@@ -40,22 +39,40 @@ abstract class ActorSystemActivator extends BundleActivator {
    */
   def start(context: BundleContext): Unit = {
     system = Some(OsgiActorSystemFactory(context).createActorSystem(Option(getActorSystemName(context))))
-    findLogService(context) foreach (log ⇒ system.foreach(sys ⇒ sys.eventStream.publish(log)))
+    system foreach (addLogServiceListener(context, _))
     system foreach (configure(context, _))
   }
 
   /**
-   * Finds a LogService in the BundleContext in any
+   * Adds a LogService Listener that will advertise the ActorSystem on LogService registration and unregistration
    *
    * @param context  the BundleContext
-   * @return An option of the LogService in the BundleContext
+   * @param  system  the ActorSystem to be advertised
    */
-  def findLogService(context: BundleContext): Option[LogService] = {
-    val logServiceTracker = new ServiceTracker(context, classOf[LogService].getName, null)
-    logServiceTracker.open()
-    Option(logServiceTracker.getService.asInstanceOf[LogService])
+  def addLogServiceListener(context: BundleContext, system: ActorSystem) {
+    val logServiceListner = new ServiceListener {
+      def serviceChanged(event: ServiceEvent) {
+        event.getType match {
+          case ServiceEvent.REGISTERED    ⇒ system.eventStream.publish(serviceForReference[LogService](context, event.getServiceReference))
+          case ServiceEvent.UNREGISTERING ⇒ system.eventStream.publish(UnregisteringLogService)
+        }
+      }
+    }
+    val filter = s"(objectclass=${classOf[LogService].getName})"
+    context.addServiceListener(logServiceListner, filter)
+
+    //Small trick to create an event if the service is registred before this start listing for
+    Option(context.getServiceReference(classOf[LogService].getName)).foreach(x ⇒ {
+      logServiceListner.serviceChanged(new ServiceEvent(ServiceEvent.REGISTERED, x))
+    })
   }
 
+  /**
+   * Convenience method to find a service by its reference.
+   */
+  def serviceForReference[T](context: BundleContext, reference: ServiceReference): T =
+    context.getService(reference).asInstanceOf[T]
+
   /**
    * Shuts down the ActorSystem when the bundle is stopped and, if necessary, unregisters a service registration.
    *

akka-osgi/src/main/scala/akka/osgi/DefaultOSGiLogger.scala

@@ -0,0 +1,83 @@
+/**
+ * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.osgi
+
+import akka.event.Logging
+import org.osgi.service.log.LogService
+import akka.event.Logging.{ DefaultLogger, LogEvent }
+import akka.event.Logging.Error.NoCause
+
+/**
+ * EventHandler for OSGi environment.
+ * Stands for an interface between akka and the OSGi LogService
+ * It uses the OSGi LogService to log the received LogEvents
+ */
+class DefaultOSGiLogger extends DefaultLogger {
+
+  val messageFormat = " %s | %s | %s | %s"
+
+  override def receive: Receive = uninitialisedReceive orElse super.receive
+
+  /**
+   * Behaviour of the EventHandler that waits for its LogService
+   * @return  Receive: Store LogEvent or become initialised
+   */
+  def uninitialisedReceive: Receive = {
+    var messagesToLog: Vector[LogEvent] = Vector()
+    //the Default Logger needs to be aware of the LogService which is published on the EventStream
+    context.system.eventStream.subscribe(self, classOf[LogService])
+    context.system.eventStream.unsubscribe(self, UnregisteringLogService.getClass)
+    /**
+     * Logs every already received LogEvent and set the EventHandler ready to log every incoming LogEvent.
+     *
+     * @param logService OSGi LogService that has been registered,
+     */
+    def setLogService(logService: LogService) {
+      messagesToLog.foreach(x ⇒ {
+        logMessage(logService, x)
+      })
+      context.become(initialisedReceive(logService))
+    }
+
+    {
+      case logService: LogService ⇒ setLogService(logService)
+      case logEvent: LogEvent     ⇒ messagesToLog :+= logEvent
+    }
+  }
+
+  /**
+   * Behaviour of the Eventhanlder that is setup (has received a LogService)
+   * @param logService registrered OSGi LogService
+   * @return Receive : Logs LogEvent or go back to the uninitialised state
+   */
+  def initialisedReceive(logService: LogService): Receive = {
+    context.system.eventStream.subscribe(self, UnregisteringLogService.getClass)
+    context.system.eventStream.unsubscribe(self, classOf[LogService])
+
+    {
+      case logEvent: LogEvent      ⇒ logMessage(logService, logEvent)
+      case UnregisteringLogService ⇒ context.become(uninitialisedReceive)
+    }
+  }
+
+  /**
+   * Logs a message in an OSGi LogService
+   *
+   * @param logService  OSGi LogService registered and used for logging
+   * @param event akka LogEvent that is log unsing the LogService
+   */
+  def logMessage(logService: LogService, event: LogEvent) {
+    event match {
+      case error: Logging.Error if error.cause != NoCause ⇒ logService.log(event.level.asInt, messageFormat.format(timestamp, event.thread.getName, event.logSource, event.message), error.cause)
+      case _ ⇒ logService.log(event.level.asInt, messageFormat.format(timestamp, event.thread.getName, event.logSource, event.message))
+    }
+  }
+
+}
+
+/**
+ * Message sent when LogService is unregistred.
+ * Sent from the ActorSystemActivator to an EventHandler (as DefaultOsgiLogger).
+ */
+case object UnregisteringLogService

akka-osgi/src/main/scala/akka/osgi/impl/DefaultOSGiLogger.scala

@@ -1,45 +0,0 @@
-/**
- *  Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
- */
-package akka.osgi.impl
-
-import akka.event.Logging.{ LogEvent, DefaultLogger }
-import org.osgi.service.log.LogService
-import akka.event.Logging
-import collection.mutable.Buffer
-
-/**
- * EventHandler for OSGi environment.
- * Stands for an interface between akka and the OSGi LogService
- * It uses the OSGi LogService to log the received LogEvents
- */
-class DefaultOSGiLogger extends DefaultLogger {
-
-  //the Default Logger needs to be aware of the LogService which is published on the EventStream
-  context.system.eventStream.subscribe(self, classOf[LogService])
-
-  val messageFormat = "[%s] %s"
-
-  var messagesToLog: Vector[LogEvent] = Vector()
-
-  override def receive: Receive = {
-    //register the log service to use
-    case logService: LogService ⇒ setLogService(logService)
-    case logEvent: LogEvent     ⇒ messagesToLog = messagesToLog :+ logEvent
-  }
-
-  def setLogService(logService: LogService) {
-      messagesToLog.foreach(logMessage(logService, _))
-      context.become(receiveEvent(logService))
-  }
-
-  def receiveEvent(logService: LogService): Receive = { case logEvent: LogEvent ⇒ logMessage(logService, logEvent) }
-
-  def logMessage(logService: LogService, event: LogEvent) {
-    event match {
-      case error: Logging.Error ⇒ logService.log(event.level.asInt, Logging.stackTraceFor(error.cause))
-      case _ =>  logService.log(event.level.asInt, messageFormat.format(event.logSource, event.message))
-    }
-  }
-
-}