Merge pull request #236 from jboner/wip-1702-settings-ext-patriknw

DOC: Extension sample for application specific settings. See #1702

akka-docs/scala/code/akka/docs/extension/ExtensionDocSpec.scala

@@ -3,16 +3,13 @@
  */
 package akka.docs.extension
 
-import org.scalatest.WordSpec
-import org.scalatest.matchers.MustMatchers
-
-//#imports
-import akka.actor._
 import java.util.concurrent.atomic.AtomicLong
-
-//#imports
+import akka.actor.Actor
+import akka.testkit.AkkaSpec
 
 //#extension
+import akka.actor.Extension
+
 class CountExtensionImpl extends Extension {
   //Since this Extension is a shared instance
   // per ActorSystem we need to be threadsafe
@@ -24,6 +21,10 @@ class CountExtensionImpl extends Extension {
 //#extension
 
 //#extensionid
+import akka.actor.ExtensionId
+import akka.actor.ExtensionIdProvider
+import akka.actor.ActorSystemImpl
+
 object CountExtension
   extends ExtensionId[CountExtensionImpl]
   with ExtensionIdProvider {
@@ -39,39 +40,37 @@ object CountExtension
 }
 //#extensionid
 
-//#extension-usage-actor
-import akka.actor.Actor
+object ExtensionDocSpec {
+  //#extension-usage-actor
 
-class MyActor extends Actor {
-  def receive = {
-    case someMessage ⇒
-      CountExtension(context.system).increment()
-  }
-}
-//#extension-usage-actor
-
-//#extension-usage-actor-trait
-import akka.actor.Actor
-
-trait Counting { self: Actor ⇒
-  def increment() = CountExtension(context.system).increment()
-}
-class MyCounterActor extends Actor with Counting {
-  def receive = {
-    case someMessage ⇒ increment()
-  }
-}
-//#extension-usage-actor-trait
-
-class ExtensionDocSpec extends WordSpec with MustMatchers {
-
-  "demonstrate how to create an extension in Scala" in {
-    val system: ActorSystem = null
-    intercept[Exception] {
-      //#extension-usage
-      CountExtension(system).increment
-      //#extension-usage
+  class MyActor extends Actor {
+    def receive = {
+      case someMessage ⇒
+        CountExtension(context.system).increment()
     }
   }
+  //#extension-usage-actor
+
+  //#extension-usage-actor-trait
+
+  trait Counting { self: Actor ⇒
+    def increment() = CountExtension(context.system).increment()
+  }
+  class MyCounterActor extends Actor with Counting {
+    def receive = {
+      case someMessage ⇒ increment()
+    }
+  }
+  //#extension-usage-actor-trait
+}
+
+class ExtensionDocSpec extends AkkaSpec {
+  import ExtensionDocSpec._
+
+  "demonstrate how to create an extension in Scala" in {
+    //#extension-usage
+    CountExtension(system).increment
+    //#extension-usage
+  }
 
 }

akka-docs/scala/code/akka/docs/extension/SettingsExtensionDocSpec.scala

@@ -0,0 +1,78 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.docs.extension
+
+//#imports
+import akka.actor.Extension
+import akka.actor.ExtensionId
+import akka.actor.ExtensionIdProvider
+import akka.actor.ActorSystemImpl
+import akka.util.Duration
+import com.typesafe.config.Config
+import java.util.concurrent.TimeUnit
+
+//#imports
+
+import akka.actor.Actor
+import akka.testkit.AkkaSpec
+
+//#extension
+class SettingsImpl(config: Config) extends Extension {
+  val DbUri: String = config.getString("myapp.db.uri")
+  val CircuitBreakerTimeout: Duration = Duration(config.getMilliseconds("myapp.circuit-breaker.timeout"), TimeUnit.MILLISECONDS)
+}
+//#extension
+
+//#extensionid
+object Settings extends ExtensionId[SettingsImpl] with ExtensionIdProvider {
+
+  override def lookup = Settings
+
+  override def createExtension(system: ActorSystemImpl) = new SettingsImpl(system.settings.config)
+}
+//#extensionid
+
+object SettingsExtensionDocSpec {
+
+  val config = """
+    //#config
+    myapp {
+      db {
+        uri = "mongodb://example1.com:27017,example2.com:27017"
+      }
+      circuit-breaker {
+        timeout = 30 seconds
+      }
+    }
+    //#config
+    """
+
+  //#extension-usage-actor
+
+  class MyActor extends Actor {
+    val settings = Settings(context.system)
+    val connection = connect(settings.DbUri, settings.CircuitBreakerTimeout)
+
+    //#extension-usage-actor
+    def receive = {
+      case someMessage ⇒
+    }
+
+    def connect(dbUri: String, circuitBreakerTimeout: Duration) = {
+      "dummy"
+    }
+  }
+
+}
+
+class SettingsExtensionDocSpec extends AkkaSpec(SettingsExtensionDocSpec.config) {
+
+  "demonstrate how to create application specific settings extension in Scala" in {
+    //#extension-usage
+    val dbUri = Settings(system).DbUri
+    val circuitBreakerTimeout = Settings(system).CircuitBreakerTimeout
+    //#extension-usage
+  }
+
+}

akka-docs/scala/extending-akka.rst

@@ -1,7 +1,9 @@
 .. _extending-akka-scala:
 
-Akka Extensions
-===============
+#########################
+ Akka Extensions (Scala)
+#########################
+
 
 .. sidebar:: Contents
 
@@ -9,19 +11,19 @@ Akka Extensions
 
 
 Building an Extension
----------------------
+=====================
 
 So let's create a sample extension that just lets us count the number of times something has happened.
 
 First, we define what our ``Extension`` should do:
 
 .. includecode:: code/akka/docs/extension/ExtensionDocSpec.scala
-   :include: imports,extension
+   :include: extension
 
 Then we need to create an ``ExtensionId`` for our extension so we can grab ahold of it.
 
 .. includecode:: code/akka/docs/extension/ExtensionDocSpec.scala
-   :include: imports,extensionid 
+   :include: extensionid
 
 Wicked! Now all we need to do is to actually use it:
 
@@ -41,13 +43,37 @@ You can also hide extension behind traits:
 That's all there is to it!
 
 Loading from Configuration
---------------------------
+==========================
 
 To be able to load extensions from your Akka configuration you must add FQCNs of implementations of either ``ExtensionId`` or ``ExtensionIdProvider``
-in the "akka.extensions" section of the config you provide to your ``ActorSystem``.
+in the ``akka.extensions`` section of the config you provide to your ``ActorSystem``.
 
 Applicability
--------------
+=============
 
 The sky is the limit!
 By the way, did you know that Akka's ``Typed Actors``, ``Serialization`` and other features are implemented as Akka Extensions?
+
+.. _extending-akka-scala.settings:
+
+Application specific settings
+-----------------------------
+
+The :ref:`configuration` can be used for application specific settings. A good practice is to place those settings in an Extension.
+
+Sample configuration:
+
+.. includecode:: code/akka/docs/extension/SettingsExtensionDocSpec.scala
+   :include: config
+
+The ``Extension``:
+
+.. includecode:: code/akka/docs/extension/SettingsExtensionDocSpec.scala
+   :include: imports,extension,extensionid
+
+
+Use it:
+
+.. includecode:: code/akka/docs/extension/SettingsExtensionDocSpec.scala
+   :include: extension-usage-actor
+

akka-docs/scala/testing.rst

@@ -1,8 +1,8 @@
 .. _akka-testkit:
 
-#####################
-Testing Actor Systems
-#####################
+##############################
+Testing Actor Systems (Scala)
+##############################
 
 .. toctree::
 

akka-docs/scala/testkit-example.rst

@@ -1,8 +1,8 @@
 .. _testkit-example:
 
-###############
-TestKit Example
-###############
+########################
+TestKit Example (Scala)
+########################
 
 Ray Roestenburg's example code from `his blog <http://roestenburg.agilesquad.com/2011/02/unit-testing-akka-actors-with-testkit_12.html>`_ adapted to work with Akka 1.1.