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

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

akka-actor-tests/src/test/java/akka/actor/JavaExtension.java

@@ -16,15 +16,13 @@ import static org.junit.Assert.*;
 
 public class JavaExtension {
 
-  static class Provider implements ExtensionIdProvider {
+  static class TestExtensionId extends AbstractExtensionId<TestExtension> implements ExtensionIdProvider {
+    public final static TestExtensionId TestExtensionProvider = new TestExtensionId();
+
     public ExtensionId<TestExtension> lookup() {
-      return defaultInstance;
+      return TestExtensionId.TestExtensionProvider;
     }
-  }
 
-  public final static TestExtensionId defaultInstance = new TestExtensionId();
-
-  static class TestExtensionId extends AbstractExtensionId<TestExtension> {
     public TestExtension createExtension(ActorSystemImpl i) {
       return new TestExtension(i);
     }
@@ -39,9 +37,11 @@ public class JavaExtension {
   }
 
   static class OtherExtension implements Extension {
-    static final ExtensionKey<OtherExtension> key = new ExtensionKey<OtherExtension>(OtherExtension.class) {};
+    static final ExtensionKey<OtherExtension> key = new ExtensionKey<OtherExtension>(OtherExtension.class) {
+    };
 
     public final ActorSystemImpl system;
+
     public OtherExtension(ActorSystemImpl i) {
       system = i;
     }
@@ -51,8 +51,8 @@ public class JavaExtension {
 
   @BeforeClass
   public static void beforeAll() {
-    Config c = ConfigFactory.parseString("akka.extensions = [ \"akka.actor.JavaExtension$Provider\" ]").withFallback(
+    Config c = ConfigFactory.parseString("akka.extensions = [ \"akka.actor.JavaExtension$TestExtensionId\" ]")
-        AkkaSpec.testConf());
+        .withFallback(AkkaSpec.testConf());
     system = ActorSystem.create("JavaExtension", c);
   }
 
@@ -64,8 +64,8 @@ public class JavaExtension {
 
   @Test
   public void mustBeAccessible() {
-    assertSame(system.extension(defaultInstance).system, system);
+    assertSame(system.extension(TestExtensionId.TestExtensionProvider).system, system);
-    assertSame(defaultInstance.apply(system).system, system);
+    assertSame(TestExtensionId.TestExtensionProvider.apply(system).system, system);
   }
 
   @Test

akka-docs/general/configuration.rst

@@ -217,3 +217,12 @@ and parsed by the actor system can be displayed like this:
   println(system.settings());
   // this is a shortcut for system.settings().config().root().render()
 
+
+Application specific settings
+-----------------------------
+
+The configuration can also be used for application specific settings.
+A good practice is to place those settings in an Extension, as described in:
+
+ * Scala API: :ref:`extending-akka-scala.settings`
+ * Java API: :ref:`extending-akka-java.settings`

akka-docs/java/code/akka/docs/extension/ExtensionDocTestBase.java

@@ -9,63 +9,65 @@ import java.util.concurrent.atomic.AtomicLong;
 
 //#imports
 
-import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
-import static org.junit.Assert.*;
 
 public class ExtensionDocTestBase {
 
-    //#extension
+  //#extension
-    public static class CountExtensionImpl implements Extension {
+  public static class CountExtensionImpl implements Extension {
-      //Since this Extension is a shared instance
+    //Since this Extension is a shared instance
-      // per ActorSystem we need to be threadsafe
+    // per ActorSystem we need to be threadsafe
-      private final AtomicLong counter = new AtomicLong(0);
+    private final AtomicLong counter = new AtomicLong(0);
 
-      //This is the operation this Extension provides
+    //This is the operation this Extension provides
-      public long increment()  {
+    public long increment() {
-          return counter.incrementAndGet();
+      return counter.incrementAndGet();
-      }
     }
-    //#extension
+  }
 
-    //#extensionid
+  //#extension
-    static class CountExtensionId extends AbstractExtensionId<CountExtensionImpl> {
-        //This method will be called by Akka
-        // to instantiate our Extension
-        public CountExtensionImpl createExtension(ActorSystemImpl i) {
-          return new CountExtensionImpl();
-        }
-    }
 
+  //#extensionid
+  public static class CountExtension extends AbstractExtensionId<CountExtensionImpl> implements ExtensionIdProvider {
     //This will be the identifier of our CountExtension
-    public final static CountExtensionId CountExtension = new CountExtensionId();
+    public final static CountExtension CountExtensionProvider = new CountExtension();
-    //#extensionid
 
-    //#extensionid-provider
+    //The lookup method is required by ExtensionIdProvider,
-    static class CountExtensionIdProvider implements ExtensionIdProvider {
+    // so we return ourselves here, this allows us
-        public CountExtensionId lookup() {
+    // to configure our extension to be loaded when
-          return CountExtension; //The public static final
+    // the ActorSystem starts up
-        }
+    public CountExtension lookup() {
-      }
+      return CountExtension.CountExtensionProvider; //The public static final
-    //#extensionid-provider
-
-    //#extension-usage-actor
-    static class MyActor extends UntypedActor {
-      public void onReceive(Object msg) {
-        CountExtension.get(getContext().system()).increment();
-      }
     }
-    //#extension-usage-actor
 
+    //This method will be called by Akka
+    // to instantiate our Extension
+    public CountExtensionImpl createExtension(ActorSystemImpl system) {
+      return new CountExtensionImpl();
+    }
+  }
 
-  @Test public void demonstrateHowToCreateAndUseAnAkkaExtensionInJava() {
+  //#extensionid
+
+  //#extension-usage-actor
+  public static class MyActor extends UntypedActor {
+    public void onReceive(Object msg) {
+      // typically you would use static import of CountExtension.CountExtensionProvider field
+      CountExtension.CountExtensionProvider.get(getContext().system()).increment();
+    }
+  }
+
+  //#extension-usage-actor
+
+  @Test
+  public void demonstrateHowToCreateAndUseAnAkkaExtensionInJava() {
     final ActorSystem system = null;
     try {
       //#extension-usage
-      CountExtension.get(system).increment();
+      // typically you would use static import of CountExtension.CountExtensionProvider field
+      CountExtension.CountExtensionProvider.get(system).increment();
       //#extension-usage
-    } catch(Exception e) {
+    } catch (Exception e) {
       //do nothing
     }
   }

akka-docs/java/code/akka/docs/extension/SettingsExtensionDocTest.scala

@@ -0,0 +1,8 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.docs.extension
+
+import org.scalatest.junit.JUnitSuite
+
+class SettingsExtensionDocTest extends SettingsExtensionDocTestBase with JUnitSuite

akka-docs/java/code/akka/docs/extension/SettingsExtensionDocTestBase.java

@@ -0,0 +1,87 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.docs.extension;
+
+//#imports
+import akka.actor.Extension;
+import akka.actor.AbstractExtensionId;
+import akka.actor.ExtensionIdProvider;
+import akka.actor.ActorSystem;
+import akka.actor.ActorSystemImpl;
+import akka.util.Duration;
+import com.typesafe.config.Config;
+import java.util.concurrent.TimeUnit;
+
+//#imports
+
+import akka.actor.UntypedActor;
+import org.junit.Test;
+
+public class SettingsExtensionDocTestBase {
+
+  //#extension
+  public static class SettingsImpl implements Extension {
+
+    public final String DB_URI;
+    public final Duration CIRCUIT_BREAKER_TIMEOUT;
+
+    public SettingsImpl(Config config) {
+      DB_URI = config.getString(config.getString("myapp.db.uri"));
+      CIRCUIT_BREAKER_TIMEOUT = Duration.create(config.getMilliseconds("myapp.circuit-breaker.timeout"),
+          TimeUnit.MILLISECONDS);
+    }
+
+  }
+
+  //#extension
+
+  //#extensionid
+  public static class Settings extends AbstractExtensionId<SettingsImpl> implements ExtensionIdProvider {
+    public final static Settings SettingsProvider = new Settings();
+
+    public Settings lookup() {
+      return Settings.SettingsProvider;
+    }
+
+    public SettingsImpl createExtension(ActorSystemImpl system) {
+      return new SettingsImpl(system.settings().config());
+    }
+  }
+
+  //#extensionid
+
+  //#extension-usage-actor
+  public static class MyActor extends UntypedActor {
+    // typically you would use static import of CountExtension.CountExtensionProvider field
+    final SettingsImpl settings = Settings.SettingsProvider.get(getContext().system());
+    Connection connection = connect(settings.DB_URI, settings.CIRCUIT_BREAKER_TIMEOUT);
+
+    //#extension-usage-actor
+
+    public Connection connect(String dbUri, Duration circuitBreakerTimeout) {
+      return new Connection();
+    }
+
+    public void onReceive(Object msg) {
+    }
+
+  }
+
+  public static class Connection {
+  }
+
+  @Test
+  public void demonstrateHowToCreateAndUseAnAkkaExtensionInJava() {
+    final ActorSystem system = null;
+    try {
+      //#extension-usage
+      // typically you would use static import of CountExtension.CountExtensionProvider field
+      String dbUri = Settings.SettingsProvider.get(system).DB_URI;
+      //#extension-usage
+    } catch (Exception e) {
+      //do nothing
+    }
+  }
+
+}

akka-docs/java/extending-akka.rst

@@ -1,7 +1,8 @@
 .. _extending-akka-java:
 
-Akka Extensions
+########################
-===============
+ Akka Extensions (Java)
+########################
 
 .. sidebar:: Contents
 
@@ -21,7 +22,7 @@ Details on how to make that happens are below, in the "Loading from Configuratio
 
 
 Building an Extension
----------------------
+=====================
 
 So let's create a sample extension that just lets us count the number of times something has happened.
 
@@ -48,16 +49,37 @@ Or from inside of an Akka Actor:
 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``.
 
-.. includecode:: code/akka/docs/extension/ExtensionDocTestBase.java
-   :include: extensionid-provider
-
 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-java.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:: ../scala/code/akka/docs/extension/SettingsExtensionDocSpec.scala
+   :include: config
+
+The ``Extension``:
+
+.. includecode:: code/akka/docs/extension/SettingsExtensionDocTestBase.java
+   :include: imports,extension,extensionid
+
+
+Use it:
+
+.. includecode:: code/akka/docs/extension/SettingsExtensionDocTestBase.java
+   :include: extension-usage-actor
+

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
-
+import akka.actor.Actor
-//#imports
+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
+object ExtensionDocSpec {
-import akka.actor.Actor
+  //#extension-usage-actor
 
-class MyActor extends Actor {
+  class MyActor extends Actor {
-  def receive = {
+    def receive = {
-    case someMessage ⇒
+      case someMessage ⇒
-      CountExtension(context.system).increment()
+        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
     }
   }
+  //#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.