Made Agent an abstract class, pushed existing implementation into a private SecretAgent class and added a java-lovin' factory method. See #3108

akka-agent/src/main/scala/akka/agent/Agent.scala

@@ -8,11 +8,83 @@ import scala.concurrent.stm._
 import scala.concurrent.{ ExecutionContext, Future, Promise }
 import akka.util.{ SerializedSuspendableExecutionContext }
 
-/**
- * Factory method for creating an Agent.
- */
 object Agent {
-  def apply[T](initialValue: T)(implicit context: ExecutionContext) = new Agent(initialValue, context)
+  /**
+   * Factory method for creating an Agent.
+   */
+  def apply[T](initialValue: T)(implicit context: ExecutionContext): Agent[T] = new SecretAgent(initialValue, context)
+
+  /**
+   *  Factory method for Java Iterop.
+   */
+  def create[T](initialValue: T, context: ExecutionContext): Agent[T] = Agent(initialValue)(context)
+
+  /**
+   * Default agent implementation.
+   */
+  private class SecretAgent[T](initialValue: T, context: ExecutionContext) extends Agent[T] {
+    private val ref = Ref(initialValue)
+    private val updater = SerializedSuspendableExecutionContext(10)(context)
+
+    def get(): T = ref.single.get
+
+    def send(newValue: T): Unit = withinTransaction(new Runnable { def run = ref.single.update(newValue) })
+
+    def send(f: T ⇒ T): Unit = withinTransaction(new Runnable { def run = ref.single.transform(f) })
+
+    def sendOff(f: T ⇒ T)(implicit ec: ExecutionContext): Unit = withinTransaction(
+      new Runnable {
+        def run =
+          try updater.suspend() finally ec.execute(new Runnable { def run = try ref.single.transform(f) finally updater.resume() })
+      })
+
+    def alter(newValue: T): Future[T] = doAlter({ ref.single.update(newValue); newValue })
+
+    def alter(f: T ⇒ T): Future[T] = doAlter(ref.single.transformAndGet(f))
+
+    def alterOff(f: T ⇒ T)(implicit ec: ExecutionContext): Future[T] = {
+      val result = Promise[T]()
+      withinTransaction(new Runnable {
+        def run = {
+          updater.suspend()
+          result completeWith Future(try ref.single.transformAndGet(f) finally updater.resume())
+        }
+      })
+      result.future
+    }
+
+    /**
+     * Internal helper method
+     */
+    private final def withinTransaction(run: Runnable): Unit = {
+      def dispatch = updater.execute(run)
+      Txn.findCurrent match {
+        case Some(txn) ⇒ Txn.afterCommit(status ⇒ dispatch)(txn)
+        case _         ⇒ dispatch
+      }
+    }
+
+    /**
+     * Internal helper method
+     */
+    private final def doAlter(f: ⇒ T): Future[T] = {
+      Txn.findCurrent match {
+        case Some(txn) ⇒
+          val result = Promise[T]()
+          Txn.afterCommit(status ⇒ result completeWith Future(f)(updater))(txn)
+          result.future
+        case _ ⇒ Future(f)(updater)
+      }
+    }
+
+    def future(): Future[T] = Future(ref.single.get)(updater)
+
+    def map[B](f: T ⇒ B): Agent[B] = Agent(f(get))(updater)
+
+    def flatMap[B](f: T ⇒ Agent[B]): Agent[B] = f(get)
+
+    def foreach[U](f: T ⇒ U): Unit = f(get)
+  }
 }
 
 /**
@@ -85,15 +157,13 @@ object Agent {
  * agent4.close
  * }}}
  */
-class Agent[T](initialValue: T, context: ExecutionContext) {
+abstract class Agent[T] {
-  private val ref = Ref(initialValue)
-  private val updater = SerializedSuspendableExecutionContext(10)(context)
 
   /**
    * Read the internal state of the agent.
    * Java API
    */
-  def get(): T = ref.single.get
+  def get(): T
 
   /**
    * Read the internal state of the agent.
@@ -104,13 +174,13 @@ class Agent[T](initialValue: T, context: ExecutionContext) {
    * Dispatch a new value for the internal state. Behaves the same
    * as sending a function (x => newValue).
    */
-  def send(newValue: T): Unit = withinTransaction(new Runnable { def run = ref.single.update(newValue) })
+  def send(newValue: T): Unit
 
   /**
    * Dispatch a function to update the internal state.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def send(f: T ⇒ T): Unit = withinTransaction(new Runnable { def run = ref.single.transform(f) })
+  def send(f: T ⇒ T): Unit
 
   /**
    * Dispatch a function to update the internal state but on its own thread.
@@ -119,25 +189,21 @@ class Agent[T](initialValue: T, context: ExecutionContext) {
    * still be executed in order.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def sendOff(f: T ⇒ T)(implicit ec: ExecutionContext): Unit = withinTransaction(
+  def sendOff(f: T ⇒ T)(implicit ec: ExecutionContext): Unit
-    new Runnable {
-      def run =
-        try updater.suspend() finally ec.execute(new Runnable { def run = try ref.single.transform(f) finally updater.resume() })
-    })
 
   /**
    * Dispatch an update to the internal state, and return a Future where
    * that new state can be obtained.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def alter(newValue: T): Future[T] = doAlter({ ref.single.update(newValue); newValue })
+  def alter(newValue: T): Future[T]
 
   /**
    * Dispatch a function to update the internal state, and return a Future where
    * that new state can be obtained.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def alter(f: T ⇒ T): Future[T] = doAlter(ref.single.transformAndGet(f))
+  def alter(f: T ⇒ T): Future[T]
 
   /**
    * Dispatch a function to update the internal state but on its own thread,
@@ -147,58 +213,31 @@ class Agent[T](initialValue: T, context: ExecutionContext) {
    * still be executed in order.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def alterOff(f: T ⇒ T)(implicit ec: ExecutionContext): Future[T] = {
+  def alterOff(f: T ⇒ T)(implicit ec: ExecutionContext): Future[T]
-    val result = Promise[T]()
-    withinTransaction(new Runnable {
-      def run = {
-        updater.suspend()
-        result completeWith Future(try ref.single.transformAndGet(f) finally updater.resume())
-      }
-    })
-    result.future
-  }
-
-  private final def withinTransaction(run: Runnable): Unit = {
-    def dispatch = updater.execute(run)
-    Txn.findCurrent match {
-      case Some(txn) ⇒ Txn.afterCommit(status ⇒ dispatch)(txn)
-      case _         ⇒ dispatch
-    }
-  }
-
-  private final def doAlter(f: ⇒ T): Future[T] = {
-    Txn.findCurrent match {
-      case Some(txn) ⇒
-        val result = Promise[T]()
-        Txn.afterCommit(status ⇒ result completeWith Future(f)(updater))(txn)
-        result.future
-      case _ ⇒ Future(f)(updater)
-    }
-  }
 
   /**
    * A future to the current value that will be completed after any currently
    * queued updates.
    */
-  def future(): Future[T] = Future(ref.single.get)(updater)
+  def future(): Future[T]
 
   /**
    * Map this agent to a new agent, applying the function to the internal state.
    * Does not change the value of this agent.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def map[B](f: T ⇒ B): Agent[B] = Agent(f(get))(updater)
+  def map[B](f: T ⇒ B): Agent[B]
 
   /**
    * Flatmap this agent to a new agent, applying the function to the internal state.
    * Does not change the value of this agent.
    * In Java, pass in an instance of `akka.dispatch.Mapper`.
    */
-  def flatMap[B](f: T ⇒ Agent[B]): Agent[B] = f(get)
+  def flatMap[B](f: T ⇒ Agent[B]): Agent[B]
 
   /**
    * Applies the function to the internal state. Does not change the value of this agent.
    * In Java, pass in an instance of `akka.dispatch.Foreach`.
    */
-  def foreach[U](f: T ⇒ U): Unit = f(get)
+  def foreach[U](f: T ⇒ U): Unit
 }

akka-docs/rst/java/code/docs/agent/AgentDocTest.java

@@ -35,7 +35,7 @@ public class AgentDocTest {
   public void createAndRead() throws Exception {
     //#create
     ExecutionContext ec = ExecutionContexts.global();
-    Agent<Integer> agent = new Agent<Integer>(5, ec);
+    Agent<Integer> agent = Agent.create(5, ec);
     //#create
 
     //#read-get
@@ -52,7 +52,7 @@ public class AgentDocTest {
 
   @Test
   public void sendAndSendOffAndReadAwait() throws Exception {
-    Agent<Integer> agent = new Agent<Integer>(5, ec);
+    Agent<Integer> agent = Agent.create(5, ec);
 
     //#send
     // send a value, enqueues this change
@@ -86,7 +86,7 @@ public class AgentDocTest {
 
     @Test
     public void alterAndAlterOff() throws Exception {
-    Agent<Integer> agent = new Agent<Integer>(5, ec);
+    Agent<Integer> agent = Agent.create(5, ec);
 
     //#alter
     // alter a value