support adding modules after actor system is created #32

Author: jw3

src/main/scala/com/github/jw3/di/InjectExt.scala

@@ -17,41 +17,50 @@ import scala.collection.mutable
  *
  * @param injector top level Guice Injector
  */
-class InjectExtImpl(val injector: Injector) extends Extension
-
-object InjectExt extends ExtensionId[InjectExtImpl] with ExtensionIdProvider with InjectExtBuilder {
+class InjectExtImpl(modules: Seq[Module]) extends Extension with InjectExtBuilder {
   private val manualModules: ThreadLocal[mutable.Set[Module]] = ThreadLocal.withInitial(
     new java.util.function.Supplier[mutable.Set[Module]] {
       override def get(): mutable.Set[Module] = mutable.Set[Module]()
-  })
+    }
+  )
+  private var acceptingModules: Boolean = true
 
   /**
-   * Manually add modules to the injector
-   * All modules must be added prior to creating the ActorSystem
-   */
-  def addModules(m: Module*): InjectExtBuilder = {
+    * Manually add modules to the injector
+    * All modules must be added prior to creating the ActorSystem
+    */
+  def addModules(m: Module*): InjectExtImpl = {
+    if(!acceptingModules) throw new UnsupportedOperationException("injector was already initialized")
     manualModules.set(manualModules.get() ++ m)
     this
   }
 
+  lazy val injector: Injector = {
+    acceptingModules = false
+    try Guice.createInjector(modules ++ manualModules.get: _*)
+    finally manualModules.remove()
+  }
+}
+
+object InjectExt extends ExtensionId[InjectExtImpl] with ExtensionIdProvider {
+
   // internals \\
 
   override def createExtension(sys: ExtendedActorSystem) = {
     import InjectExtBuilder._
 
     val config = sys.settings.config
     val modules = config.getAs[String](ModuleDiscoveryModeKey).getOrElse(DefaultModuleDiscoveryModeMode) match {
-      case ManualModuleDiscovery => manualModules.get().toList
+      case ManualModuleDiscovery => List()
       case CfgModuleDiscovery => config.getAs[Seq[String]](CfgModuleDiscoveryKey).map(_.map(strToModule)).getOrElse(Seq()).toList
       case SpiModuleDiscovery => ServiceLoader.load(classOf[Module]).iterator.asScala.toList
       case v => throw new IllegalArgumentException(s"invalid $ModuleDiscoveryModeKey value, $v")
     }
-    manualModules.remove()
 
     val finalModules = addCfgModule(config) :: modules
     val defaultModules = Seq(Defaults.actorSystem(sys))
-    val injector = Guice.createInjector(finalModules ++ defaultModules: _*)
-    new InjectExtImpl(injector)
+
+    new InjectExtImpl(finalModules ++ defaultModules)
   }
 
   override def lookup() = InjectExt
@@ -69,7 +78,7 @@ object InjectExt extends ExtensionId[InjectExtImpl] with ExtensionIdProvider wit
  * Defines the module adding interface on the InjectExt
  */
 trait InjectExtBuilder {
-  this: ExtensionId[_] =>
+  this: Extension =>
   def addModules(m: Module*): InjectExtBuilder
 }
 

src/test/scala/com/github/jw3/di/LazyManualConfigSpec.scala

@@ -0,0 +1,50 @@
+package com.github.jw3.di
+
+import akka.actor.ActorSystem
+import akka.testkit.TestKit
+import net.codingwell.scalaguice.ScalaModule
+import org.scalatest.{Matchers, WordSpecLike}
+
+// issue #32
+class LazyManualConfigSpec
+    extends TestKit(ActorSystem("lazy"))
+    with WordSpecLike
+    with Matchers {
+
+  "late modules" should {
+    "be accepted" in {
+      InjectExt(system).addModules(LateModule1)
+      InjectExt(system).addModules(LateModule2)
+    }
+
+    "be injected" in {
+      val foo: String = inject[String] annotated "foo"
+      foo shouldBe "bar"
+
+      val baz: String = inject[String] annotated "baz"
+      baz shouldBe "bash"
+    }
+
+    "be rejected once inited" in {
+      intercept[UnsupportedOperationException] {
+        InjectExt(system).addModules(LateModule3)
+      }
+    }
+  }
+}
+
+object LateModule1 extends ScalaModule {
+  override def configure(): Unit = {
+    bind[String].annotatedWithName("foo").toInstance("bar")
+  }
+}
+
+object LateModule2 extends ScalaModule {
+  override def configure(): Unit = {
+    bind[String].annotatedWithName("baz").toInstance("bash")
+  }
+}
+
+object LateModule3 extends ScalaModule {
+  override def configure(): Unit = ()
+}

src/test/scala/com/github/jw3/di/test/InjectSpec.scala

@@ -22,8 +22,9 @@ trait InjectSpec extends WordSpecLike {
    */
   def injectTest(name: String, mods: => Seq[Module] = Seq(), cfg: Option[Config] = None)(test: ActorSystem => Unit): Unit = {
     registerTest(name) {
-      InjectExt.addModules(mods: _*)
       val sys = ActorSystem(s"${name.replaceAll( """\W""", "_")}", cfg)
+      InjectExt(sys).addModules(mods: _*)
+
       try test(sys)
       finally {Await.ready(sys.terminate(), Duration.create("10s"))}
     }