From 15208dd0254875bef8b6ad1edd6adc77bf419a53 Mon Sep 17 00:00:00 2001
From: Lewuathe <lewuathe@me.com>
Date: Fri, 19 Aug 2016 15:37:03 +0900
Subject: [PATCH] Build EagerSingleton just after Session instantiation

---
 .../src/main/scala/wvlet/inject/Inject.scala  |  4 +++-
 .../main/scala/wvlet/inject/SessionImpl.scala | 15 +++++++++------
 .../test/scala/wvlet/inject/InjectTest.scala  | 19 ++++++++++++++++++-
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/wvlet-inject/src/main/scala/wvlet/inject/Inject.scala b/wvlet-inject/src/main/scala/wvlet/inject/Inject.scala
index 8f5ed979..ef9c7bef 100644
--- a/wvlet-inject/src/main/scala/wvlet/inject/Inject.scala
+++ b/wvlet-inject/src/main/scala/wvlet/inject/Inject.scala
@@ -121,7 +121,9 @@ class Inject extends LogSupport {
     }
     val keyIndex : Map[ObjectType, Int] = originalBindings.map(_.from).zipWithIndex.map(x => x._1 -> x._2).toMap
     val sortedBindings = effectiveBindings.toSeq.sortBy(x => keyIndex(x.from))
-    new SessionImpl(sortedBindings, listener.result())
+    val s = new SessionImpl(sortedBindings, listener.result())
+    s.init()
+    s
   }
 
   def addBinding(b: Binding): Inject = {
diff --git a/wvlet-inject/src/main/scala/wvlet/inject/SessionImpl.scala b/wvlet-inject/src/main/scala/wvlet/inject/SessionImpl.scala
index 78075a3c..92996ac8 100644
--- a/wvlet-inject/src/main/scala/wvlet/inject/SessionImpl.scala
+++ b/wvlet-inject/src/main/scala/wvlet/inject/SessionImpl.scala
@@ -33,12 +33,14 @@ private[inject] class SessionImpl(binding: Seq[Binding], listener: Seq[SessionLi
 
   private lazy val singletonHolder: collection.mutable.Map[ObjectType, Any] = new ConcurrentHashMap[ObjectType, Any]()
 
-  // Initialize eager singleton
-  binding.collect {
-    case s@SingletonBinding(from, to, eager) if eager =>
-      singletonHolder.getOrElseUpdate(to, buildInstance(to, Set(to)))
-    case InstanceBinding(from, obj) =>
-      registerInjectee(from, obj)
+  private[inject] def init() = {
+    // Initialize eager singleton
+    binding.collect {
+      case s@SingletonBinding(from, to, eager) if eager =>
+        singletonHolder.getOrElseUpdate(to, buildInstance(to, Set(to)))
+      case InstanceBinding(from, obj) =>
+        registerInjectee(from, obj)
+    }
   }
 
   def get[A](implicit ev: ru.WeakTypeTag[A]): A = {
@@ -89,6 +91,7 @@ private[inject] class SessionImpl(binding: Seq[Binding], listener: Seq[SessionLi
           newInstance(p.valueType, seen)
         }
         trace(s"Build a new instance for ${t}")
+        // Add TODO: enable injecting Session to concrete classes
         val obj = schema.constructor.newInstance(args)
         registerInjectee(t, obj)
       case None =>
diff --git a/wvlet-inject/src/test/scala/wvlet/inject/InjectTest.scala b/wvlet-inject/src/test/scala/wvlet/inject/InjectTest.scala
index e4981f6d..904c53cd 100644
--- a/wvlet-inject/src/test/scala/wvlet/inject/InjectTest.scala
+++ b/wvlet-inject/src/test/scala/wvlet/inject/InjectTest.scala
@@ -16,7 +16,7 @@ package wvlet.inject
 import java.io.PrintStream
 import java.util.concurrent.atomic.AtomicInteger
 
-import wvlet.log.LogSupport
+import wvlet.log.{LogLevel, LogSupport}
 import wvlet.obj.ObjectType
 import wvlet.obj.tag.@@
 import wvlet.test.WvletSpec
@@ -131,6 +131,12 @@ object ServiceMixinExample {
     val initializedTime = System.nanoTime()
   }
 
+  trait EagerSingletonWithInject extends LogSupport {
+    info("initialized")
+    val heavy = inject[HeavyObject]
+    val initializedTime = System.nanoTime()
+  }
+
   class ClassWithContext(val c: Session) extends FortunePrinterMixin with LogSupport {
     //info(s"context ${c}") // we should access context since Scala will remove private field, which is never used
   }
@@ -217,6 +223,17 @@ class InjectTest extends WvletSpec {
       s.initializedTime should be < current
     }
 
+    "create single with inject eagerly" in {
+      val start = System.nanoTime()
+      val h = new Inject
+      h.bind[EagerSingletonWithInject].toEagerSingleton
+      val c = h.newSession
+      val current = System.nanoTime()
+      val s = c.get[EagerSingletonWithInject]
+
+      s.initializedTime should be > start
+      s.initializedTime should be < current
+    }
 
     "found cyclic dependencies" in {
       val c = new Inject().newSession