From 6288a7c82f4634a15005596e78ec9e8f188697ee Mon Sep 17 00:00:00 2001
From: Patrik Nordwall <patrik.nordwall@gmail.com>
Date: Mon, 21 Mar 2016 11:00:59 +0100
Subject: [PATCH] avoid NPE in recoveryRunning, #19177

* recoveryRunning = true when called from constructor
* better exceptions if some things are used to early in FSM
  and persistent FSM
---
 akka-actor/src/main/scala/akka/actor/FSM.scala      | 13 ++++++++++---
 .../main/scala/akka/persistence/Eventsourced.scala  |  5 ++++-
 .../akka/persistence/fsm/PersistentFSMBase.scala    | 12 +++++++++---
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/akka-actor/src/main/scala/akka/actor/FSM.scala b/akka-actor/src/main/scala/akka/actor/FSM.scala
index ddab81883c..bb0c35145e 100644
--- a/akka-actor/src/main/scala/akka/actor/FSM.scala
+++ b/akka-actor/src/main/scala/akka/actor/FSM.scala
@@ -515,17 +515,24 @@ trait FSM[S, D] extends Actor with Listeners with ActorLogging {
    *
    * @see [[#startWith]]
    */
-  final def initialize(): Unit = makeTransition(currentState)
+  final def initialize(): Unit =
+    if (currentState != null) makeTransition(currentState)
+    else throw new IllegalStateException("You must call `startWith` before calling `initialize`")
 
   /**
    * Return current state name (i.e. object of type S)
    */
-  final def stateName: S = currentState.stateName
+  final def stateName: S = {
+    if (currentState != null) currentState.stateName
+    else throw new IllegalStateException("You must call `startWith` before using `stateName`")
+  }
 
   /**
    * Return current state data (i.e. object of type D)
    */
-  final def stateData: D = currentState.stateData
+  final def stateData: D =
+    if (currentState != null) currentState.stateData
+    else throw new IllegalStateException("You must call `startWith` before using `stateData`")
 
   /**
    * Return next state data (available in onTransition handlers)
diff --git a/akka-persistence/src/main/scala/akka/persistence/Eventsourced.scala b/akka-persistence/src/main/scala/akka/persistence/Eventsourced.scala
index 1ef1ed4b54..72c0067e14 100644
--- a/akka-persistence/src/main/scala/akka/persistence/Eventsourced.scala
+++ b/akka-persistence/src/main/scala/akka/persistence/Eventsourced.scala
@@ -427,7 +427,10 @@ private[persistence] trait Eventsourced extends Snapshotter with PersistenceStas
   /**
    * Returns `true` if this persistent actor is currently recovering.
    */
-  def recoveryRunning: Boolean = currentState.recoveryRunning
+  def recoveryRunning: Boolean = {
+    // currentState is null if this is called from constructor
+    if (currentState == null) true else currentState.recoveryRunning
+  }
 
   /**
    * Returns `true` if this persistent actor has successfully finished recovery.
diff --git a/akka-persistence/src/main/scala/akka/persistence/fsm/PersistentFSMBase.scala b/akka-persistence/src/main/scala/akka/persistence/fsm/PersistentFSMBase.scala
index b4a671d307..72734be987 100644
--- a/akka-persistence/src/main/scala/akka/persistence/fsm/PersistentFSMBase.scala
+++ b/akka-persistence/src/main/scala/akka/persistence/fsm/PersistentFSMBase.scala
@@ -309,17 +309,23 @@ trait PersistentFSMBase[S, D, E] extends Actor with Listeners with ActorLogging
    *
    * @see [[#startWith]]
    */
-  final def initialize(): Unit = makeTransition(currentState)
+  final def initialize(): Unit =
+    if (currentState != null) makeTransition(currentState)
+    else throw new IllegalStateException("You must call `startWith` before calling `initialize`")
 
   /**
    * Return current state name (i.e. object of type S)
    */
-  final def stateName: S = currentState.stateName
+  final def stateName: S =
+    if (currentState != null) currentState.stateName
+    else throw new IllegalStateException("You must call `startWith` before using `stateName`")
 
   /**
    * Return current state data (i.e. object of type D)
    */
-  final def stateData: D = currentState.stateData
+  final def stateData: D =
+    if (currentState != null) currentState.stateData
+    else throw new IllegalStateException("You must call `startWith` before using `stateData`")
 
   /**
    * Return all defined state names