Merge pull request #17152 from ktoso/wip-forMaxOverride-FSM-ktoso

=act #17140 FSM: forMax(Inf) can now override stateTimeout

akka-actor-tests/src/test/scala/akka/actor/FSMActorSpec.scala

@@ -4,6 +4,8 @@
 
 package akka.actor
 
+import akka.actor.FSM.StateTimeout
+
 import language.postfixOps
 import org.scalatest.{ BeforeAndAfterAll, BeforeAndAfterEach }
 import akka.testkit._
@@ -340,6 +342,40 @@ class FSMActorSpec extends AkkaSpec(Map("akka.actor.debug.fsm" -> true)) with Im
       expectMsg(Transition(fsmref, 0, 1))
     }
 
+    "allow cancelling stateTimeout by issuing forMax(Duration.Inf)" in {
+      val sys = ActorSystem("fsmEvent")
+      val p = TestProbe()(sys)
+
+      val OverrideTimeoutToInf = "override-timeout-to-inf"
+
+      val fsm = sys.actorOf(Props(new Actor with FSM[String, String] {
+
+        startWith("init", "")
+
+        when("init", stateTimeout = 1.second) {
+          case Event(StateTimeout, _) ⇒
+            p.ref ! StateTimeout
+            stay()
+
+          case Event(OverrideTimeoutToInf, _) ⇒
+            p.ref ! OverrideTimeoutToInf
+            stay() forMax Duration.Inf
+        }
+
+        initialize()
+      }))
+
+      try {
+        p.expectMsg(FSM.StateTimeout)
+
+        fsm ! OverrideTimeoutToInf
+        p.expectMsg(OverrideTimeoutToInf)
+        p.expectNoMsg(3.seconds)
+      } finally {
+        TestKit.shutdownActorSystem(sys)
+      }
+    }
+
   }
 
 }

akka-actor/src/main/scala/akka/actor/FSM.scala

@@ -8,6 +8,7 @@ import scala.concurrent.duration.Duration
 import scala.collection.mutable
 import akka.routing.{ Deafen, Listen, Listeners }
 import scala.concurrent.duration.FiniteDuration
+import scala.concurrent.duration._
 
 object FSM {
 
@@ -118,6 +119,9 @@ object FSM {
    */
   final case class LogEntry[S, D](stateName: S, stateData: D, event: Any)
 
+  /** Used by `forMax` to signal "cancel stateTimeout" */
+  private final val SomeMaxFiniteDuration = Some(Long.MaxValue.nanos)
+
   /**
    * This captures all of the managed state of the [[akka.actor.FSM]]: the state
    * name, the state data, possibly custom timeout, stop reason and replies
@@ -141,8 +145,10 @@ object FSM {
      */
     def forMax(timeout: Duration): State[S, D] = timeout match {
       case f: FiniteDuration ⇒ copy(timeout = Some(f))
-      case _                 ⇒ copy(timeout = None)
-    }
+      case Duration.Inf      ⇒ copy(timeout = SomeMaxFiniteDuration) // we map the Infinite duration to a special marker,
+      case _                 ⇒ copy(timeout = None)                  // that means "cancel stateTimeout". This marker is needed
+    }                                                                // so we do not have to break source/binary compat.
+                                                                     // TODO: Can be removed once we can break State#timeout signature to `Option[Duration]`
 
     /**
      * Send reply to sender of the current message, if available.
@@ -648,13 +654,18 @@ trait FSM[S, D] extends Actor with Listeners with ActorLogging {
         this.nextState = null
       }
       currentState = nextState
-      val timeout = if (currentState.timeout.isDefined) currentState.timeout else stateTimeouts(currentState.stateName)
-      if (timeout.isDefined) {
-        val t = timeout.get
-        if (t.isFinite && t.length >= 0) {
-          import context.dispatcher
-          timeoutFuture = Some(context.system.scheduler.scheduleOnce(t, self, TimeoutMarker(generation)))
-        }
+
+      def scheduleTimeout(d: FiniteDuration): Some[Cancellable] = {
+        import context.dispatcher
+        Some(context.system.scheduler.scheduleOnce(d, self, TimeoutMarker(generation)))
+      }
+
+      currentState.timeout match {
+        case SomeMaxFiniteDuration                    ⇒ // effectively disable stateTimeout
+        case Some(d: FiniteDuration) if d.length >= 0 ⇒ timeoutFuture = scheduleTimeout(d)
+        case _ ⇒
+          val timeout = stateTimeouts(currentState.stateName)
+          if (timeout.isDefined) timeoutFuture = scheduleTimeout(timeout.get)
       }
     }
   }
@@ -1126,7 +1137,7 @@ abstract class AbstractFSM[S, D] extends FSM[S, D] {
    * @return current state descriptor
    */
   final def setTimer(name: String, msg: Any, timeout: FiniteDuration): Unit =
-    setTimer(name, msg, timeout, false);
+    setTimer(name, msg, timeout, false)
 
   /**
    * Default reason if calling `stop()`.