[WIP] New RandomNumberGenerator API

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/internal/StubbedActorContext.scala

@@ -19,12 +19,11 @@ import pekko.actor.typed._
 import pekko.actor.typed.internal._
 import pekko.actor.{ ActorPath, ActorRefProvider, InvalidMessageException }
 import pekko.annotation.InternalApi
-import pekko.util.Helpers
+import pekko.util.{ Helpers, RandomNumberGenerator }
 import pekko.{ actor => classic }
 import org.slf4j.{ Logger, Marker }
 import org.slf4j.helpers.{ MessageFormatter, SubstituteLoggerFactory }
 
-import java.util.concurrent.ThreadLocalRandom.{ current => rnd }
 import scala.collection.immutable.TreeMap
 import scala.concurrent.ExecutionContextExecutor
 import scala.concurrent.duration.FiniteDuration
@@ -75,7 +74,7 @@ private[pekko] final class FunctionRef[-T](override val path: ActorPath, send: (
     extends ActorContextImpl[T] {
 
   def this(system: ActorSystemStub, name: String, currentBehaviorProvider: () => Behavior[T]) = {
-    this(system, (system.path / name).withUid(rnd().nextInt()), currentBehaviorProvider)
+    this(system, (system.path / name).withUid(RandomNumberGenerator.get().nextInt()), currentBehaviorProvider)
   }
 
   def this(name: String, currentBehaviorProvider: () => Behavior[T]) = {
@@ -111,7 +110,8 @@ private[pekko] final class FunctionRef[-T](override val path: ActorPath, send: (
 
   override def spawnAnonymous[U](behavior: Behavior[U], props: Props = Props.empty): ActorRef[U] = {
     checkCurrentActorThread()
-    val btk = new BehaviorTestKitImpl[U](system, (path / childName.next()).withUid(rnd().nextInt()), behavior)
+    val btk = new BehaviorTestKitImpl[U](system,
+      (path / childName.next()).withUid(RandomNumberGenerator.get().nextInt()), behavior)
     _children += btk.context.self.path.name -> btk
     btk.context.self
   }
@@ -120,7 +120,8 @@ private[pekko] final class FunctionRef[-T](override val path: ActorPath, send: (
     _children.get(name) match {
       case Some(_) => throw classic.InvalidActorNameException(s"actor name $name is already taken")
       case None =>
-        val btk = new BehaviorTestKitImpl[U](system, (path / name).withUid(rnd().nextInt()), behavior)
+        val btk =
+          new BehaviorTestKitImpl[U](system, (path / name).withUid(RandomNumberGenerator.get().nextInt()), behavior)
         _children += name -> btk
         btk.context.self
     }
@@ -172,7 +173,7 @@ private[pekko] final class FunctionRef[-T](override val path: ActorPath, send: (
   @InternalApi private[pekko] def internalSpawnMessageAdapter[U](f: U => T, name: String): ActorRef[U] = {
 
     val n = if (name != "") s"${childName.next()}-$name" else childName.next()
-    val p = (path / n).withUid(rnd().nextInt())
+    val p = (path / n).withUid(RandomNumberGenerator.get().nextInt())
     val i = new BehaviorTestKitImpl[U](system, p, BehaviorImpl.ignore)
     _children += p.name -> i
 

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/javadsl/BehaviorTestKit.scala

@@ -19,9 +19,9 @@ import pekko.actor.testkit.typed.{ CapturedLogEvent, Effect }
 import pekko.actor.typed.receptionist.Receptionist
 import pekko.actor.typed.{ ActorRef, Behavior, Signal }
 import pekko.annotation.{ ApiMayChange, DoNotInherit }
-import com.typesafe.config.Config
+import pekko.util.RandomNumberGenerator
 
-import java.util.concurrent.ThreadLocalRandom
+import com.typesafe.config.Config
 
 object BehaviorTestKit {
 
@@ -37,7 +37,7 @@ object BehaviorTestKit {
   @ApiMayChange
   def create[T](initialBehavior: Behavior[T], name: String, config: Config): BehaviorTestKit[T] = {
     val system = new ActorSystemStub("StubbedActorContext", config)
-    val uid = ThreadLocalRandom.current().nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     new BehaviorTestKitImpl(system, (system.path / name).withUid(uid), initialBehavior)
   }
 

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/javadsl/TestInbox.scala

@@ -13,25 +13,24 @@
 
 package org.apache.pekko.actor.testkit.typed.javadsl
 
-import java.util.concurrent.ThreadLocalRandom
-
 import scala.collection.immutable
 
 import org.apache.pekko
 import pekko.actor.testkit.typed.internal.TestInboxImpl
 import pekko.actor.typed.ActorRef
 import pekko.annotation.DoNotInherit
 import pekko.util.ccompat.JavaConverters._
+import pekko.util.RandomNumberGenerator
 
 object TestInbox {
   import pekko.actor.testkit.typed.scaladsl.TestInbox.address
 
   def create[T](name: String): TestInbox[T] = {
-    val uid = ThreadLocalRandom.current().nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     new TestInboxImpl((address / name).withUid(uid))
   }
   def create[T](): TestInbox[T] = {
-    val uid = ThreadLocalRandom.current().nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     new TestInboxImpl((address / "inbox").withUid(uid))
   }
 }

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/scaladsl/BehaviorTestKit.scala

@@ -19,9 +19,10 @@ import pekko.actor.testkit.typed.{ CapturedLogEvent, Effect }
 import pekko.actor.typed.receptionist.Receptionist
 import pekko.actor.typed.{ ActorRef, Behavior, Signal, TypedActorContext }
 import pekko.annotation.{ ApiMayChange, DoNotInherit }
+import pekko.util.RandomNumberGenerator
+
 import com.typesafe.config.Config
 
-import java.util.concurrent.ThreadLocalRandom
 import scala.collection.immutable
 import scala.reflect.ClassTag
 
@@ -32,7 +33,7 @@ object BehaviorTestKit {
 
   def apply[T](initialBehavior: Behavior[T], name: String, config: Config): BehaviorTestKit[T] = {
     val system = new ActorSystemStub("StubbedActorContext", config)
-    val uid = ThreadLocalRandom.current().nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     new BehaviorTestKitImpl(system, (system.path / name).withUid(uid), initialBehavior)
   }
   def apply[T](initialBehavior: Behavior[T], name: String): BehaviorTestKit[T] = {

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/scaladsl/TestInbox.scala

@@ -13,20 +13,19 @@
 
 package org.apache.pekko.actor.testkit.typed.scaladsl
 
-import java.util.concurrent.ThreadLocalRandom
-
 import scala.collection.immutable
 
 import org.apache.pekko
 import pekko.actor.{ Address, RootActorPath }
 import pekko.actor.testkit.typed.internal.TestInboxImpl
 import pekko.actor.typed.ActorRef
 import pekko.annotation.{ ApiMayChange, DoNotInherit }
+import pekko.util.RandomNumberGenerator
 
 @ApiMayChange
 object TestInbox {
   def apply[T](name: String = "inbox"): TestInbox[T] = {
-    val uid = ThreadLocalRandom.current().nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     new TestInboxImpl((address / name).withUid(uid))
   }
 

actor-tests/src/test/scala-jdk21-only/org/apache/pekko/util/RandomNumberGeneratorJava21Spec.scala

@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pekko.util
+
+import com.typesafe.config.ConfigFactory
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class RandomNumberGeneratorJava21Spec extends AnyWordSpec with Matchers {
+
+  "RandomNumberGenerator (Java 21+)" should {
+
+    "support config" in {
+      val config = ConfigFactory.parseString(
+        """pekko.random.generator-implementation = "Xoroshiro128PlusPlus"""")
+      val rng = RandomNumberGenerator.createGenerator(config)
+      rng shouldBe a[Jep356RandomNumberGenerator]
+      rng.nextInt(10) should (be >= 0 and be < 10)
+    }
+
+  }
+}

actor-tests/src/test/scala/org/apache/pekko/util/RandomNumberGeneratorSpec.scala

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pekko.util
+
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class RandomNumberGeneratorSpec extends AnyWordSpec with Matchers {
+
+  "RandomNumberGenerator" should {
+
+    "default to ThreadLocalRandom" in {
+      val rng = RandomNumberGenerator.get()
+      rng shouldEqual ThreadLocalRandomNumberGenerator
+      rng.nextInt(10) should (be >= 0 and be < 10)
+    }
+
+  }
+}

actor-typed/src/main/scala/org/apache/pekko/actor/typed/delivery/internal/WorkPullingProducerControllerImpl.scala

@@ -14,7 +14,6 @@
 package org.apache.pekko.actor.typed.delivery.internal
 
 import java.util.UUID
-import java.util.concurrent.ThreadLocalRandom
 import java.util.concurrent.TimeoutException
 
 import scala.reflect.ClassTag
@@ -39,7 +38,7 @@ import pekko.actor.typed.scaladsl.Behaviors
 import pekko.actor.typed.scaladsl.LoggerOps
 import pekko.actor.typed.scaladsl.StashBuffer
 import pekko.annotation.InternalApi
-import pekko.util.Timeout
+import pekko.util.{ RandomNumberGenerator, Timeout }
 
 /**
  * INTERNAL API
@@ -404,7 +403,7 @@ private class WorkPullingProducerControllerImpl[A: ClassTag](
       if (workers.isEmpty) {
         None
       } else {
-        val i = ThreadLocalRandom.current().nextInt(workers.size)
+        val i = RandomNumberGenerator.get().nextInt(workers.size)
         Some(workers(i))
       }
     }

actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/Supervision.scala

@@ -14,8 +14,6 @@
 package org.apache.pekko.actor.typed
 package internal
 
-import java.util.concurrent.ThreadLocalRandom
-
 import scala.concurrent.duration.Deadline
 import scala.concurrent.duration.FiniteDuration
 import scala.reflect.ClassTag
@@ -33,7 +31,7 @@ import pekko.actor.typed.scaladsl.Behaviors
 import pekko.actor.typed.scaladsl.StashBuffer
 import pekko.annotation.InternalApi
 import pekko.event.Logging
-import pekko.util.OptionVal
+import pekko.util.{ OptionVal, RandomNumberGenerator }
 import pekko.util.unused
 
 import scala.util.Try
@@ -187,7 +185,7 @@ private object RestartSupervisor {
       minBackoff: FiniteDuration,
       maxBackoff: FiniteDuration,
       randomFactor: Double): FiniteDuration = {
-    val rnd = 1.0 + ThreadLocalRandom.current().nextDouble() * randomFactor
+    val rnd = 1.0 + RandomNumberGenerator.get().nextDouble() * randomFactor
     val calculatedDuration = Try(maxBackoff.min(minBackoff * math.pow(2, restartCount)) * rnd).getOrElse(maxBackoff)
     calculatedDuration match {
       case f: FiniteDuration => f

actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/routing/RoutingLogic.scala

@@ -13,13 +13,12 @@
 
 package org.apache.pekko.actor.typed.internal.routing
 
-import java.util.concurrent.ThreadLocalRandom
-
 import org.apache.pekko
 import pekko.actor.Address
 import pekko.actor.typed.ActorRef
 import pekko.annotation.InternalApi
 import pekko.routing.ConsistentHash
+import pekko.util.RandomNumberGenerator
 
 /**
  * Kept in the behavior, not shared between instances, meant to be stateful.
@@ -89,7 +88,7 @@ private[pekko] object RoutingLogics {
     private var currentRoutees: Array[ActorRef[T]] = _
 
     override def selectRoutee(msg: T): ActorRef[T] = {
-      val selectedIdx = ThreadLocalRandom.current().nextInt(currentRoutees.length)
+      val selectedIdx = RandomNumberGenerator.get().nextInt(currentRoutees.length)
       currentRoutees(selectedIdx)
     }
 

actor/src/main/resources/reference.conf

@@ -1396,4 +1396,13 @@ pekko {
   }
   #//#circuit-breaker-default
 
+  random {
+    # The default random number generator used by the Pekko library.
+    # This setting does not affect SecureRandom use cases.
+    # This option is ignored if you are not using Java 17+. The default is "ThreadLocalRandom".
+    # Valid options are listed in
+    # https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/random/package-summary.html#algorithms
+    generator-implementation = "ThreadLocalRandom"
+  }
+
 }

actor/src/main/scala/org/apache/pekko/actor/ActorCell.scala

@@ -14,7 +14,6 @@
 package org.apache.pekko.actor
 
 import java.io.{ NotSerializableException, ObjectOutputStream }
-import java.util.concurrent.ThreadLocalRandom
 
 import scala.annotation.{ switch, tailrec }
 import scala.annotation.nowarn
@@ -31,6 +30,7 @@ import pekko.dispatch.sysmsg._
 import pekko.event.Logging.{ Debug, Error, LogEvent }
 import pekko.japi.Procedure
 import pekko.util.unused
+import pekko.util.RandomNumberGenerator
 
 /**
  * The actor context - the view of the actor cell from the actor.
@@ -392,7 +392,7 @@ private[pekko] object ActorCell {
   @tailrec final def newUid(): Int = {
     // Note that this uid is also used as hashCode in ActorRef, so be careful
     // to not break hashing if you change the way uid is generated
-    val uid = ThreadLocalRandom.current.nextInt()
+    val uid = RandomNumberGenerator.get().nextInt()
     if (uid == undefinedUid) newUid()
     else uid
   }

actor/src/main/scala/org/apache/pekko/actor/ActorSystem.scala

@@ -814,7 +814,7 @@ private[pekko] class ActorSystemImpl(
     setup: ActorSystemSetup)
     extends ExtendedActorSystem {
 
-  val uid: Long = ThreadLocalRandom.current.nextLong()
+  val uid: Long = RandomNumberGenerator.get().nextLong()
 
   if (!name.matches("""^[a-zA-Z0-9][a-zA-Z0-9-_]*$"""))
     throw new IllegalArgumentException(

actor/src/main/scala/org/apache/pekko/io/dns/IdGenerator.scala

@@ -17,11 +17,12 @@
 
 package org.apache.pekko.io.dns
 
-import org.apache.pekko.annotation.InternalApi
+import org.apache.pekko
+import pekko.annotation.InternalApi
+import pekko.util.RandomNumberGenerator
 
 import java.security.SecureRandom
 import java.util.Random
-import java.util.concurrent.ThreadLocalRandom
 
 /**
  * INTERNAL API
@@ -52,19 +53,25 @@ private[pekko] object IdGenerator {
   }
 
   def apply(policy: Policy): IdGenerator = policy match {
-    case Policy.ThreadLocalRandom        => random(ThreadLocalRandom.current())
+    case Policy.ThreadLocalRandom        => random(RandomNumberGenerator.get())
     case Policy.SecureRandom             => random(new SecureRandom())
     case Policy.EnhancedDoubleHashRandom => new EnhancedDoubleHashGenerator(new SecureRandom())
   }
 
-  def apply(): IdGenerator = random(ThreadLocalRandom.current())
+  def apply(): IdGenerator = random(RandomNumberGenerator.get())
 
   /**
    * @return a random sequence of ids for production
    */
   def random(rand: java.util.Random): IdGenerator =
     () => (rand.nextInt(UnsignedShortBound) + Short.MinValue).toShort
 
+  /**
+   * @return a random sequence of ids for production
+   */
+  private def random(rand: RandomNumberGenerator): IdGenerator =
+    () => (rand.nextInt(UnsignedShortBound) + Short.MinValue).toShort
+
   private[pekko] class EnhancedDoubleHashGenerator(seed: Random) extends IdGenerator {
 
     /**