refactor: Use RandomGenerator as randomness source

This change updates the modules of OpenDC to always accept
the `RandomGenerator` interface as source of randomness. This interface
is implemented by the slower `java.util.Random` class, but also by the
faster `java.util.SplittableRandom` class

2 files changed, 7 insertions, 5 deletions

diff --git a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/router/RandomRoutingPolicy.kt b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/router/RandomRoutingPolicy.kt
index 5bd9d4d3..22bf7266 100644
--- a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/router/RandomRoutingPolicy.kt
+++ b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/router/RandomRoutingPolicy.kt
@@ -24,13 +24,15 @@ package org.opendc.faas.service.router
 
 import org.opendc.faas.service.FunctionObject
 import org.opendc.faas.service.deployer.FunctionInstance
-import kotlin.random.Random
+import java.util.SplittableRandom
+import java.util.random.RandomGenerator
 
 /**
  * A [RoutingPolicy] that selects a random function instance.
  */
-public class RandomRoutingPolicy(private val random: Random = Random(0)) : RoutingPolicy {
+public class RandomRoutingPolicy(private val random: RandomGenerator = SplittableRandom(0)) : RoutingPolicy {
     override fun select(instances: List<FunctionInstance>, function: FunctionObject): FunctionInstance {
-        return instances.random(random)
+        val idx = random.nextInt(instances.size)
+        return instances.elementAt(idx)
     }
 }
diff --git a/opendc-faas/opendc-faas-simulator/src/main/kotlin/org/opendc/faas/simulator/delay/StochasticDelayInjector.kt b/opendc-faas/opendc-faas-simulator/src/main/kotlin/org/opendc/faas/simulator/delay/StochasticDelayInjector.kt
index d3b31bb9..de7b4aa5 100644
--- a/opendc-faas/opendc-faas-simulator/src/main/kotlin/org/opendc/faas/simulator/delay/StochasticDelayInjector.kt
+++ b/opendc-faas/opendc-faas-simulator/src/main/kotlin/org/opendc/faas/simulator/delay/StochasticDelayInjector.kt
@@ -23,13 +23,13 @@
 package org.opendc.faas.simulator.delay
 
 import org.opendc.faas.service.deployer.FunctionInstance
-import java.util.Random
+import java.util.random.RandomGenerator
 import kotlin.math.abs
 
 /*
  * Interface for instance deployment delay estimation.
  */
-public class StochasticDelayInjector(private val model: ColdStartModel, private val random: Random) : DelayInjector {
+public class StochasticDelayInjector(private val model: ColdStartModel, private val random: RandomGenerator) : DelayInjector {
     override fun getColdStartDelay(instance: FunctionInstance): Long {
         val (mean, sd) = model.coldStartParam(instance.function.memorySize.toInt())
         return abs(random.nextGaussian() * sd + mean).toLong()