refactor(sim/compute): Extract Random dependency from interference model

This change moves the Random dependency outside the interference model,
to allow the interference model to be completely immutable and passable
between different simulations.

8 files changed, 49 insertions, 42 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
index 98dab28f..2cabeece 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
@@ -31,6 +31,7 @@ import org.opendc.simulator.compute.model.ProcessingUnit
 import org.opendc.simulator.compute.workload.SimWorkload
 import org.opendc.simulator.flow.*
 import org.opendc.simulator.flow.mux.FlowMultiplexer
+import java.util.SplittableRandom
 import kotlin.math.roundToLong
 
 /**
@@ -38,10 +39,12 @@ import kotlin.math.roundToLong
  *
  * @param engine The [FlowEngine] to drive the simulation.
  * @param scalingGovernor The scaling governor to use for scaling the CPU frequency of the underlying hardware.
+ * @param random A randomness generator for the interference calculations.
  */
 public abstract class SimAbstractHypervisor(
     protected val engine: FlowEngine,
-    private val scalingGovernor: ScalingGovernor?
+    private val scalingGovernor: ScalingGovernor?,
+    private val random: SplittableRandom
 ) : SimHypervisor, FlowConvergenceListener {
     /**
      * The machine on which the hypervisor runs.
@@ -142,8 +145,12 @@ public abstract class SimAbstractHypervisor(
         if (delta > 0) {
             _counters.record()
 
+            val mux = mux
+            val load = mux.rate / mux.capacity.coerceAtLeast(1.0)
+            val random = random
+
             for (vm in _vms) {
-                vm._counters.record()
+                vm._counters.record(random, load)
             }
         }
 
@@ -351,7 +358,7 @@ public abstract class SimAbstractHypervisor(
         /**
          * Record the CPU time of the hypervisor.
          */
-        fun record() {
+        fun record(random: SplittableRandom, load: Double) {
             val cpuTime = _cpuTime
             val previous = _previous
 
@@ -383,9 +390,7 @@ public abstract class SimAbstractHypervisor(
             // Compute the performance penalty due to flow interference
             val key = key
             if (key != null) {
-                val mux = mux
-                val load = mux.rate / mux.capacity.coerceAtLeast(1.0)
-                val penalty = 1 - key.apply(load)
+                val penalty = 1 - key.apply(random, load)
                 val interference = (actualDelta * d * penalty).roundToLong()
 
                 if (interference > 0) {
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisor.kt
index 66453835..4435a422 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisor.kt
@@ -29,6 +29,7 @@ import org.opendc.simulator.compute.workload.SimWorkload
 import org.opendc.simulator.flow.FlowEngine
 import org.opendc.simulator.flow.mux.FlowMultiplexer
 import org.opendc.simulator.flow.mux.MaxMinFlowMultiplexer
+import java.util.SplittableRandom
 
 /**
  * A [SimHypervisor] that distributes the computing requirements of multiple [SimWorkload]s on a single [SimMachine]
@@ -36,11 +37,13 @@ import org.opendc.simulator.flow.mux.MaxMinFlowMultiplexer
  *
  * @param engine The [FlowEngine] to manage the machine's resources.
  * @param scalingGovernor The CPU frequency scaling governor to use for the hypervisor.
+ * @param random A randomness generator for the interference calculations.
  */
 public class SimFairShareHypervisor(
     engine: FlowEngine,
-    scalingGovernor: ScalingGovernor?
-) : SimAbstractHypervisor(engine, scalingGovernor) {
+    scalingGovernor: ScalingGovernor?,
+    random: SplittableRandom
+) : SimAbstractHypervisor(engine, scalingGovernor, random) {
     /**
      * The multiplexer that distributes the computing capacity.
      */
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisorProvider.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisorProvider.kt
index ad8177d3..c7008652 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisorProvider.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimFairShareHypervisorProvider.kt
@@ -24,6 +24,7 @@ package org.opendc.simulator.compute.kernel
 
 import org.opendc.simulator.compute.kernel.cpufreq.ScalingGovernor
 import org.opendc.simulator.flow.FlowEngine
+import java.util.*
 
 /**
  * A [SimHypervisorProvider] for the [SimFairShareHypervisor] implementation.
@@ -33,6 +34,7 @@ public class SimFairShareHypervisorProvider : SimHypervisorProvider {
 
     override fun create(
         engine: FlowEngine,
+        random: SplittableRandom,
         scalingGovernor: ScalingGovernor?,
-    ): SimHypervisor = SimFairShareHypervisor(engine, scalingGovernor)
+    ): SimHypervisor = SimFairShareHypervisor(engine, scalingGovernor, random)
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorProvider.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorProvider.kt
index 6ee523fd..020a2a60 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorProvider.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorProvider.kt
@@ -24,6 +24,7 @@ package org.opendc.simulator.compute.kernel
 
 import org.opendc.simulator.compute.kernel.cpufreq.ScalingGovernor
 import org.opendc.simulator.flow.FlowEngine
+import java.util.SplittableRandom
 
 /**
  * A service provider interface for constructing a [SimHypervisor].
@@ -40,5 +41,5 @@ public interface SimHypervisorProvider {
     /**
      * Create a new [SimHypervisor] instance.
      */
-    public fun create(engine: FlowEngine, scalingGovernor: ScalingGovernor? = null): SimHypervisor
+    public fun create(engine: FlowEngine, random: SplittableRandom, scalingGovernor: ScalingGovernor? = null): SimHypervisor
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisor.kt
index 7976077c..51bf4ce5 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisor.kt
@@ -27,14 +27,20 @@ import org.opendc.simulator.compute.model.MachineModel
 import org.opendc.simulator.flow.FlowEngine
 import org.opendc.simulator.flow.mux.FlowMultiplexer
 import org.opendc.simulator.flow.mux.ForwardingFlowMultiplexer
+import java.util.SplittableRandom
 
 /**
  * A [SimHypervisor] that allocates its sub-resources exclusively for the virtual machine that it hosts.
+ *
+ * @param engine The [FlowEngine] to manage the machine's resources.
+ * @param scalingGovernor The CPU frequency scaling governor to use for the hypervisor.
+ * @param random A randomness generator for the interference calculations.
  */
 public class SimSpaceSharedHypervisor(
     engine: FlowEngine,
     scalingGovernor: ScalingGovernor?,
-) : SimAbstractHypervisor(engine, scalingGovernor) {
+    random: SplittableRandom
+) : SimAbstractHypervisor(engine, scalingGovernor, random) {
     override val mux: FlowMultiplexer = ForwardingFlowMultiplexer(engine, this)
 
     override fun canFit(model: MachineModel): Boolean {
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorProvider.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorProvider.kt
index f7456797..05c54528 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorProvider.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorProvider.kt
@@ -24,6 +24,7 @@ package org.opendc.simulator.compute.kernel
 
 import org.opendc.simulator.compute.kernel.cpufreq.ScalingGovernor
 import org.opendc.simulator.flow.FlowEngine
+import java.util.*
 
 /**
  * A [SimHypervisorProvider] for the [SimSpaceSharedHypervisor] implementation.
@@ -33,6 +34,7 @@ public class SimSpaceSharedHypervisorProvider : SimHypervisorProvider {
 
     override fun create(
         engine: FlowEngine,
+        random: SplittableRandom,
         scalingGovernor: ScalingGovernor?,
-    ): SimHypervisor = SimSpaceSharedHypervisor(engine, scalingGovernor)
+    ): SimHypervisor = SimSpaceSharedHypervisor(engine, scalingGovernor, random)
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceMember.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceMember.kt
index 2f3dd74b..04203c63 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceMember.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceMember.kt
@@ -22,6 +22,8 @@
 
 package org.opendc.simulator.compute.kernel.interference
 
+import java.util.*
+
 /**
  * A participant of an interference domain.
  */
@@ -39,9 +41,10 @@ public interface VmInterferenceMember {
     /**
      * Compute the performance score of the member in this interference domain.
      *
+     * @param random The source of randomness to apply when computing the performance score.
      * @param load The overall load on the interference domain.
      * @return A score representing the performance score to be applied to the member, with 1
      * meaning no influence, <1 means that performance degrades, and >1 means that performance improves.
      */
-    public fun apply(load: Double): Double
+    public fun apply(random: SplittableRandom, load: Double): Double
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceModel.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceModel.kt
index b9eee536..3ea869d4 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceModel.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/interference/VmInterferenceModel.kt
@@ -32,7 +32,6 @@ import java.util.*
  * @param members The members belonging to each group.
  * @param membership The identifier of each key.
  * @param size The number of groups.
- * @param seed The seed to use for randomly selecting the virtual machines that are affected.
  */
 public class VmInterferenceModel private constructor(
     private val idMapping: Map<String, Int>,
@@ -40,25 +39,12 @@ public class VmInterferenceModel private constructor(
     private val membership: Array<IntArray>,
     private val targets: DoubleArray,
     private val scores: DoubleArray,
-    private val size: Int,
-    seed: Long,
+    private val size: Int
 ) {
     /**
-     * A [SplittableRandom] used for selecting the virtual machines that are affected.
-     */
-    private val random = SplittableRandom(seed)
-
-    /**
      * Construct a new [VmInterferenceDomain].
      */
-    public fun newDomain(): VmInterferenceDomain = InterferenceDomainImpl(idMapping, members, membership, targets, scores, random)
-
-    /**
-     * Create a copy of this model with a different seed.
-     */
-    public fun withSeed(seed: Long): VmInterferenceModel {
-        return VmInterferenceModel(idMapping, members, membership, targets, scores, size, seed)
-    }
+    public fun newDomain(): VmInterferenceDomain = InterferenceDomainImpl(idMapping, members, membership, targets, scores)
 
     public companion object {
         /**
@@ -73,11 +59,6 @@ public class VmInterferenceModel private constructor(
      */
     public class Builder internal constructor() {
         /**
-         * The initial capacity of the builder.
-         */
-        private val INITIAL_CAPACITY = 256
-
-        /**
          * The target load of each group.
          */
         private var _targets = DoubleArray(INITIAL_CAPACITY) { Double.POSITIVE_INFINITY }
@@ -125,7 +106,7 @@ public class VmInterferenceModel private constructor(
         /**
          * Build the [VmInterferenceModel].
          */
-        public fun build(seed: Long = 0): VmInterferenceModel {
+        public fun build(): VmInterferenceModel {
             val size = size
             val targets = _targets
             val scores = _scores
@@ -176,8 +157,7 @@ public class VmInterferenceModel private constructor(
                 membership.map { it.value.toIntArray() }.toTypedArray(),
                 newTargets,
                 newScores,
-                size,
-                seed
+                size
             )
         }
 
@@ -191,6 +171,13 @@ public class VmInterferenceModel private constructor(
             _targets = _targets.copyOf(newSize)
             _scores = _scores.copyOf(newSize)
         }
+
+        private companion object {
+            /**
+             * The initial capacity of the builder.
+             */
+            const val INITIAL_CAPACITY = 256
+        }
     }
 
     /**
@@ -202,7 +189,6 @@ public class VmInterferenceModel private constructor(
         private val membership: Array<IntArray>,
         private val targets: DoubleArray,
         private val scores: DoubleArray,
-        private val random: SplittableRandom
     ) : VmInterferenceDomain {
         /**
          * Keys registered with this domain.
@@ -221,7 +207,7 @@ public class VmInterferenceModel private constructor(
 
         override fun getMember(id: String): VmInterferenceMember? {
             val intId = idMapping[id] ?: return null
-            return keys.computeIfAbsent(intId) { InterferenceMemberImpl(it, this, membership[it], members, targets, scores, random) }
+            return keys.computeIfAbsent(intId) { InterferenceMemberImpl(it, this, membership[it], members, targets, scores) }
         }
 
         override fun toString(): String = "VmInterferenceDomain"
@@ -307,8 +293,7 @@ public class VmInterferenceModel private constructor(
         @JvmField val membership: IntArray,
         private val members: Array<IntArray>,
         private val targets: DoubleArray,
-        private val scores: DoubleArray,
-        private val random: SplittableRandom
+        private val scores: DoubleArray
     ) : VmInterferenceMember, Comparable<InterferenceMemberImpl> {
         /**
          * The active groups to which the key belongs.
@@ -333,7 +318,7 @@ public class VmInterferenceModel private constructor(
             }
         }
 
-        override fun apply(load: Double): Double {
+        override fun apply(random: SplittableRandom, load: Double): Double {
             val groupsSize = groupsSize
 
             if (groupsSize == 0) {