Add support for hypervisor selection

This change allows users to select the hypervisor scheduler to use when
deploying hypervisors onto bare-metal machines.

4 files changed, 27 insertions, 23 deletions

diff --git a/simulator/opendc-compute/opendc-compute-simulator/build.gradle.kts b/simulator/opendc-compute/opendc-compute-simulator/build.gradle.kts
index d7570e54..dc93e956 100644
--- a/simulator/opendc-compute/opendc-compute-simulator/build.gradle.kts
+++ b/simulator/opendc-compute/opendc-compute-simulator/build.gradle.kts
@@ -29,10 +29,10 @@ plugins {
 
 dependencies {
     api(project(":opendc-compute:opendc-compute-core"))
+    api(project(":opendc-simulator:opendc-simulator-compute"))
+    api(project(":opendc-simulator:opendc-simulator-failures"))
     implementation(project(":opendc-utils"))
     implementation("io.github.microutils:kotlin-logging:1.7.9")
-    implementation(project(":opendc-simulator:opendc-simulator-compute"))
-    api(project(":opendc-simulator:opendc-simulator-failures"))
 
     testImplementation(project(":opendc-simulator:opendc-simulator-core"))
     testRuntimeOnly("org.slf4j:slf4j-simple:${Library.SLF4J}")
diff --git a/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtDriver.kt b/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtDriver.kt
index 508720e2..d7a8a8b2 100644
--- a/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtDriver.kt
+++ b/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtDriver.kt
@@ -44,7 +44,7 @@ import java.util.*
 /**
  * A [VirtDriver] that is simulates virtual machines on a physical machine using [SimHypervisor].
  */
-public class SimVirtDriver(private val coroutineScope: CoroutineScope) : VirtDriver, SimWorkload {
+public class SimVirtDriver(private val coroutineScope: CoroutineScope, hypervisor: SimHypervisorProvider) : VirtDriver, SimWorkload {
     /**
      * The execution context in which the [VirtDriver] runs.
      */
@@ -71,7 +71,7 @@ public class SimVirtDriver(private val coroutineScope: CoroutineScope) : VirtDri
     /**
      * The hypervisor to run multiple workloads.
      */
-    private val hypervisor = SimFairShareHypervisor(
+    private val hypervisor = hypervisor.create(
         object : SimHypervisor.Listener {
             override fun onSliceFinish(
                 hypervisor: SimHypervisor,
@@ -132,7 +132,6 @@ public class SimVirtDriver(private val coroutineScope: CoroutineScope) : VirtDri
         )
         availableMemory -= requiredMemory
 
-
         val vm = VirtualMachine(server, events, hypervisor.createMachine(flavor.toMachineModel()))
         vms.add(vm)
         vmStarted(vm)
diff --git a/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtProvisioningService.kt b/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtProvisioningService.kt
index 6b0021e1..defea888 100644
--- a/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtProvisioningService.kt
+++ b/simulator/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimVirtProvisioningService.kt
@@ -40,7 +40,9 @@ import org.opendc.compute.core.virt.service.VirtProvisioningEvent
 import org.opendc.compute.core.virt.service.VirtProvisioningService
 import org.opendc.compute.core.virt.service.events.*
 import org.opendc.compute.simulator.allocation.AllocationPolicy
+import org.opendc.simulator.compute.SimHypervisorProvider
 import org.opendc.trace.core.EventTracer
+import org.opendc.utils.TimerScheduler
 import org.opendc.utils.flow.EventFlow
 import java.time.Clock
 import java.util.*
@@ -55,7 +57,8 @@ public class SimVirtProvisioningService(
     private val provisioningService: ProvisioningService,
     public val allocationPolicy: AllocationPolicy,
     private val tracer: EventTracer,
-    private val schedulingQuantum: Long = 300000 // 5 minutes in milliseconds
+    private val hypervisor: SimHypervisorProvider,
+    private val schedulingQuantum: Long = 300000, // 5 minutes in milliseconds
 ) : VirtProvisioningService {
     /**
      * The logger instance to use.
@@ -75,7 +78,7 @@ public class SimVirtProvisioningService(
     /**
      * The incoming images to be processed by the provisioner.
      */
-    private val incomingImages: MutableSet<ImageView> = mutableSetOf()
+    private val incomingImages: Deque<ImageView> = ArrayDeque()
 
     /**
      * The active images in the system.
@@ -103,11 +106,16 @@ public class SimVirtProvisioningService(
 
     override val events: Flow<VirtProvisioningEvent> = eventFlow
 
+    /**
+     * The [TimerScheduler] to use for scheduling the scheduler cycles.
+     */
+    private var scheduler: TimerScheduler<Unit> = TimerScheduler(coroutineScope, clock)
+
     init {
         coroutineScope.launch {
             val provisionedNodes = provisioningService.nodes()
             provisionedNodes.forEach { node ->
-                val workload = SimVirtDriver(coroutineScope)
+                val workload = SimVirtDriver(coroutineScope, hypervisor)
                 val hypervisorImage = SimWorkloadImage(UUID.randomUUID(), "vmm", emptyMap(), workload)
                 launch {
                     var init = false
@@ -169,10 +177,9 @@ public class SimVirtProvisioningService(
         provisionedNodes.forEach { node -> provisioningService.stop(node) }
     }
 
-    private var call: Job? = null
-
     private fun requestCycle() {
-        if (call != null) {
+        // Bail out in case we have already requested a new cycle.
+        if (scheduler.isTimerActive(Unit)) {
             return
         }
 
@@ -181,23 +188,19 @@ public class SimVirtProvisioningService(
         // We calculate here the delay until the next scheduling slot.
         val delay = schedulingQuantum - (clock.millis() % schedulingQuantum)
 
-        val call = coroutineScope.launch {
-            delay(delay)
-            this@SimVirtProvisioningService.call = null
-            schedule()
+        scheduler.startSingleTimer(Unit, delay) {
+            coroutineScope.launch { schedule() }
         }
-        this.call = call
     }
 
     private suspend fun schedule() {
-        val imagesToBeScheduled = incomingImages.toSet()
-
-        for (imageInstance in imagesToBeScheduled) {
+        while (incomingImages.isNotEmpty()) {
+            val imageInstance = incomingImages.peekFirst()
             val requiredMemory = imageInstance.flavor.memorySize
             val selectedHv = allocationLogic.select(availableHypervisors, imageInstance)
 
             if (selectedHv == null || !selectedHv.driver.canFit(imageInstance.flavor)) {
-                logger.debug { "Server ${imageInstance.server} selected for scheduling but no capacity available for it." }
+                logger.trace { "Image ${imageInstance.image} selected for scheduling but no capacity available for it." }
 
                 if (requiredMemory > maxMemory || imageInstance.flavor.cpuCount > maxCores) {
                     tracer.commit(VmSubmissionInvalidEvent(imageInstance.name))
@@ -215,7 +218,8 @@ public class SimVirtProvisioningService(
                         )
                     )
 
-                    incomingImages -= imageInstance
+                    // Remove the incoming image
+                    incomingImages.poll()
 
                     logger.warn("Failed to spawn ${imageInstance.image}: does not fit [${clock.millis()}]")
                     continue
@@ -226,7 +230,7 @@ public class SimVirtProvisioningService(
 
             try {
                 logger.info { "[${clock.millis()}] Spawning ${imageInstance.image} on ${selectedHv.server.uid} ${selectedHv.server.name} ${selectedHv.server.flavor}" }
-                incomingImages -= imageInstance
+                incomingImages.poll()
 
                 // Speculatively update the hypervisor view information to prevent other images in the queue from
                 // deciding on stale values.
diff --git a/simulator/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimVirtDriverTest.kt b/simulator/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimVirtDriverTest.kt
index 163b326a..1831eae0 100644
--- a/simulator/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimVirtDriverTest.kt
+++ b/simulator/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimVirtDriverTest.kt
@@ -34,6 +34,7 @@ import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertAll
 import org.opendc.compute.core.Flavor
 import org.opendc.compute.core.virt.HypervisorEvent
+import org.opendc.simulator.compute.SimFairShareHypervisorProvider
 import org.opendc.simulator.compute.SimMachineModel
 import org.opendc.simulator.compute.model.MemoryUnit
 import org.opendc.simulator.compute.model.ProcessingNode
@@ -75,7 +76,7 @@ internal class SimVirtDriverTest {
         var overcommittedWork = 0L
 
         scope.launch {
-            val virtDriver = SimVirtDriver(this)
+            val virtDriver = SimVirtDriver(this, SimFairShareHypervisorProvider())
             val vmm = SimWorkloadImage(UUID.randomUUID(), "vmm", emptyMap(), virtDriver)
             val duration = 5 * 60L
             val vmImageA = SimWorkloadImage(