compute: Make VirtProvisoningService responsible for Server lifecycle

This change refactors the OpenDC Compute module so that the
VirtProvisioningService is now responsible for managing the lifecycle of
Server objects as opposed to the VirtDriver and BareMetalDriver
previously.

7 files changed, 151 insertions, 98 deletions

diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/Host.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/Host.kt
new file mode 100644
index 00000000..60a31b69
--- /dev/null
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/Host.kt
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.core.virt
+
+import kotlinx.coroutines.flow.Flow
+import org.opendc.compute.core.Server
+import java.util.*
+
+/**
+ * Base interface for representing compute resources that host virtualized [Server] instances.
+ */
+public interface Host {
+    /**
+     * A unique identifier representing the host.
+     */
+    public val uid: UUID
+
+    /**
+     * The state of the host.
+     */
+    public val state: HostState
+
+    /**
+     * The events emitted by the driver.
+     */
+    public val events: Flow<HostEvent>
+
+    /**
+     * Determine whether the specified [instance][server] can still fit on this host.
+     */
+    public fun canFit(server: Server): Boolean
+
+    /**
+     * Register the specified [instance][server] on the host.
+     *
+     * Once the method returns, the instance should be running if [start] is true or else the instance should be
+     * stopped.
+     */
+    public suspend fun spawn(server: Server, start: Boolean = true)
+
+    /**
+     * Determine whether the specified [instance][server] exists on the host.
+     */
+    public operator fun contains(server: Server): Boolean
+
+    /**
+     * Stat the server [instance][server] if it is currently not running on this host.
+     *
+     * @throws IllegalArgumentException if the server is not present on the host.
+     */
+    public suspend fun start(server: Server)
+
+    /**
+     * Stop the server [instance][server] if it is currently running on this host.
+     *
+     * @throws IllegalArgumentException if the server is not present on the host.
+     */
+    public suspend fun stop(server: Server)
+
+    /**
+     * Terminate the specified [instance][server] on this host and cleanup all resources associated with it.
+     */
+    public suspend fun terminate(server: Server)
+
+    /**
+     * Add a [HostListener] to this host.
+     */
+    public fun addListener(listener: HostListener)
+
+    /**
+     * Remove a [HostListener] from this host.
+     */
+    public fun removeListener(listener: HostListener)
+}
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HypervisorEvent.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostEvent.kt
index d1c8d790..a07523e8 100644
--- a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HypervisorEvent.kt
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostEvent.kt
@@ -23,16 +23,15 @@
 package org.opendc.compute.core.virt
 
 import org.opendc.compute.core.metal.Node
-import org.opendc.compute.core.virt.driver.VirtDriver
 
 /**
- * An event that is emitted by a [VirtDriver].
+ * An event that is emitted by a [Host].
  */
-public sealed class HypervisorEvent {
+public sealed class HostEvent {
     /**
      * The driver that emitted the event.
      */
-    public abstract val driver: VirtDriver
+    public abstract val driver: Host
 
     /**
      * This event is emitted when the number of active servers on the server managed by this driver is updated.
@@ -42,10 +41,10 @@ public sealed class HypervisorEvent {
      * @property availableMemory The available memory, in MB.
      */
     public data class VmsUpdated(
-        override val driver: VirtDriver,
+        override val driver: Host,
         public val numberOfActiveServers: Int,
         public val availableMemory: Long
-    ) : HypervisorEvent()
+    ) : HostEvent()
 
     /**
      * This event is emitted when a slice is finished.
@@ -63,7 +62,7 @@ public sealed class HypervisorEvent {
      * @property numberOfDeployedImages The number of images deployed on this hypervisor.
      */
     public data class SliceFinished(
-        override val driver: VirtDriver,
+        override val driver: Host,
         public val requestedBurst: Long,
         public val grantedBurst: Long,
         public val overcommissionedBurst: Long,
@@ -72,5 +71,5 @@ public sealed class HypervisorEvent {
         public val cpuDemand: Double,
         public val numberOfDeployedImages: Int,
         public val host: Node
-    ) : HypervisorEvent()
+    ) : HostEvent()
 }
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/Hypervisor.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostListener.kt
index 1ae52baa..b14d9bb5 100644
--- a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/Hypervisor.kt
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostListener.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020 AtLarge Research
+ * Copyright (c) 2021 AtLarge Research
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -22,35 +22,20 @@
 
 package org.opendc.compute.core.virt
 
-import kotlinx.coroutines.flow.Flow
-import org.opendc.core.Identity
-import java.util.UUID
+import org.opendc.compute.core.Server
+import org.opendc.compute.core.ServerState
 
 /**
- * A hypervisor (or virtual machine monitor) is software or firmware that virtualizes the host compute environment
- * into several virtual guest machines.
+ * Listener interface for events originating from a [Host].
  */
-public class Hypervisor(
+public interface HostListener {
     /**
-     * The unique identifier of the hypervisor.
+     * This method is invoked when the state of an [instance][server] on [host] changes.
      */
-    override val uid: UUID,
+    public fun onStateChange(host: Host, server: Server, newState: ServerState) {}
 
     /**
-     * The optional name of the hypervisor.
+     * This method is invoked when the state of a [Host] has changed.
      */
-    override val name: String,
-
-    /**
-     * Metadata of the hypervisor.
-     */
-    public val metadata: Map<String, Any>,
-
-    /**
-     * The events that are emitted by the hypervisor.
-     */
-    public val events: Flow<HypervisorEvent>
-) : Identity {
-    override fun hashCode(): Int = uid.hashCode()
-    override fun equals(other: Any?): Boolean = other is Hypervisor && uid == other.uid
+    public fun onStateChange(host: Host, newState: HostState) {}
 }
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostState.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostState.kt
new file mode 100644
index 00000000..7f87f5f7
--- /dev/null
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/HostState.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.core.virt
+
+/**
+ * The state of a host.
+ */
+public enum class HostState {
+    /**
+     * The host is up.
+     */
+    UP,
+
+    /**
+     * The host is down.
+     */
+    DOWN
+}
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/driver/InsufficientMemoryOnServerException.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/InsufficientMemoryOnServerException.kt
index 6fe84ea6..0f7b5826 100644
--- a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/driver/InsufficientMemoryOnServerException.kt
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/InsufficientMemoryOnServerException.kt
@@ -1,3 +1,3 @@
-package org.opendc.compute.core.virt.driver
+package org.opendc.compute.core.virt
 
 public class InsufficientMemoryOnServerException : IllegalStateException("Insufficient memory left on server.")
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/driver/VirtDriver.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/driver/VirtDriver.kt
deleted file mode 100644
index 68cc7b50..00000000
--- a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/driver/VirtDriver.kt
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright (c) 2020 AtLarge Research
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- */
-
-package org.opendc.compute.core.virt.driver
-
-import kotlinx.coroutines.flow.Flow
-import org.opendc.compute.core.Flavor
-import org.opendc.compute.core.Server
-import org.opendc.compute.core.image.Image
-import org.opendc.compute.core.virt.HypervisorEvent
-import org.opendc.core.services.AbstractServiceKey
-import java.util.UUID
-
-/**
- * A driver interface for a hypervisor running on some host server and communicating with the central compute service to
- * provide virtualization for that particular resource.
- */
-public interface VirtDriver {
-    /**
-     * The events emitted by the driver.
-     */
-    public val events: Flow<HypervisorEvent>
-
-    /**
-     * Determine whether the specified [flavor] can still fit on this driver.
-     */
-    public fun canFit(flavor: Flavor): Boolean
-
-    /**
-     * Spawn the given [Image] on the compute resource of this driver.
-     *
-     * @param name The name of the server to spawn.
-     * @param image The image to deploy.
-     * @param flavor The flavor of the server which this driver is controlling.
-     * @return The virtual server spawned by this method.
-     */
-    public suspend fun spawn(
-        name: String,
-        image: Image,
-        flavor: Flavor
-    ): Server
-
-    public companion object Key : AbstractServiceKey<VirtDriver>(UUID.randomUUID(), "virtual-driver")
-}
diff --git a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/service/VirtProvisioningService.kt b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/service/VirtProvisioningService.kt
index b967044c..8da849af 100644
--- a/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/service/VirtProvisioningService.kt
+++ b/simulator/opendc-compute/opendc-compute-core/src/main/kotlin/org/opendc/compute/core/virt/service/VirtProvisioningService.kt
@@ -26,7 +26,7 @@ import kotlinx.coroutines.flow.Flow
 import org.opendc.compute.core.Flavor
 import org.opendc.compute.core.Server
 import org.opendc.compute.core.image.Image
-import org.opendc.compute.core.virt.driver.VirtDriver
+import org.opendc.compute.core.virt.Host
 
 /**
  * A service for VM provisioning on a cloud.
@@ -40,7 +40,7 @@ public interface VirtProvisioningService {
     /**
      * Obtain the active hypervisors for this provisioner.
      */
-    public suspend fun drivers(): Set<VirtDriver>
+    public suspend fun drivers(): Set<Host>
 
     /**
      * The number of hosts available in the system.