From 21270e0b4250bd6927e85227fa825cf8ed59aaed Mon Sep 17 00:00:00 2001
From: Fabian Mastenbroek <mail.fabianm@gmail.com>
Date: Thu, 22 Sep 2022 10:55:13 +0200
Subject: refactor(compute): Add separate error host state

This change adds a new HostState to indicate that the host is in an
error state as opposed to being purposefully unavailable.
---
 .../org/opendc/compute/service/driver/HostState.kt | 11 ++++++++---
 .../compute/service/internal/ComputeServiceImpl.kt |  2 +-
 .../kotlin/org/opendc/compute/simulator/SimHost.kt | 23 ++++++++--------------
 3 files changed, 17 insertions(+), 19 deletions(-)

(limited to 'opendc-compute')

diff --git a/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/driver/HostState.kt b/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/driver/HostState.kt
index 6d85ee2d..ca6c625c 100644
--- a/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/driver/HostState.kt
+++ b/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/driver/HostState.kt
@@ -27,12 +27,17 @@ package org.opendc.compute.service.driver
  */
 public enum class HostState {
     /**
-     * The host is up.
+     * The host is up and able to host guests.
      */
     UP,
 
     /**
-     * The host is down.
+     * The host is in a (forced) down state and unable to host any guests.
      */
-    DOWN
+    DOWN,
+
+    /**
+     * The host is in an error state and unable to host any guests.
+     */
+    ERROR,
 }
diff --git a/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/internal/ComputeServiceImpl.kt b/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/internal/ComputeServiceImpl.kt
index 21aaa19e..52ee780b 100644
--- a/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/internal/ComputeServiceImpl.kt
+++ b/opendc-compute/opendc-compute-service/src/main/kotlin/org/opendc/compute/service/internal/ComputeServiceImpl.kt
@@ -411,7 +411,7 @@ internal class ComputeServiceImpl(
                 // Re-schedule on the new machine
                 requestSchedulingCycle()
             }
-            HostState.DOWN -> {
+            else -> {
                 logger.debug { "[${clock.instant()}] Host ${host.uid} state changed: $newState" }
 
                 val hv = hostToView[host] ?: return
diff --git a/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimHost.kt b/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimHost.kt
index ece3f752..56b1c8d1 100644
--- a/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimHost.kt
+++ b/opendc-compute/opendc-compute-simulator/src/main/kotlin/org/opendc/compute/simulator/SimHost.kt
@@ -59,7 +59,7 @@ public class SimHost(
     override val name: String,
     model: MachineModel,
     override val meta: Map<String, Any>,
-    context: CoroutineContext,
+    private val context: CoroutineContext,
     engine: FlowEngine,
     hypervisorProvider: SimHypervisorProvider,
     random: SplittableRandom,
@@ -69,11 +69,6 @@ public class SimHost(
     private val interferenceDomain: VmInterferenceDomain? = null,
     private val optimize: Boolean = false
 ) : Host, AutoCloseable {
-    /**
-     * The [CoroutineScope] of the host bounded by the lifecycle of the host.
-     */
-    private val scope: CoroutineScope = CoroutineScope(context + Job())
-
     /**
      * The clock instance used by the host.
      */
@@ -148,7 +143,7 @@ public class SimHost(
             val interferenceKey = interferenceDomain?.getMember(key.name)
             val machine = hypervisor.newMachine(key.flavor.toMachineModel(), interferenceKey)
             val newGuest = Guest(
-                scope.coroutineContext,
+                context,
                 clock,
                 this,
                 hypervisor,
@@ -195,8 +190,7 @@ public class SimHost(
     }
 
     override fun close() {
-        reset()
-        scope.cancel()
+        reset(HostState.DOWN)
         machine.cancel()
     }
 
@@ -271,7 +265,7 @@ public class SimHost(
     override fun toString(): String = "SimHost[uid=$uid,name=$name,model=$model]"
 
     public suspend fun fail() {
-        reset()
+        reset(HostState.ERROR)
 
         for (guest in _guests) {
             guest.fail()
@@ -310,7 +304,7 @@ public class SimHost(
                     _state = HostState.UP
                     hypervisor.onStart(ctx)
                 } catch (cause: Throwable) {
-                    _state = HostState.DOWN
+                    _state = HostState.ERROR
                     _ctx = null
                     throw cause
                 }
@@ -320,7 +314,6 @@ public class SimHost(
                 try {
                     hypervisor.onStop(ctx)
                 } finally {
-                    _state = HostState.DOWN
                     _ctx = null
                 }
             }
@@ -330,12 +323,12 @@ public class SimHost(
     /**
      * Reset the machine.
      */
-    private fun reset() {
+    private fun reset(state: HostState) {
         updateUptime()
 
         // Stop the hypervisor
         _ctx?.close()
-        _state = HostState.DOWN
+        _state = state
     }
 
     /**
@@ -386,7 +379,7 @@ public class SimHost(
 
         if (_state == HostState.UP) {
             _uptime += duration
-        } else if (_state == HostState.DOWN && scope.isActive) {
+        } else if (_state == HostState.ERROR) {
             // Only increment downtime if the machine is in a failure state
             _downtime += duration
         }
-- 
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