fix(compute): Disallow duplicate UIDs for SimHost

This change fixes an issue with the ComputeServiceHelper where it
allowed users to register multiple SimHost objects with the same UID.

See this issue for more information:
https://github.com/atlarge-research/opendc/issues/51

2 files changed, 7 insertions, 1 deletions

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 95921e8b..43f33f27 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
@@ -249,6 +249,12 @@ public class SimHost(
         machine.cancel()
     }
 
+    override fun hashCode(): Int = uid.hashCode()
+
+    override fun equals(other: Any?): Boolean {
+        return other is SimHost && uid == other.uid
+    }
+
     override fun toString(): String = "SimHost[uid=$uid,name=$name,model=$model]"
 
     public suspend fun fail() {
diff --git a/opendc-compute/opendc-compute-workload/src/main/kotlin/org/opendc/compute/workload/ComputeServiceHelper.kt b/opendc-compute/opendc-compute-workload/src/main/kotlin/org/opendc/compute/workload/ComputeServiceHelper.kt
index a1a65da3..4b0b343f 100644
--- a/opendc-compute/opendc-compute-workload/src/main/kotlin/org/opendc/compute/workload/ComputeServiceHelper.kt
+++ b/opendc-compute/opendc-compute-workload/src/main/kotlin/org/opendc/compute/workload/ComputeServiceHelper.kt
@@ -169,7 +169,7 @@ public class ComputeServiceHelper(
             optimize = optimize
         )
 
-        _hosts.add(host)
+        require(_hosts.add(host)) { "Host with uid ${spec.uid} already exists" }
         service.addHost(host)
 
         return host