fix(simulator): Support trace fragments with zero cores available

This change fixes an issue with the simulator where trace fragments with
zero cores to execute would give a NaN amount of work.

2 files changed, 36 insertions, 1 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
index fc49f357..48be8e1a 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
@@ -89,7 +89,10 @@ public class SimTraceWorkload(public val trace: Sequence<Fragment>, private val
                 return SimResourceCommand.Idle(timestamp)
             }
 
-            val usage = fragment.usage / fragment.cores
+            val usage = if (fragment.cores > 0)
+                fragment.usage / fragment.cores
+            else
+                0.0
             val deadline = timestamp + fragment.duration
             val duration = deadline - now
             val work = duration * usage / 1000
@@ -103,6 +106,11 @@ public class SimTraceWorkload(public val trace: Sequence<Fragment>, private val
 
     /**
      * A fragment of the workload.
+     *
+     * @param timestamp The timestamp at which the fragment starts.
+     * @param duration The duration of the fragment.
+     * @param usage The CPU usage during the fragment.
+     * @param cores The amount of cores utilized during the fragment.
      */
     public data class Fragment(val timestamp: Long, val duration: Long, val usage: Double, val cores: Int)
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkloadTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkloadTest.kt
index 39c1eb5a..78019c2e 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkloadTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkloadTest.kt
@@ -130,4 +130,31 @@ class SimTraceWorkloadTest {
             machine.close()
         }
     }
+
+    @Test
+    fun testZeroCores() = runBlockingSimulation {
+        val machine = SimBareMetalMachine(
+            SimResourceInterpreter(coroutineContext, clock),
+            machineModel,
+            SimplePowerDriver(ConstantPowerModel(0.0))
+        )
+
+        val workload = SimTraceWorkload(
+            sequenceOf(
+                SimTraceWorkload.Fragment(0, 1000, 2 * 28.0, 2),
+                SimTraceWorkload.Fragment(1000, 1000, 2 * 3100.0, 2),
+                SimTraceWorkload.Fragment(2000, 1000, 0.0, 0),
+                SimTraceWorkload.Fragment(3000, 1000, 2 * 73.0, 2)
+            ),
+            offset = 0
+        )
+
+        try {
+            machine.run(workload)
+
+            assertEquals(4000, clock.millis())
+        } finally {
+            machine.close()
+        }
+    }
 }