Fix issues with web runner (v2) (#118)

This is a second pull request to address several issues that were present 
in the web runner and the associated experiments:

* Re-use topology across repeats
* Disallow re-use of `SimTraceWorkload`
* Construct new `SimTraceWorkload` for each simulation run

1 files changed, 3 insertions, 1 deletions

diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
index 694a928b..ffb332d1 100644
--- a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
@@ -34,12 +34,14 @@ import org.opendc.simulator.resources.consumer.SimConsumerBarrier
  * consumption for some period of time.
  */
 public class SimTraceWorkload(public val trace: Sequence<Fragment>) : SimWorkload {
-    private var offset = 0L
+    private var offset = Long.MIN_VALUE
     private val iterator = trace.iterator()
     private var fragment: Fragment? = null
     private lateinit var barrier: SimConsumerBarrier
 
     override fun onStart(ctx: SimMachineContext) {
+        check(offset == Long.MIN_VALUE) { "Workload does not support re-use" }
+
         barrier = SimConsumerBarrier(ctx.cpus.size)
         fragment = nextFragment()
         offset = ctx.clock.millis()