feat(sim/compute): Add support for snapshotting workloads

This change updates the interface of `SimWorkload` to support
snapshotting workloads. We introduce a new method `snapshot()` to this
interface which returns a new `SimWorkload` that can be started at a
later point in time and on another `SimMachine`, which continues
progress from the moment the workload was snapshotted.

2 files changed, 47 insertions, 8 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
index cde6763c..2acf6ec7 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
@@ -177,6 +177,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
     }
 
@@ -197,6 +199,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
     }
 
@@ -217,6 +221,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
 
         assertEquals(1000, clock.millis())
@@ -243,6 +249,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
 
         assertEquals(40, clock.millis())
@@ -266,6 +274,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
 
         assertEquals(4000, clock.millis())
@@ -289,6 +299,8 @@ class SimMachineTest {
             }
 
             override fun onStop(ctx: SimMachineContext) {}
+
+            override fun snapshot(): SimWorkload = TODO()
         })
 
         assertEquals(4000, clock.millis())
diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimChainWorkloadTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimChainWorkloadTest.kt
index 2210374d..d0b0efaa 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimChainWorkloadTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimChainWorkloadTest.kt
@@ -25,6 +25,8 @@ package org.opendc.simulator.compute.workload
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.spyk
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
@@ -67,8 +69,8 @@ class SimChainWorkloadTest {
 
         val workload =
             SimWorkloads.chain(
-                SimRuntimeWorkload(1000, 1.0),
-                SimRuntimeWorkload(1000, 1.0)
+                SimWorkloads.runtime(1000, 1.0),
+                SimWorkloads.runtime(1000, 1.0)
             )
 
         machine.runWorkload(workload)
@@ -93,7 +95,7 @@ class SimChainWorkloadTest {
         val workload =
             SimWorkloads.chain(
                 workloadA,
-                SimRuntimeWorkload(1000, 1.0)
+                SimWorkloads.runtime(1000, 1.0)
             )
 
         assertThrows<IllegalStateException> { machine.runWorkload(workload) }
@@ -117,9 +119,9 @@ class SimChainWorkloadTest {
 
         val workload =
             SimWorkloads.chain(
-                SimRuntimeWorkload(1000, 1.0),
+                SimWorkloads.runtime(1000, 1.0),
                 workloadA,
-                SimRuntimeWorkload(1000, 1.0)
+                SimWorkloads.runtime(1000, 1.0)
             )
 
         assertThrows<IllegalStateException> { machine.runWorkload(workload) }
@@ -143,7 +145,7 @@ class SimChainWorkloadTest {
         val workload =
             SimWorkloads.chain(
                 workloadA,
-                SimRuntimeWorkload(1000, 1.0)
+                SimWorkloads.runtime(1000, 1.0)
             )
 
         assertThrows<IllegalStateException> { machine.runWorkload(workload) }
@@ -166,9 +168,9 @@ class SimChainWorkloadTest {
 
         val workload =
             SimWorkloads.chain(
-                SimRuntimeWorkload(1000, 1.0),
+                SimWorkloads.runtime(1000, 1.0),
                 workloadA,
-                SimRuntimeWorkload(1000, 1.0)
+                SimWorkloads.runtime(1000, 1.0)
             )
 
         assertThrows<IllegalStateException> { machine.runWorkload(workload) }
@@ -255,4 +257,29 @@ class SimChainWorkloadTest {
         assertEquals(1, exc.cause!!.suppressedExceptions.size)
         assertEquals(1000, clock.millis())
     }
+
+    @Test
+    fun testSnapshot() = runSimulation {
+        val engine = FlowEngine.create(coroutineContext, clock)
+        val graph = engine.newGraph()
+
+        val machine = SimBareMetalMachine.create(graph, machineModel)
+        val workload =
+            SimWorkloads.chain(
+                SimWorkloads.runtime(1000, 1.0),
+                SimWorkloads.runtime(1000, 1.0)
+            )
+
+        val job = launch { machine.runWorkload(workload) }
+        delay(500L)
+        val snapshot = workload.snapshot()
+
+        job.join()
+
+        assertEquals(2000, clock.millis())
+
+        machine.runWorkload(snapshot)
+
+        assertEquals(3500, clock.millis())
+    }
 }