merge: Implement multi-flow stages in simulator (#110)

This pull request introduces the new `flow2` multi-flow simulator into the OpenDC codebase
and adjust all existing modules to make use of this new simulator.

The new simulator models flow as a network of components, which can each receive flow
from (potentially) multiple other components. In the previous simulator, the framework itself
supported only single flows between components and required re-implementation of many
components to support multiplexing flows.

Initial benchmarks show performance improvements in the range 2x–4x for large scale experiments
such as the Capelin benchmarks.

## Implementation Notes :hammer_and_pick:

* Add support for multi-flow stages
* Support flow transformations
* Add forwarding flow multiplexer
* Expose metrics on FlowMultiplexer
* Re-implement network sim using flow2
* Re-implement power sim using flow2 
* Re-implement compute sim using flow2
* Optimize workload implementation of SimTrace 
* Remove old flow simulator 
* Add log4j-core dependency 

## External Dependencies :four_leaf_clover:

* N/A

## Breaking API Changes :warning:

* Removal of the `org.opendc.simulator.flow` package. You should now use
   the new flow simulator located in `org.opendc.simulator.flow2`.
* `PowerModel` interface is replaced by the `CpuPowerModel` interface.
* `PowerDriver` interface is replaced by the `SimPsu` and `SimPsuFactory` interfaces.
* Removal of `SimTraceWorkload`. Instead, create a workload from a `SimTrace` using 
  `createWorkload(offset)`.
* `ScalingGovernor` has been split in a `ScalingGovernor` and `ScalingGovernorFactory`.
* All modules in `opendc-simulator` are now written in Java. This means that default 
   parameters are not supported anymore for these modules.

5 files changed, 29 insertions, 15 deletions

diff --git a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/FailureModel.kt b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/FailureModel.kt
index e0d6fdc1..81a5cf33 100644
--- a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/FailureModel.kt
+++ b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/FailureModel.kt
@@ -35,5 +35,10 @@ public interface FailureModel {
     /**
      * Construct a [HostFaultInjector] for the specified [service].
      */
-    public fun createInjector(context: CoroutineContext, clock: Clock, service: ComputeService, random: Random): HostFaultInjector
+    public fun createInjector(
+        context: CoroutineContext,
+        clock: Clock,
+        service: ComputeService,
+        random: Random
+    ): HostFaultInjector
 }
diff --git a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/HostsProvisioningStep.kt b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/HostsProvisioningStep.kt
index 9fa8d00c..292be929 100644
--- a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/HostsProvisioningStep.kt
+++ b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/HostsProvisioningStep.kt
@@ -29,7 +29,7 @@ import org.opendc.experiments.provisioner.ProvisioningContext
 import org.opendc.experiments.provisioner.ProvisioningStep
 import org.opendc.simulator.compute.SimBareMetalMachine
 import org.opendc.simulator.compute.kernel.SimHypervisor
-import org.opendc.simulator.flow.FlowEngine
+import org.opendc.simulator.flow2.FlowEngine
 import java.util.SplittableRandom
 
 /**
@@ -46,19 +46,20 @@ public class HostsProvisioningStep internal constructor(
 ) : ProvisioningStep {
     override fun apply(ctx: ProvisioningContext): AutoCloseable {
         val service = requireNotNull(ctx.registry.resolve(serviceDomain, ComputeService::class.java)) { "Compute service $serviceDomain does not exist" }
-        val engine = FlowEngine(ctx.coroutineContext, ctx.clock)
+        val engine = FlowEngine.create(ctx.coroutineContext, ctx.clock)
+        val graph = engine.newGraph()
         val hosts = mutableSetOf<SimHost>()
 
         for (spec in specs) {
-            val machine = SimBareMetalMachine(engine, spec.model, spec.powerDriver)
-            val hypervisor = SimHypervisor(engine, spec.multiplexerFactory, SplittableRandom(ctx.seeder.nextLong()))
+            val machine = SimBareMetalMachine.create(graph, spec.model, spec.psuFactory)
+            val hypervisor = SimHypervisor.create(spec.multiplexerFactory, SplittableRandom(ctx.seeder.nextLong()))
 
             val host = SimHost(
                 spec.uid,
                 spec.name,
                 spec.meta,
                 ctx.coroutineContext,
-                ctx.clock,
+                graph,
                 machine,
                 hypervisor,
                 optimize = optimize
diff --git a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/TraceHelpers.kt b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/TraceHelpers.kt
index e98636fa..f0e31932 100644
--- a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/TraceHelpers.kt
+++ b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/TraceHelpers.kt
@@ -29,7 +29,6 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.yield
 import org.opendc.compute.service.ComputeService
-import org.opendc.simulator.compute.workload.SimTraceWorkload
 import java.time.Clock
 import java.util.Random
 import kotlin.coroutines.coroutineContext
@@ -82,7 +81,7 @@ public suspend fun ComputeService.replay(
                 }
 
                 val workloadOffset = -offset + 300001
-                val workload = SimTraceWorkload(entry.trace, workloadOffset)
+                val workload = entry.trace.createWorkload(workloadOffset)
                 val meta = mutableMapOf<String, Any>("workload" to workload)
 
                 val interferenceProfile = entry.interferenceProfile
diff --git a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/telemetry/table/ServiceData.kt b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/telemetry/table/ServiceData.kt
index 5b6960a3..e19d7c68 100644
--- a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/telemetry/table/ServiceData.kt
+++ b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/telemetry/table/ServiceData.kt
@@ -43,5 +43,15 @@ public data class ServiceData(
  * Convert a [ServiceTableReader] into a persistent object.
  */
 public fun ServiceTableReader.toServiceData(): ServiceData {
-    return ServiceData(timestamp, hostsUp, hostsDown, serversTotal, serversPending, serversActive, attemptsSuccess, attemptsFailure, attemptsError)
+    return ServiceData(
+        timestamp,
+        hostsUp,
+        hostsDown,
+        serversTotal,
+        serversPending,
+        serversActive,
+        attemptsSuccess,
+        attemptsFailure,
+        attemptsError
+    )
 }
diff --git a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/topology/HostSpec.kt b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/topology/HostSpec.kt
index b5dbaaeb..08c3dca2 100644
--- a/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/topology/HostSpec.kt
+++ b/opendc-experiments/opendc-experiments-compute/src/main/kotlin/org/opendc/experiments/compute/topology/HostSpec.kt
@@ -22,11 +22,10 @@
 
 package org.opendc.experiments.compute.topology
 
+import org.opendc.simulator.compute.SimPsuFactories
+import org.opendc.simulator.compute.SimPsuFactory
 import org.opendc.simulator.compute.model.MachineModel
-import org.opendc.simulator.compute.power.LinearPowerModel
-import org.opendc.simulator.compute.power.PowerDriver
-import org.opendc.simulator.compute.power.SimplePowerDriver
-import org.opendc.simulator.flow.mux.FlowMultiplexerFactory
+import org.opendc.simulator.flow2.mux.FlowMultiplexerFactory
 import java.util.UUID
 
 /**
@@ -36,7 +35,7 @@ import java.util.UUID
  * @param name The name of the host.
  * @param meta The metadata of the host.
  * @param model The physical model of the machine.
- * @param powerDriver The [PowerDriver] to model the power consumption of the machine.
+ * @param psuFactory The [SimPsuFactory] to construct the PSU that models the power consumption of the machine.
  * @param multiplexerFactory The [FlowMultiplexerFactory] that is used to multiplex the virtual machines over the host.
  */
 public data class HostSpec(
@@ -44,6 +43,6 @@ public data class HostSpec(
     val name: String,
     val meta: Map<String, Any>,
     val model: MachineModel,
-    val powerDriver: PowerDriver = SimplePowerDriver(LinearPowerModel(350.0, idlePower = 200.0)),
+    val psuFactory: SimPsuFactory = SimPsuFactories.noop(),
     val multiplexerFactory: FlowMultiplexerFactory = FlowMultiplexerFactory.maxMinMultiplexer()
 )