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.

2 files changed, 3 insertions, 4 deletions

diff --git a/opendc-experiments/opendc-experiments-faas/src/main/kotlin/org/opendc/experiments/faas/FunctionTraceWorkload.kt b/opendc-experiments/opendc-experiments-faas/src/main/kotlin/org/opendc/experiments/faas/FunctionTraceWorkload.kt
index 90e76dac..71a2536c 100644
--- a/opendc-experiments/opendc-experiments-faas/src/main/kotlin/org/opendc/experiments/faas/FunctionTraceWorkload.kt
+++ b/opendc-experiments/opendc-experiments-faas/src/main/kotlin/org/opendc/experiments/faas/FunctionTraceWorkload.kt
@@ -25,13 +25,12 @@ package org.opendc.experiments.faas
 import org.opendc.faas.simulator.workload.SimFaaSWorkload
 import org.opendc.simulator.compute.workload.SimTrace
 import org.opendc.simulator.compute.workload.SimTraceFragment
-import org.opendc.simulator.compute.workload.SimTraceWorkload
 import org.opendc.simulator.compute.workload.SimWorkload
 
 /**
  * A [SimFaaSWorkload] for a [FunctionTrace].
  */
 public class FunctionTraceWorkload(trace: FunctionTrace) :
-    SimFaaSWorkload, SimWorkload by SimTraceWorkload(SimTrace.ofFragments(trace.samples.map { SimTraceFragment(it.timestamp, it.duration, it.cpuUsage, 1) })) {
+    SimFaaSWorkload, SimWorkload by SimTrace.ofFragments(trace.samples.map { SimTraceFragment(it.timestamp, it.duration, it.cpuUsage, 1) }).createWorkload(0) {
     override suspend fun invoke() {}
 }
diff --git a/opendc-experiments/opendc-experiments-faas/src/test/kotlin/org/opendc/experiments/faas/FaaSExperiment.kt b/opendc-experiments/opendc-experiments-faas/src/test/kotlin/org/opendc/experiments/faas/FaaSExperiment.kt
index 2342c3f6..1ad9c57f 100644
--- a/opendc-experiments/opendc-experiments-faas/src/test/kotlin/org/opendc/experiments/faas/FaaSExperiment.kt
+++ b/opendc-experiments/opendc-experiments-faas/src/test/kotlin/org/opendc/experiments/faas/FaaSExperiment.kt
@@ -82,8 +82,8 @@ class FaaSExperiment {
         val cpuNode = ProcessingNode("Intel", "Xeon", "amd64", 2)
 
         return MachineModel(
-            cpus = List(cpuNode.coreCount) { ProcessingUnit(cpuNode, it, 1000.0) },
-            memory = List(4) { MemoryUnit("Crucial", "MTA18ASF4G72AZ-3G2B1", 3200.0, 32_000) }
+            /*cpus*/ List(cpuNode.coreCount) { ProcessingUnit(cpuNode, it, 1000.0) },
+            /*memory*/ List(4) { MemoryUnit("Crucial", "MTA18ASF4G72AZ-3G2B1", 3200.0, 32_000) }
         )
     }
 }