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, 5 insertions, 5 deletions

diff --git a/opendc-workflow/opendc-workflow-service/build.gradle.kts b/opendc-workflow/opendc-workflow-service/build.gradle.kts
index 6908a5af..446c43a4 100644
--- a/opendc-workflow/opendc-workflow-service/build.gradle.kts
+++ b/opendc-workflow/opendc-workflow-service/build.gradle.kts
@@ -38,5 +38,6 @@ dependencies {
     testImplementation(projects.opendcExperiments.opendcExperimentsWorkflow)
     testImplementation(projects.opendcTrace.opendcTraceApi)
     testRuntimeOnly(projects.opendcTrace.opendcTraceGwf)
+    testRuntimeOnly(libs.log4j.core)
     testRuntimeOnly(libs.log4j.slf4j)
 }
diff --git a/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceTest.kt b/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceTest.kt
index 977f5677..c7123000 100644
--- a/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceTest.kt
+++ b/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceTest.kt
@@ -41,13 +41,12 @@ import org.opendc.experiments.workflow.WorkflowSchedulerSpec
 import org.opendc.experiments.workflow.replay
 import org.opendc.experiments.workflow.setupWorkflowService
 import org.opendc.experiments.workflow.toJobs
+import org.opendc.simulator.compute.SimPsuFactories
 import org.opendc.simulator.compute.model.MachineModel
 import org.opendc.simulator.compute.model.MemoryUnit
 import org.opendc.simulator.compute.model.ProcessingNode
 import org.opendc.simulator.compute.model.ProcessingUnit
-import org.opendc.simulator.compute.power.ConstantPowerModel
-import org.opendc.simulator.compute.power.SimplePowerDriver
-import org.opendc.simulator.flow.mux.FlowMultiplexerFactory
+import org.opendc.simulator.flow2.mux.FlowMultiplexerFactory
 import org.opendc.simulator.kotlin.runSimulation
 import org.opendc.trace.Trace
 import org.opendc.workflow.service.scheduler.job.NullJobAdmissionPolicy
@@ -120,7 +119,7 @@ internal class WorkflowServiceTest {
                 },
                 { assertEquals(0, metrics.tasksRunning, "Not all started tasks finished") },
                 { assertEquals(metrics.tasksSubmitted, metrics.tasksFinished, "Not all started tasks finished") },
-                { assertEquals(32649883L, clock.millis()) { "Total duration incorrect" } }
+                { assertEquals(46102707L, clock.millis()) { "Total duration incorrect" } }
             )
         }
     }
@@ -141,7 +140,7 @@ internal class WorkflowServiceTest {
             "host-$uid",
             emptyMap(),
             machineModel,
-            SimplePowerDriver(ConstantPowerModel(0.0)),
+            SimPsuFactories.noop(),
             FlowMultiplexerFactory.forwardingMultiplexer()
         )
     }