merge: Extract scheduler from simulation coroutine dispatcher (#106)

This pull request extracts the scheduler from the `SimulationCoroutineDispatcher` into 
a separate `SimulationScheduler` class which allows users to re-use the scheduler 
between different coroutine dispatchers.

We implement the `SimulationScheduler` in Java, removing the explicit dependency on 
Kotlin or `kotlinx-coroutines`. The scheduler uses a separate specialized priority queue 
implementation that eliminates allocation in the hot path of the simulator.

## Implementation Notes :hammer_and_pick:

* Add Java-based simulator core
* Use SimulationScheduler in coroutine dispatcher
* Rename runBlockingSimulation to runSimulation

## External Dependencies :four_leaf_clover:

* N/A 

## Breaking API Changes :warning:

* The Kotlin API for simulation has been moved to `org.opendc.simulator.kotlin`.
* `runBlockingSImulation` renamed to `runSimulation`

2 files changed, 6 insertions, 6 deletions

diff --git a/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/TensorFlowTest.kt b/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/TensorFlowTest.kt
index 328f1326..eee8b730 100644
--- a/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/TensorFlowTest.kt
+++ b/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/TensorFlowTest.kt
@@ -30,7 +30,7 @@ import org.opendc.experiments.tf20.distribute.MirroredStrategy
 import org.opendc.experiments.tf20.distribute.OneDeviceStrategy
 import org.opendc.experiments.tf20.util.MLEnvironmentReader
 import org.opendc.simulator.compute.power.LinearPowerModel
-import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.kotlin.runSimulation
 import java.util.*
 
 /**
@@ -41,7 +41,7 @@ class TensorFlowTest {
      * Smoke test that tests the capabilities of the TensorFlow application model in OpenDC.
      */
     @Test
-    fun testSmokeAlexNet() = runBlockingSimulation {
+    fun testSmokeAlexNet() = runSimulation {
         val envInput = checkNotNull(TensorFlowTest::class.java.getResourceAsStream("/kth.json"))
         val def = MLEnvironmentReader().readEnvironment(envInput).first()
 
@@ -71,7 +71,7 @@ class TensorFlowTest {
      * Smoke test that tests the capabilities of the TensorFlow application model in OpenDC.
      */
     @Test
-    fun testSmokeVGG() = runBlockingSimulation {
+    fun testSmokeVGG() = runSimulation {
         val envInput = checkNotNull(TensorFlowTest::class.java.getResourceAsStream("/kth.json"))
         val def = MLEnvironmentReader().readEnvironment(envInput).first()
 
@@ -101,7 +101,7 @@ class TensorFlowTest {
      * Smoke test that tests the capabilities of the TensorFlow application model in OpenDC.
      */
     @Test
-    fun testSmokeDistribute() = runBlockingSimulation {
+    fun testSmokeDistribute() = runSimulation {
         val envInput = checkNotNull(TensorFlowTest::class.java.getResourceAsStream("/kth.json"))
         val def = MLEnvironmentReader().readEnvironment(envInput).first()
 
diff --git a/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/core/SimTFDeviceTest.kt b/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/core/SimTFDeviceTest.kt
index 051d5730..966ca5ef 100644
--- a/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/core/SimTFDeviceTest.kt
+++ b/opendc-experiments/opendc-experiments-tf20/src/test/kotlin/org/opendc/experiments/tf20/core/SimTFDeviceTest.kt
@@ -31,7 +31,7 @@ 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.LinearPowerModel
-import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.kotlin.runSimulation
 import java.util.*
 
 /**
@@ -39,7 +39,7 @@ import java.util.*
  */
 internal class SimTFDeviceTest {
     @Test
-    fun testSmoke() = runBlockingSimulation {
+    fun testSmoke() = runSimulation {
         val puNode = ProcessingNode("NVIDIA", "Tesla V100", "unknown", 1)
         val pu = ProcessingUnit(puNode, 0, 960 * 1230.0)
         val memory = MemoryUnit("NVIDIA", "Tesla V100", 877.0, 32_000)