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, 7 insertions, 7 deletions

diff --git a/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimHostTest.kt b/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimHostTest.kt
index a7993291..f63d4c6f 100644
--- a/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimHostTest.kt
+++ b/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/SimHostTest.kt
@@ -41,9 +41,9 @@ import org.opendc.simulator.compute.power.SimplePowerDriver
 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.core.runBlockingSimulation
 import org.opendc.simulator.flow.FlowEngine
 import org.opendc.simulator.flow.mux.FlowMultiplexerFactory
+import org.opendc.simulator.kotlin.runSimulation
 import java.time.Instant
 import java.util.*
 import kotlin.coroutines.resume
@@ -68,7 +68,7 @@ internal class SimHostTest {
      * Test overcommitting of resources by the hypervisor.
      */
     @Test
-    fun testOvercommitted() = runBlockingSimulation {
+    fun testOvercommitted() = runSimulation {
         val duration = 5 * 60L
         val engine = FlowEngine(coroutineContext, clock)
         val machine = SimBareMetalMachine(engine, machineModel, SimplePowerDriver(ConstantPowerModel(0.0)))
@@ -152,7 +152,7 @@ internal class SimHostTest {
      * Test failure of the host.
      */
     @Test
-    fun testFailure() = runBlockingSimulation {
+    fun testFailure() = runSimulation {
         val duration = 5 * 60L
         val engine = FlowEngine(coroutineContext, clock)
         val machine = SimBareMetalMachine(engine, machineModel, SimplePowerDriver(ConstantPowerModel(0.0)))
diff --git a/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/failure/HostFaultInjectorTest.kt b/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/failure/HostFaultInjectorTest.kt
index f240a25f..90f534e6 100644
--- a/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/failure/HostFaultInjectorTest.kt
+++ b/opendc-compute/opendc-compute-simulator/src/test/kotlin/org/opendc/compute/simulator/failure/HostFaultInjectorTest.kt
@@ -29,7 +29,7 @@ import org.apache.commons.math3.distribution.LogNormalDistribution
 import org.apache.commons.math3.random.Well19937c
 import org.junit.jupiter.api.Test
 import org.opendc.compute.simulator.SimHost
-import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.kotlin.runSimulation
 import java.time.Clock
 import java.time.Duration
 import kotlin.coroutines.CoroutineContext
@@ -43,7 +43,7 @@ internal class HostFaultInjectorTest {
      * Simple test case to test that nothing happens when the injector is not started.
      */
     @Test
-    fun testInjectorNotStarted() = runBlockingSimulation {
+    fun testInjectorNotStarted() = runSimulation {
         val host = mockk<SimHost>(relaxUnitFun = true)
 
         val injector = createSimpleInjector(coroutineContext, clock, setOf(host))
@@ -58,7 +58,7 @@ internal class HostFaultInjectorTest {
      * Simple test case to test a start stop fault where the machine is stopped and started after some time.
      */
     @Test
-    fun testInjectorStopsMachine() = runBlockingSimulation {
+    fun testInjectorStopsMachine() = runSimulation {
         val host = mockk<SimHost>(relaxUnitFun = true)
 
         val injector = createSimpleInjector(coroutineContext, clock, setOf(host))
@@ -77,7 +77,7 @@ internal class HostFaultInjectorTest {
      * Simple test case to test a start stop fault where multiple machines are stopped.
      */
     @Test
-    fun testInjectorStopsMultipleMachines() = runBlockingSimulation {
+    fun testInjectorStopsMultipleMachines() = runSimulation {
         val hosts = listOf<SimHost>(
             mockk(relaxUnitFun = true),
             mockk(relaxUnitFun = true)