compute: Implement filter scheduler

This pull request implements the filter scheduler modeled after the scheduler 
from [OpenStack](https://docs.openstack.org/nova/latest/user/filter-scheduler.html). 
The scheduler is functionally equivalent to the old allocation policies, but is more 
flexible and allows policies to be combined.

* A new interface, `ComputeScheduler` is introduced, which is used by the 
  `ComputeServiceImpl` to pick hosts to schedule on.
* `FilterScheduler` is implemented, which works by filtering and weighing the available hosts.

**Breaking API Changes**

* Removal of the `AllocationPolicy` interface and its implementations. 
   Users should migrate to the filter scheduler which offers the same functionality and more.

1 files changed, 15 insertions, 6 deletions

diff --git a/simulator/opendc-experiments/opendc-experiments-capelin/src/test/kotlin/org/opendc/experiments/capelin/CapelinIntegrationTest.kt b/simulator/opendc-experiments/opendc-experiments-capelin/src/test/kotlin/org/opendc/experiments/capelin/CapelinIntegrationTest.kt
index d2e7473f..4a47922d 100644
--- a/simulator/opendc-experiments/opendc-experiments-capelin/src/test/kotlin/org/opendc/experiments/capelin/CapelinIntegrationTest.kt
+++ b/simulator/opendc-experiments/opendc-experiments-capelin/src/test/kotlin/org/opendc/experiments/capelin/CapelinIntegrationTest.kt
@@ -34,7 +34,10 @@ import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertAll
 import org.opendc.compute.service.driver.Host
-import org.opendc.compute.service.scheduler.AvailableCoreMemoryAllocationPolicy
+import org.opendc.compute.service.scheduler.FilterScheduler
+import org.opendc.compute.service.scheduler.filters.ComputeCapabilitiesFilter
+import org.opendc.compute.service.scheduler.filters.ComputeFilter
+import org.opendc.compute.service.scheduler.weights.CoreMemoryWeigher
 import org.opendc.experiments.capelin.model.Workload
 import org.opendc.experiments.capelin.monitor.ExperimentMonitor
 import org.opendc.experiments.capelin.trace.Sc20ParquetTraceReader
@@ -71,7 +74,10 @@ class CapelinIntegrationTest {
         val failures = false
         val seed = 0
         val chan = Channel<Unit>(Channel.CONFLATED)
-        val allocationPolicy = AvailableCoreMemoryAllocationPolicy()
+        val allocationPolicy = FilterScheduler(
+            filters = listOf(ComputeFilter(), ComputeCapabilitiesFilter()),
+            weighers = listOf(CoreMemoryWeigher() to -1.0)
+        )
         val traceReader = createTestTraceReader()
         val environmentReader = createTestEnvironmentReader()
         lateinit var monitorResults: ComputeMetrics
@@ -118,9 +124,9 @@ class CapelinIntegrationTest {
             { assertEquals(0, monitorResults.runningVms, "All VMs should finish after a run") },
             { assertEquals(0, monitorResults.unscheduledVms, "No VM should not be unscheduled") },
             { assertEquals(0, monitorResults.queuedVms, "No VM should not be in the queue") },
-            { assertEquals(207388095207, monitor.totalRequestedBurst) { "Incorrect requested burst" } },
-            { assertEquals(204745144701, monitor.totalGrantedBurst) { "Incorrect granted burst" } },
-            { assertEquals(2642950497, monitor.totalOvercommissionedBurst) { "Incorrect overcommitted burst" } },
+            { assertEquals(207389912923, monitor.totalRequestedBurst) { "Incorrect requested burst" } },
+            { assertEquals(207122087280, monitor.totalGrantedBurst) { "Incorrect granted burst" } },
+            { assertEquals(267825640, monitor.totalOvercommissionedBurst) { "Incorrect overcommitted burst" } },
             { assertEquals(0, monitor.totalInterferedBurst) { "Incorrect interfered burst" } }
         )
     }
@@ -130,7 +136,10 @@ class CapelinIntegrationTest {
         val clock = DelayControllerClockAdapter(this)
         val seed = 1
         val chan = Channel<Unit>(Channel.CONFLATED)
-        val allocationPolicy = AvailableCoreMemoryAllocationPolicy()
+        val allocationPolicy = FilterScheduler(
+            filters = listOf(ComputeFilter(), ComputeCapabilitiesFilter()),
+            weighers = listOf(CoreMemoryWeigher() to -1.0)
+        )
         val traceReader = createTestTraceReader(0.5, seed)
         val environmentReader = createTestEnvironmentReader("single")