refactor(compute): Expose CPU and system stats via Host interface

This change updates the `Host` interface to directly expose CPU and
system stats to be used by components that interface with the `Host`
interface.

Previously, this would require the user to interact with the OpenTelemetry SDK.
Although that is still possible for more advanced usage cases, users can
use the following methods to easily access common host and guest
statistics.

1 files changed, 24 insertions, 96 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 f0325023..67689dc8 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
@@ -22,8 +22,7 @@
 
 package org.opendc.compute.simulator
 
-import io.opentelemetry.sdk.metrics.SdkMeterProvider
-import io.opentelemetry.sdk.resources.Resource
+import io.opentelemetry.api.metrics.MeterProvider
 import kotlinx.coroutines.*
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.BeforeEach
@@ -42,13 +41,6 @@ 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.telemetry.compute.ComputeMetricExporter
-import org.opendc.telemetry.compute.HOST_ID
-import org.opendc.telemetry.compute.table.HostTableReader
-import org.opendc.telemetry.compute.table.ServerTableReader
-import org.opendc.telemetry.sdk.metrics.export.CoroutineMetricReader
-import org.opendc.telemetry.sdk.toOtelClock
-import java.time.Duration
 import java.util.*
 import kotlin.coroutines.resume
 
@@ -73,45 +65,16 @@ internal class SimHostTest {
      */
     @Test
     fun testOvercommitted() = runBlockingSimulation {
-        var idleTime = 0L
-        var activeTime = 0L
-        var stealTime = 0L
-
-        val hostId = UUID.randomUUID()
-        val hostResource = Resource.builder()
-            .put(HOST_ID, hostId.toString())
-            .build()
-
-        // Setup metric reader
         val duration = 5 * 60L
-        val reader = CoroutineMetricReader(
-            this,
-            object : ComputeMetricExporter() {
-                override fun record(reader: HostTableReader) {
-                    activeTime += reader.cpuActiveTime
-                    idleTime += reader.cpuIdleTime
-                    stealTime += reader.cpuStealTime
-                }
-            },
-            exportInterval = Duration.ofSeconds(duration)
-        )
-
-        val meterProvider = SdkMeterProvider
-            .builder()
-            .setResource(hostResource)
-            .setClock(clock.toOtelClock())
-            .registerMetricReader(reader)
-            .build()
-
         val engine = FlowEngine(coroutineContext, clock)
-        val virtDriver = SimHost(
-            uid = hostId,
+        val host = SimHost(
+            uid = UUID.randomUUID(),
             name = "test",
             model = machineModel,
             meta = emptyMap(),
             coroutineContext,
             engine,
-            meterProvider,
+            MeterProvider.noop(),
             SimFairShareHypervisorProvider()
         )
         val vmImageA = MockImage(
@@ -150,11 +113,11 @@ internal class SimHostTest {
         val flavor = MockFlavor(2, 0)
 
         coroutineScope {
-            launch { virtDriver.spawn(MockServer(UUID.randomUUID(), "a", flavor, vmImageA)) }
-            launch { virtDriver.spawn(MockServer(UUID.randomUUID(), "b", flavor, vmImageB)) }
+            launch { host.spawn(MockServer(UUID.randomUUID(), "a", flavor, vmImageA)) }
+            launch { host.spawn(MockServer(UUID.randomUUID(), "b", flavor, vmImageB)) }
 
             suspendCancellableCoroutine<Unit> { cont ->
-                virtDriver.addListener(object : HostListener {
+                host.addListener(object : HostListener {
                     private var finished = 0
 
                     override fun onStateChanged(host: Host, server: Server, newState: ServerState) {
@@ -168,13 +131,14 @@ internal class SimHostTest {
 
         // Ensure last cycle is collected
         delay(1000L * duration)
-        virtDriver.close()
-        meterProvider.close()
+        host.close()
+
+        val cpuStats = host.getCpuStats()
 
         assertAll(
-            { assertEquals(658, activeTime, "Active time does not match") },
-            { assertEquals(2341, idleTime, "Idle time does not match") },
-            { assertEquals(637, stealTime, "Steal time does not match") },
+            { assertEquals(658, cpuStats.activeTime, "Active time does not match") },
+            { assertEquals(2341, cpuStats.idleTime, "Idle time does not match") },
+            { assertEquals(637, cpuStats.stealTime, "Steal time does not match") },
             { assertEquals(1500001, clock.millis()) }
         )
     }
@@ -184,54 +148,16 @@ internal class SimHostTest {
      */
     @Test
     fun testFailure() = runBlockingSimulation {
-        var activeTime = 0L
-        var idleTime = 0L
-        var uptime = 0L
-        var downtime = 0L
-        var guestUptime = 0L
-        var guestDowntime = 0L
-
-        val hostId = UUID.randomUUID()
-        val hostResource = Resource.builder()
-            .put(HOST_ID, hostId.toString())
-            .build()
-
-        // Setup metric reader
         val duration = 5 * 60L
-        val reader = CoroutineMetricReader(
-            this,
-            object : ComputeMetricExporter() {
-                override fun record(reader: HostTableReader) {
-                    activeTime += reader.cpuActiveTime
-                    idleTime += reader.cpuIdleTime
-                    uptime += reader.uptime
-                    downtime += reader.downtime
-                }
-
-                override fun record(reader: ServerTableReader) {
-                    guestUptime += reader.uptime
-                    guestDowntime += reader.downtime
-                }
-            },
-            exportInterval = Duration.ofSeconds(duration)
-        )
-
-        val meterProvider = SdkMeterProvider
-            .builder()
-            .setResource(hostResource)
-            .setClock(clock.toOtelClock())
-            .registerMetricReader(reader)
-            .build()
-
         val engine = FlowEngine(coroutineContext, clock)
         val host = SimHost(
-            uid = hostId,
+            uid = UUID.randomUUID(),
             name = "test",
             model = machineModel,
             meta = emptyMap(),
             coroutineContext,
             engine,
-            meterProvider,
+            MeterProvider.noop(),
             SimFairShareHypervisorProvider()
         )
         val image = MockImage(
@@ -275,15 +201,17 @@ internal class SimHostTest {
         // Ensure last cycle is collected
         delay(1000L * duration)
 
-        meterProvider.close()
+        val cpuStats = host.getCpuStats()
+        val sysStats = host.getSystemStats()
+        val guestSysStats = host.getSystemStats(server)
 
         assertAll(
-            { assertEquals(1775, idleTime, "Idle time does not match") },
-            { assertEquals(624, activeTime, "Active time does not match") },
-            { assertEquals(900001, uptime, "Uptime does not match") },
-            { assertEquals(300000, downtime, "Downtime does not match") },
-            { assertEquals(900000, guestUptime, "Guest uptime does not match") },
-            { assertEquals(300000, guestDowntime, "Guest downtime does not match") },
+            { assertEquals(1775, cpuStats.idleTime, "Idle time does not match") },
+            { assertEquals(624, cpuStats.activeTime, "Active time does not match") },
+            { assertEquals(900001, sysStats.uptime.toMillis(), "Uptime does not match") },
+            { assertEquals(300000, sysStats.downtime.toMillis(), "Downtime does not match") },
+            { assertEquals(900001, guestSysStats.uptime.toMillis(), "Guest uptime does not match") },
+            { assertEquals(300000, guestSysStats.downtime.toMillis(), "Guest downtime does not match") },
         )
     }