Integrate OpenTelemetry into OpenDC

This pull request resolves issue #91 by adopting the industry-standard OpenTelemetry standard
for collecting traces and metrics in OpenDC simulations:

* Metrics will now be exposed through OpenTelemetry's metrics API
* `opendc-telemetry` provides complementary code to support
    gathering telemetry in OpenDC.

**Breaking API Changes**
* `opendc-tracer` has been removed.
* `EventFlow` and all usages of it have been removed.
* `opendc-experiments-sc18` has been removed for now, but a 
    suitable replacement will follow soon.

3 files changed, 162 insertions, 139 deletions

diff --git a/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/StageWorkflowSchedulerIntegrationTest.kt b/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/StageWorkflowSchedulerIntegrationTest.kt
deleted file mode 100644
index 2161f5f2..00000000
--- a/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/StageWorkflowSchedulerIntegrationTest.kt
+++ /dev/null
@@ -1,139 +0,0 @@
-/*
- * Copyright (c) 2021 AtLarge Research
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- */
-
-package org.opendc.workflow.service
-
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.test.TestCoroutineScope
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNotEquals
-import org.junit.jupiter.api.DisplayName
-import org.junit.jupiter.api.Test
-import org.junit.jupiter.api.assertAll
-import org.opendc.compute.service.ComputeService
-import org.opendc.compute.service.scheduler.NumberOfActiveServersAllocationPolicy
-import org.opendc.compute.simulator.SimHost
-import org.opendc.format.environment.sc18.Sc18EnvironmentReader
-import org.opendc.format.trace.gwf.GwfTraceReader
-import org.opendc.simulator.compute.SimSpaceSharedHypervisorProvider
-import org.opendc.simulator.utils.DelayControllerClockAdapter
-import org.opendc.trace.core.EventTracer
-import org.opendc.workflow.service.internal.WorkflowServiceImpl
-import org.opendc.workflow.service.scheduler.WorkflowSchedulerMode
-import org.opendc.workflow.service.scheduler.job.NullJobAdmissionPolicy
-import org.opendc.workflow.service.scheduler.job.SubmissionTimeJobOrderPolicy
-import org.opendc.workflow.service.scheduler.task.NullTaskEligibilityPolicy
-import org.opendc.workflow.service.scheduler.task.SubmissionTimeTaskOrderPolicy
-import kotlin.math.max
-
-/**
- * Integration test suite for the [WorkflowServiceImpl].
- */
-@DisplayName("WorkflowServiceImpl")
-@OptIn(ExperimentalCoroutinesApi::class)
-internal class StageWorkflowSchedulerIntegrationTest {
-    /**
-     * A large integration test where we check whether all tasks in some trace are executed correctly.
-     */
-    @Test
-    fun testTrace() {
-        var jobsSubmitted = 0L
-        var jobsStarted = 0L
-        var jobsFinished = 0L
-        var tasksStarted = 0L
-        var tasksFinished = 0L
-
-        val testScope = TestCoroutineScope()
-        val clock = DelayControllerClockAdapter(testScope)
-        val tracer = EventTracer(clock)
-
-        val scheduler = let {
-            val hosts = Sc18EnvironmentReader(object {}.javaClass.getResourceAsStream("/environment.json"))
-                .use { it.read() }
-                .map { def ->
-                    SimHost(
-                        def.uid,
-                        def.name,
-                        def.model,
-                        def.meta,
-                        testScope.coroutineContext,
-                        clock,
-                        SimSpaceSharedHypervisorProvider()
-                    )
-                }
-
-            val compute = ComputeService(testScope.coroutineContext, clock, tracer, NumberOfActiveServersAllocationPolicy(), schedulingQuantum = 1000)
-
-            hosts.forEach { compute.addHost(it) }
-
-            WorkflowService(
-                testScope.coroutineContext,
-                clock,
-                tracer,
-                compute.newClient(),
-                mode = WorkflowSchedulerMode.Batch(100),
-                jobAdmissionPolicy = NullJobAdmissionPolicy,
-                jobOrderPolicy = SubmissionTimeJobOrderPolicy(),
-                taskEligibilityPolicy = NullTaskEligibilityPolicy,
-                taskOrderPolicy = SubmissionTimeTaskOrderPolicy(),
-            )
-        }
-
-        testScope.launch {
-            scheduler.events
-                .onEach { event ->
-                    when (event) {
-                        is WorkflowEvent.JobStarted -> jobsStarted++
-                        is WorkflowEvent.JobFinished -> jobsFinished++
-                        is WorkflowEvent.TaskStarted -> tasksStarted++
-                        is WorkflowEvent.TaskFinished -> tasksFinished++
-                    }
-                }
-                .collect()
-        }
-
-        testScope.launch {
-            val reader = GwfTraceReader(object {}.javaClass.getResourceAsStream("/trace.gwf"))
-
-            while (reader.hasNext()) {
-                val entry = reader.next()
-                jobsSubmitted++
-                delay(max(0, entry.start - clock.millis()))
-                scheduler.submit(entry.workload)
-            }
-        }
-
-        testScope.advanceUntilIdle()
-
-        assertAll(
-            { assertEquals(emptyList<Throwable>(), testScope.uncaughtExceptions) },
-            { assertNotEquals(0, jobsSubmitted, "No jobs submitted") },
-            { assertEquals(jobsSubmitted, jobsStarted, "Not all submitted jobs started") },
-            { assertEquals(jobsSubmitted, jobsFinished, "Not all started jobs finished") },
-            { assertEquals(tasksStarted, tasksFinished, "Not all started tasks finished") }
-        )
-    }
-}
diff --git a/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceIntegrationTest.kt b/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceIntegrationTest.kt
new file mode 100644
index 00000000..46c0d835
--- /dev/null
+++ b/simulator/opendc-workflow/opendc-workflow-service/src/test/kotlin/org/opendc/workflow/service/WorkflowServiceIntegrationTest.kt
@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.workflow.service
+
+import io.opentelemetry.api.metrics.MeterProvider
+import io.opentelemetry.sdk.metrics.SdkMeterProvider
+import io.opentelemetry.sdk.metrics.export.MetricProducer
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.runBlockingTest
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertAll
+import org.opendc.compute.service.ComputeService
+import org.opendc.compute.service.scheduler.NumberOfActiveServersAllocationPolicy
+import org.opendc.compute.simulator.SimHost
+import org.opendc.format.environment.sc18.Sc18EnvironmentReader
+import org.opendc.format.trace.gwf.GwfTraceReader
+import org.opendc.simulator.compute.SimSpaceSharedHypervisorProvider
+import org.opendc.simulator.utils.DelayControllerClockAdapter
+import org.opendc.telemetry.sdk.toOtelClock
+import org.opendc.workflow.service.internal.WorkflowServiceImpl
+import org.opendc.workflow.service.scheduler.WorkflowSchedulerMode
+import org.opendc.workflow.service.scheduler.job.NullJobAdmissionPolicy
+import org.opendc.workflow.service.scheduler.job.SubmissionTimeJobOrderPolicy
+import org.opendc.workflow.service.scheduler.task.NullTaskEligibilityPolicy
+import org.opendc.workflow.service.scheduler.task.SubmissionTimeTaskOrderPolicy
+import kotlin.math.max
+
+/**
+ * Integration test suite for the [WorkflowServiceImpl].
+ */
+@DisplayName("WorkflowServiceImpl")
+@OptIn(ExperimentalCoroutinesApi::class)
+internal class WorkflowServiceIntegrationTest {
+    /**
+     * A large integration test where we check whether all tasks in some trace are executed correctly.
+     */
+    @Test
+    fun testTrace() = runBlockingTest {
+        val clock = DelayControllerClockAdapter(this)
+
+        val meterProvider: MeterProvider = SdkMeterProvider
+            .builder()
+            .setClock(clock.toOtelClock())
+            .build()
+
+        val hosts = Sc18EnvironmentReader(object {}.javaClass.getResourceAsStream("/environment.json"))
+            .use { it.read() }
+            .map { def ->
+                SimHost(
+                    def.uid,
+                    def.name,
+                    def.model,
+                    def.meta,
+                    coroutineContext,
+                    clock,
+                    MeterProvider.noop().get("opendc-compute-simulator"),
+                    SimSpaceSharedHypervisorProvider()
+                )
+            }
+
+        val meter = MeterProvider.noop().get("opendc-compute")
+        val compute = ComputeService(coroutineContext, clock, meter, NumberOfActiveServersAllocationPolicy(), schedulingQuantum = 1000)
+
+        hosts.forEach { compute.addHost(it) }
+
+        val scheduler = WorkflowService(
+            coroutineContext,
+            clock,
+            meterProvider.get("opendc-workflow"),
+            compute.newClient(),
+            mode = WorkflowSchedulerMode.Batch(100),
+            jobAdmissionPolicy = NullJobAdmissionPolicy,
+            jobOrderPolicy = SubmissionTimeJobOrderPolicy(),
+            taskEligibilityPolicy = NullTaskEligibilityPolicy,
+            taskOrderPolicy = SubmissionTimeTaskOrderPolicy(),
+        )
+
+        val reader = GwfTraceReader(object {}.javaClass.getResourceAsStream("/trace.gwf"))
+        var offset = Long.MIN_VALUE
+
+        coroutineScope {
+            while (reader.hasNext()) {
+                val entry = reader.next()
+
+                if (offset < 0) {
+                    offset = entry.start - clock.millis()
+                }
+
+                delay(max(0, (entry.start - offset) - clock.millis()))
+                launch {
+                    scheduler.run(entry.workload)
+                }
+            }
+        }
+
+        hosts.forEach(SimHost::close)
+        scheduler.close()
+        compute.close()
+
+        val metrics = collectMetrics(meterProvider as MetricProducer)
+
+        assertAll(
+            { assertEquals(758, metrics.jobsSubmitted, "No jobs submitted") },
+            { assertEquals(0, metrics.jobsActive, "Not all submitted jobs started") },
+            { assertEquals(metrics.jobsSubmitted, metrics.jobsFinished, "Not all started jobs finished") },
+            { assertEquals(0, metrics.tasksActive, "Not all started tasks finished") },
+            { assertEquals(metrics.tasksSubmitted, metrics.tasksFinished, "Not all started tasks finished") }
+        )
+    }
+
+    class WorkflowMetrics {
+        var jobsSubmitted = 0L
+        var jobsActive = 0L
+        var jobsFinished = 0L
+        var tasksSubmitted = 0L
+        var tasksActive = 0L
+        var tasksFinished = 0L
+    }
+
+    /**
+     * Collect the metrics of the workflow service.
+     */
+    private fun collectMetrics(metricProducer: MetricProducer): WorkflowMetrics {
+        val metrics = metricProducer.collectAllMetrics().associateBy { it.name }
+        val res = WorkflowMetrics()
+        res.jobsSubmitted = metrics["jobs.submitted"]?.longSumData?.points?.last()?.value ?: 0
+        res.jobsActive = metrics["jobs.active"]?.longSumData?.points?.last()?.value ?: 0
+        res.jobsFinished = metrics["jobs.finished"]?.longSumData?.points?.last()?.value ?: 0
+        res.tasksSubmitted = metrics["tasks.submitted"]?.longSumData?.points?.last()?.value ?: 0
+        res.tasksActive = metrics["tasks.active"]?.longSumData?.points?.last()?.value ?: 0
+        res.tasksFinished = metrics["tasks.finished"]?.longSumData?.points?.last()?.value ?: 0
+        return res
+    }
+}
diff --git a/simulator/opendc-workflow/opendc-workflow-service/src/test/resources/log4j2.xml b/simulator/opendc-workflow/opendc-workflow-service/src/test/resources/log4j2.xml
index 70a0eacc..edcf41ed 100644
--- a/simulator/opendc-workflow/opendc-workflow-service/src/test/resources/log4j2.xml
+++ b/simulator/opendc-workflow/opendc-workflow-service/src/test/resources/log4j2.xml
@@ -28,6 +28,9 @@
         </Console>
     </Appenders>
     <Loggers>
+        <Logger name="org.opendc.workflow" level="info" additivity="false">
+            <AppenderRef ref="Console"/>
+        </Logger>
         <Root level="warn">
             <AppenderRef ref="Console"/>
         </Root>