merge: Improve workflow service (#43)

This pull request is the first in a series of changes to the workflow service. 
This pull request aims to help users setup workflow simulations. 
The next pull requests will focus on improving the design of the workflow service.

* Remove WorkflowSchedulerMode 
* Add helper tools for workflow simulations (e.g. `WorkflowServiceHelper`)

**Breaking API Changes**

* Removal of `WorkflowSchedulerMode`
* Rename from `ComputeWorkloadRunner` to `ComputeServiceHelper`

4 files changed, 295 insertions, 0 deletions

diff --git a/opendc-workflow/opendc-workflow-workload/build.gradle.kts b/opendc-workflow/opendc-workflow-workload/build.gradle.kts
new file mode 100644
index 00000000..dfb77a39
--- /dev/null
+++ b/opendc-workflow/opendc-workflow-workload/build.gradle.kts
@@ -0,0 +1,39 @@
+/*
+ * 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.
+ */
+
+description = "Support library for simulating workflows with OpenDC"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+    `testing-conventions`
+}
+
+dependencies {
+    api(platform(projects.opendcPlatform))
+    api(projects.opendcWorkflow.opendcWorkflowService)
+
+    implementation(projects.opendcSimulator.opendcSimulatorCompute)
+    implementation(projects.opendcTrace.opendcTraceApi)
+    implementation(projects.opendcTelemetry.opendcTelemetrySdk)
+    implementation(libs.opentelemetry.semconv)
+}
diff --git a/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/TraceHelpers.kt b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/TraceHelpers.kt
new file mode 100644
index 00000000..73995d08
--- /dev/null
+++ b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/TraceHelpers.kt
@@ -0,0 +1,93 @@
+/*
+ * 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.
+ */
+
+@file:JvmName("TraceHelpers")
+package org.opendc.workflow.workload
+
+import org.opendc.simulator.compute.workload.SimFlopsWorkload
+import org.opendc.trace.*
+import org.opendc.workflow.api.Job
+import org.opendc.workflow.api.Task
+import org.opendc.workflow.api.WORKFLOW_TASK_CORES
+import org.opendc.workflow.api.WORKFLOW_TASK_DEADLINE
+import java.util.*
+import kotlin.collections.HashMap
+import kotlin.collections.HashSet
+import kotlin.math.min
+
+/**
+ * Convert [Trace] into a list of [Job]s that can be submitted to the workflow service.
+ */
+public fun Trace.toJobs(): List<Job> {
+    val table = checkNotNull(getTable(TABLE_TASKS))
+    val reader = table.newReader()
+
+    val jobs = mutableMapOf<Long, Job>()
+    val tasks = mutableMapOf<Long, Task>()
+    val taskDependencies = mutableMapOf<Task, Set<Long>>()
+
+    try {
+        while (reader.nextRow()) {
+            // Bag of tasks without workflow ID all share the same workflow
+            val workflowId = if (reader.hasColumn(TASK_WORKFLOW_ID)) reader.get(TASK_WORKFLOW_ID).toLong() else 0L
+            val workflow = jobs.computeIfAbsent(workflowId) { id -> Job(UUID(0L, id), "<unnamed>", HashSet(), HashMap()) }
+
+            val id = reader.get(TASK_ID).toLong()
+            val grantedCpus = if (reader.hasColumn(TASK_ALLOC_NCPUS))
+                reader.getInt(TASK_ALLOC_NCPUS)
+            else
+                reader.getInt(TASK_REQ_NCPUS)
+            val submitTime = reader.get(TASK_SUBMIT_TIME)
+            val runtime = reader.get(TASK_RUNTIME)
+            val flops: Long = 4000 * runtime.seconds * grantedCpus
+            val workload = SimFlopsWorkload(flops)
+            val task = Task(
+                UUID(0L, id),
+                "<unnamed>",
+                HashSet(),
+                mapOf(
+                    "workload" to workload,
+                    WORKFLOW_TASK_CORES to grantedCpus,
+                    WORKFLOW_TASK_DEADLINE to runtime.toMillis()
+                ),
+            )
+
+            tasks[id] = task
+            taskDependencies[task] = reader.get(TASK_PARENTS).map { it.toLong() }.toSet()
+
+            (workflow.metadata as MutableMap<String, Any>).merge("WORKFLOW_SUBMIT_TIME", submitTime.toEpochMilli()) { a, b -> min(a as Long, b as Long) }
+            (workflow.tasks as MutableSet<Task>).add(task)
+        }
+
+        // Resolve dependencies for all tasks
+        for ((task, deps) in taskDependencies) {
+            for (dep in deps) {
+                val parent = requireNotNull(tasks[dep]) { "Dependency task with id $dep not found" }
+                (task.dependencies as MutableSet<Task>).add(parent)
+            }
+        }
+    } finally {
+        reader.close()
+    }
+
+    return jobs.values.toList()
+}
diff --git a/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowSchedulerSpec.kt b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowSchedulerSpec.kt
new file mode 100644
index 00000000..d6a375b6
--- /dev/null
+++ b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowSchedulerSpec.kt
@@ -0,0 +1,40 @@
+/*
+ * 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.workload
+
+import org.opendc.workflow.service.scheduler.job.JobAdmissionPolicy
+import org.opendc.workflow.service.scheduler.job.JobOrderPolicy
+import org.opendc.workflow.service.scheduler.task.TaskEligibilityPolicy
+import org.opendc.workflow.service.scheduler.task.TaskOrderPolicy
+import java.time.Duration
+
+/**
+ * Specification of the scheduling policies of the workflow scheduler.
+ */
+public data class WorkflowSchedulerSpec(
+    val schedulingQuantum: Duration,
+    val jobAdmissionPolicy: JobAdmissionPolicy,
+    val jobOrderPolicy: JobOrderPolicy,
+    val taskEligibilityPolicy: TaskEligibilityPolicy,
+    val taskOrderPolicy: TaskOrderPolicy,
+)
diff --git a/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowServiceHelper.kt b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowServiceHelper.kt
new file mode 100644
index 00000000..0198900f
--- /dev/null
+++ b/opendc-workflow/opendc-workflow-workload/src/main/kotlin/org/opendc/workflow/workload/WorkflowServiceHelper.kt
@@ -0,0 +1,123 @@
+/*
+ * 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.workload
+
+import io.opentelemetry.sdk.metrics.SdkMeterProvider
+import io.opentelemetry.sdk.metrics.export.MetricProducer
+import io.opentelemetry.sdk.resources.Resource
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import org.opendc.compute.api.ComputeClient
+import org.opendc.telemetry.sdk.toOtelClock
+import org.opendc.workflow.api.Job
+import org.opendc.workflow.service.WorkflowService
+import java.time.Clock
+import kotlin.coroutines.CoroutineContext
+
+/**
+ * Helper class to simulate workflow-based workloads in OpenDC.
+ *
+ * @param context [CoroutineContext] to run the simulation in.
+ * @param clock [Clock] instance tracking simulation time.
+ * @param computeClient A [ComputeClient] instance to communicate with the cluster scheduler.
+ * @param schedulerSpec The configuration of the workflow scheduler.
+ */
+public class WorkflowServiceHelper(
+    private val context: CoroutineContext,
+    private val clock: Clock,
+    private val computeClient: ComputeClient,
+    private val schedulerSpec: WorkflowSchedulerSpec
+) : AutoCloseable {
+    /**
+     * The [WorkflowService] that is constructed by this runner.
+     */
+    public val service: WorkflowService
+
+    /**
+     * The [MetricProducer] exposed by the [WorkflowService].
+     */
+    public val metricProducer: MetricProducer
+
+    init {
+        val resource = Resource.builder()
+            .put(ResourceAttributes.SERVICE_NAME, "opendc-workflow")
+            .build()
+
+        val meterProvider = SdkMeterProvider.builder()
+            .setClock(clock.toOtelClock())
+            .setResource(resource)
+            .build()
+        metricProducer = meterProvider
+
+        service = WorkflowService(
+            context,
+            clock,
+            meterProvider,
+            computeClient,
+            schedulerSpec.schedulingQuantum,
+            jobAdmissionPolicy = schedulerSpec.jobAdmissionPolicy,
+            jobOrderPolicy = schedulerSpec.jobOrderPolicy,
+            taskEligibilityPolicy = schedulerSpec.taskEligibilityPolicy,
+            taskOrderPolicy = schedulerSpec.taskOrderPolicy,
+        )
+    }
+
+    /**
+     * Run the specified list of [jobs] using the workflow service and suspend execution until all jobs have
+     * finished.
+     */
+    public suspend fun replay(jobs: List<Job>) {
+        // Sort jobs by their arrival time
+        val orderedJobs = jobs.sortedBy { it.metadata.getOrDefault("WORKFLOW_SUBMIT_TIME", Long.MAX_VALUE) as Long }
+        if (orderedJobs.isEmpty()) {
+            return
+        }
+
+        // Wait until the trace is started
+        val startTime = orderedJobs[0].metadata.getOrDefault("WORKFLOW_SUBMIT_TIME", Long.MAX_VALUE) as Long
+        var offset = 0L
+
+        if (startTime != Long.MAX_VALUE) {
+            offset = startTime - clock.millis()
+            delay(offset.coerceAtLeast(0))
+        }
+
+        coroutineScope {
+            for (job in orderedJobs) {
+                val submitTime = job.metadata.getOrDefault("WORKFLOW_SUBMIT_TIME", Long.MAX_VALUE) as Long
+                if (submitTime != Long.MAX_VALUE) {
+                    delay(((submitTime - offset) - clock.millis()).coerceAtLeast(0))
+                }
+
+                launch { service.invoke(job) }
+            }
+        }
+    }
+
+    override fun close() {
+        computeClient.close()
+        service.close()
+    }
+}