refactor(workflow/service): Directly expose scheduler stats to user

This change updates the `WorkflowService` interface to directly expose
statistics about the scheduler to the user, such that they do not
necessarily have to interact with OpenTelemetry to obtain these values

3 files changed, 67 insertions, 0 deletions

diff --git a/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/WorkflowService.kt b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/WorkflowService.kt
index ebace07d..b8bc0e33 100644
--- a/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/WorkflowService.kt
+++ b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/WorkflowService.kt
@@ -30,6 +30,7 @@ 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 org.opendc.workflow.service.telemetry.SchedulerStats
 import java.time.Clock
 import java.time.Duration
 import kotlin.coroutines.CoroutineContext
@@ -46,6 +47,11 @@ public interface WorkflowService : AutoCloseable {
     public suspend fun invoke(job: Job)
 
     /**
+     * Collect statistics about the workflow scheduler.
+     */
+    public fun getSchedulerStats(): SchedulerStats
+
+    /**
      * Terminate the lifecycle of the workflow service, stopping all running workflows.
      */
     public override fun close()
diff --git a/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/internal/WorkflowServiceImpl.kt b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/internal/WorkflowServiceImpl.kt
index cdaec021..9c7f18a2 100644
--- a/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/internal/WorkflowServiceImpl.kt
+++ b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/internal/WorkflowServiceImpl.kt
@@ -34,6 +34,7 @@ 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 org.opendc.workflow.service.telemetry.SchedulerStats
 import java.time.Clock
 import java.time.Duration
 import java.util.*
@@ -145,6 +146,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of submitted jobs")
         .setUnit("1")
         .build()
+    private var _workflowsSubmitted: Int = 0
 
     /**
      * The number of jobs that are running.
@@ -153,6 +155,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of jobs running")
         .setUnit("1")
         .build()
+    private var _workflowsRunning: Int = 0
 
     /**
      * The number of jobs that have finished running.
@@ -161,6 +164,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of jobs that finished running")
         .setUnit("1")
         .build()
+    private var _workflowsFinished: Int = 0
 
     /**
      * The number of tasks that have been submitted to the service.
@@ -169,6 +173,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of submitted tasks")
         .setUnit("1")
         .build()
+    private var _tasksSubmitted: Int = 0
 
     /**
      * The number of jobs that are running.
@@ -177,6 +182,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of tasks running")
         .setUnit("1")
         .build()
+    private var _tasksRunning: Int = 0
 
     /**
      * The number of jobs that have finished running.
@@ -185,6 +191,7 @@ public class WorkflowServiceImpl(
         .setDescription("Number of tasks that finished running")
         .setUnit("1")
         .build()
+    private var _tasksFinished: Int = 0
 
     /**
      * The [Pacer] to use for scheduling the scheduler cycles.
@@ -223,16 +230,22 @@ public class WorkflowServiceImpl(
             }
 
             submittedTasks.add(1)
+            _tasksSubmitted++
         }
 
         instances.values.toCollection(jobInstance.tasks)
         incomingJobs += jobInstance
         rootListener.jobSubmitted(jobInstance)
         submittedJobs.add(1)
+        _workflowsSubmitted++
 
         pacer.enqueue()
     }
 
+    override fun getSchedulerStats(): SchedulerStats {
+        return SchedulerStats(_workflowsSubmitted, _workflowsRunning, _workflowsFinished, _tasksSubmitted, _tasksRunning, _tasksFinished)
+    }
+
     override fun close() {
         scope.cancel()
     }
@@ -271,6 +284,7 @@ public class WorkflowServiceImpl(
             activeJobs += jobInstance
 
             runningJobs.add(1)
+            _workflowsRunning++
             rootListener.jobStarted(jobInstance)
         }
 
@@ -350,6 +364,7 @@ public class WorkflowServiceImpl(
                 val task = taskByServer.getValue(server)
                 task.startedAt = clock.millis()
                 runningTasks.add(1)
+                _tasksRunning++
                 rootListener.taskStarted(task)
             }
             ServerState.TERMINATED, ServerState.ERROR -> {
@@ -368,6 +383,8 @@ public class WorkflowServiceImpl(
 
                 runningTasks.add(-1)
                 finishedTasks.add(1)
+                _tasksRunning--
+                _tasksFinished++
                 rootListener.taskFinished(task)
 
                 // Add job roots to the scheduling queue
@@ -395,6 +412,8 @@ public class WorkflowServiceImpl(
         activeJobs -= job
         runningJobs.add(-1)
         finishedJobs.add(1)
+        _workflowsRunning--
+        _workflowsFinished++
         rootListener.jobFinished(job)
 
         job.cont.resume(Unit)
diff --git a/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/telemetry/SchedulerStats.kt b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/telemetry/SchedulerStats.kt
new file mode 100644
index 00000000..7c7d7c4d
--- /dev/null
+++ b/opendc-workflow/opendc-workflow-service/src/main/kotlin/org/opendc/workflow/service/telemetry/SchedulerStats.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2022 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.telemetry
+
+/**
+ * Statistics about the workflow scheduler.
+ *
+ * @property workflowsSubmitted The number of workflows submitted to the scheduler.
+ * @property workflowsRunning The number of workflows that are currently running.
+ * @property workflowsFinished The number of workflows that have completed since the scheduler started.
+ * @property tasksSubmitted The number of tasks submitted to the scheduler.
+ * @property tasksRunning The number of tasks that are currently running.
+ * @property tasksFinished The number of tasks that have completed.
+ */
+public data class SchedulerStats(
+    val workflowsSubmitted: Int,
+    val workflowsRunning: Int,
+    val workflowsFinished: Int,
+    val tasksSubmitted: Int,
+    val tasksRunning: Int,
+    val tasksFinished: Int
+)