feat(query): namespace cardinality publisher

coordinator/src/main/scala/filodb.coordinator/ShardManager.scala

@@ -37,6 +37,16 @@ private[coordinator] final class ShardManager(settings: FilodbSettings,
   private val _coordinators = new mutable.LinkedHashMap[Address, ActorRef]
   private val _errorShardReassignedAt = new mutable.HashMap[DatasetRef, mutable.HashMap[Int, Long]]
 
+  private val _tenantIngestionMeteringOpt =
+    if (settings.config.getBoolean("shard-key-level-ingestion-metrics-enabled")) {
+      val inst = TenantIngestionMetering(
+                   settings,
+                   () => { _datasetInfo.map{ case (dsRef, _) => dsRef}.toIterator },
+                   () => { _coordinators.head._2 })
+      inst.schedulePeriodicPublishJob()
+      Some(inst)
+    } else None
+
   val shardReassignmentMinInterval = settings.config.getDuration("shard-manager.reassignment-min-interval")
 
   /* These workloads were in an actor and exist now in an unprotected class.

coordinator/src/main/scala/filodb.coordinator/TenantIngestionMetering.scala

@@ -0,0 +1,89 @@
+package filodb.coordinator
+
+import java.util.concurrent.TimeUnit
+
+import scala.concurrent.duration.FiniteDuration
+import scala.util.{Failure, Success}
+
+import akka.actor.ActorRef
+import com.typesafe.scalalogging.StrictLogging
+import kamon.Kamon
+import kamon.tag.TagSet
+import monix.execution.Scheduler.Implicits.{global => scheduler}
+
+import filodb.coordinator.client.Client
+import filodb.coordinator.client.QueryCommands.LogicalPlan2Query
+import filodb.core.DatasetRef
+import filodb.query.{QueryError, QueryResult, TsCardinalities}
+
+/**
+ * Periodically queries a node for all namespace cardinalities.
+ * Kamon gauges are updated with the response data.
+ *
+ * The intent is to publish a low-cardinality metric such that namespace
+ * cardinality queries can be efficiently answered.
+ *
+ * @param dsIterProducer produces an iterator to step through all datasets.
+ * @param coordActorProducer produces a single actor to ask a query. Actors are
+ *          queried in the order they're returned from this function.
+ */
+case class TenantIngestionMetering(settings: FilodbSettings,
+                                   dsIterProducer: () => Iterator[DatasetRef],
+                                   coordActorProducer: () => ActorRef) extends StrictLogging{
+
+  private val ASK_TIMEOUT = FiniteDuration(
+    settings.config.getDuration("metering-query-interval").toSeconds,
+    TimeUnit.SECONDS)
+  private val SCHED_INIT_DELAY = ASK_TIMEOUT  // time until first job is scheduled
+  private val SCHED_DELAY = ASK_TIMEOUT  // time between all jobs after the first
+
+  private val CLUSTER_TYPE = settings.config.getString("cluster-type")
+
+  private val METRIC_ACTIVE = "active_timeseries_by_tenant"
+  private val METRIC_TOTAL = "total_timeseries_by_tenant"
+
+  def schedulePeriodicPublishJob() : Unit = {
+    // NOTE: the FiniteDuration overload of scheduleWithFixedDelay
+    //  does not work. Unsure why, but that's why these FiniteDurations are
+    //  awkwardly parsed into seconds.
+    scheduler.scheduleWithFixedDelay(
+      SCHED_INIT_DELAY.toSeconds,
+      SCHED_DELAY.toSeconds,
+      TimeUnit.SECONDS,
+      () => queryAndSchedulePublish())
+  }
+
+  /**
+   * For each dataset, ask a Coordinator with a TsCardinalities LogicalPlan.
+   * Schedules a job to publish the Coordinator's response.
+   */
+  private def queryAndSchedulePublish() : Unit = {
+    import filodb.query.exec.TsCardExec._
+    val groupDepth = 1  // group cardinalities at the second level (i.e. ws & ns)
+    val prefix = Nil  // query for cardinalities regardless of first-level name (i.e. ws name)
+    dsIterProducer().foreach { dsRef =>
+      val fut = Client.asyncAsk(
+        coordActorProducer(),
+        LogicalPlan2Query(dsRef, TsCardinalities(prefix, groupDepth)),
+        ASK_TIMEOUT)
+      fut.onComplete {
+        case Success(QueryResult(_, _, rv, _, _, _)) =>
+          rv.foreach(_.rows().foreach{ rr =>
+            // publish a cardinality metric for each namespace
+            val data = RowData.fromRowReader(rr)
+            val prefix = data.group.toString.split(PREFIX_DELIM)
+            val tags = Map("metric_ws" -> prefix(0),
+                           "metric_ns" -> prefix(1),
+                           "dataset" -> dsRef.dataset,
+                           "cluster_type" -> CLUSTER_TYPE)
+            Kamon.gauge(METRIC_ACTIVE).withTags(TagSet.from(tags)).update(data.counts.active.toDouble)
+            Kamon.gauge(METRIC_TOTAL).withTags(TagSet.from(tags)).update(data.counts.total.toDouble)
+          })
+        case Success(QueryError(_, _, t)) => logger.warn("QueryError: " + t.getMessage)
+        case Failure(t) => logger.warn("Failure: " + t.getMessage)
+        // required to compile
+        case _ => throw new IllegalArgumentException("should never reach here; attempted to match: " + fut)
+      }
+    }
+  }
+}

core/src/main/resources/filodb-defaults.conf

@@ -161,6 +161,8 @@ filodb {
   spread-assignment = []
 
   shard-key-level-ingestion-metrics-enabled = true
+  # Time between each TenantIngestionMetering query/publish job
+  metering-query-interval = 15 minutes
   # info config used for metric breakdown
   cluster-type = "raw" // possible values: downsample, raw, recRule, aggregates etc.
   # Name of the deployment partition that this FiloDB cluster belongs to

core/src/test/scala/filodb.core/memstore/ratelimit/RocksDbCardinalityStoreSpec.scala

@@ -0,0 +1,29 @@
+package filodb.core.memstore.ratelimit
+
+import org.scalatest.funspec.AnyFunSpec
+import org.scalatest.matchers.should.Matchers
+
+import filodb.core.memstore.ratelimit.CardinalityStore._
+import filodb.core.MetricsTestData
+
+class RocksDbCardinalityStoreSpec extends AnyFunSpec with Matchers {
+  it ("should correctly return overflow record") {
+    val dset = MetricsTestData.timeseriesDatasetMultipleShardKeys
+    val shard = 0
+    val numOverflow = 123
+
+    val db = new RocksDbCardinalityStore(dset.ref, shard)
+
+    (0 until MAX_RESULT_SIZE + numOverflow).foreach{ i =>
+      val prefix = Seq("ws", "ns", s"metric-$i")
+      db.store(CardinalityRecord(shard, prefix, 1, 1, 1, 1))
+    }
+
+    Seq(Nil, Seq("ws"), Seq("ws", "ns")).foreach{ prefix =>
+      val res = db.scanChildren(prefix, 3)
+      res.size shouldEqual MAX_RESULT_SIZE + 1  // one extra for the overflow CardinalityRecord
+      res.contains(CardinalityRecord(shard, OVERFLOW_PREFIX,
+        numOverflow, numOverflow, numOverflow, numOverflow)) shouldEqual true
+    }
+  }
+}

query/src/main/scala/filodb/query/exec/MetadataExecPlan.scala

@@ -361,12 +361,14 @@ final case object TsCardExec {
   // row name assigned to overflow counts
   val OVERFLOW_GROUP = prefixToGroup(CardinalityStore.OVERFLOW_PREFIX)
 
+  val PREFIX_DELIM = ","
+
   /**
    * Convert a shard key prefix to a row's group name.
    */
   def prefixToGroup(prefix: Seq[String]): ZeroCopyUTF8String = {
     // just concat the prefix together with a single char delimiter
-    prefix.mkString(",").utf8
+    prefix.mkString(PREFIX_DELIM).utf8
   }
 
   case class CardCounts(active: Int, total: Int) {