Github user huitseeker commented on a diff in the pull request:
https://github.com/apache/spark/pull/9256#discussion_r44187957
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/rdd/TrackStateRDD.scala ---
@@ -0,0 +1,192 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.streaming.rdd
+
+import java.io.{IOException, ObjectInputStream, ObjectOutputStream}
+
+import scala.collection.mutable.ArrayBuffer
+import scala.reflect.ClassTag
+
+import org.apache.spark.rdd.{MapPartitionsRDD, RDD}
+import org.apache.spark.streaming.{StateImpl, State}
+import org.apache.spark.streaming.util.{EmptyStateMap, StateMap}
+import org.apache.spark.util.Utils
+import org.apache.spark._
+
+private[streaming] case class TrackStateRDDRecord[K, S, T](
+ var stateMap: StateMap[K, S], var emittedRecords: Seq[T]) {
+ /*
+ private def writeObject(outputStream: ObjectOutputStream): Unit = {
+ outputStream.writeObject(stateMap)
+ outputStream.writeInt(emittedRecords.size)
+ val iterator = emittedRecords.iterator
+ while(iterator.hasNext) {
+ outputStream.writeObject(iterator.next)
+ }
+ }
+
+ private def readObject(inputStream: ObjectInputStream): Unit = {
+ stateMap = inputStream.readObject().asInstanceOf[StateMap[K, S]]
+ val numEmittedRecords = inputStream.readInt()
+ val array = new Array[T](numEmittedRecords)
+ var i = 0
+ while(i < numEmittedRecords) {
+ array(i) = inputStream.readObject().asInstanceOf[T]
+ }
+ emittedRecords = array.toSeq
+ }*/
+}
+
+
+private[streaming] class TrackStateRDDPartition(
+ idx: Int,
+ @transient private var prevStateRDD: RDD[_],
+ @transient private var partitionedDataRDD: RDD[_]) extends Partition {
+
+ private[rdd] var previousSessionRDDPartition: Partition = null
+ private[rdd] var partitionedDataRDDPartition: Partition = null
+
+ override def index: Int = idx
+ override def hashCode(): Int = idx
+
+ @throws(classOf[IOException])
+ private def writeObject(oos: ObjectOutputStream): Unit =
Utils.tryOrIOException {
+ // Update the reference to parent split at the time of task
serialization
+ previousSessionRDDPartition = prevStateRDD.partitions(index)
+ partitionedDataRDDPartition = partitionedDataRDD.partitions(index)
+ oos.defaultWriteObject()
+ }
+}
+
+
+/**
+ * RDD storing the keyed-state of trackStateByKey and corresponding
emitted records.
+ * Each partition of this RDD has a single record that contains a StateMap
storing
+ */
+private[streaming] class TrackStateRDD[K: ClassTag, V: ClassTag, S:
ClassTag, T: ClassTag](
+ private var prevStateRDD: RDD[TrackStateRDDRecord[K, S, T]],
+ private var partitionedDataRDD: RDD[(K, V)],
+ trackingFunction: (K, Option[V], State[S]) => Option[T],
+ currentTime: Long, timeoutThresholdTime: Option[Long]
+ ) extends RDD[TrackStateRDDRecord[K, S, T]](
+ partitionedDataRDD.sparkContext,
+ List(
+ new OneToOneDependency[TrackStateRDDRecord[K, S, T]](prevStateRDD),
+ new OneToOneDependency(partitionedDataRDD))
+ ) {
+
+ @volatile private var doFullScan = false
+
+ require(prevStateRDD.partitioner.nonEmpty)
+ require(partitionedDataRDD.partitioner == prevStateRDD.partitioner)
+
+ override val partitioner = prevStateRDD.partitioner
+
+ override def checkpoint(): Unit = {
+ super.checkpoint()
+ doFullScan = true
+ }
+
+ override def compute(
+ partition: Partition, context: TaskContext):
Iterator[TrackStateRDDRecord[K, S, T]] = {
+
+ val stateRDDPartition = partition.asInstanceOf[TrackStateRDDPartition]
+ val prevStateRDDIterator = prevStateRDD.iterator(
+ stateRDDPartition.previousSessionRDDPartition, context)
+ val dataIterator = partitionedDataRDD.iterator(
+ stateRDDPartition.partitionedDataRDDPartition, context)
+
+ val newStateMap = if (prevStateRDDIterator.hasNext) {
+ prevStateRDDIterator.next().stateMap.copy()
+ } else {
+ new EmptyStateMap[K, S]()
+ }
+
+ val emittedRecords = new ArrayBuffer[T]
+
+ val wrappedState = new StateImpl[S]()
+
+ dataIterator.foreach { case (key, value) =>
+ wrappedState.wrap(newStateMap.get(key))
+ val emittedRecord = trackingFunction(key, Some(value), wrappedState)
+ if (wrappedState.isRemoved) {
+ newStateMap.remove(key)
+ } else if (wrappedState.isUpdated) {
+ newStateMap.put(key, wrappedState.get(), currentTime)
+ }
+ emittedRecords ++= emittedRecord
+ }
+
+ if (doFullScan) {
+ if (timeoutThresholdTime.isDefined) {
+ newStateMap.getByTime(timeoutThresholdTime.get).foreach { case
(key, state, _) =>
+ wrappedState.wrapTiminoutState(state)
+ val emittedRecord = trackingFunction(key, None, wrappedState)
+ emittedRecords ++= emittedRecord
+ newStateMap.remove(key)
+ }
+ }
+ }
+
+ Iterator(TrackStateRDDRecord(newStateMap, emittedRecords))
+ }
+
+ override protected def getPartitions: Array[Partition] = {
+ Array.tabulate(prevStateRDD.partitions.length) { i =>
+ new TrackStateRDDPartition(i, prevStateRDD, partitionedDataRDD)}
+ }
+
+ override def clearDependencies() {
--- End diff --
I'd rather see [procedure syntax
avoided](http://docs.scala-lang.org/style/declarations.html).
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