Merge pull request #373 from Reinvigorate/sm-updateStateByKey

StateDStream changes to give updateStateByKey consistent behavior

4 files changed, 78 insertions, 6 deletions

diff --git a/streaming/src/main/scala/spark/streaming/StreamingContext.scala b/streaming/src/main/scala/spark/streaming/StreamingContext.scala
index 14500bdcb1..3cec35cb37 100644
--- a/streaming/src/main/scala/spark/streaming/StreamingContext.scala
+++ b/streaming/src/main/scala/spark/streaming/StreamingContext.scala
@@ -283,17 +283,31 @@ class StreamingContext private (
   }
 
   /**
-   * Creates a input stream from an queue of RDDs. In each batch,
+   * Creates an input stream from a queue of RDDs. In each batch,
    * it will process either one or all of the RDDs returned by the queue.
    * @param queue      Queue of RDDs
    * @param oneAtATime Whether only one RDD should be consumed from the queue in every interval
-   * @param defaultRDD Default RDD is returned by the DStream when the queue is empty
    * @tparam T         Type of objects in the RDD
    */
   def queueStream[T: ClassManifest](
       queue: Queue[RDD[T]],
-      oneAtATime: Boolean = true,
-      defaultRDD: RDD[T] = null
+      oneAtATime: Boolean = true
+    ): DStream[T] = {
+    queueStream(queue, oneAtATime, sc.makeRDD(Seq[T](), 1))
+  }
+
+  /**
+   * Creates an input stream from a queue of RDDs. In each batch,
+   * it will process either one or all of the RDDs returned by the queue.
+   * @param queue      Queue of RDDs
+   * @param oneAtATime Whether only one RDD should be consumed from the queue in every interval
+   * @param defaultRDD Default RDD is returned by the DStream when the queue is empty. Set as null if no RDD should be returned when empty
+   * @tparam T         Type of objects in the RDD
+   */
+  def queueStream[T: ClassManifest](
+      queue: Queue[RDD[T]],
+      oneAtATime: Boolean,
+      defaultRDD: RDD[T]
     ): DStream[T] = {
     val inputStream = new QueueInputDStream(this, queue, oneAtATime, defaultRDD)
     registerInputStream(inputStream)
diff --git a/streaming/src/main/scala/spark/streaming/dstream/StateDStream.scala b/streaming/src/main/scala/spark/streaming/dstream/StateDStream.scala
index b4506c74aa..db62955036 100644
--- a/streaming/src/main/scala/spark/streaming/dstream/StateDStream.scala
+++ b/streaming/src/main/scala/spark/streaming/dstream/StateDStream.scala
@@ -48,8 +48,16 @@ class StateDStream[K: ClassManifest, V: ClassManifest, S: ClassManifest](
             //logDebug("Generating state RDD for time " + validTime)
             return Some(stateRDD)
           }
-          case None => {    // If parent RDD does not exist, then return old state RDD
-            return Some(prevStateRDD)
+          case None => {    // If parent RDD does not exist
+
+            // Re-apply the update function to the old state RDD
+            val updateFuncLocal = updateFunc
+            val finalFunc = (iterator: Iterator[(K, S)]) => {
+              val i = iterator.map(t => (t._1, Seq[V](), Option(t._2)))
+              updateFuncLocal(i)
+            }
+            val stateRDD = prevStateRDD.mapPartitions(finalFunc, preservePartitioning)
+            return Some(stateRDD)
           }
         }
       }
diff --git a/streaming/src/test/scala/spark/streaming/BasicOperationsSuite.scala b/streaming/src/test/scala/spark/streaming/BasicOperationsSuite.scala
index bfdf32c73e..d98b840b8e 100644
--- a/streaming/src/test/scala/spark/streaming/BasicOperationsSuite.scala
+++ b/streaming/src/test/scala/spark/streaming/BasicOperationsSuite.scala
@@ -165,6 +165,51 @@ class BasicOperationsSuite extends TestSuiteBase {
     testOperation(inputData, updateStateOperation, outputData, true)
   }
 
+  test("updateStateByKey - object lifecycle") {
+    val inputData =
+      Seq(
+        Seq("a","b"),
+        null,
+        Seq("a","c","a"),
+        Seq("c"),
+        null,
+        null
+      )
+
+    val outputData =
+      Seq(
+        Seq(("a", 1), ("b", 1)),
+        Seq(("a", 1), ("b", 1)),
+        Seq(("a", 3), ("c", 1)),
+        Seq(("a", 3), ("c", 2)),
+        Seq(("c", 2)),
+        Seq()
+      )
+
+    val updateStateOperation = (s: DStream[String]) => {
+      class StateObject(var counter: Int = 0, var expireCounter: Int = 0) extends Serializable
+
+      // updateFunc clears a state when a StateObject is seen without new values twice in a row
+      val updateFunc = (values: Seq[Int], state: Option[StateObject]) => {
+        val stateObj = state.getOrElse(new StateObject)
+        values.foldLeft(0)(_ + _) match {
+          case 0 => stateObj.expireCounter += 1 // no new values
+          case n => { // has new values, increment and reset expireCounter
+            stateObj.counter += n
+            stateObj.expireCounter = 0
+          }
+        }
+        stateObj.expireCounter match {
+          case 2 => None // seen twice with no new values, give it the boot
+          case _ => Option(stateObj)
+        }
+      }
+      s.map(_ -> 1).updateStateByKey[StateObject](updateFunc).mapValues(_.counter)
+    }
+
+    testOperation(inputData, updateStateOperation, outputData, true)
+  }
+
   test("forgetting of RDDs - map and window operations") {
     assert(batchDuration === Seconds(1), "Batch duration has changed from 1 second")
 
diff --git a/streaming/src/test/scala/spark/streaming/TestSuiteBase.scala b/streaming/src/test/scala/spark/streaming/TestSuiteBase.scala
index 49129f3964..c2733831b2 100644
--- a/streaming/src/test/scala/spark/streaming/TestSuiteBase.scala
+++ b/streaming/src/test/scala/spark/streaming/TestSuiteBase.scala
@@ -28,6 +28,11 @@ class TestInputStream[T: ClassManifest](ssc_ : StreamingContext, input: Seq[Seq[
     logInfo("Computing RDD for time " + validTime)
     val index = ((validTime - zeroTime) / slideDuration - 1).toInt
     val selectedInput = if (index < input.size) input(index) else Seq[T]()
+
+    // lets us test cases where RDDs are not created
+    if (selectedInput == null)
+      return None
+
     val rdd = ssc.sc.makeRDD(selectedInput, numPartitions)
     logInfo("Created RDD " + rdd.id + " with " + selectedInput)
     Some(rdd)