[SPARK-7554] [STREAMING] Throw exception when an active/stopped Strea…

…mingContext is used to create DStreams and output operations

Author: Tathagata Das <[email protected]>

Closes apache#6099 from tdas/SPARK-7554 and squashes the following commits:

2cd4158 [Tathagata Das] Throw exceptions on attempts to add stuff to active and stopped contexts.

streaming/src/main/scala/org/apache/spark/streaming/DStreamGraph.scala

@@ -45,7 +45,7 @@ final private[streaming] class DStreamGraph extends Serializable with Logging {
       startTime = time
       outputStreams.foreach(_.initialize(zeroTime))
       outputStreams.foreach(_.remember(rememberDuration))
-      outputStreams.foreach(_.validate)
+      outputStreams.foreach(_.validateAtStart)
       inputStreams.par.foreach(_.start())
     }
   }

streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala

@@ -60,6 +60,8 @@ abstract class DStream[T: ClassTag] (
     @transient private[streaming] var ssc: StreamingContext
   ) extends Serializable with Logging {
 
+  validateAtInit()
+
   // =======================================================================
   // Methods that should be implemented by subclasses of DStream
   // =======================================================================
@@ -171,7 +173,22 @@ abstract class DStream[T: ClassTag] (
     dependencies.foreach(_.initialize(zeroTime))
   }
 
-  private[streaming] def validate() {
+  private def validateAtInit(): Unit = {
+    ssc.getState() match {
+      case StreamingContextState.INITIALIZED =>
+        // good to go
+      case StreamingContextState.ACTIVE =>
+        throw new SparkException(
+          "Adding new inputs, transformations, and output operations after " +
+            "starting a context is not supported")
+      case StreamingContextState.STOPPED =>
+        throw new SparkException(
+          "Adding new inputs, transformations, and output operations after " +
+            "stopping a context is not supported")
+    }
+  }
+
+  private[streaming] def validateAtStart() {
     assert(rememberDuration != null, "Remember duration is set to null")
 
     assert(
@@ -226,7 +243,7 @@ abstract class DStream[T: ClassTag] (
         math.ceil(rememberDuration.milliseconds / 1000.0).toInt + " seconds."
     )
 
-    dependencies.foreach(_.validate())
+    dependencies.foreach(_.validateAtStart())
 
     logInfo("Slide time = " + slideDuration)
     logInfo("Storage level = " + storageLevel)

streaming/src/test/scala/org/apache/spark/streaming/StreamingContextSuite.scala

@@ -651,6 +651,45 @@ class StreamingContextSuite extends FunSuite with BeforeAndAfter with Timeouts w
     testPackage.test()
   }
 
+  test("throw exception on using active or stopped context") {
+    val conf = new SparkConf()
+      .setMaster(master)
+      .setAppName(appName)
+      .set("spark.streaming.clock", "org.apache.spark.util.ManualClock")
+    ssc = new StreamingContext(conf, batchDuration)
+    require(ssc.getState() === StreamingContextState.INITIALIZED)
+    val input = addInputStream(ssc)
+    val transformed = input.map { x => x}
+    transformed.foreachRDD { rdd => rdd.count }
+
+    def testForException(clue: String, expectedErrorMsg: String)(body: => Unit): Unit = {
+      withClue(clue) {
+        val ex = intercept[SparkException] {
+          body
+        }
+        assert(ex.getMessage.toLowerCase().contains(expectedErrorMsg))
+      }
+    }
+
+    ssc.start()
+    require(ssc.getState() === StreamingContextState.ACTIVE)
+    testForException("no error on adding input after start", "start") {
+      addInputStream(ssc) }
+    testForException("no error on adding transformation after start", "start") {
+      input.map { x => x * 2 } }
+    testForException("no error on adding output operation after start", "start") {
+      transformed.foreachRDD { rdd => rdd.collect() } }
+
+    ssc.stop()
+    require(ssc.getState() === StreamingContextState.STOPPED)
+    testForException("no error on adding input after stop", "stop") {
+      addInputStream(ssc) }
+    testForException("no error on adding transformation after stop", "stop") {
+      input.map { x => x * 2 } }
+    testForException("no error on adding output operation after stop", "stop") {
+      transformed.foreachRDD { rdd => rdd.collect() } }
+  }
+
   def addInputStream(s: StreamingContext): DStream[Int] = {
     val input = (1 to 100).map(i => 1 to i)
     val inputStream = new TestInputStream(s, input, 1)