Removed stream id from the constructor of NetworkReceiver to make it easier for PluggableNetworkInputDStream.

examples/src/main/scala/spark/streaming/examples/twitter/TwitterInputDStream.scala

@@ -23,16 +23,17 @@ class TwitterInputDStream(
     ) extends NetworkInputDStream[Status](ssc_)  {
 
   override def createReceiver(): NetworkReceiver[Status] = {
-    new TwitterReceiver(id, username, password, filters, storageLevel)
+    new TwitterReceiver(username, password, filters, storageLevel)
   }
 }
 
-class TwitterReceiver(streamId: Int,
-                      username: String,
-                      password: String,
-                      filters: Seq[String],
-                      storageLevel: StorageLevel
-    ) extends NetworkReceiver[Status](streamId) {
+class TwitterReceiver(
+    username: String,
+    password: String,
+    filters: Seq[String],
+    storageLevel: StorageLevel
+  ) extends NetworkReceiver[Status] {
+
   var twitterStream: TwitterStream = _
   lazy val blockGenerator = new BlockGenerator(storageLevel)
 

streaming/src/main/scala/spark/streaming/NetworkInputTracker.scala

@@ -18,7 +18,10 @@ private[streaming] case class RegisterReceiver(streamId: Int, receiverActor: Act
 private[streaming] case class AddBlocks(streamId: Int, blockIds: Seq[String], metadata: Any) extends NetworkInputTrackerMessage
 private[streaming] case class DeregisterReceiver(streamId: Int, msg: String) extends NetworkInputTrackerMessage
 
-
+/**
+ * This class manages the execution of the receivers of NetworkInputDStreams.
+ */
+private[streaming]
 class NetworkInputTracker(
     @transient ssc: StreamingContext, 
     @transient networkInputStreams: Array[NetworkInputDStream[_]])
@@ -32,16 +35,20 @@ class NetworkInputTracker(
 
   var currentTime: Time = null
 
+  /** Start the actor and receiver execution thread. */
   def start() {
     ssc.env.actorSystem.actorOf(Props(new NetworkInputTrackerActor), "NetworkInputTracker")
     receiverExecutor.start()
   }
 
+  /** Stop the receiver execution thread. */
   def stop() {
+    // TODO: stop the actor as well
     receiverExecutor.interrupt()
     receiverExecutor.stopReceivers()
   }
 
+  /** Return all the blocks received from a receiver. */
   def getBlockIds(receiverId: Int, time: Time): Array[String] = synchronized {
     val queue =  receivedBlockIds.synchronized {
       receivedBlockIds.getOrElse(receiverId, new Queue[String]())
@@ -53,6 +60,7 @@ class NetworkInputTracker(
     result.toArray
   }
 
+  /** Actor to receive messages from the receivers. */
   private class NetworkInputTrackerActor extends Actor {
     def receive = {
       case RegisterReceiver(streamId, receiverActor) => {
@@ -83,7 +91,8 @@ class NetworkInputTracker(
       }
     }
   }
-  
+
+  /** This thread class runs all the receivers on the cluster.  */
   class ReceiverExecutor extends Thread {
     val env = ssc.env
         
@@ -97,13 +106,22 @@ class NetworkInputTracker(
         stopReceivers()
       }
     }
-    
+
+    /**
+     * Get the receivers from the NetworkInputDStreams, distributes them to the
+     * worker nodes as a parallel collection, and runs them.
+     */
     def startReceivers() {
-      val receivers = networkInputStreams.map(_.createReceiver())
+      val receivers = networkInputStreams.map(nis => {
+        val rcvr = nis.createReceiver()
+        rcvr.setStreamId(nis.id)
+        rcvr
+      })
 
       // Right now, we only honor preferences if all receivers have them
       val hasLocationPreferences = receivers.map(_.getLocationPreference().isDefined).reduce(_ && _)
 
+      // Create the parallel collection of receivers to distributed them on the worker nodes
       val tempRDD =
         if (hasLocationPreferences) {
           val receiversWithPreferences = receivers.map(r => (r, Seq(r.getLocationPreference().toString)))
@@ -113,21 +131,21 @@ class NetworkInputTracker(
           ssc.sc.makeRDD(receivers, receivers.size)
         }
 
+      // Function to start the receiver on the worker node
       val startReceiver = (iterator: Iterator[NetworkReceiver[_]]) => {
         if (!iterator.hasNext) {
           throw new Exception("Could not start receiver as details not found.")
         }
         iterator.next().start()
       }
+      // Distribute the receivers and start them
       ssc.sc.runJob(tempRDD, startReceiver)
     }
     
+    /** Stops the receivers. */
     def stopReceivers() {
-      //implicit val ec = env.actorSystem.dispatcher
+      // Signal the receivers to stop
       receiverInfo.values.foreach(_ ! StopReceiver)
-      //val listOfFutures = receiverInfo.values.map(_.ask(StopReceiver)(timeout)).toList
-      //val futureOfList = Future.sequence(listOfFutures)
-      //Await.result(futureOfList, timeout)
     }
   }
 }

streaming/src/main/scala/spark/streaming/dstream/FlumeInputDStream.scala

@@ -26,7 +26,7 @@ class FlumeInputDStream[T: ClassManifest](
 ) extends NetworkInputDStream[SparkFlumeEvent](ssc_) {
 
   override def createReceiver(): NetworkReceiver[SparkFlumeEvent] = {
-    new FlumeReceiver(id, host, port, storageLevel)
+    new FlumeReceiver(host, port, storageLevel)
   }
 }
 
@@ -112,11 +112,10 @@ class FlumeEventServer(receiver : FlumeReceiver) extends AvroSourceProtocol {
   * Flume Avro interface.*/
 private[streaming]
 class FlumeReceiver(
-    streamId: Int,
     host: String,
     port: Int,
     storageLevel: StorageLevel
-  ) extends NetworkReceiver[SparkFlumeEvent](streamId) {
+  ) extends NetworkReceiver[SparkFlumeEvent] {
 
   lazy val blockGenerator = new BlockGenerator(storageLevel)
 

streaming/src/main/scala/spark/streaming/dstream/KafkaInputDStream.scala

@@ -96,15 +96,15 @@ class KafkaInputDStream[T: ClassManifest](
   } */
 
   def createReceiver(): NetworkReceiver[T] = {
-    new KafkaReceiver(id, host, port,  groupId, topics, initialOffsets, storageLevel)
+    new KafkaReceiver(host, port,  groupId, topics, initialOffsets, storageLevel)
         .asInstanceOf[NetworkReceiver[T]]
   }
 }
 
 private[streaming]
-class KafkaReceiver(streamId: Int, host: String, port: Int, groupId: String, 
+class KafkaReceiver(host: String, port: Int, groupId: String,
   topics: Map[String, Int], initialOffsets: Map[KafkaPartitionKey, Long], 
-  storageLevel: StorageLevel) extends NetworkReceiver[Any](streamId) {
+  storageLevel: StorageLevel) extends NetworkReceiver[Any] {
 
   // Timeout for establishing a connection to Zookeper in ms.
   val ZK_TIMEOUT = 10000

streaming/src/main/scala/spark/streaming/dstream/NetworkInputDStream.scala

@@ -17,6 +17,15 @@ import akka.util.duration._
 import spark.streaming.util.{RecurringTimer, SystemClock}
 import java.util.concurrent.ArrayBlockingQueue
 
+/**
+ * Abstract class for defining any InputDStream that has to start a receiver on worker
+ * nodes to receive external data. Specific implementations of NetworkInputDStream must
+ * define the createReceiver() function that creates the receiver object of type
+ * [[spark.streaming.dstream.NetworkReceiver]] that will be sent to the workers to receive
+ * data.
+ * @param ssc_ Streaming context that will execute this input stream
+ * @tparam T Class type of the object of this stream
+ */
 abstract class NetworkInputDStream[T: ClassManifest](@transient ssc_ : StreamingContext)
   extends InputDStream[T](ssc_) {
 
@@ -25,7 +34,7 @@ abstract class NetworkInputDStream[T: ClassManifest](@transient ssc_ : Streaming
   val id = ssc.getNewNetworkStreamId()
 
   /**
-   * This method creates the receiver object that will be sent to the workers
+   * Creates the receiver object that will be sent to the worker nodes
    * to receive data. This method needs to defined by any specific implementation
    * of a NetworkInputDStream.
    */
@@ -48,7 +57,11 @@ private[streaming] case class StopReceiver(msg: String) extends NetworkReceiverM
 private[streaming] case class ReportBlock(blockId: String, metadata: Any) extends NetworkReceiverMessage
 private[streaming] case class ReportError(msg: String) extends NetworkReceiverMessage
 
-abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Serializable with Logging {
+/**
+ * Abstract class of a receiver that can be run on worker nodes to receive external data. See
+ * [[spark.streaming.dstream.NetworkInputDStream]] for an explanation.
+ */
+abstract class NetworkReceiver[T: ClassManifest]() extends Serializable with Logging {
 
   initLogging()
 
@@ -59,17 +72,22 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
 
   lazy protected val receivingThread = Thread.currentThread()
 
-  /** This method will be called to start receiving data. */
+  protected var streamId: Int = -1
+
+  /**
+   * This method will be called to start receiving data. All your receiver
+   * starting code should be implemented by defining this function.
+   */
   protected def onStart()
 
   /** This method will be called to stop receiving data. */
   protected def onStop()
 
-  /** This method conveys a placement preference (hostname) for this receiver. */
+  /** Conveys a placement preference (hostname) for this receiver. */
   def getLocationPreference() : Option[String] = None
 
   /**
-   * This method starts the receiver. First is accesses all the lazy members to
+   * Starts the receiver. First is accesses all the lazy members to
    * materialize them. Then it calls the user-defined onStart() method to start
    * other threads, etc required to receiver the data.
    */
@@ -92,7 +110,7 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
   }
 
   /**
-   * This method stops the receiver. First it interrupts the main receiving thread,
+   * Stops the receiver. First it interrupts the main receiving thread,
    * that is, the thread that called receiver.start(). Then it calls the user-defined
    * onStop() method to stop other threads and/or do cleanup.
    */
@@ -103,7 +121,7 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
   }
 
   /**
-   * This method stops the receiver and reports to exception to the tracker.
+   * Stops the receiver and reports to exception to the tracker.
    * This should be called whenever an exception has happened on any thread
    * of the receiver.
    */
@@ -115,7 +133,7 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
 
 
   /**
-   * This method pushes a block (as iterator of values) into the block manager.
+   * Pushes a block (as iterator of values) into the block manager.
    */
   def pushBlock(blockId: String, iterator: Iterator[T], metadata: Any, level: StorageLevel) {
     val buffer = new ArrayBuffer[T] ++ iterator
@@ -125,7 +143,7 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
   }
 
   /**
-   * This method pushes a block (as bytes) into the block manager.
+   * Pushes a block (as bytes) into the block manager.
    */
   def pushBlock(blockId: String, bytes: ByteBuffer, metadata: Any, level: StorageLevel) {
     env.blockManager.putBytes(blockId, bytes, level)
@@ -157,6 +175,10 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
     }
   }
 
+  protected[streaming] def setStreamId(id: Int) {
+    streamId = id
+  }
+
   /**
    * Batches objects created by a [[spark.streaming.NetworkReceiver]] and puts them into
    * appropriately named blocks at regular intervals. This class starts two threads,
@@ -202,7 +224,7 @@ abstract class NetworkReceiver[T: ClassManifest](val streamId: Int) extends Seri
         val newBlockBuffer = currentBuffer
         currentBuffer = new ArrayBuffer[T]
         if (newBlockBuffer.size > 0) {
-          val blockId = "input-" + NetworkReceiver.this.streamId + "- " + (time - blockInterval)
+          val blockId = "input-" + NetworkReceiver.this.streamId + "-" + (time - blockInterval)
           val newBlock = createBlock(blockId, newBlockBuffer.toIterator)
           blocksForPushing.add(newBlock)
         }

streaming/src/main/scala/spark/streaming/dstream/RawInputDStream.scala

@@ -26,13 +26,13 @@ class RawInputDStream[T: ClassManifest](
   ) extends NetworkInputDStream[T](ssc_ ) with Logging {
 
   def createReceiver(): NetworkReceiver[T] = {
-    new RawNetworkReceiver(id, host, port, storageLevel).asInstanceOf[NetworkReceiver[T]]
+    new RawNetworkReceiver(host, port, storageLevel).asInstanceOf[NetworkReceiver[T]]
   }
 }
 
 private[streaming]
-class RawNetworkReceiver(streamId: Int, host: String, port: Int, storageLevel: StorageLevel)
-  extends NetworkReceiver[Any](streamId) {
+class RawNetworkReceiver(host: String, port: Int, storageLevel: StorageLevel)
+  extends NetworkReceiver[Any] {
 
   var blockPushingThread: Thread = null
 

streaming/src/main/scala/spark/streaming/dstream/SocketInputDStream.scala

@@ -16,18 +16,17 @@ class SocketInputDStream[T: ClassManifest](
   ) extends NetworkInputDStream[T](ssc_) {
 
   def createReceiver(): NetworkReceiver[T] = {
-    new SocketReceiver(id, host, port, bytesToObjects, storageLevel)
+    new SocketReceiver(host, port, bytesToObjects, storageLevel)
   }
 }
 
 private[streaming]
 class SocketReceiver[T: ClassManifest](
-    streamId: Int,
     host: String,
     port: Int,
     bytesToObjects: InputStream => Iterator[T],
     storageLevel: StorageLevel
-  ) extends NetworkReceiver[T](streamId) {
+  ) extends NetworkReceiver[T] {
 
   lazy protected val blockGenerator = new BlockGenerator(storageLevel)