[SPARK-8975][Streaming] Adds a mechanism to send a new rate from the driver to the block generator

streaming/src/main/scala/org/apache/spark/streaming/receiver/RateLimiter.scala

@@ -34,12 +34,32 @@ import org.apache.spark.{Logging, SparkConf}
   */
 private[receiver] abstract class RateLimiter(conf: SparkConf) extends Logging {
 
-  private val desiredRate = conf.getInt("spark.streaming.receiver.maxRate", 0)
-  private lazy val rateLimiter = GuavaRateLimiter.create(desiredRate)
+  // treated as an upper limit
+  private val maxRateLimit = conf.getLong("spark.streaming.receiver.maxRate", Long.MaxValue)
+  private lazy val rateLimiter = GuavaRateLimiter.create(maxRateLimit.toDouble)
 
   def waitToPush() {
-    if (desiredRate > 0) {
-      rateLimiter.acquire()
-    }
+    rateLimiter.acquire()
   }
+
+  /**
+   * Return the current rate limit. If no limit has been set so far, it returns {{{Long.MaxValue}}}.
+   */
+  def getCurrentLimit: Long =
+    rateLimiter.getRate.toLong
+
+  /**
+   * Set the rate limit to `newRate`. The new rate will not exceed the maximum rate configured by
+   * {{{spark.streaming.receiver.maxRate}}}, even if `newRate` is higher than that.
+   *
+   * @param newRate A new rate in events per second. It has no effect if it's 0 or negative.
+   */
+  private[receiver] def updateRate(newRate: Long): Unit =
+    if (newRate > 0) {
+      if (maxRateLimit > 0) {
+        rateLimiter.setRate(newRate.min(maxRateLimit))
+      } else {
+        rateLimiter.setRate(newRate)
+      }
+    }
 }

streaming/src/main/scala/org/apache/spark/streaming/receiver/Receiver.scala

@@ -271,7 +271,7 @@ abstract class Receiver[T](val storageLevel: StorageLevel) extends Serializable
   }
 
   /** Get the attached executor. */
-  private def executor = {
+  private def executor: ReceiverSupervisor = {
     assert(executor_ != null, "Executor has not been attached to this receiver")
     executor_
   }

streaming/src/main/scala/org/apache/spark/streaming/receiver/ReceiverMessage.scala

@@ -23,4 +23,5 @@ import org.apache.spark.streaming.Time
 private[streaming] sealed trait ReceiverMessage extends Serializable
 private[streaming] object StopReceiver extends ReceiverMessage
 private[streaming] case class CleanupOldBlocks(threshTime: Time) extends ReceiverMessage
-
+private[streaming] case class UpdateRateLimit(elementsPerSecond: Long)
+                   extends ReceiverMessage

streaming/src/main/scala/org/apache/spark/streaming/receiver/ReceiverSupervisor.scala

@@ -58,6 +58,9 @@ private[streaming] abstract class ReceiverSupervisor(
   /** Time between a receiver is stopped and started again */
   private val defaultRestartDelay = conf.getInt("spark.streaming.receiverRestartDelay", 2000)
 
+  /** The current maximum rate limit for this receiver. */
+  private[streaming] def getCurrentRateLimit: Option[Long] = None
+
   /** Exception associated with the stopping of the receiver */
   @volatile protected var stoppingError: Throwable = null
 

streaming/src/main/scala/org/apache/spark/streaming/receiver/ReceiverSupervisorImpl.scala

@@ -77,6 +77,9 @@ private[streaming] class ReceiverSupervisorImpl(
         case CleanupOldBlocks(threshTime) =>
           logDebug("Received delete old batch signal")
           cleanupOldBlocks(threshTime)
+        case UpdateRateLimit(eps) =>
+          logInfo(s"Received a new rate limit: $eps.")
+          blockGenerator.updateRate(eps)
       }
     })
 
@@ -98,6 +101,9 @@ private[streaming] class ReceiverSupervisorImpl(
     }
   }, streamId, env.conf)
 
+  override private[streaming] def getCurrentRateLimit: Option[Long] =
+    Some(blockGenerator.getCurrentLimit)
+
   /** Push a single record of received data into block generator. */
   def pushSingle(data: Any) {
     blockGenerator.addData(data)

streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceiverTracker.scala

@@ -27,7 +27,7 @@ import org.apache.spark.{Logging, SparkEnv, SparkException}
 import org.apache.spark.rpc._
 import org.apache.spark.streaming.{StreamingContext, Time}
 import org.apache.spark.streaming.receiver.{CleanupOldBlocks, Receiver, ReceiverSupervisorImpl,
-  StopReceiver}
+  StopReceiver, UpdateRateLimit}
 import org.apache.spark.util.SerializableConfiguration
 
 /**
@@ -180,6 +180,13 @@ class ReceiverTracker(ssc: StreamingContext, skipReceiverLaunch: Boolean = false
     logError(s"Deregistered receiver for stream $streamId: $messageWithError")
   }
 
+  /** Update a receiver's maximum ingestion rate */
+  def sendRateUpdate(streamUID: Int, newRate: Long): Unit = {
+    for (info <- receiverInfo.get(streamUID); eP <- Option(info.endpoint)) {
+      eP.send(UpdateRateLimit(newRate))
+    }
+  }
+
   /** Add new blocks for the given stream */
   private def addBlock(receivedBlockInfo: ReceivedBlockInfo): Boolean = {
     receivedBlockTracker.addBlock(receivedBlockInfo)

streaming/src/test/scala/org/apache/spark/streaming/receiver/RateLimiterSuite.scala

@@ -0,0 +1,46 @@
+/*
+ * 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.receiver
+
+import org.apache.spark.SparkConf
+import org.apache.spark.SparkFunSuite
+
+/** Testsuite for testing the network receiver behavior */
+class RateLimiterSuite extends SparkFunSuite {
+
+  test("rate limiter initializes even without a maxRate set") {
+    val conf = new SparkConf()
+    val rateLimiter = new RateLimiter(conf){}
+    rateLimiter.updateRate(105)
+    assert(rateLimiter.getCurrentLimit == 105)
+  }
+
+  test("rate limiter updates when below maxRate") {
+    val conf = new SparkConf().set("spark.streaming.receiver.maxRate", "110")
+    val rateLimiter = new RateLimiter(conf){}
+    rateLimiter.updateRate(105)
+    assert(rateLimiter.getCurrentLimit == 105)
+  }
+
+  test("rate limiter stays below maxRate despite large updates") {
+    val conf = new SparkConf().set("spark.streaming.receiver.maxRate", "100")
+    val rateLimiter = new RateLimiter(conf){}
+    rateLimiter.updateRate(105)
+    assert(rateLimiter.getCurrentLimit === 100)
+  }
+}

streaming/src/test/scala/org/apache/spark/streaming/scheduler/ReceiverTrackerSuite.scala

@@ -17,11 +17,17 @@
 
 package org.apache.spark.streaming.scheduler
 
+import org.scalatest.concurrent.Eventually._
+import org.scalatest.concurrent.Timeouts
+import org.scalatest.time.SpanSugar._
 import org.apache.spark.streaming._
 import org.apache.spark.SparkConf
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.receiver._
 import org.apache.spark.util.Utils
+import org.apache.spark.streaming.dstream.InputDStream
+import scala.reflect.ClassTag
+import org.apache.spark.streaming.dstream.ReceiverInputDStream
 
 /** Testsuite for receiver scheduling */
 class ReceiverTrackerSuite extends TestSuiteBase {
@@ -72,8 +78,64 @@ class ReceiverTrackerSuite extends TestSuiteBase {
     assert(locations(0).length === 1)
     assert(locations(3).length === 1)
   }
+
+  test("Receiver tracker - propagates rate limit") {
+    object ReceiverStartedWaiter extends StreamingListener {
+      @volatile
+      var started = false
+
+      override def onReceiverStarted(receiverStarted: StreamingListenerReceiverStarted): Unit = {
+        started = true
+      }
+    }
+
+    ssc.addStreamingListener(ReceiverStartedWaiter)
+    ssc.scheduler.listenerBus.start(ssc.sc)
+
+    val newRateLimit = 100L
+    val inputDStream = new RateLimitInputDStream(ssc)
+    val tracker = new ReceiverTracker(ssc)
+    tracker.start()
+
+    // we wait until the Receiver has registered with the tracker,
+    // otherwise our rate update is lost
+    eventually(timeout(5 seconds)) {
+      assert(ReceiverStartedWaiter.started)
+    }
+    tracker.sendRateUpdate(inputDStream.id, newRateLimit)
+    // this is an async message, we need to wait a bit for it to be processed
+    eventually(timeout(3 seconds)) {
+      assert(inputDStream.getCurrentRateLimit.get === newRateLimit)
+    }
+  }
 }
 
+/** An input DStream with a hard-coded receiver that gives access to internals for testing. */
+private class RateLimitInputDStream(@transient ssc_ : StreamingContext)
+  extends ReceiverInputDStream[Int](ssc_) {
+
+  override def getReceiver(): DummyReceiver = SingletonDummyReceiver
+
+  def getCurrentRateLimit: Option[Long] = {
+    invokeExecutorMethod.getCurrentRateLimit
+  }
+
+  private def invokeExecutorMethod: ReceiverSupervisor = {
+    val c = classOf[Receiver[_]]
+    val ex = c.getDeclaredMethod("executor")
+    ex.setAccessible(true)
+    ex.invoke(SingletonDummyReceiver).asInstanceOf[ReceiverSupervisor]
+  }
+}
+
+/**
+ * A Receiver as an object so we can read its rate limit.
+ *
+ * @note It's necessary to be a top-level object, or else serialization would create another
+ *       one on the executor side and we won't be able to read its rate limit.
+ */
+private object SingletonDummyReceiver extends DummyReceiver
+
 /**
  * Dummy receiver implementation
  */