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

Author: huitseeker

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

@@ -17,6 +17,8 @@
 
 package org.apache.spark.streaming.receiver
 
+import java.util.concurrent.atomic.AtomicInteger
+
 import com.google.common.util.concurrent.{RateLimiter => GuavaRateLimiter}
 
 import org.apache.spark.{Logging, SparkConf}
@@ -34,12 +36,28 @@ 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.getInt("spark.streaming.receiver.maxRate", 0)
+  private[receiver] var currentRateLimit = new AtomicInteger(maxRateLimit)
+  private lazy val rateLimiter = GuavaRateLimiter.create(currentRateLimit.get())
 
   def waitToPush() {
-    if (desiredRate > 0) {
+    if (currentRateLimit.get() > 0) {
       rateLimiter.acquire()
     }
   }
+
+  private[receiver] def updateRate(newRate: Int): Unit =
+    if (newRate > 0) {
+      try {
+        if (maxRateLimit > 0) {
+          currentRateLimit.set(newRate.min(maxRateLimit))
+        }
+        else {
+          currentRateLimit.set(newRate)
+        }
+      } finally {
+        rateLimiter.setRate(currentRateLimit.get())
+      }
+    }
 }

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/ReceiverSupervisorImpl.scala

@@ -77,6 +77,8 @@ private[streaming] class ReceiverSupervisorImpl(
         case CleanupOldBlocks(threshTime) =>
           logDebug("Received delete old batch signal")
           cleanupOldBlocks(threshTime)
+        case UpdateRateLimit(eps) =>
+          blockGenerator.updateRate(eps.toInt)
       }
     })
 

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 +180,12 @@ class ReceiverTracker(ssc: StreamingContext, skipReceiverLaunch: Boolean = false
     logError(s"Deregistered receiver for stream $streamId: $messageWithError")
   }
 
+  /** Update a receiver's maximum rate from an estimator's update */
+  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)