Github user harishreedharan commented on a diff in the pull request:
https://github.com/apache/spark/pull/2940#discussion_r19510767
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/receiver/ReceivedBlockHandler.scala
---
@@ -0,0 +1,144 @@
+package org.apache.spark.streaming.receiver
+
+import java.nio.ByteBuffer
+
+import scala.collection.mutable.ArrayBuffer
+import scala.concurrent.{Await, ExecutionContext, Future}
+import scala.concurrent.duration._
+import scala.language.{existentials, postfixOps}
+
+import WriteAheadLogBasedBlockHandler._
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.fs.Path
+import org.apache.spark.{SparkException, Logging, SparkConf}
+import org.apache.spark.storage.{BlockManager, StorageLevel, StreamBlockId}
+import org.apache.spark.streaming.util.{Clock, SystemClock,
WriteAheadLogManager}
+import org.apache.spark.util.Utils
+
+private[streaming] sealed trait ReceivedBlock
+private[streaming] case class ArrayBufferBlock(arrayBuffer:
ArrayBuffer[_]) extends ReceivedBlock
+private[streaming] case class IteratorBlock(iterator: Iterator[_]) extends
ReceivedBlock
+private[streaming] case class ByteBufferBlock(byteBuffer: ByteBuffer)
extends ReceivedBlock
+
+
+/** Trait that represents a class that handles the storage of blocks
received by receiver */
+private[streaming] trait ReceivedBlockHandler {
+
+ /** Store a received block with the given block id */
+ def storeBlock(blockId: StreamBlockId, receivedBlock: ReceivedBlock):
Option[AnyRef]
+
+ /** Cleanup old blocks older than the given threshold time */
+ def cleanupOldBlock(threshTime: Long)
+}
+
+/**
+ * Implementation of a
[[org.apache.spark.streaming.receiver.ReceivedBlockHandler]] which
+ * stores the received blocks into a block manager with the specified
storage level.
+ */
+private[streaming] class BlockManagerBasedBlockHandler(
+ blockManager: BlockManager, storageLevel: StorageLevel)
+ extends ReceivedBlockHandler with Logging {
+
+ def storeBlock(blockId: StreamBlockId, receivedBlock: ReceivedBlock):
Option[AnyRef] = {
+ val putResult = receivedBlock match {
+ case ArrayBufferBlock(arrayBuffer) =>
+ blockManager.putIterator(blockId, arrayBuffer.iterator,
storageLevel, tellMaster = true)
+ case IteratorBlock(iterator) =>
+ blockManager.putIterator(blockId, iterator, storageLevel,
tellMaster = true)
+ case ByteBufferBlock(byteBuffer) =>
+ blockManager.putBytes(blockId, byteBuffer, storageLevel,
tellMaster = true)
+ case _ =>
+ throw new SparkException(s"Could not store $blockId to block
manager, unexpected block type")
+ }
+ if (!putResult.map { _._1 }.contains(blockId)) {
+ throw new SparkException(
+ s"Could not store $blockId to block manager with storage level
$storageLevel")
+ }
+ None
+ }
+
+ def cleanupOldBlock(threshTime: Long) {
+ // this is not used as blocks inserted into the BlockManager are
cleared by DStream's clearing
+ // of BlockRDDs.
+ }
+}
+
+/**
+ * Implementation of a
[[org.apache.spark.streaming.receiver.ReceivedBlockHandler]] which
+ * stores the received blocks in both, a write ahead log and a block
manager.
+ */
+private[streaming] class WriteAheadLogBasedBlockHandler(
+ blockManager: BlockManager,
+ streamId: Int,
+ storageLevel: StorageLevel,
+ conf: SparkConf,
+ hadoopConf: Configuration,
+ checkpointDir: String,
+ clock: Clock = new SystemClock
+ ) extends ReceivedBlockHandler with Logging {
+
+ private val blockStoreTimeout = conf.getInt(
+ "spark.streaming.receiver.blockStoreTimeout", 30).seconds
+ private val rollingInterval = conf.getInt(
+ "spark.streaming.receiver.writeAheadLog.rollingInterval", 60)
+ private val maxFailures = conf.getInt(
+ "spark.streaming.receiver.writeAheadLog.maxFailures", 3)
+
+ private val logManager = new WriteAheadLogManager(
+ checkpointDirToLogDir(checkpointDir, streamId),
+ hadoopConf, rollingInterval, maxFailures,
+ callerName = "WriteAheadLogBasedBlockHandler",
+ clock = clock
+ )
+
+ // For processing futures used in parallel block storing into block
manager and write ahead log
+ implicit private val executionContext =
ExecutionContext.fromExecutorService(
+ Utils.newDaemonFixedThreadPool(1, "WriteAheadLogBasedBlockHandler"))
--- End diff --
Shouldn't this be higher? If there are multiple threads receiving data,
storeBlock could end being called from each of these in parallel. At that
point, this would block on threads being available to do the writes correct?
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