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Reorg code that fetches blocks from HDFS #23

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Reorg code that fetches blocks from HDFS #23

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24 changes: 16 additions & 8 deletions streaming/src/main/scala/org/apache/spark/streaming/rdd/HDFSBackedBlockRDD.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -20,10 +20,10 @@ import scala.reflect.ClassTag

import org.apache.hadoop.conf.Configuration

import org.apache.spark._
import org.apache.spark.rdd.BlockRDD
import org.apache.spark.storage.{BlockId, StorageLevel}
import org.apache.spark.streaming.util.{WriteAheadLogFileSegment, HdfsUtils, WriteAheadLogRandomReader}
import org.apache.spark._

private[streaming]
class HDFSBackedBlockRDDPartition(
Expand All @@ -36,7 +36,7 @@ private[streaming]
class HDFSBackedBlockRDD[T: ClassTag](
@transient sc: SparkContext,
@transient hadoopConfiguration: Configuration,
@transient override val blockIds: Array[BlockId],
@transient blockIds: Array[BlockId],
@transient val segments: Array[WriteAheadLogFileSegment],
val storeInBlockManager: Boolean,
val storageLevel: StorageLevel
Expand All @@ -46,7 +46,7 @@ class HDFSBackedBlockRDD[T: ClassTag](
"Number of block ids must be the same as number of segments!")

// Hadoop Configuration is not serializable, so broadcast it as a serializable.
val broadcastedHadoopConf = sc.broadcast(new SerializableWritable(hadoopConfiguration))
private val broadcastedHadoopConf = sc.broadcast(new SerializableWritable(hadoopConfiguration))

override def getPartitions: Array[Partition] = {
assertValid()
Expand Down Expand Up @@ -82,11 +82,19 @@ class HDFSBackedBlockRDD[T: ClassTag](
}

override def getPreferredLocations(split: Partition): Seq[String] = {
/*
* First, look up the block manager to see if the block is available with Spark itself. If
* they are, then return the location of the block. Else find the data nodes where the file
* segment is located on HDFS and use those as the preferred locations.
*/
val partition = split.asInstanceOf[HDFSBackedBlockRDDPartition]
val locations = getBlockIdLocations()
locations.getOrElse(partition.blockId,
HdfsUtils.getBlockLocations(partition.segment.path, partition.segment.offset,
partition.segment.length, hadoopConfiguration)
.getOrElse(new Array[String](0)).toSeq)
getBlockIdLocations().get(partition.blockId) match {
case Some(locations) => locations
case None =>
val segment = partition.segment
HdfsUtils
.getBlockLocations(segment.path, segment.offset, segment.length, hadoopConfiguration)
.getOrElse(Seq.empty)
}
}
}
4 changes: 2 additions & 2 deletions streaming/src/main/scala/org/apache/spark/streaming/util/HdfsUtils.scala
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Expand Up @@ -53,12 +53,12 @@ private[streaming] object HdfsUtils {
}

def getBlockLocations(path: String, offset: Long, length: Long, conf: Configuration):
Option[Array[String]] = {
Option[Seq[String]] = {
val dfsPath = new Path(path)
val dfs = getFileSystemForPath(dfsPath, conf)
val fileStatus = dfs.getFileStatus(dfsPath)
val blockLocs = Option(dfs.getFileBlockLocations(fileStatus, offset, length))
blockLocs.map(_.flatMap(_.getHosts))
blockLocs.map(_.flatMap(_.getHosts).toSeq)
}

def getFileSystemForPath(path: Path, conf: Configuration): FileSystem = {
Expand Down