Small code cleanup for readability

Author: massie

core/src/main/scala/org/apache/spark/shuffle/hash/BlockStoreShuffleFetcher.scala

@@ -51,7 +51,16 @@ private[hash] object BlockStoreShuffleFetcher extends Logging {
         (address, splits.map(s => (ShuffleBlockId(shuffleId, s._1, reduceId), s._2)))
     }
 
-    def unpackBlock(blockPair: (BlockId, Try[InputStream])) : (BlockId, InputStream) = {
+    val blockFetcherItr = new ShuffleBlockFetcherIterator(
+      context,
+      SparkEnv.get.blockManager.shuffleClient,
+      blockManager,
+      blocksByAddress,
+      // Note: we use getSizeAsMb when no suffix is provided for backwards compatibility
+      SparkEnv.get.conf.getSizeAsMb("spark.reducer.maxSizeInFlight", "48m") * 1024 * 1024)
+
+    // Make sure that fetch failures are wrapped inside a FetchFailedException for the scheduler
+    blockFetcherItr.map { blockPair =>
       val blockId = blockPair._1
       val blockOption = blockPair._2
       blockOption match {
@@ -70,15 +79,5 @@ private[hash] object BlockStoreShuffleFetcher extends Logging {
         }
       }
     }
-
-    val blockFetcherItr = new ShuffleBlockFetcherIterator(
-      context,
-      SparkEnv.get.blockManager.shuffleClient,
-      blockManager,
-      blocksByAddress,
-      // Note: we use getSizeAsMb when no suffix is provided for backwards compatibility
-      SparkEnv.get.conf.getSizeAsMb("spark.reducer.maxSizeInFlight", "48m") * 1024 * 1024)
-
-    blockFetcherItr.map(unpackBlock)
   }
 }