[SPARK-4080] Only throw IOException from [write|read][Object|External]

If classes implementing Serializable or Externalizable interfaces throw
exceptions other than IOException or ClassNotFoundException from their
(de)serialization methods, then this results in an unhelpful
"IOException: unexpected exception type" rather than the actual exception that
produced the (de)serialization error.

This patch fixes this by adding a utility method that re-wraps any uncaught
exceptions in IOException (unless they are already instances of IOException).

Author: Josh Rosen <joshrosen@databricks.com>

Closes #2932 from JoshRosen/SPARK-4080 and squashes the following commits:

cd3a9be [Josh Rosen] [SPARK-4080] Only throw IOException from [write|read][Object|External].

1 files changed, 2 insertions, 2 deletions

diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
index 4b2ea45fb8..2de2a7926b 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
@@ -66,7 +66,7 @@ class SparkFlumeEvent() extends Externalizable {
   var event : AvroFlumeEvent = new AvroFlumeEvent()
 
   /* De-serialize from bytes. */
-  def readExternal(in: ObjectInput) {
+  def readExternal(in: ObjectInput): Unit = Utils.tryOrIOException {
     val bodyLength = in.readInt()
     val bodyBuff = new Array[Byte](bodyLength)
     in.readFully(bodyBuff)
@@ -93,7 +93,7 @@ class SparkFlumeEvent() extends Externalizable {
   }
 
   /* Serialize to bytes. */
-  def writeExternal(out: ObjectOutput) {
+  def writeExternal(out: ObjectOutput): Unit = Utils.tryOrIOException {
     val body = event.getBody.array()
     out.writeInt(body.length)
     out.write(body)