Add an optional closure parameter to HadoopRDD instantiation to used when...

Add an optional closure parameter to HadoopRDD instantiation to used when creating any local JobConfs.

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -330,7 +330,7 @@ class SparkContext(
   }
 
   /**
-   * Get an RDD for a Hadoop-readable dataset from a Hadoop JobConf giving its InputFormat and any
+   * Get an RDD for a Hadoop-readable dataset from a Hadoop JobConf given its InputFormat and any
    * other necessary info (e.g. file name for a filesystem-based dataset, table name for HyperTable,
    * etc).
    */
@@ -346,34 +346,49 @@ class SparkContext(
     new HadoopRDD(this, conf, inputFormatClass, keyClass, valueClass, minSplits)
   }
 
-  /** Get an RDD for a Hadoop file with an arbitrary InputFormat */
-  def hadoopFile[K, V](
+  /**
+   * Get an RDD for a Hadoop file with an arbitray InputFormat. Accept a Hadoop Configuration
+   * that has already been broadcast and use it to construct JobConfs local to each process. These
+   * JobConfs will be initialized using an optional, user-specified closure.
+   */
+  def hadoopRDD[K, V](
       path: String,
+      confBroadcast: Broadcast[SerializableWritable[Configuration]],
+      initLocalJobConfOpt: Option[JobConf => Unit],
       inputFormatClass: Class[_ <: InputFormat[K, V]],
       keyClass: Class[K],
       valueClass: Class[V],
-      minSplits: Int = defaultMinSplits
-      ): RDD[(K, V)] = {
-    // A Hadoop configuration can be about 10 KB, which is pretty big, so broadcast it.
-    val confBroadcast = broadcast(new SerializableWritable(hadoopConfiguration))
-    hadoopFile(path, confBroadcast, inputFormatClass, keyClass, valueClass, minSplits)
+      minSplits: Int
+    ): RDD[(K, V)] = {
+    new HadoopRDD(
+      this,
+      confBroadcast,
+      initLocalJobConfOpt,
+      inputFormatClass,
+      keyClass,
+      valueClass,
+      minSplits)
   }
 
-  /**
-   * Get an RDD for a Hadoop file with an arbitray InputFormat. Accept a Hadoop Configuration
-   * that has already been broadcast, assuming that it's safe to use it to construct a
-   * HadoopFileRDD (i.e., except for file 'path', all other configuration properties can be resued).
-   */
+  /** Get an RDD for a Hadoop file with an arbitrary InputFormat */
   def hadoopFile[K, V](
       path: String,
-      confBroadcast: Broadcast[SerializableWritable[Configuration]],
       inputFormatClass: Class[_ <: InputFormat[K, V]],
       keyClass: Class[K],
       valueClass: Class[V],
-      minSplits: Int
+      minSplits: Int = defaultMinSplits
       ): RDD[(K, V)] = {
-    new HadoopFileRDD(
-      this, path, confBroadcast, inputFormatClass, keyClass, valueClass, minSplits)
+    // A Hadoop configuration can be about 10 KB, which is pretty big, so broadcast it.
+    val confBroadcast = broadcast(new SerializableWritable(hadoopConfiguration))
+    val setInputPathsFunc = Some((jobConf: JobConf) => FileInputFormat.setInputPaths(jobConf, path))
+    new HadoopRDD(
+      this,
+      confBroadcast,
+      setInputPathsFunc,
+      inputFormatClass,
+      keyClass,
+      valueClass,
+      minSplits)
   }
 
   /**

core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala

@@ -33,41 +33,6 @@ import org.apache.spark.broadcast.Broadcast
 import org.apache.spark.util.NextIterator
 import org.apache.hadoop.conf.{Configuration, Configurable}
 
-/**
- * An RDD that reads a file (or multiple files) from Hadoop (e.g. files in HDFS, the local file
- * system, or S3).
- * This accepts a general, broadcasted Hadoop Configuration because those tend to remain the same
- * across multiple reads; the 'path' is the only variable that is different across new JobConfs
- * created from the Configuration.
- */
-class HadoopFileRDD[K, V](
-    sc: SparkContext,
-    path: String,
-    broadcastedConf: Broadcast[SerializableWritable[Configuration]],
-    inputFormatClass: Class[_ <: InputFormat[K, V]],
-    keyClass: Class[K],
-    valueClass: Class[V],
-    minSplits: Int)
-  extends HadoopRDD[K, V](sc, broadcastedConf, inputFormatClass, keyClass, valueClass, minSplits) {
-
-  override def getJobConf(): JobConf = {
-    if (HadoopRDD.containsCachedMetadata(jobConfCacheKey)) {
-      // getJobConf() has been called previously, so there is already a local cache of the JobConf
-      // needed by this RDD.
-      return HadoopRDD.getCachedMetadata(jobConfCacheKey).asInstanceOf[JobConf]
-    } else {
-      // Create a new JobConf, set the input file/directory paths to read from, and cache the
-      // JobConf (i.e., in a shared hash map in the slave's JVM process that's accessible through
-      // HadoopRDD.putCachedMetadata()), so that we only create one copy across multiple
-      // getJobConf() calls for this RDD in the local process.
-      // The caching helps minimize GC, since a JobConf can contain ~10KB of temporary objects.
-      val newJobConf = new JobConf(broadcastedConf.value.value)
-      FileInputFormat.setInputPaths(newJobConf, path)
-      HadoopRDD.putCachedMetadata(jobConfCacheKey, newJobConf)
-      return newJobConf
-    }
-  }
-}
 
 /**
  * A Spark split class that wraps around a Hadoop InputSplit.
@@ -83,11 +48,24 @@ private[spark] class HadoopPartition(rddId: Int, idx: Int, @transient s: InputSp
 }
 
 /**
- * A base class that provides core functionality for reading data partitions stored in Hadoop.
+ * An RDD that provides core functionality for reading data stored in Hadoop (e.g., files in HDFS,
+ * sources in HBase, or S3).
+ *
+ * @param sc The SparkContext to associate the RDD with.
+ * @param broadCastedConf A general Hadoop Configuration, or a subclass of it. If the enclosed
+ *     variabe references an instance of JobConf, then that JobConf will be used for the Hadoop job.
+ *     Otherwise, a new JobConf will be created on each slave using the enclosed Configuration.
+ * @param initLocalJobConfFuncOpt Optional closure used to initialize any JobCOnf that HadoopRDD
+ *     creates.
+ * @param inputFormatClass Storage format of the data to be read.
+ * @param keyClass Class of the key associated with the inputFormatClass.
+ * @param valueClass Class of the value associated with the inputFormatClass.
+ * @param minSplits Minimum number of Hadoop Splits (HadoopRDD partitions) to generate.
  */
 class HadoopRDD[K, V](
     sc: SparkContext,
     broadcastedConf: Broadcast[SerializableWritable[Configuration]],
+    initLocalJobConfFuncOpt: Option[JobConf => Unit],
     inputFormatClass: Class[_ <: InputFormat[K, V]],
     keyClass: Class[K],
     valueClass: Class[V],
@@ -105,6 +83,7 @@ class HadoopRDD[K, V](
       sc,
       sc.broadcast(new SerializableWritable(conf))
         .asInstanceOf[Broadcast[SerializableWritable[Configuration]]],
+      None /* initLocalJobConfFuncOpt */,
       inputFormatClass,
       keyClass,
       valueClass,
@@ -130,6 +109,7 @@ class HadoopRDD[K, V](
       // local process. The local cache is accessed through HadoopRDD.putCachedMetadata().
       // The caching helps minimize GC, since a JobConf can contain ~10KB of temporary objects.
       val newJobConf = new JobConf(broadcastedConf.value.value)
+      initLocalJobConfFuncOpt.map(f => f(newJobConf))
       HadoopRDD.putCachedMetadata(jobConfCacheKey, newJobConf)
       return newJobConf
     }